%% Papers Published
@article{fds335053,
Author = {Suthakar, U and Magnoni, L and Smith, DR and Khan,
A},
Title = {Optimised Lambda Architecture for Monitoring Scientific
Infrastructure},
Journal = {IEEE Transactions on Parallel and Distributed
Systems},
Volume = {32},
Number = {6},
Pages = {1395-1408},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2021},
Month = {June},
url = {http://dx.doi.org/10.1109/TPDS.2017.2772241},
Abstract = {Within scientific infrastructuscientists execute millions of
computational jobs daily, resulting in the movement of
petabytes of data over the heterogeneous infrastructure.
Monitoring the computing and user activities over such a
complex infrastructure is incredibly demanding. Whereas
present solutions are traditionally based on a Relational
Database Management System (RDBMS) for data storage and
processing, recent developments evaluate the Lambda
Architecture (LA). In particular these studies have
evaluated data storage and batch processing for processing
large-scale monitoring datasets using Hadoop and its
MapReduce framework. Although LA performed better than the
RDBMS following evaluation, it was fairly complex to
implement and maintain. This paper presents an Optimised
Lambda Architecture (OLA) using the Apache Spark ecosystem,
which involves modelling an efficient way of joining batch
computation and real-time computation transparently without
the need to add complexity. A few models were explored: pure
streaming, pure batch computation, and the combination of
both batch and streaming. An evaluation of the OLA on the
CERN IT on-premises Hadoop cluster and the public Amazon
cloud infrastructure for the monitoring WLCG Data acTivities
(WDT) use case are both presented, demonstrating how the new
architecture can offer benefits by combining both batch and
real-time processing to compensate for batch-processing
latency.},
Doi = {10.1109/TPDS.2017.2772241},
Key = {fds335053}
}
@article{fds345912,
Author = {Fern, GR and Hobson, PR and Metcalfe, A and Smith,
DR},
Title = {Performance of four CVD diamond radiation sensors at high
temperature},
Journal = {Nuclear Instruments and Methods in Physics Research, Section
A: Accelerators, Spectrometers, Detectors and Associated
Equipment},
Volume = {958},
Year = {2020},
Month = {April},
url = {http://dx.doi.org/10.1016/j.nima.2019.162486},
Abstract = {Ionising radiation detectors based on wide band-gap
materials have the potential to operate at temperatures
higher than 200°C. Such detectors are important in
applications such as monitoring near nuclear reactors and in
deep oil and gas well borehole logging. We discuss the
development of alpha particle detectors, based on CVD
diamond, which operate with high charge collection
efficiency and energy resolution at temperatures up to
225°C. Four nominally identical commercial, electronic
grade, CVD diamonds have been coated with a thin metal
conductive layer in our laboratory and then attached to
ceramic PCB. We present the I–V characteristics, the
charge collection efficiency and the energy resolution for
alpha particles from a mixed 239Pu,241Am,244Cm source, for
the four sensors operating at temperatures from 20 to
250°C. Monte Carlo simulations of the energy spectra and
charge collection efficiency and experimental measurements
of these are presented. Energy resolutions between 1.6% and
4.0% at elevated temperatures with charge collection
efficiency exceeding 96% were measured. The potential for
thermal neutron detection is discussed.},
Doi = {10.1016/j.nima.2019.162486},
Key = {fds345912}
}
@article{fds347047,
Author = {Ruiz, JR and Guttenfelder, W and White, AE and Howard, NT and Candy, J and Ren, Y and Smith, DR and Loureiro, NF and Holland, C and Domier,
CW},
Title = {Validation of gyrokinetic simulations of a National
Spherical Torus eXperiment H-mode plasma and comparisons
with a high-k scattering synthetic diagnostic},
Journal = {Plasma Physics and Controlled Fusion},
Volume = {61},
Number = {11},
Year = {2019},
Month = {October},
url = {http://dx.doi.org/10.1088/1361-6587/ab4742},
Abstract = {A new extensive validation study performed for a modest-beta
National Spherical Torus eXperiment (NSTX) neutral beam
injection-heated H-mode discharge predicts that electron
thermal transport can be entirely explained by
short-wavelength electron-scale turbulence fluctuations
driven by the electron temperature gradient mode (ETG), both
in conditions of strong and weak ETG turbulence drive.
Quantitative comparisons between high-k fluctuation
measurements (Smith et al 2008 Rev. Sci. Instrum. 79 123501)
and simulations are performed via a novel synthetic high-k
diagnostic. Computationally intensive electron-scale
simulations featuring an unusually large domain (L r, L θ)
∼ (20, 20)ρ s are shown to be required for accurate
deployment of the synthetic diagnostic. Ion thermal
transport is shown to be close to neoclassical levels,
consistent with stable ion-scale turbulence simulations
conducted with the GYRO code (Candy and Waltz 2003 J.
Comput. Phys. 186 545). Electron-scale GYRO simulations are
shown to match the thermal power-balance estimates from
TRANSP. The frequency spectra characteristics of
electron-scale turbulence (spectral peak and width) can be
consistently reproduced by the synthetic spectra, but these
reveal not to be a critical constraint on the simulation
model. The shape of the high-k wavenumber spectrum and the
fluctuation level ratio between the strong and weak ETG
conditions can also be simultaneously matched by
electron-scale simulations within sensitivity scans about
the experimental profile values, and result to be great
discriminators of the turbulence models analyzed. Together,
electron thermal power comparisons and quantitative
agreement of electron-scale turbulence spectra give strong
evidence supporting electron-scale ETG fluctuations as the
main mechanism driving anomalous electron thermal transport
in the two outer-core conditions of the modest-beta NSTX
H-mode analyzed.},
Doi = {10.1088/1361-6587/ab4742},
Key = {fds347047}
}
@article{fds349393,
Author = {Hobson, PR and Smith, DR},
Title = {A portable test-bench for real-time radiation damage
measurements in scintillating and wavelength-shifting
fibres},
Journal = {2019 IEEE Nuclear Science Symposium and Medical Imaging
Conference, NSS/MIC 2019},
Year = {2019},
Month = {October},
ISBN = {9781728141640},
url = {http://dx.doi.org/10.1109/NSS/MIC42101.2019.9059764},
Abstract = {A portable test-bench has been developed to enable the
real-time measurement of radiation-induced absorption in
scintillating and wavelength-shifting fibres. Such fibres
are typically used in the readout of fibre calorimeters or
scintillating tiles such as those used in some hadron
calorimeters. The testbench has been designed to be used in
a range of facilities, such as 60Co irradiators or
high-intensity test beam facilities, and can accommodate
fibres with length up to 300 mm and diameter greater than
1.0 mm. The test fibres are illuminated using a combined
deuterium and halogen light source focussed onto the end of
the fibre with a 0.25 NA radiation-tolerant quartz lens. The
light transmitted by the fibre is collected by an identical
lens and measured as a function of wavelength with a linear
charge-coupled device spectrometer covering a wavelength
range of 190 to 850 nm. We present the design of the
test-bench, and studies of the systematic errors arising
from the components. We measured induced absorbance in the
fibres tested and determined the major systematic error to
be the stability of the light source. Planned enhancements
to the test-bench are discussed.},
Doi = {10.1109/NSS/MIC42101.2019.9059764},
Key = {fds349393}
}
@article{fds346473,
Author = {Ren, Y and Smith, DR and Zweben, SJ and Bell, R and Guttenfelder, W and Kaye, SM and Leblanc, BP and Mazzucato, E and Lee, KC and Domier, CW and Sun, PJ and Yuh, H},
Title = {Experimental observation of electron-scale turbulence
evolution across the L-H transition in the National
Spherical Torus Experiment},
Journal = {Nuclear Fusion},
Volume = {59},
Number = {9},
Year = {2019},
Month = {August},
url = {http://dx.doi.org/10.1088/1741-4326/ab2f4f},
Abstract = {Electron-scale turbulence (for 3 k s12) was measured during
the L-H transition in the National Spherical Torus
Experiment (NSTX) (Ono et al 2000 Nucl. Fusion 40 557) using
a coherent microwave scattering system. The measurements
were carried out at a radial region adjacent to the edge
transport barrier (ETB) (at smaller radius than ETB). The
observed L-H transition occurred during current flattop,
which facilitated the measurement of electronscale
turbulence. The measured electron-scale turbulence is
observed to be quasi-stationary before the L-H transition,
and an intermittent phase for electron-scale turbulence is
observed after the start of the L-H transition with a
gradual decrease in overall turbulence density fluctuation
spectral power with intermittent large relative variations
(on ~0.5-1 ms time scale) in the total spectral power. A
turbulence-quiescent phase is observed following the
intermittent phase, and a significant reduction in the
electron-scale turbulence spectral power is only observed at
lower wavenumbers, namely ks9-10, which is also seen in
different operational NSTX scenarios due to different
stabilization mechanisms. A recovery phase is seen after the
quiescent phase, where the electron-scale density
fluctuation power starts to gradually increase. Simultaneous
ion-scale turbulence measurements at larger radius than the
electron-scale turbulence measurement location show similar
temporal behavior in ion-scale turbulence as in the measured
electron-scale turbulence. These observations demonstrate
that the suppression of turbulence during the L-H transition
is not just limited to the ETB region. None of the measured
electron-scale turbulence and ion-scale turbulence from edge
into core is found to be obviously leading in the response
to the L-H transition, and the overall turbulence
suppression after the start of the L-H transition at
different radii seems to start at the same time and is a
gradual process happening on a tens-of-ms time scale. The
trend of decrease in electron-scale turbulence during the
L-H transition is found to be consistent with a decrease in
the maximum electron erature-gradient linear growth rate
from linear gyrokinetic stability analysis. However, the
observed intermittency in electron-scale turbulence during
the intermittent phase cannot be explained by the linear
analysis.},
Doi = {10.1088/1741-4326/ab2f4f},
Key = {fds346473}
}
@article{fds346628,
Author = {Kaye, SM and Battaglia, DJ and Baver, D and Belova, E and Berkery, JW and Duarte, VN and Ferraro, N and Fredrickson, E and Gorelenkov, N and Guttenfelder, W and Hao, GZ and Heidbrink, W and Izacard, O and Kim, D and Krebs, I and La Haye and R and Lestz, J and Liu, D and Morton, LA and Myra, J and Pfefferle, D and Podesta, M and Ren, Y and Riquezes, J and Sabbagh, SA and Schneller, M and Scotti, F and Soukhanovskii, V and Zweben, SJ and Ahn,
JW and Allain, JP and Barchfeld, R and Bedoya, F and Bell, RE and Bertelli,
N and Bhattacharjee, A and Boyer, MD and Brennan, D and Canal, G and Canik,
J and Crocker, N and Darrow, D and Delgado-Aparicio, L and Diallo, A and Domier, C and Ebrahimi, F and Evans, T and Fonck, R and Frerichs, H and Gan, K and Gerhardt, S and Gray, T and Jarboe, T and Jardin, S and Jaworski, MA and Kaita, R and Koel, B and Kolemen, E and Kriete, DM and Kubota, S and Leblanc, BP and Levinton, F and Luhmann, N and Lunsford,
R and Maingi, R and Maqueda, R and Menard, JE and Mueller, D and Myers, CE and Ono, M and Park, JK and Perkins, R and Poli, F and Raman, R and Reinke, M and Rhodes, T and Rowley, C and Russell, D and Schuster, E and Schmitz, O and Sechrest, Y and Skinner, CH and Smith, DR and Stotzfus-Dueck, T and Stratton, B and Taylor, G and Tritz, K and Wang, W and Wang, Z and Waters,
I and Wirth, B},
Title = {NSTX/NSTX-U theory, modeling and analysis
results},
Journal = {Nuclear Fusion},
Volume = {59},
Number = {11},
Year = {2019},
Month = {June},
url = {http://dx.doi.org/10.1088/1741-4326/ab023a},
Abstract = {The mission of the spherical tokamak NSTX-U is to explore
the physics that drives core and pedestal transport and
stability at high-β and low collisionality, as part of the
development of the spherical tokamak (ST) concept towards a
compact, low-cost ST-based pilot plant. NSTX-U will
ultimately operate at up to 2 MA and 1 T with up to 12 MW of
neutral beam injection power for 5 s. NSTX-U will operate in
a regime where electromagnetic instabilities are expected to
dominate transport, and beam-heated NSTX-U plasmas will
explore a portion of energetic particle parameter space that
is relevant for both _-heated conventional and low aspect
ratio burning plasmas. NSTX-U will also develop the physics
understanding and control tools to ramp-up and sustain high
performance plasmas in a fullynoninductive fashion. NSTX-U
began research operations in 2016, but a failure of a
divertor magnetic field coil after ten weeks of operation
resulted in the suspension of operations and initiation of
recovery activities. During this period, there has been
considerable work in the area of analysis, theory and
modeling of data from both NSTX and NSTX-U, with a goal of
understanding the underlying physics to develop predictive
models that can be used for high-confidence projections for
both ST and higher aspect ratio regimes. These studies have
addressed issues in thermal plasma transport,
macrostability, energetic particlet-driven instabilities at
ion-cyclotron frequencies and below, and edge and divertor
physics.},
Doi = {10.1088/1741-4326/ab023a},
Key = {fds346628}
}
@article{fds342179,
Author = {Everitt, HO and Tyler, T and Caraway, BD and Bingham, CM and Llopis, A and Heimbeck, MS and Padilla, WJ and Smith, DR and Jokerst,
NM},
Title = {Strain Sensing with Metamaterial Composites},
Journal = {Advanced Optical Materials},
Volume = {7},
Number = {9},
Year = {2019},
Month = {May},
url = {http://dx.doi.org/10.1002/adom.201801397},
Abstract = {Mapping strain fields in visually opaque structural
composites—for which failure is often sudden, irreparable,
and even catastrophic—requires techniques to locate and
record regions of stress, fatigue, and incipient failure.
Many composite materials are transparent in the terahertz
spectral region, but their strain history is often too
subtle to recover. Here, terahertz metamaterials with
strain-severable junctions are introduced that can identify
structurally compromised regions of composite materials.
Specifically, multilayer arrays of aluminum meta-atoms are
designed and fabricated as strip dipole antennas with a
terahertz frequency resonance and a strong response to
cross-polarized radiation that disappears when local stress
irreversibly breaks their bowtie-shaped junction. By
spatially mapping the local polarimetric response of this
metamaterial as a function of global strain, the regions of
local stress extrema experienced by a visually opaque
material may be visualized. This proof-of-concept
demonstration heralds the opportunity for embedding
metamaterial laminates within composites to record and
recover their strain-dependent history of
fatigue.},
Doi = {10.1002/adom.201801397},
Key = {fds342179}
}
@article{fds342177,
Author = {Diebold, AV and Imani, MF and Smith, DR},
Title = {Phaseless radar coincidence imaging with a MIMO SAR
platform},
Journal = {Remote Sensing},
Volume = {11},
Number = {5},
Year = {2019},
Month = {March},
url = {http://dx.doi.org/10.3390/rs11050533},
Abstract = {The correlation-based synthetic aperture radar imaging
technique, termed radar coincidence imaging, is extended to
a fully multistatic multiple-input multiple-output (MIMO)
synthetic aperture radar (SAR) configuration. Within this
framework, we explore two distinct processing schemes:
incoherent processing of intensity data, obtained using
asynchronous receivers and inspired by optical ghost imaging
works, and coherent processing with synchronized array
elements. Improvement in resolution and image quality is
demonstrated in both cases using numerical simulations that
model an airborne MIMO SAR system at microwave frequencies.
Finally, we explore methods for reducing measurement times
and computational loads through compressive and gradient
image reconstruction using phaseless data.},
Doi = {10.3390/rs11050533},
Key = {fds342177}
}
@article{fds342178,
Author = {Zecca, R and Marks, DL and Smith, DR},
Title = {Variational design method for dipole-based volumetric
artificial media.},
Journal = {Optics express},
Volume = {27},
Number = {5},
Pages = {6512-6527},
Year = {2019},
Month = {March},
url = {http://dx.doi.org/10.1364/oe.27.006512},
Abstract = {A fundamental challenge has plagued computer-generated
volumetric holography since its inception: design methods
are available only in the perturbative limit, but this poses
serious limitations on efficiency and the amount of
multiplexing achievable. Given the recent progress in highly
tailorable artificial media, such as metamaterials, the need
for general and robust design techniques grows. We present a
method based on the electromagnetic variational principle
that applies to media that can be described as collections
of point dipoles, as most metamaterials are. We demonstrate
its efficacy by designing highly efficient,
non-perturbative, multiplexing devices.},
Doi = {10.1364/oe.27.006512},
Key = {fds342178}
}
@article{fds342386,
Author = {Huang, Z and Marks, DL and Smith, DR},
Title = {Out-of-plane computer-generated multicolor waveguide
holography},
Journal = {Optica},
Volume = {6},
Number = {2},
Pages = {119-124},
Year = {2019},
Month = {February},
url = {http://dx.doi.org/10.1364/OPTICA.6.000119},
Abstract = {Multicolor waveguide holography remains a challenge due to
its inherent design complexity, compounded by the limited
low-loss materials available in the optical range as well as
challenges in nanofabrication. In this study, we first
propose and experimentally demonstrate a multicolor,
computer-generated hologram (CGH) in an all-dielectric
waveguide metasurface system. Light beams from three
different color laser sources (red, green, and blue) are
coupled into the waveguide via a single-period grating
without any beam splitters or prisms. A multicolor
holographic image can be decoupled in the far field through
a binary metasurface CGH without any lenses. This technology
enables lensfree, ultraminiature augmented and virtual
reality displays.},
Doi = {10.1364/OPTICA.6.000119},
Key = {fds342386}
}
@article{fds349690,
Author = {Al-Karakchi, AAA and Nashad, FE and Putrus, G and Foti, S and Smith, D and Elsdon, M},
Title = {Cost-effective Integration System of Solar Cell Powered
Remote Small-Size Wireless Communication},
Journal = {2nd International Conference on Electrical, Communication,
Computer, Power and Control Engineering, ICECCPCE
2019},
Pages = {19-22},
Year = {2019},
Month = {February},
ISBN = {9781728107813},
url = {http://dx.doi.org/10.1109/ICECCPCE46549.2019.203741},
Abstract = {in this paper, a cost-effective design technique of a
combined photovoltaic solar system, with electrical energy
storage (ESS) for remote areas wireless long-term
communication integration system is presented and discussed.
Solar systems are the only possible solutions for supplying
the required power to the communication infrastructure, i.e.
antennas, in remote areas with no access to the electricity
grid. However, due to the intermittency of solar power
production support from ESS is required. As such, in periods
of solar generation excess, the ESS is charged with the
extra energy, whereas, in periods of solar generation
scarcity the ESS is discharged to provide the load. The
sizing of the overall solar-ESS system should be carefully
carried out, by considering important aspects, such as
installation and maintenance costs, operational requirements
and related constraints, i.e. desired level of reliability
and efficiency. The proposed cost-effective integration
strategy is designed for Microwave antennas, such as Ku-band
and Ku-band satellite communications (SATCOM), and this will
consider the optimal sizing of the ESS in combination with
the solar system in order to minimize investment and
operational costs, while ensuring a continuous and efficient
operation of the antenna.},
Doi = {10.1109/ICECCPCE46549.2019.203741},
Key = {fds349690}
}
@article{fds339601,
Author = {Yoo, I and Imani, MF and Sleasman, T and Pfister, HD and Smith,
DR},
Title = {Enhancing Capacity of Spatial Multiplexing Systems Using
Reconfigurable Cavity-Backed Metasurface Antennas in
Clustered MIMO Channels},
Journal = {IEEE Transactions on Communications},
Volume = {67},
Number = {2},
Pages = {1070-1084},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2019},
Month = {February},
url = {http://dx.doi.org/10.1109/TCOMM.2018.2876899},
Abstract = {We propose a spatial multiplexing system using
reconfigurable cavity-backed metasurface antennas. The
metasurface antennas consist of a printed cavity with
dynamically tunable metamaterial radiators patterned on one
side and fed by multiple radio frequency ports on the other
side (each port representing one communication node),
forming a shared aperture. By individual tuning of the
radiators, the antennas can generate steerable, concurrent
beams that can be adapted to the properties of
multiple-input-multiple-output (MIMO) channels. In this
paper, we present a 2 × 2 MIMO system with simulated
metasurface antennas as transmit and receive antennas
operating at 5.9 GHz. We demonstrate that the flexibility in
beamforming supported by the metasurface antennas can be
used to achieve low spatial correlation and high SNR gain in
clustered MIMO channels, leading to a significant
improvement of the channel capacity. Numerical studies show
2.36-fold, 2.11-fold enhancements of capacity in MIMO
channels with one and two clusters, respectively, compared
with an MIMO system consisting of linear dipoles. The MIMO
system based on the metasurface antennas can be low cost,
low profile, and low power. The metasurface antenna thus has
potential applications in small cell networks requiring high
data rate under bandwidth, energy, and cost
constraints.},
Doi = {10.1109/TCOMM.2018.2876899},
Key = {fds339601}
}
@article{fds340524,
Author = {Diebold, AV and Imani, MF and Sleasmanand, T and Smith,
DR},
Title = {Phaseless coherent and incoherent microwave ghost imaging
with dynamic metasurface apertures},
Journal = {Optica},
Volume = {5},
Number = {12},
Pages = {1529-1541},
Publisher = {The Optical Society},
Year = {2018},
Month = {December},
url = {http://dx.doi.org/10.1364/OPTICA.5.001529},
Abstract = {Phase information and spatially coherent illumination have
usually been considered indispensable components of most
microwave imaging systems. Dynamic metasurface apertures
(DMAs)—with their ability to generate spatially incoherent
illumination—have recently supplanted these assumptions in
favor of simplified imaging hardware. In light of this
development, we investigate the coherence of a phaseless
imaging system based on metasurface apertures. In doing so,
we propose and experimentally demonstrate coherent and
incoherent computational microwave ghost imaging using DMAs.
These apertures can generate a multitude of distinct speckle
fields at a single frequency by modulating the electrical
properties of radiating complementary metamaterial elements
patterned into the surface of a waveguide. We show that a
pair of dynamic apertures, one acting as transmit and the
other as receive, can achieve two-dimensional, phaseless,
coherent imaging. Further, by averaging the intensity
measurements obtained in this manner over a random set or
ensemble of receive aperture distributions, we demonstrate
that an incoherent imaging system can be achieved in which
single-port ensemble averaging by the electrically large DMA
plays the role of spatial averaging in a bucket detector. We
investigate the effects of these different imaging schemes
on the resulting reconstructions and provide experimental
demonstrations.},
Doi = {10.1364/OPTICA.5.001529},
Key = {fds340524}
}
@article{fds339664,
Author = {Marks, DL and Smith, DR},
Title = {Motion compensation of the transmitter and receiver in
bistatic frequency-modulated continuous-wave synthetic
aperture radar},
Journal = {IET Radar, Sonar and Navigation},
Volume = {12},
Number = {11},
Pages = {1336-1345},
Publisher = {Institution of Engineering and Technology
(IET)},
Year = {2018},
Month = {November},
url = {http://dx.doi.org/10.1049/iet-rsn.2018.5051},
Abstract = {Synthetic aperture radar (SAR) imaging with an independently
moving transmitter and receiver introduces motion artefacts
difficult to compensate for, especially between satellites
in separate orbits that rendezvous over a target. A solution
for polarisation-resolved bistatic frequency-modulated
continuous-wave (FMCW) SAR with independently moving
platforms is derived and demonstrated through simulation.
This solution accounts for the polarisation of the source,
susceptibility tensor of the target, and the velocity and
acceleration of the transmitter and receiver. The accuracy
of the solution is demonstrated by reconstructing simulated
point ground targets with a pair of X-band SAR satellites of
realistic parameters.},
Doi = {10.1049/iet-rsn.2018.5051},
Key = {fds339664}
}
@article{fds338565,
Author = {Liu, X and Jia, X and Fischer, M and Huang, Z and Smith,
DR},
Title = {Enhanced Two-Photon Photochromism in Metasurface Perfect
Absorbers},
Journal = {Nano Letters},
Volume = {18},
Number = {10},
Pages = {6181-6187},
Publisher = {American Chemical Society (ACS)},
Year = {2018},
Month = {October},
url = {http://dx.doi.org/10.1021/acs.nanolett.8b02042},
Abstract = {Light switchable materials are essential to optoelectronic
applications in photovoltaics, memories, sensors, and
communications. Natural switchable materials suffer from
weak absorption and slow response times, preventing their
use in low-power, ultrafast applications. Integrating light
switchable materials with metasurface perfect absorbers
offers an innovative route to achieving desirable features
for nanophotonic devices, such as directional emission,
low-power and broadband operation, high radiative quantum
efficiency, and large spontaneous emission rates. Here we
show an enhanced two-photon photochromism based on a
metasurface perfect absorber: film-coupled colloidal silver
nanocubes. The photochromic molecules, spiropyrans, are
sandwiched between the silver nanocubes and the gold
substrate. With nearly 100% absorption and an accompanying
large field enhancement in the molecular junction, the
transformation of spiropyrans to merocyanines is observed
under excitation with 792 nm laser light. Fluorescence
lifetime measurements on the merocyanine form reveal that
large Purcell enhancement in the film-coupled nanocubes
leads to large enhancements of the spontaneous emission rate
and a high quantum efficiency. An averaged incident power as
low as 10 μW is enough to initiate the two-photon
isomerization of spiropyran in the film-coupled nanocubes,
and a power of 100nW is able to excite the merocyanines to
emit fluorescence. The power consumption is orders of
magnitude lower than bare spiropyran thin films on silicon
and gold, which is highly desirable for the writing and
reading processes relevant to optical data storage. By
sweeping the plasmonic resonance of the film-coupled
nanocubes, wavelength specificity is demonstrated, which
opens up new possibilities for minimizing the cross talk
between adjacent bits in nanophotonic devices.},
Doi = {10.1021/acs.nanolett.8b02042},
Key = {fds338565}
}
@article{fds338067,
Author = {Kriete, DM and McKee, GR and Fonck, RJ and Smith, DR and Whelan, GG and Yan, Z},
Title = {Extracting the turbulent flow-field from beam emission
spectroscopy images using velocimetry.},
Journal = {The Review of scientific instruments},
Volume = {89},
Number = {10},
Pages = {10E107},
Year = {2018},
Month = {October},
url = {http://dx.doi.org/10.1063/1.5036535},
Abstract = {The 2D turbulent <i>E</i> × <i>B</i> flow-field is inferred
from density fluctuation images obtained with the beam
emission spectroscopy diagnostic on DIII-D using the
orthogonal dynamic programming velocimetry algorithm. A
synthetic turbulence model is used to test the algorithm and
optimize it for measuring zonal flows. Zonal flow
measurements are found to require a signal-to-noise ratio
above ∼10 and a zonal flow wavelength longer than ∼2 cm.
Comparison between the velocimetry-estimated flow-field and
the <i>E</i> × <i>B</i> flow-field using a nonlinear
gyrokinetic GENE simulation finds that the flow-fields have
identical spatial structure and differ only by the mean
turbulence phase velocity, which is spatially uniform in
this flux tube simulation.},
Doi = {10.1063/1.5036535},
Key = {fds338067}
}
@article{fds337399,
Author = {Del Hougne and P and Imani, MF and Fink, M and Smith, DR and Lerosey,
G},
Title = {Precise Localization of Multiple Noncooperative Objects in a
Disordered Cavity by Wave Front Shaping.},
Journal = {Physical review letters},
Volume = {121},
Number = {6},
Pages = {063901},
Year = {2018},
Month = {August},
url = {http://dx.doi.org/10.1103/physrevlett.121.063901},
Abstract = {Complicated multipath trajectories of waves in disordered
cavities cause object localization to be very challenging
with traditional ray-tracing approaches. Yet it is known
that information about the object position is encoded in the
Green's function. After a calibration step, traditional
time-reversal approaches retrieve a source's location from a
broadband impulse response measurement. Here, we show that a
nonemitting object's scattering contribution to a
reverberant medium suffices to localize the object. We
demonstrate our finding in the microwave domain. Then, we
further simplify the scheme by replacing the temporal
degrees of freedom (d.o.f.) of the broadband measurement
with spatial d.o.f. obtained from wave front shaping. A
simple electronically reconfigurable reflectarray inside the
cavity dynamically modulates parts of the cavity boundaries,
thereby providing spatial d.o.f. The demonstrated ability to
localize multiple noncooperative objects with a
single-frequency scheme may have important applications for
sensors in smart homes.},
Doi = {10.1103/physrevlett.121.063901},
Key = {fds337399}
}
@article{fds335048,
Author = {Boyarsky, M and Sleasman, T and Pulido-Mancera, L and Diebold, AV and Imani, MF and Smith, DR},
Title = {Single-frequency 3D synthetic aperture imaging with dynamic
metasurface antennas.},
Journal = {Applied optics},
Volume = {57},
Number = {15},
Pages = {4123-4134},
Year = {2018},
Month = {May},
url = {http://dx.doi.org/10.1364/ao.57.004123},
Abstract = {Through aperture synthesis, an electrically small antenna
can be used to form a high-resolution imaging system capable
of reconstructing three-dimensional (3D) scenes. However,
the large spectral bandwidth typically required in synthetic
aperture radar systems to resolve objects in range often
requires costly and complex RF components. We present here
an alternative approach based on a hybrid imaging system
that combines a dynamically reconfigurable aperture with
synthetic aperture techniques, demonstrating the capability
to resolve objects in three dimensions (3D), with
measurements taken at a single frequency. At the core of our
imaging system are two metasurface apertures, both of which
consist of a linear array of metamaterial irises that couple
to a common waveguide feed. Each metamaterial iris has
integrated within it a diode that can be biased so as to
switch the element on (radiating) or off (non-radiating),
such that the metasurface antenna can produce distinct
radiation profiles corresponding to different on/off
patterns of the metamaterial element array. The electrically
large size of the metasurface apertures enables resolution
in range and one cross-range dimension, while aperture
synthesis provides resolution in the other cross-range
dimension. The demonstrated imaging capabilities of this
system represent a step forward in the development of
low-cost, high-performance 3D microwave imaging
systems.},
Doi = {10.1364/ao.57.004123},
Key = {fds335048}
}
@article{fds335049,
Author = {Del Hougne and P and F Imani and M and Sleasman, T and Gollub, JN and Fink, M and Lerosey, G and Smith, DR},
Title = {Dynamic Metasurface Aperture as Smart Around-the-Corner
Motion Detector.},
Journal = {Scientific reports},
Volume = {8},
Number = {1},
Pages = {6536},
Year = {2018},
Month = {April},
url = {http://dx.doi.org/10.1038/s41598-018-24681-9},
Abstract = {Detecting and analysing motion is a key feature of Smart
Homes and the connected sensor vision they embrace. At
present, most motion sensors operate in line-of-sight
Doppler shift schemes. Here, we propose an alternative
approach suitable for indoor environments, which effectively
constitute disordered cavities for radio frequency (RF)
waves; we exploit the fundamental sensitivity of modes of
such cavities to perturbations, caused here by moving
objects. We establish experimentally three key features of
our proposed system: (i) ability to capture the temporal
variations of motion and discern information such as
periodicity ("smart"), (ii) non line-of-sight motion
detection, and (iii) single-frequency operation. Moreover,
we explain theoretically and demonstrate experimentally that
the use of dynamic metasurface apertures can substantially
enhance the performance of RF motion detection. Potential
applications include accurately detecting human presence and
monitoring inhabitants' vital signs.},
Doi = {10.1038/s41598-018-24681-9},
Key = {fds335049}
}
@article{fds335050,
Author = {Marks, DL and Smith, DR},
Title = {Linear solutions to metamaterial volume hologram design
using a variational approach.},
Journal = {Journal of the Optical Society of America. A, Optics, image
science, and vision},
Volume = {35},
Number = {4},
Pages = {567-576},
Publisher = {The Optical Society},
Year = {2018},
Month = {April},
url = {http://dx.doi.org/10.1364/josaa.35.000567},
Abstract = {Multiplex volume holograms are conventionally constructed by
the repeated exposure of a photosensitive medium to a
sequence of external fields, each field typically being the
superposition of a reference wave that reconstructs the
hologram and the other being a desired signal wave. Because
there are no sources of radiation internal to the hologram,
the pattern of material modulation is limited to the
solutions to Helmholtz's equation in the medium. If the
three-dimensional structure of the medium could be
engineered at each point rather than limited to the patterns
produced by standing waves, more versatile structures may
result that can overcome the typical limitations to hologram
dynamic range imposed by sequentially superimposing
holograms. Metamaterial structures and other synthetic
electromagnetic materials offer the possibility of achieving
high medium contrast engineered at the subwavelength scale.
By posing the multiplex volume holography problem as a
linear medium design problem, we explore the potential
improvements that such engineered synthetic media may
provide over conventional multiplex volume
holograms.},
Doi = {10.1364/josaa.35.000567},
Key = {fds335050}
}
@article{fds333288,
Author = {Yurduseven, O and Fromenteze, T and Smith, DR},
Title = {Relaxation of Alignment Errors and Phase Calibration in
Computational Frequency-Diverse Imaging using Phase
Retrieval},
Journal = {IEEE Access},
Volume = {6},
Pages = {14884-14894},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2018},
Month = {March},
url = {http://dx.doi.org/10.1109/ACCESS.2018.2816341},
Abstract = {We demonstrate a computational, frequency-diverse, phaseless
imaging technique at microwave frequencies that minimizes
the impacts of phase calibration and alignment errors on
image reconstruction. Phase calibration error is introduced
by means of misaligning the sub-antennas forming an
aperture, causing unwanted phase shifts between the forward
model and adjoint operation. It is shown that by leveraging
phase retrieval techniques, distinguishable images can still
be reconstructed in the presence of significant phase
errors, while complex-based reconstructions - those relying
on measurement of both phase and amplitude - produce heavily
corrupted images. Using a frequency-diverse imaging system
consisting of a cavity-backed metasurface antenna that
operates at microwave frequencies in the K-band (17.5-26.5
GHz), we demonstrate the complex-based and phaseless images
of various objects, from a simple subwavelength conducting
element to more complex metal structures. We verify that the
combination of the phase retrieval approach with the
frequency-diverse imager significantly improves the
robustness of the composite imaging system to phase errors.
While frequency-diverse computational imaging systems have
significant advantages in terms of hardware, their reliance
on a near-exact forward model places heavy requirements on
system calibration. The phase retrieval approach developed
here has the potential to alleviate this reliance,
increasing the feasibility of such systems.},
Doi = {10.1109/ACCESS.2018.2816341},
Key = {fds333288}
}
@article{fds333600,
Author = {Diebold, AV and Imani, MF and Sleasman, T and Smith,
DR},
Title = {Phaseless computational ghost imaging at microwave
frequencies using a dynamic metasurface aperture.},
Journal = {Applied optics},
Volume = {57},
Number = {9},
Pages = {2142-2149},
Publisher = {The Optical Society},
Year = {2018},
Month = {March},
url = {http://dx.doi.org/10.1364/ao.57.002142},
Abstract = {We demonstrate a dynamic metasurface aperture as a unique
tool for computational ghost imaging at microwave
frequencies. The aperture consists of a microstrip waveguide
loaded with an array of metamaterial elements, each of which
couples energy from the waveguide mode to the radiation
field. With a tuning mechanism introduced into each
independently addressable metamaterial element, the aperture
can produce diverse radiation patterns that vary as a
function of tuning state. Here, we show that fields from
such an aperture approximately obey speckle statistics in
the radiative near field. Inspired by the analogy with
optical correlation imaging, we use the dynamic aperture as
a means of illuminating a scene with structured microwave
radiation, receiving the backscattered intensity with a
simple waveguide probe. By correlating the magnitude of the
received signal with the structured intensity patterns, we
demonstrate high-fidelity, phaseless imaging of sparse
targets. The dynamic metasurface aperture as a novel ghost
imaging structure can find application in security
screening, through-wall imaging, as well as biomedical
diagnostics.},
Doi = {10.1364/ao.57.002142},
Key = {fds333600}
}
@article{fds333601,
Author = {Marks, DL and Smith, DR},
Title = {Inverse scattering with a non self-adjoint variational
formulation.},
Journal = {Optics express},
Volume = {26},
Number = {6},
Pages = {7655-7671},
Year = {2018},
Month = {March},
url = {http://dx.doi.org/10.1364/oe.26.007655},
Abstract = {The weak scattering approximation is used when designing
optical media that couple fields together, but to account
for the interactions of multiple fields in a volume or to
achieve the best efficiency, the solution must be consistent
with Maxwell's equations. We describe a method based on the
variational formulation of Maxwell's equations typically
employed in the finite element method (FEM) that finds both
the fields and the medium that couples incident and
scattered fields together, and so can be considered an
extension of the FEM when both the field and the medium are
allowed to vary. The method iteratively updates estimates of
the field and the medium and can be readily implemented. We
demonstrate designs of diffractive and refractive elements
that couple fields together using an iteratively updated
finite-difference-frequency-domain (FDFD) solution. Such
methods that are fully consistent with Maxwell's equations
are needed to design metamaterials that fully exploit
strongly interacting metamaterial elements.},
Doi = {10.1364/oe.26.007655},
Key = {fds333601}
}
@article{fds333268,
Author = {Yurduseven, O and Marks, DL and Fromenteze, T and Smith,
DR},
Title = {Dynamically reconfigurable holographic metasurface aperture
for a Mills-Cross monochromatic microwave
camera.},
Journal = {Optics express},
Volume = {26},
Number = {5},
Pages = {5281-5291},
Publisher = {The Optical Society},
Year = {2018},
Month = {March},
url = {http://dx.doi.org/10.1364/oe.26.005281},
Abstract = {We present a reconfigurable, dynamic beam steering
holographic metasurface aperture to synthesize a microwave
camera at K-band frequencies. The aperture consists of a 1D
printed microstrip transmission line with the front surface
patterned into an array of slot-shaped subwavelength
metamaterial elements (or meta-elements) dynamically tuned
between "ON" and "OFF" states using PIN diodes. The proposed
aperture synthesizes a desired radiation pattern by
converting the waveguide-mode to a free space radiation by
means of a binary modulation scheme. This is achieved in a
holographic manner; by interacting the waveguide-mode
(reference-wave) with the metasurface layer (hologram
layer). It is shown by means of full-wave simulations that
using the developed metasurface aperture, the radiated
wavefronts can be engineered in an all-electronic manner
without the need for complex phase-shifting circuits or
mechanical scanning apparatus. Using the dynamic beam
steering capability of the developed antenna, we synthesize
a Mills-Cross composite aperture, forming a single-frequency
all-electronic microwave camera.},
Doi = {10.1364/oe.26.005281},
Key = {fds333268}
}
@article{fds330573,
Author = {Liu, X and Larouche, S and Smith, DR},
Title = {Homogenized description and retrieval method of nonlinear
metasurfaces},
Journal = {Optics Communications},
Volume = {410},
Pages = {53-69},
Publisher = {Elsevier BV},
Year = {2018},
Month = {March},
url = {http://dx.doi.org/10.1016/j.optcom.2017.09.048},
Abstract = {A patterned, plasmonic metasurface can strongly scatter
incident light, functioning as an extremely low-profile
lens, filter, reflector or other optical device. When the
metasurface is patterned uniformly, its linear optical
properties can be expressed using effective surface electric
and magnetic polarizabilities obtained through a
homogenization procedure. The homogenized description of a
nonlinear metasurface, however, presents challenges both
because of the inherent anisotropy of the medium as well as
the much larger set of potential wave interactions
available, making it challenging to assign effective
nonlinear parameters to the otherwise inhomogeneous layer of
metamaterial elements. Here we show that a homogenization
procedure can be developed to describe nonlinear
metasurfaces, which derive their nonlinear response from the
enhanced local fields arising within the structured
plasmonic elements. With the proposed homogenization
procedure, we are able to assign effective nonlinear surface
polarization densities to a nonlinear metasurface, and link
these densities to the effective nonlinear surface
susceptibilities and averaged macroscopic pumping fields
across the metasurface. These effective nonlinear surface
polarization densities are further linked to macroscopic
nonlinear fields through the generalized sheet transition
conditions (GSTCs). By inverting the GSTCs, the effective
nonlinear surface susceptibilities of the metasurfaces can
be solved for, leading to a generalized retrieval method for
nonlinear metasurfaces. The application of the
homogenization procedure and the GSTCs are demonstrated by
retrieving the nonlinear susceptibilities of a SiO2
nonlinear slab. As an example, we investigate a nonlinear
metasurface which presents nonlinear magnetoelectric
coupling in near infrared regime. The method is expected to
apply to any patterned metasurface whose thickness is much
smaller than the wavelengths of operation, with inclusions
of arbitrary geometry and material composition, across the
electromagnetic spectrum.},
Doi = {10.1016/j.optcom.2017.09.048},
Key = {fds330573}
}
@article{fds332910,
Author = {Gowda, VR and Imani, MF and Sleasman, T and Yurduseven, O and Smith,
DR},
Title = {Focusing Microwaves in the Fresnel Zone with a Cavity-Backed
Holographic Metasurface},
Journal = {IEEE Access},
Volume = {6},
Pages = {12815-12824},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2018},
Month = {February},
url = {http://dx.doi.org/10.1109/ACCESS.2018.2802379},
Abstract = {We present the design and experimental demonstration of a
cavity-backed, holographic metasurface capable of focusing
microwaves in the Fresnel zone. The circular cavity consists
of two stacked plates: microwaves are injected into the
bottom plate via a coaxial connector, which forms the feed
layer, and are coupled to the top holographic metasurface
layer via an annular ring on the periphery of the cavity.
This coupling results in an inward traveling cylindrical
wave in the top layer, which serves as the reference wave
for the hologram. A sparse array of slots, patterned into
the upper plate, constitutes the hologram that produces the
focal spot. To mitigate high sidelobe levels and improve
performance, a tapered design, facilitated by varying the
slot size, is also introduced. The proposed designs-which
have a 10-cm diameter, operate at 20 GHz, and form a focal
spot at a distance of 10 cm-are validated using full-wave
simulations as well as measurements of fabricated samples.
The proposed focusing metasurface may find application as a
compact source for Fresnel zone wireless power transfer and
remote sensing schemes.},
Doi = {10.1109/ACCESS.2018.2802379},
Key = {fds332910}
}
@article{fds332909,
Author = {Jia, X and Bowen, P and Huang, Z and Liu, X and Bingham, C and Smith,
DR},
Title = {Clarification of surface modes of a periodic nanopatch
metasurface.},
Journal = {Optics express},
Volume = {26},
Number = {3},
Pages = {3004-3012},
Publisher = {The Optical Society},
Year = {2018},
Month = {February},
url = {http://dx.doi.org/10.1364/oe.26.003004},
Abstract = {We study the angle-dependent optical reflectance spectrum of
a metasurface consisting of a periodic array of film-coupled
plasmonic nanopatch particles. The nanopatch metasurface
exhibits a strong, angle-independent absorption resonance at
a wavelength defined by the nanopatch geometry and relative
density. When the nanopatches are arranged in a regular
lattice, a second, sharp absorption dip is present that
varies strongly as a function of the incidence angle. This
second resonance is a collective effect involving the
excitation of surface plasmon modes and relates to a Wood's
anomaly. Using an analytical model, we compute the surface
modes of the structure and confirm details about the various
mechanisms that contribute to the reflection spectra. The
measured reflectance spectra are in excellent agreement with
both analytical calculations and full-wave numerical
simulations.},
Doi = {10.1364/oe.26.003004},
Key = {fds332909}
}
@article{fds341932,
Author = {Yurduseven, O and Smith, DR and Fromenteze, T},
Title = {Phase Retrieval in Frequency-Diverse Imaging},
Journal = {2018 IEEE Antennas and Propagation Society International
Symposium and USNC/URSI National Radio Science Meeting,
APSURSI 2018 - Proceedings},
Pages = {1797-1798},
Year = {2018},
Month = {January},
ISBN = {9781538671023},
url = {http://dx.doi.org/10.1109/APUSNCURSINRSM.2018.8609240},
Abstract = {We demonstrate a phaseless computational frequency-diverse
imaging system at K-band frequencies. The integration of the
phase retrieval concept with computational frequency-diverse
imaging is achieved by leveraging a gradient-descent based
Wirtinger Flow algorithm. Using the developed phaseless
imaging system, imaging of complex-shaped targets, such as
the letters of the word 'DUKE', is shown, and it is observed
that the phaseless reconstructed images are on par with the
complex-based reconstructions.},
Doi = {10.1109/APUSNCURSINRSM.2018.8609240},
Key = {fds341932}
}
@article{fds337401,
Author = {Diebold, AV and Imani, MF and Sleasman, T and Smith,
DR},
Title = {Reflective microwave ghost imaging with dynamic metasurface
apertures},
Journal = {Optics InfoBase Conference Papers},
Volume = {Part F102-ISA 2018},
Publisher = {OSA},
Year = {2018},
Month = {January},
ISBN = {9781943580446},
url = {http://dx.doi.org/10.1364/ISA.2018.IM2B.5},
Abstract = {We demonstrate phaseless, single-frequency ghost imaging at
microwave frequencies using a dynamic metasurface aperture.
This aperture comprises a simplified hardware architecture
for generating diverse speckle patterns by tuning an array
of resonant metamaterial elements.},
Doi = {10.1364/ISA.2018.IM2B.5},
Key = {fds337401}
}
@article{fds341934,
Author = {Yurduseven, O and Smith, DR and Fromenteze, T},
Title = {Design of a Reconfigurable Metasurface Antenna for Dynamic
Near-Field Focusing},
Journal = {2018 IEEE Antennas and Propagation Society International
Symposium and USNC/URSI National Radio Science Meeting,
APSURSI 2018 - Proceedings},
Pages = {1707-1708},
Year = {2018},
Month = {January},
ISBN = {9781538671023},
url = {http://dx.doi.org/10.1109/APUSNCURSINRSM.2018.8609076},
Abstract = {We show the design of a dynamically reconfigurable
holographic metasurface antenna for near-field beam-focusing
applications. A metasurface layer is used to modulate the
guided-mode reference to an aperture field of interest
producing the desired radiated wavefront. Exciting the
dynamically reconfigurable metasurface layer with the
guided-mode reference produces a reconfigurable focus in the
near-field of the antenna aperture. The reconfigurable
operation is achieved in an-all electronic manner, without
the need for any mechanical moving apparatus or phase
shifting circuits.},
Doi = {10.1109/APUSNCURSINRSM.2018.8609076},
Key = {fds341934}
}
@article{fds341935,
Author = {Yurduseven, O and Smith, DR and Fromenteze, T},
Title = {Computational Millimeter-wave Spotlight Imaging using
Holographic Metasurface Antennas},
Journal = {2018 IEEE Antennas and Propagation Society International
Symposium and USNC/URSI National Radio Science Meeting,
APSURSI 2018 - Proceedings},
Pages = {1461-1462},
Year = {2018},
Month = {January},
ISBN = {9781538671023},
url = {http://dx.doi.org/10.1109/APUSNCURSINRSM.2018.8609303},
Abstract = {In this paper, a spotlight imaging system integrated with a
frequency-diverse aperture is presented for
security-screening applications. The spotlight imager
consists of holographic metasurface antennas that can
dynamically be tuned to radiate spotlight patterns allowing
the extraction of high-resolution images from a constrained
field-of-view (FOV). The spotlight aperture operates at a
single frequency, 75 GHz, within the W-band frequency regime
(75 - 110 GHz)and is used for the identification of threat
objects while the frequency-diverse aperture operates at
K-band frequencies (17.5 - 26.5 GHz)and is used for
detection purposes, determining the constrained FOV to be
imaged using the spotlight imager at high
resolution.},
Doi = {10.1109/APUSNCURSINRSM.2018.8609303},
Key = {fds341935}
}
@article{fds341936,
Author = {Yurduseven, O and Smith, DR and Fromenteze, T},
Title = {Additive Manufacturing of a Conductive Polymer Cavity-Backed
Metasurface Antenna for Computational Microwave
Imaging},
Journal = {2018 IEEE Antennas and Propagation Society International
Symposium and USNC/URSI National Radio Science Meeting,
APSURSI 2018 - Proceedings},
Pages = {233-234},
Year = {2018},
Month = {January},
ISBN = {9781538671023},
url = {http://dx.doi.org/10.1109/APUSNCURSINRSM.2018.8608895},
Abstract = {We demonstrate a new 3D printing technique, making use of a
copper-polyester conductive composite filament (Electrifi)
to achieve additive manufacturing of a frequency-diverse
metasurface antenna. Using the 3D printed antenna, we
synthesize a computational microwave camera performing 3D
imaging at K-band frequencies.},
Doi = {10.1109/APUSNCURSINRSM.2018.8608895},
Key = {fds341936}
}
@article{fds341933,
Author = {Pulido-Mancera, L and Imani, MF and Smith, DR},
Title = {Dipolar Model for Metamaterial Imaging Systems},
Journal = {2018 IEEE Antennas and Propagation Society International
Symposium and USNC/URSI National Radio Science Meeting,
APSURSI 2018 - Proceedings},
Pages = {1487-1488},
Year = {2018},
Month = {January},
ISBN = {9781538671023},
url = {http://dx.doi.org/10.1109/APUSNCURSINRSM.2018.8608502},
Abstract = {We present a comprehensive simulation platform for
computational microwave imaging systems based on
frequency-diverse metasurface antennas (FDMAs). FDMAs
consist of a waveguide patterned with complementary
metamaterial elements with resonant frequencies selected
randomly from a band of operation, enabling the generation
of distinct frequency-indexed radiation patterns. By
accurately modeling the fields produced by the FDMA using a
dipolar model, it is possible to predict the capabilities of
the imaging system in a fast and reliable manner. In
contrast to previous works, in this paper we include the
mutual interaction between metamaterial elements, and it is
demonstrated that these interactions are crucial to a better
understanding of the FDMAs' capabilities e. g. effective
aperture area and correlation of radiation patterns. The
simplicity and accuracy of the proposed model permits the
simulation of different metasurfaces for computational
microwave imaging, where traditional antenna design- and
metamaterial modeling-are prohibitively costly.},
Doi = {10.1109/APUSNCURSINRSM.2018.8608502},
Key = {fds341933}
}
@article{fds337028,
Author = {Yurduseven, O and Marks, DL and Gollub, JN and Smith,
DR},
Title = {A reconfigurable millimeter-wave spotlight metasurface
aperture integrated with a frequency-diverse microwave
imager for security screening},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {10634},
Publisher = {SPIE},
Year = {2018},
Month = {January},
ISBN = {9781510617797},
url = {http://dx.doi.org/10.1117/12.2303588},
Abstract = {In this paper, a spotlight imaging system integrated with a
frequency-diverse aperture is presented for
security-screening applications. The spotlight imager
consists of holographic metasurface antennas that can
dynamically be tuned to radiate spotlight patterns allowing
the extraction of high-resolution images from a constrained
field-of-view (FOV). The reconfigurable holographic
metasurface antennas consist of a metasurface layer used to
modulate the guided-mode reference to an aperture field of
interest producing the desired radiated wavefronts. The
reconfigurable operation is achieved in an all-electronic
manner without the need for any mechanical moving apparatus
or phase shifting circuits. The spotlight aperture operates
at a single frequency, 75 GHz, within the W-band frequency
regime (75-110 GHz) and is used for the high-resolution
identification of threat objects while the frequency-diverse
aperture operates at K-band frequencies (17.5-26.5 GHz) and
is used for low-resolution detection purposes. The scene to
be imaged is first interrogated using the K-band aperture at
low resolution and the constrained-FOV is imaged using the
W-band system to achieve the identification of threat
objects.},
Doi = {10.1117/12.2303588},
Key = {fds337028}
}
@article{fds337105,
Author = {Boyarsky, M and Sleasman, T and Pulido-Mancera, L and Diebold, AV and Imani, MF and Smith, DR},
Title = {Synthetic aperture radar imaging with reconfigurable 1d
dynamic metasurface apertures},
Journal = {Proceedings of the European Conference on Synthetic Aperture
Radar, EUSAR},
Volume = {2018-June},
Pages = {6-11},
Year = {2018},
Month = {January},
ISBN = {9783800746361},
Abstract = {Driven by the growing need for lightweight and low-cost
antennas, we investigate metasurface antennas as a potential
SAR hardware platform. Metasurface antennas can generate
arbitrary radiation patterns and electronically modulate
them without requiring complex components such as phase
shifters and amplifiers. In this work, we operate in the
radiative near field of metasurface antennas and translate
them with aperture synthesis to access 3D scene information
without requiring spectral bandwidth. This work reviews
metasurface antenna operation and examines their exciting
potential in single-frequency 3D SAR imaging
systems.},
Key = {fds337105}
}
@article{fds337400,
Author = {Diebold, AV and Imani, MF and Sleasman, T and Smith,
DR},
Title = {Spatial intensity averaging for ghost imaging with a
single-port dynamic metasurface aperture},
Journal = {Optics InfoBase Conference Papers},
Volume = {Part F105-MATH 2018},
Publisher = {OSA},
Year = {2018},
Month = {January},
ISBN = {9781943580446},
url = {http://dx.doi.org/10.1364/MATH.2018.MTu2D.6},
Abstract = {We present a method for achieving spatial intensity
integration of temporally coherent microwave radiation. The
approach consists of averaging the instantaneous intensity
over an ensemble of random radiation patterns using a
single-port metasurface aperture.},
Doi = {10.1364/MATH.2018.MTu2D.6},
Key = {fds337400}
}
@article{fds328955,
Author = {Sharma, A and Pedross-Engel, A and Arnitz, D and Watts, CM and Smith,
DR and Reynolds, MS},
Title = {A K-Band Backscatter Fiducial for Continuous Calibration in
Coherent Millimeter-Wave Imaging},
Journal = {IEEE Transactions on Microwave Theory and
Techniques},
Volume = {66},
Number = {1},
Pages = {431-438},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2018},
Month = {January},
url = {http://dx.doi.org/10.1109/TMTT.2017.2723889},
Abstract = {We present a modulated ultrawideband backscatter calibration
target (fiducial) intended for group delay calibration in
large-aperture multitransceiver millimeter-wave imagers. The
fiducial is designed to resemble a modulated point scatterer
across the K-band (17.5-26.5 GHz). Multiple such fiducials
may be used to mitigate thermal and mechanical drift across
multiple transceivers comprising the imager. This approach
allows tracking and removing both time-varying amplitude and
phase drift in the RF hardware and associated cables.
Backscatter modulation of the fiducial allows the system to
separate the fiducial from the imaged scene and clutter in
the environment. We show that the -10 dB beamwidth of the
proposed fiducial is approximately 84° along the azimuth
plane and 60° along the elevation plane. A proof of concept
group delay calibration experiment is presented for a K-band
laboratory setup, where a single fiducial and a metal plate
target are placed in a scene together. After the
backscatter-based calibration, the measured range error of
the metal plate at a two-way slant distance of 70.54 cm is
reduced to only 1.06 mm (0.15% position error).},
Doi = {10.1109/TMTT.2017.2723889},
Key = {fds328955}
}
@article{fds335052,
Author = {Nashad, FME and Foti, S and Smith, D and Elsdon, M and Yurduseven,
O},
Title = {Ku-band suspended meshed patch antenna integrated with solar
cells for remote area applications},
Journal = {Progress In Electromagnetics Research C},
Volume = {83},
Pages = {245-254},
Publisher = {EMW Publishing},
Year = {2018},
Month = {January},
url = {http://dx.doi.org/10.2528/PIERC18020608},
Abstract = {A new structure design of a dual-band suspended microstrip
meshed patch antenna integrated with a polycrystalline
silicon solar cell for Ku-band satellite applications is
proposed and presented. This antenna element is a basic
building block for a Ku-band meshed array antenna used for
two-way satellite internet and TV applications at rural and
remote locations. The antenna covers the operating frequency
range from 11.7GHz to 12.22 GHz downlink band and from
14.0GHz to 14.5GHz uplink band allocated by the ITU to the
Regions 1 and 2. While achieving 500MHz bandwidth across
each band, fully covering the Ku-band uplink and downlink
frequency bands, the antenna offers a single element gain of
6.05 dBi in the downlink band and 7.61 dBi in the uplink
band. The antenna has been fabricated and measured, and good
agreement is achieved between the experimental and simulated
results. In addition, a good compromise between RF
performance and optical transparency is obtained. The
overall visible light transmission is found to be
approximately 87%. A compact low-profile antenna element is
also achieved.},
Doi = {10.2528/PIERC18020608},
Key = {fds335052}
}
@article{fds332911,
Author = {Marks, DL and Smith, DR},
Title = {Mode diversity of weakly modulated cavity
antennas.},
Journal = {Journal of the Optical Society of America. A, Optics, image
science, and vision},
Volume = {35},
Number = {1},
Pages = {135-147},
Publisher = {The Optical Society},
Year = {2018},
Month = {January},
url = {http://dx.doi.org/10.1364/josaa.35.000135},
Abstract = {The radiating mode of a cavity antenna at a particular
frequency is fixed. However, by actively modulating the
permittivity inside the cavity, the radiating mode may be
changed. Using time-independent perturbation theory, we
derive the modes of a cavity perturbed by many modulating
elements. It is found that with a sufficient number of
modulators of sufficient strength, the number of unique
fields radiated by the cavity may reach a limit determined
by the number of unperturbed cavity modes. The number of
addressable radiated fields increases exponentially with the
number of modulators; however, perturbations involving the
interaction of several modulators become progressively
weaker. For antennas at millimeter and terahertz
frequencies, such cavity antennas can realize a great
diversity of radiation patterns using fewer active devices,
better exploiting the diversity achieved by each added
modulator.},
Doi = {10.1364/josaa.35.000135},
Key = {fds332911}
}
@article{fds331537,
Author = {Caira, NW and Smith, DR},
Title = {Multispectral metasurface hologram at millimeter
wavelengths.},
Journal = {Applied optics},
Volume = {57},
Number = {1},
Pages = {A19-A25},
Year = {2018},
Month = {January},
url = {http://dx.doi.org/10.1364/ao.57.000a19},
Abstract = {We demonstrate a computer-generated metasurface hologram in
which four distinct images are encoded at four different
W-band (75-110 GHz) frequencies. The metasurface hologram
consists of a planar array of resonant metamaterial elements
excited by a collimated reference beam incident on the
hologram at an oblique angle. Each of the images is encoded
by a subset of metamaterial elements that are resonant at
the specific excitation frequency and are spatially
positioned to achieve a desired phase distribution in the
plane in conjunction with the reference wave. The phase-only
hologram is optimized using the Gerschberg-Saxton algorithm.
The four well-defined images are produced at specific
distances within the Fresnel zone of the
aperture.},
Doi = {10.1364/ao.57.000a19},
Key = {fds331537}
}
@article{fds337697,
Author = {Zeng, B and Huang, Z and Singh, A and Yao, Y and Azad, AK and Mohite, AD and Taylor, AJ and Smith, DR and Chen, H-T},
Title = {Hybrid graphene metasurfaces for high-speed mid-infrared
light modulation and single-pixel imaging.},
Journal = {Light, science & applications},
Volume = {7},
Number = {1},
Pages = {51},
Publisher = {Springer Nature America, Inc},
Year = {2018},
Month = {January},
url = {http://dx.doi.org/10.1038/s41377-018-0055-4},
Abstract = {During the past decades, major advances have been made in
both the generation and detection of infrared light;
however, its efficient wavefront manipulation and
information processing still encounter great challenges.
Efficient and fast optoelectronic modulators and spatial
light modulators are required for mid-infrared imaging,
sensing, security screening, communication and navigation,
to name a few. However, their development remains elusive,
and prevailing methods reported so far have suffered from
drawbacks that significantly limit their practical
applications. In this study, by leveraging graphene and
metasurfaces, we demonstrate a high-performance free-space
mid-infrared modulator operating at gigahertz speeds, low
gate voltage and room temperature. We further pixelate the
hybrid graphene metasurface to form a prototype spatial
light modulator for high frame rate single-pixel imaging,
suggesting orders of magnitude improvement over conventional
liquid crystal or micromirror-based spatial light
modulators. This work opens up the possibility of exploring
wavefront engineering for infrared technologies for which
fast temporal and spatial modulations are
indispensable.},
Doi = {10.1038/s41377-018-0055-4},
Key = {fds337697}
}
@article{fds340084,
Author = {Zvolensky, T and Gowda, VR and Gollub, J and Marks, DL and Smith,
DR},
Title = {W-band sparse imaging system using frequency diverse
cavity-fed metasurface antennas},
Journal = {IEEE Access},
Volume = {6},
Pages = {73659-73668},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2018},
Month = {January},
url = {http://dx.doi.org/10.1109/ACCESS.2018.2883402},
Abstract = {We experimentally demonstrate a frequency-diverse,
computational imaging system at W-band frequencies utilizing
an array of cavity-fed metasurface antennas. Each
metasurface antenna consists of a cavity milled from
aluminum stock, with an upper plate patterned with a set of
radiating slots. As a function of frequency, the metasurface
cavities produce a set of spatially diverse radiation
patterns that probe the reflectivity distribution of a
scene. The antennas are designed to maximize the measurement
diversity and hence imaging capacity of the system. The
number and distribution of the radiating slots is optimized
by balancing the cavity quality factor (Q) and Fourier space
coverage. In the experimental realizations, the radiation
patterns from each cavity-fed metasurface antenna is first
measured using near-field scanning techniques, propagated
over the imaging domain, and then stored for use in the
image reconstruction step. Comprehensive alignment procedure
is implemented to align the measured radiation patterns with
regard to the physical position of the cavities. Using a
modeling platform, we find excellent agreement between the
simulation and experiment, indicating the validity of the
calibration and alignment procedures. The scaling of the
cavity-fed metasurface antenna represents a key step in the
development of alternative high-frequency apertures for
imaging and beam-forming applications.},
Doi = {10.1109/ACCESS.2018.2883402},
Key = {fds340084}
}
@article{fds331538,
Author = {Marks, DL and Yurduseven, O and Smith, DR},
Title = {Sparse blind deconvolution for imaging through layered
media},
Journal = {Optica},
Volume = {4},
Number = {12},
Pages = {1514-1521},
Publisher = {The Optical Society},
Year = {2017},
Month = {December},
url = {http://dx.doi.org/10.1364/OPTICA.4.001514},
Abstract = {When imaging through layered media such as walls, the
contents and thickness of the wall layers are generally not
known a priori. Furthermore, compensating for their effects
can be computationally intensive, as this generally requires
modelling the transmission and reflection of complex fields
through layered media. We propose a blind deconvolution
method that does not require knowledge of the wall layers by
directly estimating a circularly symmetric Green’s
function that models the transmission through the wall
layers, simultaneously addressing both problems. We
experimentally demonstrate this technique by measuring the
reflection through a multilayered structure of building
materials at the K-band microwave frequencies, and using the
blind deconvolution method to find the image of a reflective
object behind the layers.},
Doi = {10.1364/OPTICA.4.001514},
Key = {fds331538}
}
@article{fds331539,
Author = {Pulido-Mancera, L and Bowen, PT and Imani, MF and Kundtz, N and Smith,
D},
Title = {Polarizability extraction of complementary metamaterial
elements in waveguides for aperture modeling},
Journal = {Physical Review B},
Volume = {96},
Number = {23},
Publisher = {American Physical Society (APS)},
Year = {2017},
Month = {December},
url = {http://dx.doi.org/10.1103/PhysRevB.96.235402},
Abstract = {We consider the design and modeling of metasurfaces that
couple energy from guided waves to propagating wave fronts.
To this purpose, we develop a comprehensive, multiscale
dipolar interpretation for large arrays of complementary
metamaterial elements embedded in a waveguide structure.
Within this modeling technique, the detailed electromagnetic
response of each metamaterial element is replaced by a
polarizable dipole, described by means of an effective
polarizability. In this paper, we present two methods to
extract this effective polarizability. The first method
invokes surface equivalence principles, averaging over the
effective surface currents and charges induced in the
element's surface in order to obtain the effective dipole
moments, from which the effective polarizability can be
inferred. The second method is based in the coupled-mode
theory, from which a direct relationship between the
effective polarizability and the amplitude coefficients of
the scattered waves can be deduced. We demonstrate these
methods on several variants of waveguide-fed metasurface
elements (both one- and two-dimensional waveguides), finding
excellent agreement between the two, as well as with the
analytical expressions derived for circular and elliptical
irises. With the effective polarizabilities of the
metamaterial elements accurately determined, the radiated
fields generated by a waveguide-fed metasurface can be found
self-consistently by including the interactions between
polarizable dipoles. The dipole description provides an
effective perspective and computational framework for
engineering metasurface structures such as holograms,
lenses, and beam-forming arrays, among others.},
Doi = {10.1103/PhysRevB.96.235402},
Key = {fds331539}
}
@article{fds330946,
Author = {Diebold, AV and Pulido-Mancera, L and Sleasman, T and Boyarsky, M and Imani, MF and Smith, DR},
Title = {Generalized range migration algorithm for synthetic aperture
radar image reconstruction of metasurface antenna
measurements},
Journal = {Journal of the Optical Society of America B: Optical
Physics},
Volume = {34},
Number = {12},
Pages = {2610-2623},
Publisher = {The Optical Society},
Year = {2017},
Month = {December},
url = {http://dx.doi.org/10.1364/JOSAB.34.002610},
Abstract = {Waveguide-fed dynamic metasurface antennas (DMAs) can be
used in a variety of synthetic aperture radar (SAR)
modalities for microwave and millimeter-wave imaging. The
DMA consists of an electrically large array of resonant,
dynamically reconfigurable metamaterial radiators, each
excited by the fields of a guided wave. A given metamaterial
element can be modeled as a polarizable dipole, with
polarizability that equates to a complex weighting factor in
the context of antenna array calculations. The DMA produces
a sequence of diverse radiation patterns as a function of
the weights, which can be rapidly varied by external
control. The unconventional radiation patterns of the DMA,
however, introduce added computational complexity for
traditional SAR processing algorithms. One SAR
reconstruction approach that has successfully been adapted
for the static (motionless) DMA is the range migration
algorithm (RMA). Here, we extend the RMA to scenarios in
which the DMA is physically translated in one or two
dimensions, deriving the RMA for each case and providing
experimental demonstrations using a fabricated
microstrip-based DMA. Excellent reconstruction quality is
observed in all cases, verifying the efficacy of the
proposed algorithms and demonstrating the imaging
capabilities of the DMA in the synthetic aperture context.
The combination of the DMA platform with efficient
reconstruction algorithms can find applications in fields
such as Earth observation, security screening, and
autonomous vehicle navigation.},
Doi = {10.1364/JOSAB.34.002610},
Key = {fds330946}
}
@article{fds329404,
Author = {Sleasman, T and Boyarsky, M and Pulido-Mancera, L and Fromenteze, T and Imani, MF and Reynolds, MS and Smith, DR},
Title = {Experimental Synthetic Aperture Radar with Dynamic
Metasurfaces},
Journal = {IEEE Transactions on Antennas and Propagation},
Volume = {65},
Number = {12},
Pages = {6864-6877},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2017},
Month = {December},
url = {http://dx.doi.org/10.1109/TAP.2017.2758797},
Abstract = {We investigate the use of a dynamic metasurface as the
transmitting antenna for a synthetic aperture radar (SAR)
imaging system. The dynamic metasurface consists of a 1-D
microstrip waveguide with complementary electric resonator
(cELC) elements patterned into the upper conductor.
Integrated into each of the cELCs are two diodes that can be
used to shift each cELC resonance out of band with an
applied voltage. The aperture is designed to operate at
$K$-band frequencies (17.5-20.3 GHz). We experimentally
demonstrate imaging with a fabricated metasurface aperture
using well-known SAR modalities, showing image quality
comparable to traditional antennas. The agility of this
aperture allows it to operate in spotlight and stripmap SAR
modes, as well as in a third modality inspired by
computational imaging strategies. We describe the dynamic
metasurface antenna's operation in detail, demonstrate
high-quality imaging in both 2-D and 3-D, and examine
various tradeoffs governing the integration of dynamic
metasurfaces in the future SAR imaging platforms.},
Doi = {10.1109/TAP.2017.2758797},
Key = {fds329404}
}
@article{fds330947,
Author = {Smith, DR and Yurduseven, O and Mancera, LP and Bowen, P and Kundtz,
NB},
Title = {Analysis of a Waveguide-Fed Metasurface Antenna},
Journal = {Physical Review Applied},
Volume = {8},
Number = {5},
Publisher = {American Physical Society (APS)},
Year = {2017},
Month = {November},
url = {http://dx.doi.org/10.1103/PhysRevApplied.8.054048},
Abstract = {The metasurface concept has emerged as an advantageous
reconfigurable antenna architecture for beam forming and
wave-front shaping, with applications that include satellite
and terrestrial communications, radar, imaging, and wireless
power transfer. The metasurface antenna consists of an array
of metamaterial elements distributed over an electrically
large structure, each subwavelength in dimension and with
subwavelength separation between elements. In the antenna
configuration we consider, the metasurface is excited by the
fields from an attached waveguide. Each metamaterial element
can be modeled as a polarizable dipole that couples the
waveguide mode to radiation modes. Distinct from the phased
array and electronically-scanned-antenna architectures, a
dynamic metasurface antenna does not require active phase
shifters and amplifiers but rather achieves
reconfigurability by shifting the resonance frequency of
each individual metamaterial element. We derive the basic
properties of a one-dimensional waveguide-fed metasurface
antenna in the approximation in which the metamaterial
elements do not perturb the waveguide mode and are
noninteracting. We derive analytical approximations for the
array factors of the one-dimensional antenna, including the
effective polarizabilities needed for amplitude-only,
phase-only, and binary constraints. Using full-wave
numerical simulations, we confirm the analysis, modeling
waveguides with slots or complementary metamaterial elements
patterned into one of the surfaces.},
Doi = {10.1103/PhysRevApplied.8.054048},
Key = {fds330947}
}
@article{fds332087,
Author = {Pulido-Mancera, L and Imani, MF and Bowen, PT and Smith,
DR},
Title = {Extracting polarizability of complementary metamaterial
elements using equivalence principles},
Journal = {2017 11th International Congress on Engineered Material
Platforms for Novel Wave Phenomena, Metamaterials
2017},
Pages = {268-270},
Publisher = {IEEE},
Year = {2017},
Month = {November},
ISBN = {9781538637685},
url = {http://dx.doi.org/10.1109/MetaMaterials.2017.8107915},
Abstract = {A novel Metamaterial Dipole Model (MDM) has been proposed as
a powerful tool for modeling and designing metasurface
antennas for numerous applications such as beamforming
arrays, holograms, and flat lenses among others. In this
technique, a metasurface antenna is described as a
collection of effective magnetic dipoles characterized by
their polarizability. The utility of this modeling technique
relies on polarizability extraction, i.e.The proper
characterization of each individual metamaterial element
when it is embedded in a waveguide. In this presentation, we
employ a volumetric equivalence principle in a comprehensive
procedure for retrieving the polarizability of complementary
metamaterial elements, when these are embedded in
rectangular waveguides, planar waveguides, and periodic
metascreens. We demonstrate that the extracted
polarizability changes for each supporting waveguide
structure, highlighting the importance of proper
characterization of metamaterial elements in different
environments.},
Doi = {10.1109/MetaMaterials.2017.8107915},
Key = {fds332087}
}
@article{fds329820,
Author = {Marks, DL and Yurduseven, O and Smith, DR},
Title = {Near-field multistatic radar reconstruction with
stretched-phase Fourier accelerated multistatic
imaging},
Journal = {IET Radar, Sonar and Navigation},
Volume = {11},
Number = {11},
Pages = {1718-1729},
Publisher = {Institution of Engineering and Technology
(IET)},
Year = {2017},
Month = {November},
url = {http://dx.doi.org/10.1049/iet-rsn.2017.0130},
Abstract = {There exist few rapid reconstruction methods for
applications that use multistatic radar for targets in the
near field such as vehicle navigation and personnel
screening. Fourier accelerated multistatic imaging (FAMI) is
a method that combines the rapid reconstruction speed of
Fourier-based imaging algorithms with the flexibility of
algebraic algorithms that allow arbitrary radiation patterns
and antenna placement. Many of these new applications image
in the near field of the individual antennas of a
multistatic array, however, FAMI contains approximations
that require the target to be in the far field of each
antenna. Stretched-phase FAMI (SP-FAMI) overcomes this
limitation and allows imaging in the Fresnel region of the
antennas so that targets may be very close to the array
while retaining the computational benefits of Fourier
reconstruction. As radar wavelengths decrease with a
corresponding increase in resolution, SP-FAMI allows the
imaging of nearby targets that would otherwise be too close
for FAMI to image accurately.},
Doi = {10.1049/iet-rsn.2017.0130},
Key = {fds329820}
}
@article{fds335054,
Author = {Stewart, JW and Akselrod, GM and Smith, DR and Mikkelsen,
MH},
Title = {Multispectral metasurface absorbers for optoelectronic
devices},
Journal = {2017 Conference on Lasers and Electro-Optics, CLEO 2017 -
Proceedings},
Volume = {2017-January},
Pages = {1-2},
Year = {2017},
Month = {October},
ISBN = {9781943580279},
url = {http://dx.doi.org/10.1364/CLEO_SI-2017-SM3N.4},
Abstract = {We demonstrate multispectral metasurfaces over wafer-scale
areas exhibiting greater than 85 percent absorption, ~100 nm
linewidths from 580-1125 nm by patterning plasmonic
resonators in micron-scale pixels using a fusion of
bottom-up and top-down fabrication techniques.},
Doi = {10.1364/CLEO_SI-2017-SM3N.4},
Key = {fds335054}
}
@article{fds332912,
Author = {Yurduseven, O and Marks, DL and Gollub, JN and Smith,
DR},
Title = {Synthesizing a frequency-diverse aperture for
security-screening applications},
Journal = {2017 IEEE Antennas and Propagation Society International
Symposium, Proceedings},
Volume = {2017-January},
Pages = {2383-2384},
Publisher = {IEEE},
Year = {2017},
Month = {October},
ISBN = {9781538632840},
url = {http://dx.doi.org/10.1109/APUSNCURSINRSM.2017.8073234},
Abstract = {We demonstrate the design of a frequency-diverse aperture
for imaging of human size objects. Frequency-diversity is an
all-electronic technique, allowing the imaging to be
performed without any mechanical moving parts or active
circuit components. Leveraging computational imaging
algorithms, the concept of frequency-diverse imaging offers
a simplified alternative to conventional techniques limited
in key metrics, such as data acquisition speed, system
complexity and cost. It is shown that the
synthesized-frequency diverse aperture can reconstruct good
quality images of a human-size target by means of a simple
frequency sweep over the K-band frequency
regime.},
Doi = {10.1109/APUSNCURSINRSM.2017.8073234},
Key = {fds332912}
}
@article{fds332913,
Author = {Yurduseven, O and Gollub, JN and Marks, DL and Smith,
DR},
Title = {Alignment Correction for antenna scans in
imaging},
Journal = {2017 IEEE Antennas and Propagation Society International
Symposium, Proceedings},
Volume = {2017-January},
Pages = {2381-2382},
Publisher = {IEEE},
Year = {2017},
Month = {October},
ISBN = {9781538632840},
url = {http://dx.doi.org/10.1109/APUSNCURSINRSM.2017.8073233},
Abstract = {In this paper, we propose a software correction technique to
eliminate the misalignment errors in the measurement of
antenna radiated fields for frequency-diverse imaging. It is
shown that by using RF fiducials integrated into the
antennas, the effect of rotation (range and cross-range) and
offset misalignment errors can be corrected to a good
accuracy, holding significant potential for applications
where precise alignment is required for antenna field
measurements.},
Doi = {10.1109/APUSNCURSINRSM.2017.8073233},
Key = {fds332913}
}
@article{fds332914,
Author = {Fromenteze, T and Boyarsky, M and Yurduseven, O and Gollub, J and Marks,
DL and Smith, DR},
Title = {Computational polarimetric localization with a radiating
metasurface},
Journal = {2017 IEEE Antennas and Propagation Society International
Symposium, Proceedings},
Volume = {2017-January},
Pages = {407-408},
Publisher = {IEEE},
Year = {2017},
Month = {October},
ISBN = {9781538632840},
url = {http://dx.doi.org/10.1109/APUSNCURSINRSM.2017.8072246},
Abstract = {A novel computational technique is presented in this article
for enabling the estimation of both the localization of
radiating sources and their polarization states. To this
end, a radiating metasurface is conceived to multiplex the
polarization information received by the its aperture into a
single frequency domain signal, allowing for a massive
simplification of the architectures conventionally
implemented.},
Doi = {10.1109/APUSNCURSINRSM.2017.8072246},
Key = {fds332914}
}
@article{fds335055,
Author = {Suthakar, U and Magnoni, L and Smith, DR and Khan,
A},
Title = {Optimised lambda architecture for monitoring wlcg using
spark and spark streaming},
Journal = {2016 IEEE Nuclear Science Symposium, Medical Imaging
Conference and Room-Temperature Semiconductor Detector
Workshop, NSS/MIC/RTSD 2016},
Volume = {2017-January},
Publisher = {IEEE},
Year = {2017},
Month = {October},
ISBN = {9781509016426},
url = {http://dx.doi.org/10.1109/NSSMIC.2016.8069637},
Doi = {10.1109/NSSMIC.2016.8069637},
Key = {fds335055}
}
@article{fds335056,
Author = {Klugmann, D and Rea, S and Moyna, B and Parow-Souchon, K and Henry, M and Wang, H and Oldfield, M and Brewster, N and Hunyor, P and Merritt, M and Green, R and Smith, D and Davis, B and Obeed, A and Phillips, M and Beardsley, M and Hampton, J and Ellison, B and Howe, C and Burton, G and Marshall, A and Thomas, B and Brandt, M and Philipp, M and Sonnabend, G and Stangier, T and Hammett, R and Decoopman, T and Kangas, V and D'Addio,
S and Piironen, P},
Title = {Millimetre wave front end receivers for the MWS and MWI
instruments onboard MetOp-SG satellites},
Journal = {International Conference on Infrared, Millimeter, and
Terahertz Waves, IRMMW-THz},
Publisher = {IEEE},
Year = {2017},
Month = {October},
ISBN = {9781509060481},
url = {http://dx.doi.org/10.1109/IRMMW-THz.2017.8066886},
Abstract = {RAL Space and its project partner PRG are tasked with
providing space-qualified heterodyne receiver front-ends
operating between 165.5 GHz and 325 GHz for the Microwave
Sounder (MWS), the Microwave Imager (MWI) and the Ice Cloud
Imager (ICI) of the MetOp Second Generation (MetOp-SG)
series of satellites. The preliminary design of the receiver
front-ends is now complete. Extensive tests on performance
of the individual components, as well as of the assembled
breadboard versions of the receiver front-ends, have been
performed. The results and conclusions derived from these
tests will be presented.},
Doi = {10.1109/IRMMW-THz.2017.8066886},
Key = {fds335056}
}
@article{fds329822,
Author = {Pulido-Mancera, L and Imani, MF and Smith, DR},
Title = {Discrete dipole approximation for simulation of unusually
tapered leaky wave antennas},
Journal = {IEEE MTT-S International Microwave Symposium
Digest},
Pages = {409-412},
Publisher = {IEEE},
Year = {2017},
Month = {October},
ISBN = {9781509063604},
url = {http://dx.doi.org/10.1109/MWSYM.2017.8058581},
Abstract = {In this paper, Discrete Dipole Approximation (DDA) is
presented as a simulation tool for predicting the
electromagnetic properties of one dimensional metasurface
antennas and slotted waveguide antennas. The proposed method
is verified by demonstrating excellent agreement between DDA
predictions and that of a full-wave electromagnetic solver.
This technique is especially attractive since it allows us
to simulate and design metasurface antennas with unusual
tapering and irises with unconventional geometries (e.g.
metamaterial elements), in order to achieve the desired
radiation characteristics, such as beamwidth and sidelobe
level, while maintaining steering capabilities.},
Doi = {10.1109/MWSYM.2017.8058581},
Key = {fds329822}
}
@article{fds329821,
Author = {Fromenteze, T and Yurduseven, O and Boyarsky, M and Gollub, J and Marks,
DL and Smith, DR},
Title = {Computational polarimetric microwave imaging.},
Journal = {Optics express},
Volume = {25},
Number = {22},
Pages = {27488-27505},
Year = {2017},
Month = {October},
url = {http://dx.doi.org/10.1364/oe.25.027488},
Abstract = {We propose a polarimetric microwave imaging technique that
exploits recent advances in computational imaging. We
utilize a frequency-diverse cavity-backed metasurface,
allowing us to demonstrate high-resolution polarimetric
imaging using a single transceiver and frequency sweep over
the operational microwave bandwidth. The frequency-diverse
metasurface imager greatly simplifies the system
architecture compared with active arrays and other
conventional microwave imaging approaches. We further
develop the theoretical framework for computational
polarimetric imaging and validate the approach
experimentally using a multi-modal leaky cavity. The scalar
approximation for the interaction between the radiated waves
and the target- often applied in microwave computational
imaging schemes-is thus extended to retrieve the
susceptibility tensors, and hence provides additional
information about the targets. Computational polarimetry has
relevance for existing systems in the field that extract
polarimetric imagery, and particular for ground observation.
A growing number of short-range microwave imaging
applications can also notably benefit from computational
polarimetry, particularly for imaging objects that are
difficult to reconstruct when assuming scalar
estimations.},
Doi = {10.1364/oe.25.027488},
Key = {fds329821}
}
@article{fds329141,
Author = {Yurduseven, O and Fromenteze, T and Marks, DL and Gollub, JN and Smith,
DR},
Title = {Frequency-Diverse Computational Microwave Phaseless
Imaging},
Journal = {IEEE Antennas and Wireless Propagation Letters},
Volume = {16},
Pages = {2808-2811},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2017},
Month = {August},
url = {http://dx.doi.org/10.1109/LAWP.2017.2748139},
Abstract = {Phaseless imaging approaches provide a significant advantage
for systems where maintaining coherency during the
acquisition time is difficult. Here, we demonstrate a
phaseless, frequency-diverse, computational imaging system
that operates at K-band frequencies (17.5-26.5 GHz). The
system consists of a cavity-backed metasurface antenna
producing spatially diverse radiation patterns that vary as
a function of the driving frequency. The frequency-diverse
metasurface antenna can be used to form images at microwave
frequencies by collecting measurements at frequencies
sampled over the operational bandwidth, obviating the need
for either mechanically moving parts or phase-shifting
circuits. We show that high-fidelity images can be obtained
with the metasurface antenna using only the intensity of the
measurements by leveraging a sparse variant of the Wirtinger
Flow algorithm. In addition to the hardware simplification
achieved by using a frequency-diverse approach, we
demonstrate a significant reduction in the number of
measurements required to reconstruct a given number of
voxels for the phaseless imaging problem. This difference
from conventional phase retrieval techniques is achieved by
leveraging the sparsity concept, simplifying the complexity
of the imaging problem.},
Doi = {10.1109/LAWP.2017.2748139},
Key = {fds329141}
}
@article{fds328956,
Author = {Yurduseven, O and Smith, DR},
Title = {Dual-Polarization Printed Holographic Multibeam Metasurface
Antenna},
Journal = {IEEE Antennas and Wireless Propagation Letters},
Volume = {16},
Pages = {2738-2741},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2017},
Month = {August},
url = {http://dx.doi.org/10.1109/LAWP.2017.2743710},
Abstract = {Multibeam antennas have emerged as a promising concept for
applications where selective beam coverage is required.
Multibeam radiation can be achieved leveraging the concept
of metasurfaces, enabling the radiated wavefronts to be
tailored in an all-electronic manner, making reconfigurable
multibeam operation possible without the need for bulky
feeding structures or complex phase shifting circuits. Here
we demonstrate a simple, planar, printed-circuit-board-based
parallel-plate waveguide (PPW) holographic metasurface
antenna capable of producing dual-polarized multibeam
radiation patterns. The metasurface is synthesized using an
array of subwavelength slot-shaped unit cells (or irises)
coupling to a guided-mode reference wave launched into the
PPW using a single coaxial feed. As a design example, we
demonstrate numerically and experimentally a metasurface
antenna creating polarization-dependent multibeam radiation
patterns with three main lobes in azimuth and elevation
planes.},
Doi = {10.1109/LAWP.2017.2743710},
Key = {fds328956}
}
@article{fds328720,
Author = {Sleasman, T and Boyarsky, M and Imani, MF and Fromenteze, T and Gollub,
JN and Smith, DR},
Title = {Single-frequency microwave imaging with dynamic metasurface
apertures},
Journal = {Journal of the Optical Society of America B: Optical
Physics},
Volume = {34},
Number = {8},
Pages = {1713-1726},
Publisher = {The Optical Society},
Year = {2017},
Month = {August},
url = {http://dx.doi.org/10.1364/JOSAB.34.001713},
Abstract = {Conventional microwave imaging schemes, enabled by the
ubiquity of coherent sources and detectors, have
traditionally relied on frequency bandwidth to retrieve
range information, while using mechanical or electronic
beamsteering to obtain cross-range information. This
approach has resulted in complex and expensive hardware when
extended to large-scale systems with ultrawide bandwidth.
Relying on bandwidth can create difficulties in calibration,
alignment, and imaging of dispersive objects. We present an
alternative approach using electrically large, dynamically
reconfigurable, metasurface antennas that generate spatially
distinct radiation patterns as a function of tuning state.
The metasurface antenna consists of a waveguide feeding an
array of metamaterial radiators, each with properties that
can be modified by applying a voltage to diodes integrated
into the element. By deploying two of these apertures, one
as the transmitter and one as the receiver, we realize
sufficient spatial diversity to alleviate the dependence on
frequency bandwidth and obtain range and cross-range
information using measurements at a single frequency. We
experimentally demonstrate this proposal by using two 1D
dynamic metasurface apertures and reconstructing various 2D
scenes (range and cross-range). Furthermore, we modify a
conventional reconstruction method—the range migration
algorithm—to be compatible with such configurations,
resulting in an imaging system that is efficient in software
and hardware. The imaging scheme presented in this paper has
broad application to radio frequency imaging, including
security screening, through-wall imaging, biomedical
diagnostics, and synthetic aperture radar.},
Doi = {10.1364/JOSAB.34.001713},
Key = {fds328720}
}
@article{fds330948,
Author = {Pedross-Engel, A and Watts, CM and Smith, DR and Reynolds,
MS},
Title = {Enhanced resolution stripmap mode using dynamic metasurface
antennas},
Journal = {IEEE Transactions on Geoscience and Remote
Sensing},
Volume = {55},
Number = {7},
Pages = {3764-3772},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2017},
Month = {July},
url = {http://dx.doi.org/10.1109/TGRS.2017.2679438},
Abstract = {To maintain sufficient signal-To-noise ratio (SNR) for image
reconstruction and image interpretation, conventional
synthetic aperture radar (SAR) systems must trade off
resolution and scene size. This paper proposes a new SAR
mode of operation, which improves resolution while
maintaining good SNR and a large scene size. It leverages
the unique properties of dynamic metasurface antennas (MSAs)
to subsample a large virtual beamwidth utilizing multiple
small distinct antenna beams. Due to this parallelization in
scene sampling, the constraints on the azimuth sampling rate
can be relaxed while maintaining an aliasing-free cross
range. Due to the versatile properties of MSAs and their
cost effective manufacturing process, this paper proposes
SAR systems, which can obtain high resolution images over a
wide scene size with lower cost and complexity than
competing approaches. Point-spread functions and
proof-of-concept SAR simulations are shown to verify this
approach. In addition, laboratory experiments using a
commercial prototype MSA are presented, which show an
improvement of 62% in cross-range resolution of the proposed
approach, compared with the crossrange resolution of
stripmap mode SAR with the same aperture.},
Doi = {10.1109/TGRS.2017.2679438},
Key = {fds330948}
}
@article{fds327438,
Author = {Shin, D and Kim, J and Kim, C and Bae, K and Baek, S and Kang, G and Urzhumov,
Y and Smith, DR and Kim, K},
Title = {Scalable variable-index elasto-optic metamaterials for
macroscopic optical components and devices.},
Journal = {Nature communications},
Volume = {8},
Pages = {16090},
Year = {2017},
Month = {July},
url = {http://dx.doi.org/10.1038/ncomms16090},
Abstract = {Optical metamaterials with an artificial subwavelength
structure offer new approaches to implement advanced optical
devices. However, some of the biggest challenges associated
with the development of metamaterials in the visible
spectrum are the high costs and slow production speeds of
the nanofabrication processes. Here, we demonstrate a
macroscale (>35 mm) transformation-optics wave bender
(293 mm<sup>2</sup>) and Luneburg lens
(855 mm<sup>2</sup>) in the broadband white-light visible
wavelength range using the concept of elasto-optic
metamaterials that combines optics and solid mechanics. Our
metamaterials consist of mesoscopically homogeneous chunks
of bulk aerogels with superior, broadband optical
transparency across the visible spectrum and an adjustable,
stress-tuneable refractive index ranging from 1.43 down to
nearly the free space index (∼1.074). The experimental
results show that broadband light can be controlled and
redirected in a volume of >10<sup>5</sup>λ ×
10<sup>5</sup>λ × 10<sup>3</sup>λ, which enables natural
light to be processed directly by metamaterial-based optical
devices without any additional coupling components.},
Doi = {10.1038/ncomms16090},
Key = {fds327438}
}
@article{fds328104,
Author = {Yurduseven, O and Marks, DL and Fromenteze, T and Gollub, JN and Smith,
DR},
Title = {Millimeter-wave spotlight imager using dynamic holographic
metasurface antennas.},
Journal = {Optics express},
Volume = {25},
Number = {15},
Pages = {18230-18249},
Year = {2017},
Month = {July},
url = {http://dx.doi.org/10.1364/oe.25.018230},
Abstract = {Computational imaging systems leverage generalized
measurements to produce high-fidelity images, enabling novel
and often lower cost hardware platforms at the expense of
increased processing. However, obtaining full resolution
images across a large field-of-view (FOV) can lead to slow
reconstruction times, limiting system performance where
faster frame rates are desired. In many imaging scenarios,
the highest resolution is needed only in smaller subdomains
of interest within a scene, suggesting an aperture
supporting multiple modalities of image capture with
different resolutions can provide a path to system
optimization. We explore this concept in the context of
millimeter-wave imaging, presenting the design and
simulation of a single frequency (75 GHz), multistatic,
holographic spotlight aperture integrated into a K-band
(17.5-26.5 GHz), frequency-diverse imager. The spotlight
aperture - synthesized using an array of dynamically tuned,
holographic, metasurface antennas - illuminates a
constrained region-of-interest (ROI) identified from a
low-resolution image, extracting a high-fidelity image of
the constrained-ROI with a minimum number of measurement
modes. The designs of both the static, frequency-diverse
sub-aperture and the integrated dynamic spotlight aperture
are evaluated using simulation techniques developed for
large-scale synthetic apertures.},
Doi = {10.1364/oe.25.018230},
Key = {fds328104}
}
@article{fds335057,
Author = {Menard, JE and Allain, JP and Battaglia, DJ and Bedoya, F and Bell, RE and Belova, E and Berkery, JW and Boyer, MD and Crocker, N and Diallo, A and Ebrahimi, F and Ferraro, N and Fredrickson, E and Frerichs, H and Gerhardt, S and Gorelenkov, N and Guttenfelder, W and Heidbrink, W and Kaita, R and Kaye, SM and Kriete, DM and Kubota, S and Leblanc, BP and Liu,
D and Lunsford, R and Mueller, D and Myers, CE and Ono, M and Park, JK and Podesta, M and Raman, R and Reinke, M and Ren, Y and Sabbagh, SA and Schmitz, O and Scotti, F and Sechrest, Y and Skinner, CH and Smith, DR and Soukhanovskii, V and Stoltzfus-Dueck, T and Yuh, H and Wang, Z and Waters, I and Ahn, JW and Andre, R and Barchfeld, R and Beiersdorfer, P and Bertelli, N and Bhattacharjee, A and Brennan, D and Buttery, R and Capece, A and Canal, G and Canik, J and Chang, CS and Darrow, D and Delgado-Aparicio, L and Domier, C and Ethier, S and Evans, T and Ferron,
J and Finkenthal, M and Fonck, R and Gan, K and Gates, D and Goumiri, I and Gray, T and Hosea, J and Humphreys, D and Jarboe, T and Jardin, S and Jaworski, MA and Koel, B and Kolemen, E and Ku, S and La Haye and RJ and Levinton, F and Luhmann, N and Maingi, R and Maqueda, R and McKee, G and Meier, E and Myra, J and Perkins, R and Poli, F and Rhodes, T and Riquezes,
J and Rowley, C and Russell, D and Schuster, E and Stratton, B and Stutman,
D and Taylor, G and Tritz, K and Wang, W and Wirth, B and Zweben,
SJ},
Title = {Overview of NSTX Upgrade initial results and modelling
highlights},
Journal = {Nuclear Fusion},
Volume = {57},
Number = {10},
Pages = {102006-102006},
Publisher = {IOP Publishing},
Year = {2017},
Month = {June},
url = {http://dx.doi.org/10.1088/1741-4326/aa600a},
Abstract = {The National Spherical Torus Experiment (NSTX) has undergone
a major upgrade, and the NSTX Upgrade (NSTX-U) Project was
completed in the summer of 2015. NSTX-U first plasma was
subsequently achieved, diagnostic and control systems have
been commissioned, the H-mode accessed, magnetic error
fields identified and mitigated, and the first physics
research campaign carried out. During ten run weeks of
operation, NSTX-U surpassed NSTX record pulse-durations and
toroidal fields (TF), and high-performance ∼1 MA H-mode
plasmas comparable to the best of NSTX have been sustained
near and slightly above the n = 1 no-wall stability limit
and with H-mode confinement multiplier H98y,2 above 1.
Transport and turbulence studies in L-mode plasmas have
identified the coexistence of at least two ion-gyro-scale
turbulent micro-instabilities near the same radial location
but propagating in opposite (i.e. ion and electron
diamagnetic) directions. These modes have the
characteristics of ion-temperature gradient and
micro-tearing modes, respectively, and the role of these
modes in contributing to thermal transport is under active
investigation. The new second more tangential neutral beam
injection was observed to significantly modify the stability
of two types of Alfven eigenmodes. Improvements in offline
disruption forecasting were made in the areas of
identification of rotating MHD modes and other macroscopic
instabilities using the disruption event characterization
and forecasting code. Lastly, the materials analysis and
particle probe was utilized on NSTX-U for the first time and
enabled assessments of the correlation between boronized
wall conditions and plasma performance. These and other
highlights from the first run campaign of NSTX-U are
described.},
Doi = {10.1088/1741-4326/aa600a},
Key = {fds335057}
}
@article{fds326854,
Author = {Fromenteze, T and Boyarsky, M and Gollub, J and Sleasman, T and Imani,
M and Smith, DR},
Title = {Single-frequency near-field MIMO imaging},
Journal = {2017 11th European Conference on Antennas and Propagation,
EUCAP 2017},
Pages = {1415-1418},
Publisher = {IEEE},
Year = {2017},
Month = {May},
ISBN = {9788890701870},
url = {http://dx.doi.org/10.23919/EuCAP.2017.7928576},
Abstract = {A near-field radar imaging technique is presented based on
single-frequency measurements from a multiple-input
multiple-output (MIMO) array. Such arrays are able to fully
sample the κ-space of a region of interest. Advantageously,
both range and cross-range information can be reconstructed,
in contrast to conventional single-input multiple-output
systems which require wideband frequency illumination. A
theory of single frequency MIMO imaging is developed and
studied through numerical modeling and experimental
validation.},
Doi = {10.23919/EuCAP.2017.7928576},
Key = {fds326854}
}
@article{fds326736,
Author = {Gollub, JN and Yurduseven, O and Imani, MF and Odabasi, H and Sleasman,
T and Trofatter, KP and Boyarsky, M and Marks, DL and Smith,
DR},
Title = {Computational imaging using frequency-diverse
metasurfaces},
Journal = {2017 11th European Conference on Antennas and Propagation,
EUCAP 2017},
Pages = {1208-1211},
Publisher = {IEEE},
Year = {2017},
Month = {May},
ISBN = {9788890701870},
url = {http://dx.doi.org/10.23919/EuCAP.2017.7928774},
Abstract = {This paper summarizes the recent advances in using
frequency-diverse metasurfaces for computational imaging in
the microwave and millimeter wave regimes. Frequency-diverse
apertures are defined as structures that can generate
distinct radiation patterns as a function of frequency. Such
waveforms can multiplex a scene information into a set of
backscattered measurements, which can be decoded using
computational algorithms. In this manner, these apertures
can retrieve a scene's reflectivity map using a fast
frequency sweep (all-electronic operation), circumventing
the requirement for a mechanical scan or active circuit
components. We review recent advances in developing these
apertures and examine their performance in both simulation
and experimental settings. Finally, efforts to build large
apertures, which can image at the diffraction limit, are
discussed.},
Doi = {10.23919/EuCAP.2017.7928774},
Key = {fds326736}
}
@article{fds326737,
Author = {Yurduseven, O and Fromenteze, T and Gollub, JN and Marks, DL and Smith,
DR},
Title = {Computational frequency-diverse microwave imaging using an
air-filled cavity-backed antenna},
Journal = {2017 11th European Conference on Antennas and Propagation,
EUCAP 2017},
Pages = {3589-3592},
Publisher = {IEEE},
Year = {2017},
Month = {May},
ISBN = {9788890701870},
url = {http://dx.doi.org/10.23919/EuCAP.2017.7928063},
Abstract = {We demonstrate a frequency-diverse imaging system using an
air-filled cavity-backed antenna as a transceiver
(cavity-to-cavity system layout) for the K-band (17.5-26.5
GHz) frequency regime. Leveraging the computational imaging
concept, the frequency-diversity enables imaging in an
all-electronic manner, without the need for mechanical
raster scanning or active circuit components, minimizing the
data acquisition time and simplifying the system
architecture. It is shown that the proposed system is
capable of reconstructing good fidelity images in a
sub-second time frame, holding significant potential for
real-time imaging applications.},
Doi = {10.23919/EuCAP.2017.7928063},
Key = {fds326737}
}
@article{fds326738,
Author = {Yurduseven, O and Gollub, JN and Fromenteze, T and Marks, DL and Smith,
DR},
Title = {Optimization of frequency-diverse antennas for computational
imaging at microwave frequencies},
Journal = {2017 11th European Conference on Antennas and Propagation,
EUCAP 2017},
Pages = {1410-1414},
Publisher = {IEEE},
Year = {2017},
Month = {May},
ISBN = {9788890701870},
url = {http://dx.doi.org/10.23919/EuCAP.2017.7928064},
Abstract = {Frequency-diverse imaging is an all-electronic method,
capable of sampling the scene to be imaged without the need
for a mechanical scan or active circuit components. In order
to optimize the imaging characteristics, such as imaging
resolution and fidelity of the reconstructed images, the
antennas used within this scheme need to be optimized. It is
demonstrated that using a Mills-Cross iris distribution,
superior sampling of the Fourier components (wide support
extent and minimum sampling redundancy) can be achieved.
Using the optimized antennas, an experimental imaging system
is built, reconstructing a good quality image of a
cross-shaped target in less than 0.1 seconds.},
Doi = {10.23919/EuCAP.2017.7928064},
Key = {fds326738}
}
@article{fds326627,
Author = {Degiron, A and Vanwolleghem, M and Smith, DR},
Title = {Efficient finite element resolution of gyromagnetic and
gyroelectric nonreciprocal electromagnetic
problems.},
Journal = {Optics express},
Volume = {25},
Number = {10},
Pages = {11088-11102},
Year = {2017},
Month = {May},
url = {http://dx.doi.org/10.1364/oe.25.011088},
Abstract = {We present a rigorous derivation of the weak-form
formulation of the Helmholtz equation for electromagnetic
structures incorporating general nonreciprocal, dispersive
materials such as magnetized ferrites or magnetized
free-carrier plasmas. This formulation allows an efficient
self-consistent treatment using finite elements of a variety
of problems involving magnetic or magneto-optical materials
biased by an external DC field where the eigenmodes become
nonreciprocal or even unidirectional. The possibilities of
this method are illustrated with several examples of
TE-polarized modes at microwave frequencies and TM-polarized
modes at optical and infrared wavelengths.},
Doi = {10.1364/oe.25.011088},
Key = {fds326627}
}
@article{fds326628,
Author = {Boyarsky, M and Sleasman, T and Pulido-Mancera, L and Fromenteze, T and Pedross-Engel, A and Watts, CM and Imani, MF and Reynolds, MS and Smith,
DR},
Title = {Synthetic aperture radar with dynamic metasurface antennas:
a conceptual development.},
Journal = {Journal of the Optical Society of America. A, Optics, image
science, and vision},
Volume = {34},
Number = {5},
Pages = {A22-A36},
Year = {2017},
Month = {May},
url = {http://dx.doi.org/10.1364/josaa.34.000a22},
Abstract = {We investigate the application of dynamic metasurface
antennas (DMAs) to synthetic aperture radar (SAR) systems.
Metasurface antennas can generate a multitude of tailored
electromagnetic waveforms from a physical platform that is
low-cost, lightweight, and planar; these characteristics are
not readily available with traditional SAR technologies,
such as phased arrays and mechanically steered systems. We
show that electronically tuned DMAs can generate steerable,
directive beams for traditional stripmap and spotlight SAR
imaging modes. This capability eliminates the need for
mechanical gimbals and phase shifters, simplifying the
hardware architecture of a SAR system. Additionally, we
discuss alternative imaging modalities, including enhanced
resolution stripmap and diverse pattern stripmap, which can
achieve resolution on par with spotlight, while maintaining
a large region-of-interest, as possible with stripmap.
Further consideration is given to strategies for integrating
metasurfaces with chirped pulse RF sources. DMAs are poised
to propel SAR systems forward by offering a vast range of
capabilities from a significantly improved physical
platform.},
Doi = {10.1364/josaa.34.000a22},
Key = {fds326628}
}
@article{fds326240,
Author = {Marks, DL and Yurduseven, O and Smith, DR},
Title = {Cavity-backed metasurface antennas and their application to
frequency diversity imaging.},
Journal = {Journal of the Optical Society of America. A, Optics, image
science, and vision},
Volume = {34},
Number = {4},
Pages = {472-480},
Year = {2017},
Month = {April},
url = {http://dx.doi.org/10.1364/josaa.34.000472},
Abstract = {Frequency diversity antennas with spatially structured
radiation patterns reduce the reliance on actively switched
elements for beamforming which become increasingly expensive
and impractical as frequency increases. As the quality
factor Q of a frequency diverse antenna increases, the
antenna samples more spatial structure as the number of
unique radiated coded spatial patterns correspondingly
increases. Antennas that combine hollow cavities and
metamaterial apertures achieve both large fractional
bandwidth, in excess of 40%, and a high Q of 1600, so that
each antenna radiates over 640 unique coded patterns. As
compared to switched active antennas, such a passive antenna
replaces the 50 antennas and switches that would produce at
most (50/2)<sup>2</sup>=625 unique patterns. Furthermore,
the engineered metamaterial apertures enable a radiation
efficiency exceeding 60% to be achieved in a single desired
polarization. The theory of cavity-backed metasurface
antennas is explained, and frequency diverse imaging is
demonstrated with a pair of these antennas.},
Doi = {10.1364/josaa.34.000472},
Key = {fds326240}
}
@article{fds326241,
Author = {Bowen, PT and Baron, A and Smith, DR},
Title = {Effective-medium description of a metasurface composed of a
periodic array of nanoantennas coupled to a metallic
film},
Journal = {Physical Review A},
Volume = {95},
Number = {3},
Publisher = {American Physical Society (APS)},
Year = {2017},
Month = {March},
url = {http://dx.doi.org/10.1103/PhysRevA.95.033822},
Abstract = {We compute the reflectance properties of a metasurface that
consists of a doubly periodic array of patch nanoantennas
strongly coupled to a metallic film. Each plasmonic patch
antenna can be accurately modeled as a polarizable,
radiating, magnetic dipole. By accounting for interactions
amongst the dipoles, an equivalent surface polarizability
can be obtained, from which the effective surface impedance,
reflectivity, and other homogenized quantities of interest
can be obtained. When the metasurface is extremely close to
the metal film, the interaction between constituent dipoles
is dominated by surface plasmon mediation. We calculate
analytically the dipole interaction constant by explicitly
evaluating the infinite sum of fields from all the dipoles
in the lattice. While a single film-coupled nanoparticle
exhibits anomalous loss due to coupling to surface plasmons,
we find that for the lattice of dipoles, the radiation
reaction force due to the coupling to the surface plasmon
modes is exactly canceled by the interaction constant; the
lattice thereby conserves energy in the limit of zero Ohmic
loss. When Ohmic losses are present, absorption to surface
plasmons reemerges and can be compared with the losses to
radiation and Ohmic absorption in the metasurface.},
Doi = {10.1103/PhysRevA.95.033822},
Key = {fds326241}
}
@article{fds335058,
Author = {Ren, Y and Belova, E and Gorelenkov, N and Guttenfelder, W and Kaye, SM and Mazzucato, E and Peterson, JL and Smith, DR and Stutman, D and Tritz, K and Wang, WX and Yuh, H and Bell, RE and Domier, CW and Le Blanc,
BP},
Title = {Recent progress in understanding electron thermal transport
in NSTX},
Journal = {Nuclear Fusion},
Volume = {57},
Number = {7},
Pages = {072002-072002},
Publisher = {IOP Publishing},
Year = {2017},
Month = {March},
url = {http://dx.doi.org/10.1088/1741-4326/aa4fba},
Abstract = {The anomalous level of electron thermal transport inferred
in magnetically confined configurations is one of the most
challenging problems for the ultimate realization of fusion
power using toroidal devices: tokamaks, spherical tori and
stellarators. It is generally believed that plasma
instabilities driven by the abundant free energy in fusion
plasmas are responsible for the electron thermal transport.
The National Spherical Torus eXperiment (NSTX) (Ono et al
2000 Nucl. Fusion 40 557) provides a unique laboratory for
studying plasma instabilities and their relation to electron
thermal transport due to its low toroidal field, high plasma
beta, low aspect ratio and large E × B flow shear. Recent
findings on NSTX have shown that multiple instabilities are
required to explain observed electron thermal transport,
given the wide range of equilibrium parameters due to
different operational scenarios and radial regions in fusion
plasmas. Here we review the recent progresses in
understanding anomalous electron thermal transport in NSTX
and focus on mechanisms that could drive electron thermal
transport in the core region. The synergy between experiment
and theoretical/numerical modeling is essential to achieving
these progresses. The plans for newly commissioned
NSTX-Upgrade will also be discussed.},
Doi = {10.1088/1741-4326/aa4fba},
Key = {fds335058}
}
@article{fds335059,
Author = {Klugmann, D and Parow-Souchon, K and Smith, D and Davis, B and Ellison,
B and Alderman, B},
Title = {Optimisation of millimetre wave amplifiers for satellite
based radiometer},
Journal = {Proceedings of IEEE 9th UK-Europe-China Workshop on
Millimetre Waves and Terahertz Technologies, UCMMT
2016},
Pages = {82-83},
Publisher = {IEEE},
Year = {2017},
Month = {March},
ISBN = {9781509022755},
url = {http://dx.doi.org/10.1109/UCMMT.2016.7873969},
Abstract = {STFC / RAL Space has been involved in the development of an
extensive variety of satellite mission payloads operating
across a wide range of the electromagnetic spectrum. The RAL
Space Millimetre-wave Technology Group (MMTG) has undertaken
the development of instrumentation in support of spaceborne
earth observation. Most recently, the MMTG is contributing
towards a next generation of weather monitoring satellites
that will utilise state-of-the-art low-noise amplifier (LNA)
technology as the first reception stage of heterodyne
receivers. This contribution describes the performance
optimisation of an LNA used in a 183GHz receiver chain.
Device optimisation includes variation in impedance
transformation between waveguide and LNA millimetre-wave
integrated circuit (MMIC), and under different MMIC DC bias
conditions, to achieve required performance. Extensive and
accurate LNA measurements have been made and, in addition to
the optimisation procedures used, example results will be
presented, described and discussed.},
Doi = {10.1109/UCMMT.2016.7873969},
Key = {fds335059}
}
@article{fds335060,
Author = {Metcalfe, A and Fern, GR and Hobson, PR and Ireland, T and Salimian, A and Silver, J and Smith, DR and Lefeuvre, G and Saenger,
R},
Title = {Development of high temperature, radiation hard detectors
based on diamond},
Journal = {Nuclear Instruments and Methods in Physics Research, Section
A: Accelerators, Spectrometers, Detectors and Associated
Equipment},
Volume = {845},
Pages = {128-131},
Publisher = {Elsevier BV},
Year = {2017},
Month = {February},
url = {http://dx.doi.org/10.1016/j.nima.2016.06.091},
Abstract = {Single crystal CVD diamond has many desirable properties
compared to current, well developed, detector materials;
exceptional radiation, chemical and physical hardness,
chemical inertness, low Z (close to human tissue, good for
dosimetry), wide bandgap and an intrinsic pathway to fast
neutron detection through the 12C(n,α)9Be reaction. However
effective exploitation of these properties requires
development of a suitable metallisation scheme to give
stable contacts for high temperature applications. To best
utilise available processing techniques to optimise sensor
response through geometry and conversion media
configurations, a reliable model is required. This must
assess the performance in terms of spectral response and
overall efficiency as a function of detector and converter
geometry. The same is also required for proper
interpretation of experimental data. Sensors have been
fabricated with varying metallisation schemes indented to
permit high temperature operation; Present test results
indicate that viable fabrication schemes for high
temperature contacts have been developed and present
modelling results, supported by preliminary data from
partners indicate simulations provide a useful
representation of response.},
Doi = {10.1016/j.nima.2016.06.091},
Key = {fds335060}
}
@article{fds324875,
Author = {Gollub, JN and Yurduseven, O and Trofatter, KP and Arnitz, D and F
Imani, M and Sleasman, T and Boyarsky, M and Rose, A and Pedross-Engel,
A and Odabasi, H and Zvolensky, T and Lipworth, G and Brady, D and Marks,
DL and Reynolds, MS and Smith, DR},
Title = {Large Metasurface Aperture for Millimeter Wave Computational
Imaging at the Human-Scale.},
Journal = {Scientific reports},
Volume = {7},
Pages = {42650},
Year = {2017},
Month = {February},
url = {http://dx.doi.org/10.1038/srep42650},
Abstract = {We demonstrate a low-profile holographic imaging system at
millimeter wavelengths based on an aperture composed of
frequency-diverse metasurfaces. Utilizing measurements of
spatially-diverse field patterns, diffraction-limited images
of human-sized subjects are reconstructed. The system is
driven by a single microwave source swept over a band of
frequencies (17.5-26.5 GHz) and switched between a
collection of transmit and receive metasurface panels. High
fidelity image reconstruction requires a precise model for
each field pattern generated by the aperture, as well as the
manner in which the field scatters from objects in the
scene. This constraint makes scaling of computational
imaging systems inherently challenging for electrically
large, coherent apertures. To meet the demanding
requirements, we introduce computational methods and
calibration approaches that enable rapid and accurate
imaging performance.},
Doi = {10.1038/srep42650},
Key = {fds324875}
}
@article{fds324876,
Author = {Watts, CM and Pedross-Engel, A and Smith, DR and Reynolds,
MS},
Title = {X-band SAR imaging with a liquid-crystal-based dynamic
metasurface antenna},
Journal = {Journal of the Optical Society of America B: Optical
Physics},
Volume = {34},
Number = {2},
Pages = {300-306},
Publisher = {The Optical Society},
Year = {2017},
Month = {February},
url = {http://dx.doi.org/10.1364/JOSAB.34.000300},
Abstract = {Synthetic aperture radar (SAR) synthesizes a large effective
aperture via coherent processing of multiple measurements
taken from a moving platform. We present an approach for SAR
imaging using an X-band (10-13.7 GHz) dynamic metasurface
antenna (MSA). This newly developed antenna has over 6000
liquid-crystal-switched radiating elements that cover a
circular area with an approximate diameter of 0.45 m. The
MSA's main beam can be steered electronically to spherical
angles of up to ±70°. To the best of our knowledge, we
present the first-reported laboratory-scale imaging
experiments with a liquid-crystal-switched MSA. We leverage
the beam-steering capabilities of the MSA in a spotlight SAR
mode to achieve a measured cross-range resolution of 1.6 cm,
a 62% improvement over the 4.2 cm cross-range resolution
achieved with the same aperture without the
metasurface-enabled beam steering. The dynamic MSA offers
the superior image resolution of a beam-steering device
without the hardware burden of conventional phased array
antennas.},
Doi = {10.1364/JOSAB.34.000300},
Key = {fds324876}
}
@article{fds322740,
Author = {Stewart, JW and Akselrod, GM and Smith, DR and Mikkelsen,
MH},
Title = {Toward Multispectral Imaging with Colloidal Metasurface
Pixels.},
Journal = {Advanced materials (Deerfield Beach, Fla.)},
Volume = {29},
Number = {6},
Year = {2017},
Month = {February},
url = {http://dx.doi.org/10.1002/adma.201602971},
Abstract = {Multispectral colloidal metasurfaces are fabricated that
exhibit greater than 85% absorption and ≈100 nm linewidths
by patterning film-coupled nanocubes in pixels using a
fusion of bottom-up and top-down fabrication techniques over
wafer-scale areas. With this technique, the authors realize
a multispectral pixel array consisting of six resonances
between 580 and 1125 nm and reconstruct an RGB image with
9261 color combinations.},
Doi = {10.1002/adma.201602971},
Key = {fds322740}
}
@article{fds335061,
Author = {Metcalfe, A and Fern, GR and Hobson, PR and Smith, DR and Lefeuvre, G and Saenger, R},
Title = {Diamond based detectors for high temperature, high radiation
environments},
Journal = {Journal of Instrumentation},
Volume = {12},
Number = {1},
Pages = {C01066-C01066},
Publisher = {IOP Publishing},
Year = {2017},
Month = {January},
url = {http://dx.doi.org/10.1088/1748-0221/12/01/C01066},
Abstract = {Single crystal CVD diamond has many desirable properties as
a radiation detector; exceptional radiation hardness and
physical hardness, chemical inertness, low Z (close to human
tissue, good for dosimetry and transmission mode
applications), wide bandgap (high temperature operation with
low noise and solar blind), an intrinsic pathway to fast
neutron detection through the 12C(n,α)9Be reaction. This
combination of radiation hardness, temperature tolerance and
ability to detect mixed radiation types with a single sensor
makes diamond particularly attractive as a detector material
for harsh environments such as nuclear power station
monitoring (fission and fusion) and oil well logging.
Effective exploitation of these properties requires the
development of a metallisation scheme to give contacts that
remain stable over extended periods at elevated temperatures
(up to 250°C in this instance). Due to the cost of the
primary detector material, computational modelling is
essential to best utilise the available processing methods
for optimising sensor response through geometry and
conversion media configurations and to fully interpret
experimental data. Monte Carlo simulations of our diamond
based sensor have been developed, using MCNP6 and FLUKA2011,
assessing the sensor performance in terms of spectral
response and overall efficiency as a function of the
detector and converter geometry. Sensors with varying
metallisation schemes for high temperature operation have
been fabricated at Brunel University London and by Micron
Semiconductor Limited. These sensors have been tested under
a varied set of conditions including irradiation with fast
neutrons and alpha particles at high temperatures. The
presented study indicates that viable metallisation schemes
for high temperature contacts have been successfully
developed and the modelling results, supported by
preliminary experimental data from partners, indicate that
the simulations provide a reasonable representation of
detector response.},
Doi = {10.1088/1748-0221/12/01/C01066},
Key = {fds335061}
}
@article{fds330887,
Author = {Smith, DR and Gowda, VR and Yurduseven, O and Larouche, S and Lipworth,
G and Urzhumov, Y and Reynolds, MS},
Title = {An analysis of beamed wireless power transfer in the Fresnel
zone using a dynamic, metasurface aperture},
Journal = {Journal of Applied Physics},
Volume = {121},
Number = {1},
Pages = {014901-014901},
Publisher = {AIP Publishing},
Year = {2017},
Month = {January},
url = {http://dx.doi.org/10.1063/1.4973345},
Abstract = {Wireless power transfer (WPT) has been an active topic of
research, with a number of WPT schemes implemented in the
near-field (coupling) and far-field (radiation) regimes.
Here, we consider a beamed WPT scheme based on a dynamically
reconfigurable source aperture transferring power to
receiving devices within the Fresnel region. In this
context, the dynamic aperture resembles a reconfigurable
lens capable of focusing power to a well-defined spot, whose
dimension can be related to a point spread function. The
necessary amplitude and phase distribution of the field
imposed over the aperture can be determined in a holographic
sense, by interfering a hypothetical point source located at
the receiver location with a plane wave at the aperture
location. While conventional technologies, such as phased
arrays, can achieve the required control over phase and
amplitude, they typically do so at a high cost;
alternatively, metasurface apertures can achieve dynamic
focusing with potentially lower cost. We present an initial
tradeoff analysis of the Fresnel region WPT concept assuming
a metasurface aperture, relating the key parameters such as
spot size, aperture size, wavelength, and focal distance, as
well as reviewing system considerations such as the
availability of sources and power transfer efficiency. We
find that approximate design formulas derived from the
Gaussian optics approximation provide useful estimates of
system performance, including transfer efficiency and
coverage volume. The accuracy of these formulas is confirmed
through numerical studies.},
Doi = {10.1063/1.4973345},
Key = {fds330887}
}
@article{fds325393,
Author = {Nashad, F and Foti, S and Smith, D and Elsdon, M and Yurduseven,
O},
Title = {Development of transparent patch antenna element integrated
with solar cells for Ku-band satellite applications},
Journal = {2016 Loughborough Antennas and Propagation Conference, LAPC
2016},
Publisher = {IEEE},
Year = {2017},
Month = {January},
ISBN = {9781509007820},
url = {http://dx.doi.org/10.1109/LAPC.2016.7807579},
Abstract = {In this paper, a design of broadband compact microstrip
meshed patch antenna integrated with solar cells for Ku-band
satellite applications is presented. A Plexiglas transparent
substrate is also employed to enable the light to pass
through with high efficiency to illuminate the solar panel
cells while the RF performance is maintained with minimal
degradation. This meshed patch antenna for two-way satellite
internet and TV applications at remote areas, covering the
communications frequency range from 11.7GHz to 12.22GHz
(downlink) and 14.0GHz to 14.5GHz (uplink) bands allocated
by the ITU to the Regions 1 and 2. The effect of replacing
the solid elements of a microwave suspended patch antenna
with meshed element is examined. A compact flat meshed
element is obtained and simulated in CST Microwave Studio
and achieved the broadband width of 500 MHz in both portions
and the nominal element gain is 7.47dBi downlink and 8.51
dBi uplink, suffering only by 0.23 dBi and 0.14 dBi
respectively, comparing to the original suspended solid
patch antenna design. The visible light transmission is
found at normal incidence and an oblique angle to be
approximately 87% and 80%, respectively.},
Doi = {10.1109/LAPC.2016.7807579},
Key = {fds325393}
}
@article{fds327443,
Author = {Pulido Mancera and L and Fromenteze, T and Sleasman, T and Boyarsky, M and Imani, MF and Reynolds, MS and Smith, DR},
Title = {Adapting range migration techniques for imaging with
metasurface antennas: Analysis and limitations},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {10201},
Publisher = {SPIE},
Year = {2017},
Month = {January},
ISBN = {9781510609037},
url = {http://dx.doi.org/10.1117/12.2262906},
Abstract = {Dynamic metasurface antennas are planar structures that
exhibit remarkable capabilities in controlling
electromagnetic wave-fronts, advantages which are
particularly attractive for microwave imaging. These
antennas exhibit strong frequency dispersion and produce
diverse radiation patterns. Such behavior presents unique
challenges for integration with conventional imaging
algorithms. We analyze an adapted version of the range
migration algorithm (RMA) for use with dynamic metasurfaces
in image reconstruction. Focusing on the the proposed
pre-processing step, that ultimately allows a fast
processing of the backscattered signal in the spatial
frequency domain from which the fast Fourier transform can
efficiently reconstruct the scene. Numerical studies
illustrate imaging performance using both conventional
methods and the adapted RMA, demonstrating that the RMA can
reconstruct images with comparable quality in a fraction of
the time. In this paper, we demonstrate the capabilities of
the algorithm as a fast reconstruction tool, and we analyze
the limitations of the presented technique in terms of image
quality.},
Doi = {10.1117/12.2262906},
Key = {fds327443}
}
@article{fds327442,
Author = {Sleasman, T and Imani, MF and Boyarsky, M and Pulido-Mancera, L and Reynolds, MS and Smith, DR},
Title = {Reconfigurable metasurface aperture for security screening
and microwave imaging},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {10189},
Publisher = {SPIE},
Year = {2017},
Month = {January},
ISBN = {9781510608795},
url = {http://dx.doi.org/10.1117/12.2262848},
Abstract = {Microwave imaging systems have seen growing interest in
recent decades for applications ranging from security
screening to space/earth observation. However, hardware
architectures commonly used for this purpose have not seen
drastic changes. With the advent of metamaterials a wealth
of opportunities have emerged for honing metasurface
apertures for microwave imaging systems. Recent thrusts have
introduced dynamic reconfigurability directly into the
aperture layer, providing powerful capabilities from a
physical layer with considerable simplicity. The waveforms
generated from such dynamic metasurfaces make them suitable
for application in synthetic aperture radar (SAR) and, more
generally, computational imaging. In this paper, we
investigate a dynamic metasurface aperture capable of
performing microwave imaging in the K-band (17.5-26.5 GHz).
The proposed aperture is planar and promises an inexpensive
fabrication process via printed circuit board techniques.
These traits are further augmented by the tunability of
dynamic metasurfaces, which provides the dexterity necessary
to generate field patterns ranging from a sequence of
steered beams to a series of uncorrelated radiation
patterns. Imaging is experimentally demonstrated with a
voltage-Tunable metasurface aperture. We also demonstrate
the aperture's utility in real-Time measurements and perform
volumetric SAR imaging. The capabilities of a prototype are
detailed and the future prospects of general dynamic
metasurface apertures are discussed.},
Doi = {10.1117/12.2262848},
Key = {fds327442}
}
@article{fds327441,
Author = {Boyarsky, M and Sleasman, T and Pulido-Mancera, L and Imani, MF and Reynolds, MS and Smith, DR},
Title = {Alternative synthetic aperture radar (SAR) modalities using
a 1D dynamic metasurface antenna},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {10189},
Publisher = {SPIE},
Year = {2017},
Month = {January},
ISBN = {9781510608795},
url = {http://dx.doi.org/10.1117/12.2262855},
Abstract = {Synthetic aperture radar (SAR) systems conventionally rely
on mechanically-Actuated reflector dishes or large phased
arrays for generating steerable directive beams. While these
systems have yielded high-resolution images, the hardware
suffers from considerable weight, high cost, substantial
power consumption, and moving parts. Since these
disadvantages are particularly relevant in airborne and
spaceborne systems, a flat, lightweight, and low-cost
solution is a sought-After goal. Dynamic metasurface
antennas have emerged as a recent technology for generating
waveforms with desired characteristics. Metasurface antennas
consist of an electrically-large waveguide loaded with
numerous subwavelength radiators which selectively leak
energy from a guided wave into free space to form various
radiation patterns. By tuning each radiating element, we can
modulate the aperture's overall radiation pattern to
generate steered directive beams, without moving parts or
phase shifters. Furthermore, by using established
manufacturing methods, these apertures can be made to be
lightweight, low-cost, and planar, while maintaining high
performance. In addition to their hardware benefits, dynamic
metasurfaces can leverage their dexterity and high switching
speeds to enable alternative SAR modalities for improved
performance. In this work, we briefly discuss how dynamic
metasurfaces can conduct existing SAR modalities with
similar performance as conventional systems from a
significantly simpler hardware platform. We will also
describe two additional modalities which may achieve
improved performance as compared to traditional modalities.
These modalities, enhanced resolution stripmap and diverse
pattern stripmap, offer the ability to circumvent the
trade-off between resolution and region-of-interest size
that exists within stripmap and spotlight. Imaging results
with a simulated dynamic metasurface verify the benefits of
these modalities and a discussion of implementation
considerations and noise effects is also included.
Ultimately, the hardware gains coupled with the additional
modalities well-suited to dynamic metasurface antennas has
poised them to propel the SAR field forward and open the
door to exciting opportunities.},
Doi = {10.1117/12.2262855},
Key = {fds327441}
}
@article{fds327440,
Author = {Smith, DR and Reynolds, MS and Gollub, JN and Marks, DL and Imani, MF and Yurduseven, O and Arnitz, D and Pedross-Engel, A and Sleasman, T and Trofatter, P and Boyarsky, M and Rose, A and Odabasi, H and Lipworth,
G},
Title = {Security screening via computational imaging using
frequency-diverse metasurface apertures},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {10189},
Publisher = {SPIE},
Year = {2017},
Month = {January},
ISBN = {9781510608795},
url = {http://dx.doi.org/10.1117/12.2262899},
Abstract = {Computational imaging is a proven strategy for obtaining
high-quality images with fast acquisition rates and simpler
hardware. Metasurfaces provide exquisite control over
electromagnetic fields, enabling the radiated field to be
molded into unique patterns. The fusion of these two
concepts can bring about revolutionary advances in the
design of imaging systems for security screening. In the
context of computational imaging, each field pattern serves
as a single measurement of a scene; imaging a scene can then
be interpreted as estimating the reflectivity distribution
of a target from a set of measurements. As with any
computational imaging system, the key challenge is to arrive
at a minimal set of measurements from which a
diffraction-limited image can be resolved. Here, we show
that the information content of a frequency-diverse
metasurface aperture can be maximized by design, and used to
construct a complete millimeter-wave imaging system spanning
a 2 m by 2 m area, consisting of 96 metasurfaces, capable of
producing diffraction-limited images of human-scale targets.
The metasurfacebased frequency-diverse system presented in
this work represents an inexpensive, but tremendously
flexible alternative to traditional hardware paradigms,
offering the possibility of low-cost, real-Time, and
ubiquitous screening platforms.},
Doi = {10.1117/12.2262899},
Key = {fds327440}
}
@article{fds326739,
Author = {Stewart, JW and Akselrod, GM and Smith, DR and Mikkelsen,
MH},
Title = {Multispectral metasurface absorbers for optoelectronic
devices},
Journal = {Optics InfoBase Conference Papers},
Volume = {Part F41-CLEO_SI 2017},
Publisher = {OSA},
Year = {2017},
Month = {January},
ISBN = {9781943580279},
url = {http://dx.doi.org/10.1364/CLEO_SI.2017.SM3N.4},
Abstract = {We demonstrate multispectral metasurfaces over wafer-scale
areas exhibiting greater than 85 percent absorption, ~100 nm
linewidths from 580-1125 nm by patterning plasmonic
resonators in micron-scale pixels using a fusion of
bottom-up and top-down fabrication techniques.},
Doi = {10.1364/CLEO_SI.2017.SM3N.4},
Key = {fds326739}
}
@article{fds328954,
Author = {Zvolensky, T and Gollub, JN and Marks, DL and Smith,
DR},
Title = {Design and Analysis of a W-Band Metasurface-Based
Computational Imaging System},
Journal = {IEEE Access},
Volume = {5},
Pages = {9911-9918},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2017},
Month = {January},
url = {http://dx.doi.org/10.1109/ACCESS.2017.2703860},
Abstract = {We design and numerically analyze a coherent computational
imaging system that utilizes a sparse detector array of
planar, frequency-diverse, metasurface antennas designed to
operate over the W-band frequency range (75-110 GHz). Each
of the metasurface antennas consists of a parallel plate
waveguide, into which a center coaxial feed is inserted into
the lower plate, launching a cylindrical guided wave. A
dense array of metamaterial resonators patterned into the
upper plate couples energy from the waveguide to free space
radiative modes. The resonance frequency of each element,
determined by its specific geometry, can be positioned
anywhere within the W-band. The geometry of each element is
chosen to produce a resonance frequency selected randomly
from the W-band. Since a random subset of elements is
resonant at any given frequency, the metasurface antenna
forms a sequence of spatially diverse radiation patterns as
a function of the excitation frequency. We analyze the
metasurface aperture as an imaging system, optimizing key
parameters relevant to image quality and resolution,
including: aperture size; density and quality factor of the
metamaterial resonators; number of detectors and their
spatial distribution; bandwidth; and the number of frequency
samples. A point-spread function analysis is used to compare
the metasurface imager with traditional synthetic aperture
radar. The singular value spectrum corresponding to the
system transfer function and the mean-square-error
associated with reconstructed images are both metrics used
to characterize the system performance.},
Doi = {10.1109/ACCESS.2017.2703860},
Key = {fds328954}
}
@article{fds329140,
Author = {Yurduseven, O and Marks, DL and Gollub, JN and Smith,
DR},
Title = {Design and Analysis of a Reconfigurable Holographic
Metasurface Aperture for Dynamic Focusing in the Fresnel
Zone},
Journal = {IEEE Access},
Volume = {5},
Pages = {15055-15065},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2017},
Month = {January},
url = {http://dx.doi.org/10.1109/ACCESS.2017.2712659},
Abstract = {We present numerical simulations of the near-field focusing
capabilities of a dynamically reconfigurable holographic
metasurface aperture. The aperture consists of a
parallel-plate waveguide in which the upper plate is
patterned with a number of metamaterial irises that can be
dynamically switched between radiating (ON) and
non-radiating (OFF) states. A cylindrically symmetric
waveguide mode, excited by a coaxial probe in the center of
the lower plate, serves to excite the radiating irises,
forming a focused spot in the radiating near-field (or
Fresnel zone). The layout of the metamaterial elements and
their tuning states is determined using holographic design
principles, in which the interference pattern of the
waveguide (or reference) mode and the desired radiated field
pattern leads to the required phase distribution over the
surface of the aperture. We also develop an analytical model
of the aperture to confirm the numerical simulations, and to
illustrate the advantage of the guided-mode as the reference
wave versus a plane-wave. We further leverage this
analytical model to analyze the diffracted order
characteristics of the holographic metasurface aperture,
showing high-fidelity focusing patterns even for difficult
focusing scenarios across the entire investigated
field-of-view.},
Doi = {10.1109/ACCESS.2017.2712659},
Key = {fds329140}
}
@article{fds330949,
Author = {Thornton, J and Smith, D},
Title = {Feed and loss effects in spherical lens antennas for
satellite communications},
Journal = {International Journal of RF and Microwave Computer-Aided
Engineering},
Volume = {27},
Number = {1},
Pages = {e21036-e21036},
Publisher = {WILEY},
Year = {2017},
Month = {January},
url = {http://dx.doi.org/10.1002/mmce.21036},
Abstract = {The hemispherical lens antenna is a candidate for satellite
communications-on-the-move, offering good scan performance
in a reduced height. A short focal length minimizes height
but presents challenges in illuminating the lens. Aperture
efficiency is dominated by both the primary feed and
dielectric loss. Feed effects are investigated in a
threefold approach: spherical wave theory, commercial
solver, and measurements. Gain and loss in a 432 mm diameter
polyethylene/polystyrene lens are also measured. Gain for a
waveguide-fed array of two lenses is 36.3, 38.8, and 41.1
dBi, respectively, at 12.5, 20, and 30 GHz. The performance
of a proposed four-element array of equivalent area is then
estimated.},
Doi = {10.1002/mmce.21036},
Key = {fds330949}
}
@article{fds327439,
Author = {Sleasman, T and Imani, MF and Yurduseven, O and Trofatter, KP and Gowda,
VR and Marks, DL and Gollub, JN and Smith, DR},
Title = {Near field scan alignment procedure for electrically large
apertures},
Journal = {IEEE Transactions on Antennas and Propagation},
Volume = {65},
Number = {6},
Pages = {3257-3262},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2017},
Month = {January},
url = {http://dx.doi.org/10.1109/TAP.2017.2691465},
Abstract = {Computational imaging at microwave frequencies has gained
traction due to its potential for obtaining high-quality
images with fast acquisition rates. Complex and diverse
radiation patterns form the cornerstone of this approach.
Electrically large antennas, such as modemixing cavities and
metamaterial apertures, have proven to be effective
platforms for generating such waveforms. Due to the complex
nature of these antennas, near field scanning is often
required to characterize their radiation patterns. However,
accurate knowledge of the produced waveforms' spatial
distribution, with respect to the physical position of the
antenna, is imperative. This relies on precise alignment
between the antenna and the near field scan stage during the
characterization process-a requirement that is especially
cumbersome to achieve when operating at high frequencies. We
present an effective method to address this problem; by
introducing RF markers into the antenna the position of the
antenna under test within the near field scanning setup can
be obtained directly from the measurements. The proposed
method is experimentally verified through comparison with
measurements made using optical photogrammetry. The proposed
process will find application in the alignment of
computational and multistatic imaging systems, commonly used
in security screening and threat detection, as well as in
tiled electrically large antenna structures.},
Doi = {10.1109/TAP.2017.2691465},
Key = {fds327439}
}
@article{fds326242,
Author = {Zhu, R and Lipworth, G and Zvolensky, T and Smith, DR and Marks,
DL},
Title = {Versatile Manufacturing of Split-Block Microwave Devices
Using Rapid Prototyping and Electroplating},
Journal = {IEEE Antennas and Wireless Propagation Letters},
Volume = {16},
Pages = {157-160},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2017},
Month = {January},
url = {http://dx.doi.org/10.1109/LAWP.2016.2563398},
Abstract = {We present a novel method of rapid prototyping waveguide and
antenna using plating on plastic technique. The part is
created by high-precision three-dimensional printing and
plated with copper using both electroless plating and
electroplating. The performance is comparable to
industry-made waveguides and antennas, but the time and cost
for creating these parts are largely reduced.},
Doi = {10.1109/LAWP.2016.2563398},
Key = {fds326242}
}
@article{fds325783,
Author = {Marks, DL and Yurduseven, O and Smith, DR},
Title = {Fourier Accelerated Multistatic Imaging: A Fast
Reconstruction Algorithm for Multiple-Input-Multiple-Output
Radar Imaging},
Journal = {IEEE Access},
Volume = {5},
Pages = {1796-1809},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2017},
Month = {January},
url = {http://dx.doi.org/10.1109/ACCESS.2017.2661068},
Abstract = {Multiple-input-multiple-output (MIMO) radar image processing
presents problems difficult to address by modifying
conventional monostatic radar methods as Fourier range
migration. When the distance between the transmitter and
receiver is comparable to the target size, the single phase
center approximation is not accurate. Furthermore, if the
antenna radiation pattern significantly deviates from a
spherical wave, the symmetries assumed in most range
migration techniques are violated. We present a rapid
Fourier-based MIMO reconstruction called Fourier accelerated
multistatic imaging (FAMI) suitable for massively parallel
computation that accounts for frequency-dependent radiation
patterns, does not require the single phase center
approximation, and is able to dynamically adapt to different
target support volume shapes. FAMI is especially suitable
for frequency-diversity antenna systems that use spectrally
modulated coded spatial radiation patterns.},
Doi = {10.1109/ACCESS.2017.2661068},
Key = {fds325783}
}
@article{fds322742,
Author = {Zecca, R and Bowen, PT and Smith, DR and Larouche,
S},
Title = {Transformation-optics simulation method for stimulated
Brillouin scattering},
Journal = {Physical Review A},
Volume = {94},
Number = {6},
Publisher = {American Physical Society (APS)},
Year = {2016},
Month = {December},
url = {http://dx.doi.org/10.1103/PhysRevA.94.063818},
Abstract = {We develop an approach to enable the full-wave simulation of
stimulated Brillouin scattering and related phenomena in a
frequency-domain, finite-element environment. The method
uses transformation-optics techniques to implement a
time-harmonic coordinate transform that reconciles the
different frames of reference used by electromagnetic and
mechanical finite-element solvers. We show how this strategy
can be successfully applied to bulk and guided systems,
comparing the results with the predictions of established
theory.},
Doi = {10.1103/PhysRevA.94.063818},
Key = {fds322742}
}
@article{fds322741,
Author = {Moradi, A and Akhlaghi, EA and Hajizedeh, F and Reihani,
SNS},
Title = {Digital holography based submicron thermometry.},
Journal = {Optics express},
Volume = {24},
Number = {25},
Pages = {28678-28685},
Publisher = {The Optical Society},
Year = {2016},
Month = {December},
url = {http://dx.doi.org/10.1364/oe.24.028678},
Abstract = {Here we introduce a phase-shifting digital holography-based
method to determine the temperature profile around an
irradiated (sub-)micron spherical bead. The method utilizes
a Mach-Zehnder interferometer implemented into an open setup
microscope. The results of irradiated gold spheres with
diameter of 400 nm and also silver-coated micron-sized
silica beads embedded in silicone oil are presented. We show
that the applied method is able to accurately determine the
surface temperature with accuracy of 1 °C. Our experimental
results perfectly confirm the theoretical prediction of
temperature profile around the irradiated
bead.},
Doi = {10.1364/oe.24.028678},
Key = {fds322741}
}
@article{fds335062,
Author = {Suthakar, U and Magnoni, L and Smith, DR and Khan, A and Andreeva,
J},
Title = {An efficient strategy for the collection and storage of
large volumes of data for computation},
Journal = {Journal of Big Data},
Volume = {3},
Number = {1},
Publisher = {Springer Nature},
Year = {2016},
Month = {December},
url = {http://dx.doi.org/10.1186/s40537-016-0056-1},
Abstract = {In recent years, there has been an increasing amount of data
being produced and stored, which is known as Big Data. The
social networks, internet of things, scientific experiments
and commercial services play a significant role in
generating a vast amount of data. Three main factors are
important in Big Data; Volume, Velocity and Variety. One
needs to consider all three factors when designing a
platform to support Big Data. The Large Hadron Collider
(LHC) particle accelerator at CERN consists of a number of
data-intensive experiments, which are estimated to produce a
volume of about 30 PB of data, annually. The velocity of
these data that are propagated will be extremely fast.
Traditional methods of collecting, storing and analysing
data have become insufficient in managing the rapidly
growing volume of data. Therefore, it is essential to have
an efficient strategy to capture these data as they are
produced. In this paper, a number of models are explored to
understand what should be the best approach for collecting
and storing Big Data for analytics. An evaluation of the
performance of full execution cycles of these approaches on
the monitoring of the Worldwide LHC Computing Grid (WLCG)
infrastructure for collecting, storing and analysing data is
presented. Moreover, the models discussed are applied to a
community driven software solution, Apache Flume, to show
how they can be integrated, seamlessly.},
Doi = {10.1186/s40537-016-0056-1},
Key = {fds335062}
}
@article{fds320767,
Author = {Sleasman, T and Imani, MF and Gollub, JN and Smith,
DR},
Title = {Microwave Imaging Using a Disordered Cavity with a
Dynamically Tunable Impedance Surface},
Journal = {Physical Review Applied},
Volume = {6},
Number = {5},
Publisher = {American Physical Society (APS)},
Year = {2016},
Month = {November},
url = {http://dx.doi.org/10.1103/PhysRevApplied.6.054019},
Abstract = {We perform microwave imaging using a dynamically
reconfigurable aperture based on a tunable disordered
cavity. The electrically large cavity is cubic with a
spherical deformation and supports a multitude of distinct
electromagnetic modes that vary as a function of excitation
frequency. With a set of irises introduced into one wall of
the cavity, the cavity modes couple to spatially distinct
radiative modes that vary as a function of the driving
frequency. To increase the diversity of the radiated fields,
we replace one of the cavity walls with a variable impedance
surface consisting of a set of varactor-populated mushroom
structures grouped into pixels. The reflection phase of each
pixel is independently changed with application of a voltage
bias, effectively altering the surface impedance. We
demonstrate high-fidelity imaging and examine the role of
the impedance-tunable boundary condition, revealing superior
performance in comparison with just frequency-diverse
measurements. We also demonstrate single-frequency imaging,
which can significantly reduce the demands on the required
microwave source. The dynamic cavity imager may find
relevance in security screening, through-wall imaging,
biomedical diagnostics, and radar applications.},
Doi = {10.1103/PhysRevApplied.6.054019},
Key = {fds320767}
}
@article{fds330950,
Author = {Pulido-Mancera, LM and Imani, MF and Smith, DR},
Title = {Discrete dipole approximation for the simulation of the edge
effects on metasurfaces},
Journal = {2016 IEEE Antennas and Propagation Society International
Symposium, APSURSI 2016 - Proceedings},
Pages = {107-108},
Publisher = {IEEE},
Year = {2016},
Month = {October},
ISBN = {9781509028863},
url = {http://dx.doi.org/10.1109/APS.2016.7695762},
Abstract = {A dipole-based simulation method is presented to study the
effects of edges on finite metasurfaces. This technique can
accurately account for the physical limitations associated
with fabrication and thereby leads to high fidelity
predictions needed in practical applications. Moreover, it
establishes a platform to improve the metasurface design
process, given the fact that no periodic boundary condition
is required and the interaction between different meta-atoms
within the surface is taken into account. This paper
presents the initial results of using this technique for a
finite lens, composed of split-ring-resonators. The dipole
moments are found and the far-field is computed and compared
with full-wave simulations.},
Doi = {10.1109/APS.2016.7695762},
Key = {fds330950}
}
@article{fds320768,
Author = {Yurduseven, O and Gollub, JN and Marks, DL and Smith,
DR},
Title = {Field repeatability in frequency diverse
imaging},
Journal = {2016 IEEE Antennas and Propagation Society International
Symposium, APSURSI 2016 - Proceedings},
Pages = {853-854},
Publisher = {IEEE},
Year = {2016},
Month = {October},
ISBN = {9781509028863},
url = {http://dx.doi.org/10.1109/APS.2016.7696135},
Abstract = {We consider multi-static imaging systems composed of
frequency-diverse transmitting antenna arrays (or
apertures). In these frequency diverse imaging modalities,
accurate near-field characterization of the antennas is
vital to achieving imaging. It is shown that considerable
simplification in system characterization can be achieved
without compromising the image quality when planar cavity
antennas are used, because their radiation characteristics
can be manufacture repeatable. In contrast, it is also
demonstrated that the increased complexity of antennas
utilizing sub-wavelength elements significantly reduces
fabrication tolerances, making it necessary to characterize
the metamaterial apertures individually.},
Doi = {10.1109/APS.2016.7696135},
Key = {fds320768}
}
@article{fds320769,
Author = {Yurduseven, O and Gollub, JN and Marks, DL and Smith,
DR},
Title = {Metallization of a 3D printed cavitiy for
imaging},
Journal = {2016 IEEE Antennas and Propagation Society International
Symposium, APSURSI 2016 - Proceedings},
Pages = {855-856},
Publisher = {IEEE},
Year = {2016},
Month = {October},
ISBN = {9781509028863},
url = {http://dx.doi.org/10.1109/APS.2016.7696136},
Abstract = {In this paper, we propose a metallized 3D printed cavity for
K-band imaging and investigate the effect of metallization
type on mode diversity and image reconstruction. The 3D
printed cavity acts as a frequency-diverse aperture and is
capable of imaging objects in an all-electronic manner
utilizing computational imaging techniques. We demonstrate
that metallization material choice can increase the mode
diversity by 90.8%, significantly improving
imaging.},
Doi = {10.1109/APS.2016.7696136},
Key = {fds320769}
}
@article{fds320770,
Author = {Sleasman, T and Imani, MF and Gollub, JN and Smith,
DR},
Title = {Toward a tunable mode-mixing cavity for computational
imaging},
Journal = {2016 IEEE Antennas and Propagation Society International
Symposium, APSURSI 2016 - Proceedings},
Pages = {1901-1902},
Publisher = {IEEE},
Year = {2016},
Month = {October},
ISBN = {9781509028863},
url = {http://dx.doi.org/10.1109/APS.2016.7696657},
Abstract = {A mode-mixing cavity, consisting of an electrically-large
rectangular cavity with one deformed corner, supports
distinct modes as a function of driving frequency.
Perforating one side of this cavity, the modes formed within
can be projected into an imaging domain, multiplexing the
scene's spatial content into backscattered signals that is
post-processed to obtain high-quality images. While this
device has shown great promise as a platform for
computational imaging at microwave frequencies, its premise
necessitates a large bandwidth, a requirement that
complicates circuit design and may not be readily available.
In this presentation, we propose and report preliminary
experimental results for a cavity containing a tunable
artificial impedance surface in one of its walls. By varying
the electromagnetic response of the cavity's boundary the
field distribution within the cavity can be altered, thus
generating distinct radiation patterns without a large
bandwidth.},
Doi = {10.1109/APS.2016.7696657},
Key = {fds320770}
}
@article{fds319556,
Author = {Imani, MF and Sleasman, T and Gollub, JN and Smith,
DR},
Title = {Analytical modeling of printed metasurface cavities for
computational imaging},
Journal = {Journal of Applied Physics},
Volume = {120},
Number = {14},
Pages = {144903-144903},
Publisher = {AIP Publishing},
Year = {2016},
Month = {October},
url = {http://dx.doi.org/10.1063/1.4964336},
Abstract = {We derive simple analytical expressions to model the
electromagnetic response of an electrically large printed
cavity. The analytical model is then used to develop printed
cavities for microwave imaging purposes. The proposed cavity
is excited by a cylindrical source and has boundaries formed
by subwavelength metallic cylinders (vias) placed at
subwavelength distances apart. Given their small size, the
electric currents induced on the vias are assumed to have no
angular dependence. Applying this approximation simplifies
the electromagnetic problem to a matrix equation which can
be solved to directly compute the electric current induced
on each via. Once the induced currents are known, the
electromagnetic field inside the cavity can be computed for
every location. We verify the analytical model by comparing
its prediction to full-wave simulations. To utilize this
cavity in imaging settings, we perforate one side of the
printed cavity with radiative slots such that they act as
the physical layer of a computational imaging system. An
analytical approximation for the slots is also developed,
enabling us to obtain estimates of the cavity performance in
imaging scenarios. This ability allows us to make informed
decisions on the design of the printed metasurface cavity.
The utility of the proposed model is further highlighted by
demonstrating high-quality experimental imaging; performance
metrics, which are consistent between theory and experiment,
are also estimated.},
Doi = {10.1063/1.4964336},
Key = {fds319556}
}
@article{fds319557,
Author = {Pulido-Mancera, L and Fromenteze, T and Sleasman, T and Boyarsky, M and Imani, MF and Reynolds, M and Smith, D},
Title = {Application of range migration algorithms to imaging with a
dynamic metasurface antenna},
Journal = {Journal of the Optical Society of America B: Optical
Physics},
Volume = {33},
Number = {10},
Pages = {2082-2092},
Publisher = {The Optical Society},
Year = {2016},
Month = {October},
url = {http://dx.doi.org/10.1364/JOSAB.33.002082},
Abstract = {Dynamic metasurface antennas are planar structures that
exhibit remarkable capabilities in controlling
electromagnetic wavefronts, advantages that are particularly
attractive for microwave imaging. These antennas exhibit
strong frequency dispersion and produce rapidly varying
radiation patterns. Such behavior presents unique challenges
for integration with conventional imaging algorithms. We
adapt the range migration algorithm (RMA) for use with
dynamic metasurfaces and propose a preprocessing step that
ultimately allows for expression of measurements in the
spatial frequency domain, from which the fast Fourier
transform can efficiently reconstruct the scene. Numerical
studies illustrate imaging performance using conventional
methods and the adapted RMA, demonstrating that the RMA can
reconstruct images with comparable quality in a fraction of
the time. The algorithm can be extended to a broad class of
complex antennas for application in synthetic aperture radar
and MIMO imaging.},
Doi = {10.1364/JOSAB.33.002082},
Key = {fds319557}
}
@article{fds319558,
Author = {Yurduseven, O and Gowda, VR and Gollub, JN and Smith,
DR},
Title = {Multistatic microwave imaging with arrays of planar
cavities},
Journal = {IET Microwaves, Antennas and Propagation},
Volume = {10},
Number = {11},
Pages = {1174-1181},
Publisher = {Institution of Engineering and Technology
(IET)},
Year = {2016},
Month = {August},
url = {http://dx.doi.org/10.1049/iet-map.2015.0836},
Abstract = {The authors present a multistatic imaging system at
microwave frequencies based on arrays of planar cavity
sub-apertures, or panels. The cavity imager consists of sets
of transmit and receive panels, loaded with radiating irises
distributed over the sub-apertures in an aperiodic pattern.
This frequency-diverse aperture produces distinct radiation
patterns as a function of frequency that encode scene
information onto a set of measurements, images are
subsequently reconstructed using computational imaging
approaches. Similar to previously reported computational
imaging systems, the cavity-based imager presents a simple
system architecture, minimising the number and expense of
components required in traditional microwave imaging
systems. The cavity imager builds on previous
frequencydiverse approaches, such as the recently reported
metamaterial and air-filled cavity systems, by utilising
frequencydiverse panels for both the transmit and receive
sub-apertures of the imaging system. Though the
panel-to-panel architecture has greater sensitivity to
calibration error, this implementation nevertheless
increases mode diversity and, in the context of a
computational imaging system, results in improved image
reconstructions.},
Doi = {10.1049/iet-map.2015.0836},
Key = {fds319558}
}
@article{fds319559,
Author = {Lipworth, G and Caira, NW and Larouche, S and Smith,
DR},
Title = {Phase and magnitude constrained metasurface holography at
W-band frequencies.},
Journal = {Optics express},
Volume = {24},
Number = {17},
Pages = {19372-19387},
Year = {2016},
Month = {August},
url = {http://dx.doi.org/10.1364/oe.24.019372},
Abstract = {Holographic optics are an essential tool for the control of
light, generating highly complex and tailored light field
distributions that can represent physical objects or
abstract information. Conceptually, a hologram is a region
of space in which an arbitrary phase shift and amplitude
variation are added to an incident reference wave at every
spatial location, such that the reference wave will produce
a desired field distribution as it scatters from the medium.
Practical holograms are composed of materials, however,
which have limited properties that constrain the possible
field distributions. Here, we show it is possible to produce
a hologram with continuous phase distribution and a
non-uniform amplitude variation at every point by leveraging
resonant metamaterial elements and constraining the
hologram's pixels to match the elements' resonant behavior.
We demonstrate the viability of the resonant metamaterial
approach with a single layer, co-polarized holographic
metasurface that produces an image at millimeter wavelengths
(92.5 GHz) despite the elements' limited phase range and
coupled amplitude dependency.},
Doi = {10.1364/oe.24.019372},
Key = {fds319559}
}
@article{fds330951,
Author = {Abadi, MM and Ghassemlooy, Z and Zvanovec, S and Smith, D and Bhatnagar,
MR and Wu, Y},
Title = {Dual purpose antenna for hybrid free space optics/RF
communication systems},
Journal = {Journal of Lightwave Technology},
Volume = {34},
Number = {14},
Pages = {3432-3439},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2016},
Month = {July},
url = {http://dx.doi.org/10.1109/JLT.2016.2571846},
Abstract = {The concept of hybrid free space optical/radio frequency
(FSO/RF) communications has been considered for the last
mile access network applications. The existing schemes
mostly use two separate transceiver antennas for outdoor
terrestrial links of few kilometres long. In this paper, we
propose and investigate a single hybrid FSO/RF antenna that
could be used in high-speed access networks. We outline the
design procedures based on the concept of Cassegrain
antenna, and show how the FSO transceiver is incorporated
into the original design. The proposed antenna is fabricated
and extensive measurements are carried out for the radiation
pattern, return loss, RF signal-to-noise ratio and the FSO
received power. By performing link budget analysis and the
results obtained from experiments, we demonstrate the
operation of proposed hybrid antenna with 1 × 3
single-input multiple-output configuration and an equal gain
combining at the receiver under moderate regime turbulence
regime.},
Doi = {10.1109/JLT.2016.2571846},
Key = {fds330951}
}
@article{fds319560,
Author = {Fromenteze, T and Liu, X and Boyarsky, M and Gollub, J and Smith,
DR},
Title = {Phaseless computational imaging with a radiating
metasurface.},
Journal = {Optics express},
Volume = {24},
Number = {15},
Pages = {16760-16776},
Year = {2016},
Month = {July},
url = {http://dx.doi.org/10.1364/oe.24.016760},
Abstract = {Computational imaging modalities support a simplification of
the active architectures required in an imaging system and
these approaches have been validated across the
electromagnetic spectrum. Recent implementations have
utilized pseudo-orthogonal radiation patterns to illuminate
an object of interest-notably, frequency-diverse
metasurfaces have been exploited as fast and low-cost
alternative to conventional coherent imaging systems.
However, accurately measuring the complex-valued signals in
the frequency domain can be burdensome, particularly for
sub-centimeter wavelengths. Here, computational imaging is
studied under the relaxed constraint of intensity-only
measurements. A novel 3D imaging system is conceived based
on 'phaseless' and compressed measurements, with benefits
from recent advances in the field of phase retrieval. In
this paper, the methodology associated with this novel
principle is described, studied, and experimentally
demonstrated in the microwave range. A comparison of the
estimated images from both complex valued and phaseless
measurements are presented, verifying the fidelity of
phaseless computational imaging.},
Doi = {10.1364/oe.24.016760},
Key = {fds319560}
}
@article{fds319562,
Author = {Bowen, PT and Baron, A and Smith, DR},
Title = {Theory of patch-antenna metamaterial perfect
absorbers},
Journal = {Physical Review A},
Volume = {93},
Number = {6},
Publisher = {American Physical Society (APS)},
Year = {2016},
Month = {June},
url = {http://dx.doi.org/10.1103/PhysRevA.93.063849},
Abstract = {A metasurface that absorbs waves from all directions of
incidence can be achieved if the surface impedance is made
to vary as a function of incidence angle in a specific
manner. Here we show that a periodic array of planar
nanoparticles coupled to a metal film can act as an
absorbing metasurface with an angle-dependent impedance.
Through a semi-analytical calculation based on coupled-mode
theory, we find the perfect absorbing condition is
equivalent to balancing the Ohmic and radiative losses of
the nanoparticles at normal incidence. Absorption over a
wide range of incidence angles can then be obtained by
tailoring the scattered far-field pattern of the individual
planar nanoparticles such that their radiative losses remain
constant. The theory provides a means of understanding the
behavior of perfect absorbing structures that have been
observed experimentally or numerically, reconciling
previously published theories and enabling the optimization
of absorbing surfaces.},
Doi = {10.1103/PhysRevA.93.063849},
Key = {fds319562}
}
@article{fds319561,
Author = {Sleasman, T and Boyarsky, M and Imani, MF and Gollub, JN and Smith,
DR},
Title = {Design considerations for a dynamic metamaterial aperture
for computational imaging at microwave frequencies},
Journal = {Journal of the Optical Society of America B: Optical
Physics},
Volume = {33},
Number = {6},
Pages = {1098-1111},
Publisher = {The Optical Society},
Year = {2016},
Month = {June},
url = {http://dx.doi.org/10.1364/JOSAB.33.001098},
Abstract = {We investigate the imaging capabilities of a
one-dimensional, dynamic, metamaterial aperture that
operates at the lower part of K-band microwave frequencies
(17.5-21.1 GHz). The dynamic aperture consists of a
microstrip transmission line with an array of radiating,
complementary, subwavelength metamaterial irises patterned
into the upper conductor. Diodes integrated into the
metamaterial resonators provide voltage-controlled switching
of the resonant metamaterial elements between radiating and
nonradiating states. Applying a series of on/off patterns to
the metamaterial resonators produces a series of distinct
radiation patterns that sequentially illuminate a scene. The
backscattered signal contains encoded scene information over
a set of measurements that can be postprocessed to
reconstruct an image. We present a series of design
considerations for the dynamic aperture, as well as a series
of experimental studies performed using a dynamic aperture
prototype. High-fidelity, real-time, diffractionlimited
imaging using the prototype is demonstrated. The dynamic
aperture suggests a path to fast and reliable imaging with
low-cost and versatile hardware, for a variety of
applications including security screening, biomedical
diagnostics, and through-wall imaging.},
Doi = {10.1364/JOSAB.33.001098},
Key = {fds319561}
}
@article{fds330952,
Author = {Thornton, J and Dalay, B and Smith, D},
Title = {Additive manufacturing of waveguide for Ku-band satellite
communications antenna},
Journal = {2016 10th European Conference on Antennas and Propagation,
EuCAP 2016},
Publisher = {IEEE},
Year = {2016},
Month = {May},
ISBN = {9788890701863},
url = {http://dx.doi.org/10.1109/EuCAP.2016.7481435},
Abstract = {A metal waveguide feed chain in a Ku-band scanning lens
array antenna comprises 5 parts. These are: two iris
polarisers, two bend-feeds, and a central power combiner.
The combiner comprises a pair of septum polarisers and tee
junctions. The feed chain generates a controllable, linear
polarised E-field at each of two hemispherical lenses.
Additive manufacturing was used to produce a copy of the
power combiner and each bend-feed in copper plated plastic.
In satellite receive-only trials at 10.7-12 GHz the plastic
parts and metal parts performed equivalently.},
Doi = {10.1109/EuCAP.2016.7481435},
Key = {fds330952}
}
@article{fds315031,
Author = {Yurduseven, O and Gowda, VR and Gollub, JN and Smith,
DR},
Title = {Printed Aperiodic Cavity for Computational and Microwave
Imaging},
Journal = {IEEE Microwave and Wireless Components Letters},
Volume = {26},
Number = {5},
Pages = {367-369},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2016},
Month = {May},
ISSN = {1531-1309},
url = {http://dx.doi.org/10.1109/LMWC.2016.2548443},
Abstract = {We demonstrate a frequency-diverse aperture for microwave
imaging based on a planar cavity at K-band frequencies
(18-26.5 GHz). The structure consists of an array of
radiating circular irises patterned into the front surface
of a double-sided printed circuit board. The irises are
distributed in a Fibonacci pattern to maximize spatial
diversity at the scene. The printed cavity is a
phase-diverse system and encodes imaged scene information
onto a set of frequencies that span the K-band. Similar to
recently reported metamaterial apertures, the printed cavity
imager does not require any mechanically moving parts or
complex phase shifting networks. Imaging of a number of
targets is shown; these reconstructed images demonstrate the
ability of the system to perform imaging at the diffraction
limit. The proposed printed cavity imager possesses a
relatively large quality factor that can be traded off to
achieve higher radiation efficiency. The general mode
characteristics of the printed cavity suggest advantages
when used in computational imaging scenarios.},
Doi = {10.1109/LMWC.2016.2548443},
Key = {fds315031}
}
@article{fds316894,
Author = {Marks, DL and Gollub, J and Smith, DR},
Title = {Spatially resolving antenna arrays using frequency
diversity.},
Journal = {Journal of the Optical Society of America. A, Optics, image
science, and vision},
Volume = {33},
Number = {5},
Pages = {899-912},
Year = {2016},
Month = {May},
ISSN = {1084-7529},
url = {http://dx.doi.org/10.1364/josaa.33.000899},
Abstract = {Radio imaging devices and synthetic aperture radar typically
use either mechanical scanning or phased arrays to
illuminate a target with spatially varying radiation
patterns. Mechanical scanning is unsuitable for many
high-speed imaging applications, and phased arrays contain
many active components and are technologically and cost
prohibitive at millimeter and terahertz frequencies. We show
that antennas deliberately designed to produce many
different radiation patterns as the frequency is varied can
reduce the number of active components necessary while still
capturing high-quality images. This approach, called
frequency-diversity imaging, can capture an entire
two-dimensional image using only a single transmit and
receive antenna with broadband illumination. We provide
simple principles that ascertain whether a design is likely
to achieve particular resolution specifications, and
illustrate these principles with simulations.},
Doi = {10.1364/josaa.33.000899},
Key = {fds316894}
}
@article{fds315572,
Author = {Yurduseven, O and Gollub, JN and Marks, DL and Smith,
DR},
Title = {Frequency-diverse microwave imaging using planar Mills-Cross
cavity apertures.},
Journal = {Optics express},
Volume = {24},
Number = {8},
Pages = {8907-8925},
Year = {2016},
Month = {April},
url = {http://dx.doi.org/10.1364/oe.24.008907},
Abstract = {We demonstrate a frequency diverse, multistatic microwave
imaging system based on a set of transmit and receive,
radiating, planar cavity apertures. The cavities consist of
double-sided, copper-clad circuit boards, with a series of
circular radiating irises patterned into the upper
conducting plate. The iris arrangement is such that for any
given transmitting and receiving aperture pair, a
Mills-Cross pattern is formed from the overlapped patterns.
The Mills-Cross distribution provides optimum coverage of
the imaging scene in the spatial Fourier domain (k-space).
The Mills-Cross configuration of the apertures produces
measurement modes that are diverse and consistent with the
computational imaging approach used for frequency-diverse
apertures, yet significantly minimizes the redundancy of
information received from the scene. We present a detailed
analysis of the Mills-Cross aperture design, with numerical
simulations that predict the performance of the apertures as
part of an imaging system. Images reconstructed using
fabricated apertures are presented, confirming the
anticipated performance.},
Doi = {10.1364/oe.24.008907},
Key = {fds315572}
}
@article{fds335063,
Author = {Smith, DR and Fonck, RJ and McKee, GR and Diallo, A and Kaye, SM and Leblanc, BP and Sabbagh, SA},
Title = {Evolution patterns and parameter regimes in edge localized
modes on the National Spherical Torus Experiment},
Journal = {Plasma Physics and Controlled Fusion},
Volume = {58},
Number = {4},
Pages = {045003-045003},
Publisher = {IOP Publishing},
Year = {2016},
Month = {January},
url = {http://dx.doi.org/10.1088/0741-3335/58/4/045003},
Abstract = {We implement unsupervised machine learning techniques to
identify characteristic evolution patterns and associated
parameter regimes in edge localized mode (ELM) events
observed on the National Spherical Torus Experiment.
Multi-channel, localized measurements spanning the pedestal
region capture the complex evolution patterns of ELM events
on Alfvén timescales. Some ELM events are active for less
than 100 μs, but others persist for up to 1 ms. Also, some
ELM events exhibit a single dominant perturbation, but
others are oscillatory. Clustering calculations with
time-series similarity metrics indicate the ELM database
contains at least two and possibly three groups of ELMs with
similar evolution patterns. The identified ELM groups
trigger similar stored energy loss, but the groups occupy
distinct parameter regimes for ELM-relevant quantities like
plasma current, triangularity, and pedestal height. Notably,
the pedestal electron pressure gradient is not an effective
parameter for distinguishing the ELM groups, but the ELM
groups segregate in terms of electron density gradient and
electron temperature gradient. The ELM evolution patterns
and corresponding parameter regimes can shape the
formulation or validation of nonlinear ELM models. Finally,
the techniques and results demonstrate an application of
unsupervised machine learning at a data-rich fusion
facility.},
Doi = {10.1088/0741-3335/58/4/045003},
Key = {fds335063}
}
@article{fds330365,
Author = {Dechaux, M and Tichit, PH and Ciracì, C and Benedicto, J and Pollès,
R and Centeno, E and Smith, DR and Moreau, A},
Title = {Influence of spatial dispersion in metals on the optical
response of deeply subwavelength slit arrays},
Journal = {Physical Review B},
Volume = {93},
Number = {4},
Publisher = {American Physical Society (APS)},
Year = {2016},
Month = {January},
url = {http://dx.doi.org/10.1103/PhysRevB.93.045413},
Abstract = {In the framework of the hydrodynamic model describing the
response of electrons in a metal, we show that arrays of
very narrow and shallow metallic slits have an optical
response that is influenced by the spatial dispersion in
metals arising from the repulsive interaction between
electrons. As a simple Fabry-Perot model is not accurate
enough to describe the structure's behavior, we propose
considering the slits as generalized cavities with two
modes, one being propagative and the other evanescent. This
very general model allows us to conclude that the impact of
spatial dispersion on the propagative mode is the key factor
explaining why the whole structure is sensitive to spatial
dispersion. As the fabrication of such structures with
relatively large gaps compared to previous experiments is
within our reach, this work paves the way for future much
needed experiments on nonlocality.},
Doi = {10.1103/PhysRevB.93.045413},
Key = {fds330365}
}
@article{fds335064,
Author = {Soman, MR and Allanwood, EAH and Holland, AD and Stefanov, K and Pratlong, J and Leese, M and Gow, JPD and Smith, DR},
Title = {Electro-optic and radiation damage performance of the
CIS115, an imaging sensor for the JANUS optical camera
onboard JUICE},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {9915},
Publisher = {SPIE},
Year = {2016},
Month = {January},
ISBN = {9781510602090},
url = {http://dx.doi.org/10.1117/12.2234290},
Abstract = {The Jupiter Icy Moon Explorer (JUICE) has been officially
adopted as the next Large class mission by the European
Space Agency, with a launch date of 2022. The science
payload includes an optical camera, JANUS, which will
perform imaging and mapping observations of Jupiter, its
moons and icy rings. A 13 slot filter wheel will be used to
provide spectral information in order for the JANUS
experiment to study the geology and physical properties of
Ganymede, Europa and Io, and to investigate processes and
structures in the atmosphere of Jupiter. The sensor selected
for JANUS is the back-Thinned CIS115, a 3 MPixel CMOS Image
Sensor from e2v technologies. The CIS115 has a 4-Transistor
pixel design with a pinned photodiode to improve signal to
noise performance by reducing dark current and allowing for
reset level subtraction. The JUICE mission will consist of
an 8 year cruise phase followed by a 3 year science phase in
the Jovian system. Models of the radiation environment
throughout the JUICE mission predict that the End of Life
(EOL) non-ionising damage will be equivalent to 1010 protons
cm-2 (10 MeV) and the EOL ionising dose will be 100
krad(Si), once the shielding from the spacecraft and
instrument design is taken into account. An extensive
radiation campaign is therefore being carried out to qualify
and characterise the CIS115 for JANUS, as well as other
space and terrestrial applications. Radiation testing to
take the CIS115 to twice the ionising dose and displacement
damage levels was completed in 2015 and the change in sensor
performance has been characterised. Good sensor performance
has been observed following irradiation and a summary of the
key results from the campaign using gamma irradiation
(ionising dose) will be presented here, including its soft
X-ray detection capabilities, flat-band voltage shift and
readout noise. In 2016, further radiation campaigns on
flight-representative CIS115s will be undertaken and their
results will be disseminated in future publications.},
Doi = {10.1117/12.2234290},
Key = {fds335064}
}
@article{fds319563,
Author = {Yurduseven, O and Gollub, JN and Rose, A and Marks, DL and Smith,
DR},
Title = {Design and Simulation of a Frequency-Diverse Aperture for
Imaging of Human-Scale Targets},
Journal = {IEEE Access},
Volume = {4},
Number = {99},
Pages = {5436-5451},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2016},
Month = {January},
url = {http://dx.doi.org/10.1109/ACCESS.2016.2604823},
Abstract = {We present the design and simulation of a frequency-diverse
aperture for imaging of human-size targets at microwave
wavelengths. Predominantly relying on a frequency sweep to
produce diverse radiation patterns, the frequency-diverse
aperture provides a path to all-electronic operation,
sampling a scene without the requirement for mechanical
scanning or expensive active components. Similar to other
computational imaging schemes, the frequency diverse
aperture removes many hardware constraints by placing an
increased burden on processing and analysis. While
proof-of-concept simulations of scaled-down versions of the
frequency-diverse imager and simple targets can be performed
with relative ease, the end-to-end modeling of a full-size
aperture capable of fully resolving human-size targets
presents many challenges, particularly if parametric studies
need to be performed during a design or optimization phase.
Here, we show that an in-house developed simulation code can
be adapted and parallelized for the rapid design and
optimization of a full-size, frequency-diverse aperture.
Using files of human models in stereolithography format, the
software can model the entire imaging scenario in seconds,
including mode generation and propagation, scattering from
the human model, and measured backscatter. We illustrate the
performance of several frequency-diverse aperture designs
using images of human-scale targets reconstructed with
various algorithms and compare with a conventional synthetic
aperture radar approach. We demonstrate the potential of one
aperture for threat object detection in security-screening
applications.},
Doi = {10.1109/ACCESS.2016.2604823},
Key = {fds319563}
}
@article{fds319564,
Author = {Yurduseven, O and Gollub, JN and Trofatter, KP and Marks, DL and Rose,
A and Smith, DR},
Title = {Software Calibration of a Frequency-Diverse, Multistatic,
Computational Imaging System},
Journal = {IEEE Access},
Volume = {4},
Pages = {2488-2497},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2016},
Month = {January},
url = {http://dx.doi.org/10.1109/ACCESS.2016.2570678},
Abstract = {We demonstrate a technique for calibrating a
frequency-diverse, multistatic, computational imaging
system. A frequency-diverse aperture enables an image to be
reconstructed primarily from a set of scattered field
measurements taken over a band of frequencies, avoiding
mechanical scanning and active components. Since
computational imaging systems crucially rely on the accuracy
of a forward model that relates the measured and transmitted
fields, deviations of the actual system from that model will
rapidly degrade imaging performance. Here, we study the
performance of a computational imaging system at microwave
frequencies based on a set of frequency-diverse aperture
antennas, or panels. We propose a calibration scheme that
compares the measured versus simulated scattered field from
a cylinder and calculates a compensating phase difference to
be applied at each of the panels comprising the system. The
calibration of the entire system needs be performed only
once, avoiding a more laborious manual calibration step for
each transmitting and receiving path. Imaging measurements
performed using the system confirm the efficacy and
importance of the calibration step.},
Doi = {10.1109/ACCESS.2016.2570678},
Key = {fds319564}
}
@article{fds330953,
Author = {Chen, H and Pendry, JB and Smith, DR},
Title = {Special issue on transformation optics},
Journal = {Journal of Optics (United Kingdom)},
Volume = {18},
Number = {4},
Pages = {040201-040201},
Publisher = {IOP Publishing},
Year = {2016},
Month = {January},
url = {http://dx.doi.org/10.1088/2040-8978/18/4/040201},
Doi = {10.1088/2040-8978/18/4/040201},
Key = {fds330953}
}
@article{fds330954,
Author = {Sleasman, T and Imani, MF and Xu, W and Hunt, J and Driscoll, T and Reynolds, MS and Smith, DR},
Title = {Waveguide-Fed Tunable Metamaterial Element for Dynamic
Apertures},
Journal = {IEEE Antennas and Wireless Propagation Letters},
Volume = {15},
Pages = {606-609},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2016},
Month = {January},
url = {http://dx.doi.org/10.1109/LAWP.2015.2462818},
Abstract = {We present the design of a tunable metamaterial element that
can serve as the building block for a dynamically
reconfigurable aperture. The element - a complimentary
electric-LC (cELC) resonator - is patterned into the upper
conductor of a microstrip transmission line, providing both
a means of exciting the radiating metamaterial element as
well as independent access for biasing circuitry. PIN diodes
are connected across the capacitive gaps of the cELC, and a
dc bias current is used to switch the junction between
conducting and insulating states. The leakage of RF signal
through the bias line is mitigated by integration of a
radial decoupling stub. The proposed design and operation of
the element are demonstrated through full-wave
electromagnetic simulations. We discuss the potential
application of the cELC element as a building block for
metamaterial apertures capable of dynamic beamforming,
imaging, or security screening applications.},
Doi = {10.1109/LAWP.2015.2462818},
Key = {fds330954}
}
@article{fds322743,
Author = {Gowda, VR and Yurduseven, O and Lipworth, G and Zupan, T and Reynolds,
MS and Smith, DR},
Title = {Wireless Power Transfer in the Radiative Near
Field},
Journal = {IEEE Antennas and Wireless Propagation Letters},
Volume = {15},
Pages = {1865-1868},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2016},
Month = {January},
url = {http://dx.doi.org/10.1109/LAWP.2016.2542138},
Abstract = {A scheme for wireless power transfer (WPT) in the radiative
near-field (Fresnel) region is presented. The proposed
Fresnel WPT scheme is designed to focus microwaves to a
diffraction-limited region where a detector can be
positioned, achieving reasonably high power transfer
efficiency over moderate distances. The configuration
consists of transmit and receive microstrip patch array
antennas, with the receiving antenna connected to a
power-harvesting half-wave rectifier (rectenna). Fresnel
region operation enables the fields radiated by the
transmitting aperture to be localized both in range and
cross-range. Using Fresnel region focusing, we achieve an
increase of 66.8% in the amount of received power when
compared to the performance of a conventional beamforming
array. We also demonstrate the efficiency improvement by
powering an LED using the on-axis and off-axis focusing
configurations.},
Doi = {10.1109/LAWP.2016.2542138},
Key = {fds322743}
}
@article{fds320771,
Author = {Pulido-Mancera, LM and Zvolensky, T and Imani, MF and Bowen, PT and Valayil, M and Smith, DR},
Title = {Discrete Dipole Approximation Applied to Highly Directive
Slotted Waveguide Antennas},
Journal = {IEEE Antennas and Wireless Propagation Letters},
Volume = {15},
Pages = {1823-1826},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2016},
Month = {January},
url = {http://dx.doi.org/10.1109/LAWP.2016.2538202},
Abstract = {We present an analysis of a slotted waveguide antenna (SWA)
whose directivity has been enhanced by using metamaterial
parasitic elements. We apply an adapted form of the discrete
dipole approximation (DDA) as a modeling tool and verify the
accuracy and versatility of this method for different
configurations, including matched and shorted SWAs, and with
and without parasitic elements. The results presented in
this letter demonstrate the capabilities of the DDA for the
fast and accurate simulation of aperture antennas composed
of small radiators, and its further application for the
design of complex metamaterial structures.},
Doi = {10.1109/LAWP.2016.2538202},
Key = {fds320771}
}
@article{fds320772,
Author = {Odabasi, H and Imani, MF and Lipworth, G and Gollub, J and Smith,
DR},
Title = {Investigation of alignment errors on multi-static microwave
imaging based on frequency-diverse metamaterial
apertures},
Journal = {Progress In Electromagnetics Research B},
Volume = {70},
Number = {1},
Pages = {101-112},
Publisher = {EMW Publishing},
Year = {2016},
Month = {January},
url = {http://dx.doi.org/10.2528/PIERB16052801},
Abstract = {We examine the effect of alignment errors on the performance
of a frequency-diverse imaging system composed of
metamaterial apertures. In a frequency-diverse imaging
system, a sequence of distinct radiation patterns, indexed
by frequency, provides measurements of the spatial content
of a scene. This set of measurements can then be used to
obtain a high-fidelity estimate of the scene using
computational imaging techniques. As with any computational
imaging system, realizing the full potential of the
frequency-diverse system requires accurate characterization
of the complex radiation patterns. This characterization
entails precise knowledge of the locations and orientations
of the transmitters and receivers; any discrepancy between
the modeled and actual locations will introduce phase error
and degrade the quality of image reconstructions. Here, we
study the effect of various misalignment errors on the
performance of a sparse, bi-static, frequency diverse
imaging system and provide an estimate on the levels of
error within which the frequency-diverse apertures can
reconstruct high quality images. Depending on the
misalignment type (i.e., displacement, rotation) and
direction the phase error can change significantly. As a
result, for instance, we show that the imaging system is
significantly less sensitive to cross-range displacement
errors than to range displacement errors. We also show that
the displacement errors are reduced for larger systems
comprising many sub-apertures, due to the reduced averaged
phase error. We find the impact of rotational errors is
small compared to that of the displacement errors. However,
as the sub-aperture size increases, rotational errors become
more pronounced, becoming severe for larger sub-apertures
with multiple feeds.},
Doi = {10.2528/PIERB16052801},
Key = {fds320772}
}
@article{fds315030,
Author = {Fromenteze, T and Kpre, EL and Decroze, C and Carsenat, D and Yurduseven, O and Imani, M and Gollub, J and Smith,
DR},
Title = {Unification of compressed imaging techniques in the
microwave range and deconvolution strategy},
Journal = {2015 European Radar Conference, EuRAD 2015 -
Proceedings},
Pages = {161-164},
Publisher = {IEEE},
Year = {2015},
Month = {December},
ISBN = {9782874870415},
url = {http://dx.doi.org/10.1109/EuRAD.2015.7346262},
Abstract = {In recent years, several techniques of imaging have emerged
based on compressive sensing. Thus, using passive devices
able to code and sum the information measured on a radiating
aperture, complex UWB beamforming hardwares can be replaced
by inverse problems to solve using deconvolution techniques.
Two similar compressive techniques have been developed
independently, based on a passive multiplexer and on a
metamaterial aperture. This paper proposes an unification of
these approaches, using a common mathematical formulation
and comparing the deconvolution strategy adopted by each
research team.},
Doi = {10.1109/EuRAD.2015.7346262},
Key = {fds315030}
}
@article{fds300151,
Author = {Akselrod, GM and Huang, J and Hoang, TB and Bowen, PT and Su, L and Smith,
DR and Mikkelsen, MH},
Title = {Large-Area Metasurface Perfect Absorbers from Visible to
Near-Infrared.},
Journal = {Advanced materials (Deerfield Beach, Fla.)},
Volume = {27},
Number = {48},
Pages = {8028-8034},
Year = {2015},
Month = {December},
ISSN = {0935-9648},
url = {http://dx.doi.org/10.1002/adma.201503281},
Abstract = {An absorptive metasurface based on film-coupled colloidal
silver nanocubes is demonstrated. The metasurfaces are
fabricated using simple dip-coating methods and can be
deposited over large areas and on arbitrarily shaped
objects. The surfaces show nearly complete absorption, good
off-angle performance, and the resonance can be tuned from
the visible to the near-infrared.},
Doi = {10.1002/adma.201503281},
Key = {fds300151}
}
@article{fds305680,
Author = {Bowen, PT and Smith, DR and Urzhumov, YA},
Title = {Wake control with permeable multilayer structures: The
spherical symmetry case.},
Journal = {Physical review. E, Statistical, nonlinear, and soft matter
physics},
Volume = {92},
Number = {6},
Pages = {063030},
Year = {2015},
Month = {December},
ISSN = {1539-3755},
url = {http://dx.doi.org/10.1103/physreve.92.063030},
Abstract = {We explore the possibility of controlling the wake and drag
of a spherical object independently of each other, using
radial distributions of permeability in the Brinkman-Stokes
formalism. By discretizing a graded-permeability shell into
discrete, macroscopically homogeneous layers, we are able to
sample the entire functional space of spherically-symmetric
permeabilities and observe quick convergence to a certain
manifold in the wake-drag coordinates. Monte Carlo samplings
with 10^{4}-10^{5} points have become possible thanks to our
new algorithm, which is based on exact analytical solutions
for the Stokes flow through an arbitrary multilayer porous
sphere. The algorithm is not restricted to the
Brinkman-Stokes equation and can be modified to account for
other types of scattering problems for spherically-symmetric
systems with arbitrary radial complexity. Our main practical
finding for Stokes flow is that it is possible to reduce a
certain measure of wake of a spherical object without any
energy penalty and without active (power-consuming) force
generation.},
Doi = {10.1103/physreve.92.063030},
Key = {fds305680}
}
@article{fds312160,
Author = {Huang, Z and Baron, A and Larouche, S and Argyropoulos, C and Smith,
DR},
Title = {Optical bistability with film-coupled metasurfaces.},
Journal = {Optics letters},
Volume = {40},
Number = {23},
Pages = {5638-5641},
Year = {2015},
Month = {December},
ISSN = {0146-9592},
url = {http://dx.doi.org/10.1364/ol.40.005638},
Abstract = {Metasurfaces comprising arrays of film-coupled, nanopatch
antennas are a promising platform for low-energy,
all-optical switches. The large field enhancements that can
be achieved in the dielectric spacer region between the
nanopatch and the metallic substrate can substantially
enhance optical nonlinear processes. Here we consider a
dielectric material that exhibits an optical Kerr effect as
the spacer layer and numerically calculate the optical
bistability of a metasurface using the finite element method
(FEM). We expect the proposed method to be highly accurate
compared with other numerical approaches, such as those
based on graphical post-processing techniques, because it
self-consistently solves for both the spatial field
distribution and the intensity-dependent refractive index
distribution of the spacer layer. This method offers an
alternative approach to finite-difference time-domain (FDTD)
modeling. We use this numerical tool to design a metasurface
optical switch and our optimized design exhibits
exceptionally low switching intensity of 33 kW/cm2,
corresponding to switching energy on the order of tens of
attojoules per resonator, a value much smaller than those
found for most devices reported in the literature. We
propose our method as a tool for designing all-optical
switches and modulators.},
Doi = {10.1364/ol.40.005638},
Key = {fds312160}
}
@article{fds335066,
Author = {Ruiz Ruiz and J and Ren, Y and Guttenfelder, W and White, AE and Kaye, SM and Leblanc, BP and Mazzucato, E and Lee, KC and Domier, CW and Smith, DR and Yuh, H},
Title = {Stabilization of electron-scale turbulence by electron
density gradient in national spherical torus
experiment},
Journal = {Physics of Plasmas},
Volume = {22},
Number = {12},
Pages = {122501-122501},
Publisher = {AIP Publishing},
Year = {2015},
Month = {December},
url = {http://dx.doi.org/10.1063/1.4936110},
Abstract = {Theory and experiments have shown that electron temperature
gradient (ETG) turbulence on the electron gyro-scale,
k⊥ρe ≲ 1, can be responsible for anomalous electron
thermal transport in NSTX. Electron scale (high-k)
turbulence is diagnosed in NSTX with a high-k microwave
scattering system [D. R. Smith et al., Rev. Sci. Instrum.
79, 123501 (2008)]. Here we report on stabilization effects
of the electron density gradient on electron-scale density
fluctuations in a set of neutral beam injection heated
H-mode plasmas. We found that the absence of high-k density
fluctuations from measurements is correlated with large
equilibrium density gradient, which is shown to be
consistent with linear stabilization of ETG modes due to the
density gradient using the analytical ETG linear threshold
in F. Jenko et al. [Phys. Plasmas 8, 4096 (2001)] and linear
gyrokinetic simulations with GS2 [M. Kotschenreuther et al.,
Comput. Phys. Commun. 88, 128 (1995)]. We also found that
the observed power of electron-scale turbulence (when it
exists) is anti-correlated with the equilibrium density
gradient, suggesting density gradient as a nonlinear
stabilizing mechanism. Higher density gradients give rise to
lower values of the plasma frame frequency, calculated based
on the Doppler shift of the measured density fluctuations.
Linear gyrokinetic simulations show that higher values of
the electron density gradient reduce the value of the real
frequency, in agreement with experimental observation.
Nonlinear electron-scale gyrokinetic simulations show that
high electron density gradient reduces electron heat flux
and stiffness, and increases the ETG nonlinear threshold,
consistent with experimental observations.},
Doi = {10.1063/1.4936110},
Key = {fds335066}
}
@article{fds293133,
Author = {Sleasman, T and F. Imani and M and Gollub, JN and Smith,
DR},
Title = {Dynamic metamaterial aperture for microwave
imaging},
Journal = {Applied Physics Letters},
Volume = {107},
Number = {20},
Pages = {204104-204104},
Publisher = {AIP Publishing},
Year = {2015},
Month = {November},
ISSN = {0003-6951},
url = {http://dx.doi.org/10.1063/1.4935941},
Abstract = {We present a dynamic metamaterial aperture for use in
computational imaging schemes at microwave frequencies. The
aperture consists of an array of complementary, resonant
metamaterial elements patterned into the upper conductor of
a microstrip line. Each metamaterial element contains two
diodes connected to an external control circuit such that
the resonance of the metamaterial element can be damped by
application of a bias voltage. Through applying different
voltages to the control circuit, select subsets of the
elements can be switched on to create unique radiation
patterns that illuminate the scene. Spatial information of
an imaging domain can thus be encoded onto this set of
radiation patterns, or measurements, which can be processed
to reconstruct the targets in the scene using compressive
sensing algorithms. We discuss the design and operation of a
metamaterial imaging system and demonstrate reconstructed
images with a 10:1 compression ratio. Dynamic metamaterial
apertures can potentially be of benefit in microwave or
millimeter wave systems such as those used in security
screening and through-wall imaging. In addition,
feature-specific or adaptive imaging can be facilitated
through the use of the dynamic aperture.},
Doi = {10.1063/1.4935941},
Key = {fds293133}
}
@article{fds315573,
Author = {Lipworth, G and Rose, A and Yurduseven, O and Gowda, VR and Imani, MF and Odabasi, H and Trofatter, P and Gollub, J and Smith,
DR},
Title = {Comprehensive simulation platform for a metamaterial imaging
system.},
Journal = {Applied optics},
Volume = {54},
Number = {31},
Pages = {9343-9353},
Year = {2015},
Month = {November},
ISSN = {0003-6935},
url = {http://dx.doi.org/10.1364/ao.54.009343},
Abstract = {Recently, a frequency-diverse, metamaterial-based aperture
has been introduced in the context of microwave and
millimeter wave imaging. The generic form of the aperture is
that of a parallel plate waveguide, in which complementary
metamaterial elements patterned into the upper plate couple
energy from the waveguide mode to the scene. To reliably
predict the imaging performance of such an aperture prior to
fabrication and experiments, it is necessary to have an
accurate forward model that predicts radiation from the
aperture, a model for scattering from an arbitrary target in
the scene, and a set of image reconstruction approaches that
allow scene estimation from an arbitrary set of
measurements. Here, we introduce a forward model in which
the metamaterial elements are approximated as polarizable
magnetic dipoles, excited by the fields propagating within
the waveguide. The dipoles used in the model can have
arbitrarily assigned polarizability characteristics.
Alternatively, fields measured from actual metamaterial
samples can be decomposed into a set of effective dipole
radiators, allowing the performance of actual samples to be
quantitatively modeled and compared with simulated
apertures. To confirm the validity of our model, we simulate
measurements and scene reconstructions with a virtual
multiaperture imaging system operating in the K-band
spectrum (18-26.5 GHz) and compare its performance with an
experimental system.},
Doi = {10.1364/ao.54.009343},
Key = {fds315573}
}
@article{fds335067,
Author = {Ren, Y and Wang, WX and LeBlanc, BP and Guttenfelder, W and Kaye, SM and Ethier, S and Mazzucato, E and Lee, KC and Domier, CW and Bell, R and Smith, DR and Yuh, H},
Title = {Fast response of electron-scale turbulence to auxiliary
heating cessation in National Spherical Torus
Experiment},
Journal = {Physics of Plasmas},
Volume = {22},
Number = {11},
Pages = {110701-110701},
Publisher = {AIP Publishing},
Year = {2015},
Month = {November},
url = {http://dx.doi.org/10.1063/1.4935113},
Abstract = {In this letter, we report the first observation of the fast
response of electron-scale turbulence to auxiliary heating
cessation in National Spherical Torus eXperiment [Ono et
al., Nucl. Fusion 40, 557 (2000)]. The observation was made
in a set of RF-heated L-mode plasmas with toroidal magnetic
field of 0.55 T and plasma current of 300 kA. It is observed
that electron-scale turbulence spectral power (measured with
a high-k collective microwave scattering system) decreases
significantly following fast cessation of RF heating that
occurs in less than 200 μs. The large drop in the
turbulence spectral power has a short time delay of about
1-2 ms relative to the RF cessation and happens on a time
scale of 0.5-1 ms, much smaller than the energy confinement
time of about 10 ms. Power balance analysis shows a factor
of about 2 decrease in electron thermal diffusivity after
the sudden drop of turbulence spectral power. Measured small
changes in equilibrium profiles across the RF cessation are
unlikely able to explain this sudden reduction in the
measured turbulence and decrease in electron thermal
transport, supported by local linear stability analysis and
both local and global nonlinear gyrokinetic simulations. The
observations imply that nonlocal flux-driven mechanism may
be important for the observed turbulence and electron
thermal transport.},
Doi = {10.1063/1.4935113},
Key = {fds335067}
}
@article{fds330574,
Author = {Argyropoulos, C and Akselrod, GM and Ciraci, C and Hoang, TB and Fang,
C and Huang, J and Smith, DR and Mikkelsen, MH},
Title = {Directional plasmonic nanoantennas to enhance the purcell
effect},
Journal = {2015 USNC-URSI Radio Science Meeting (Joint with AP-S
Symposium), USNC-URSI 2015 - Proceedings},
Pages = {65},
Publisher = {IEEE},
Year = {2015},
Month = {October},
ISBN = {9781479978175},
url = {http://dx.doi.org/10.1109/USNC-URSI.2015.7303349},
Abstract = {We will present plasmonic nanoantennas, composed of silver
nanocubes strongly coupled to gold films, which are the
optical and infrared (IR) frequency counterparts to the
well-established patch antennas used in microwave
frequencies for mobile communications. These nanoantennas
are ideal platforms to boost several photodynamic processes,
such as spontaneous emission. Interestingly, they can be
built based on bottom-up chemical synthesis approaches and
their radiation spectrum can be easily controlled.},
Doi = {10.1109/USNC-URSI.2015.7303349},
Key = {fds330574}
}
@article{fds330955,
Author = {Yurduseven, O and Gollub, J and Odabasi, H and Imani, MF and Lipworth,
G and Rose, A and Trofetter, P and Smith, DR},
Title = {Probe configuration study for the metamaterial aperture
imager},
Journal = {2015 9th European Conference on Antennas and Propagation,
EuCAP 2015},
Year = {2015},
Month = {August},
ISBN = {9788890701856},
Abstract = {We investigate a metamaterial imager (metaimager) consisting
of one transmitting metamaterial panel and a collection of
broadband receiving probes. Image reconstruction is
performed by interrogating a scene with a set of radiative
measurement modes encoded in the frequency response of the
metamaterial panel. The image quality is a function of the
ability of the receiving probes to capture the reflected
energy. Here, the number and configuration of the receiving
probe antennas is investigated. It is demonstrated that
increasing the number of probe antennas and distributing
their placement in space increases the effective receiver
aperture size and the number of measurement modes, enhancing
the image reconstruction for the metamaterial imager. The
imaging of a smiley face target is performed using one-probe
and five-probe metaimager configurations and successfully
reconstructed images are demonstrated.},
Key = {fds330955}
}
@article{fds330956,
Author = {Yurduseven, O and Gollub, J and Odabasi, H and Imani, MF and Lipworth,
G and Rose, A and Trofetter, P and Smith, DR},
Title = {Comparison of different reconstruction algorithms for image
reconstruction in metamaterial aperture based imaging
system},
Journal = {2015 9th European Conference on Antennas and Propagation,
EuCAP 2015},
Year = {2015},
Month = {August},
ISBN = {9788890701856},
Abstract = {We investigate the performance of various image
reconstruction algorithms for the design of a metamaterial
aperture-based imaging system. The metamaterial imaging
system consists of a transmitting metamaterial aperture
panel and a receiving low-gain probe antenna. Imaging of a 3
cm resolution target is performed using a number of
reconstruction algorithms, including pseudo-inverse, matched
filter, conjugate gradient squares (CGS), and two-step
iterative shrinkage/thresholding (TwIST) methods. The
differing quality of the resulting reconstructed images is
shown as a function of these reconstruction
techniques.},
Key = {fds330956}
}
@article{fds330958,
Author = {Baron, A and Hoang, TB and Fang, C and Mikkelsen, MH and Smith,
DR},
Title = {Large and ultrafast nonlinear absorption of an air/gold
plasmonic waveguide},
Journal = {Conference on Lasers and Electro-Optics Europe - Technical
Digest},
Volume = {2015-August},
Year = {2015},
Month = {August},
ISBN = {9781557529688},
Abstract = {We investigate theoretically and experimentally the
nonlinear propagation of surface plasmons on an air/gold
interface which reveals large and ultrafast (∼100 fs)
self-induced absorption. The experiment enables a direct
measurement of the third-order nonlinear
susceptibility.},
Key = {fds330958}
}
@article{fds330959,
Author = {Baron, A and Larouche, S and Gauthier, DJ and Smith,
DR},
Title = {Scaling of the nonlinear response of metal/dielectric
plasmonic waveguides},
Journal = {Conference on Lasers and Electro-Optics Europe - Technical
Digest},
Volume = {2015-August},
Year = {2015},
Month = {August},
ISBN = {9781557529688},
Abstract = {The scaling of the nonlinear response of a single-interface
plasmonic waveguide is studied, where both the metal and
dielectric display nonlinearity. We introduce a
figure-of-merit that guides metal/dielectric nanophotonic
device design for specific applications.},
Key = {fds330959}
}
@article{fds330960,
Author = {Bowen, PT and Baron, A and Smith, DR},
Title = {Analytic modeling of metmaterial absorbers},
Journal = {Conference on Lasers and Electro-Optics Europe - Technical
Digest},
Volume = {2015-August},
Year = {2015},
Month = {August},
ISBN = {9781557529688},
Abstract = {We present a fully analytical model that describes ideal
absorbing metasurfaces composed of film-coupled optical
nanoantennas. The model predicts the spectrum and the
angular dependence of the absorption and is compared to
full-wave numerical simulations.},
Key = {fds330960}
}
@article{fds330961,
Author = {Chandrasekar, R and Emani, NK and Lagutchev, A and Shalaev, VM and Ciraci, C and Smith, DR and Kildishev, AV},
Title = {Studying the interplay of electric and magnetic
resonance-enhanced second harmonic generation: Theory and
experiments},
Journal = {Conference on Lasers and Electro-Optics Europe - Technical
Digest},
Volume = {2015-August},
Year = {2015},
Month = {August},
ISBN = {9781557529688},
Abstract = {We present an experimental study of a metasurface, which
exhibits electric and magnetic resonances, in order to
understand their independent contributions to
second-harmonic generation. A hydrodynamic model framework
is used to match experimental results.},
Key = {fds330961}
}
@article{fds330957,
Author = {Akselrod, GM and Argyropoulos, C and Hoang, TB and Ciraci, C and Fang,
C and Huang, J and Smith, DR and Mikkelsen, MH},
Title = {Plasmonic nanopatch antennas for large purcell
enhancement},
Journal = {Conference on Lasers and Electro-Optics Europe - Technical
Digest},
Volume = {2015-August},
Year = {2015},
Month = {August},
ISBN = {9781557529688},
Abstract = {We demonstrate Purcell enhancements of-1000 from fluorescent
molecules embedded in a plasmonic antenna with sub-10 nm gap
between metals. Simulations and experiments reveal the high
radiative efficiency and directionality of the
antenna.},
Key = {fds330957}
}
@article{fds269549,
Author = {Benedicto, J and Pollès, R and Ciracì, C and Centeno, E and Smith, DR and Moreau, A},
Title = {Numerical tool to take nonlocal effects into account in
metallo-dielectric multilayers.},
Journal = {Journal of the Optical Society of America. A, Optics, image
science, and vision},
Volume = {32},
Number = {8},
Pages = {1581-1588},
Year = {2015},
Month = {August},
ISSN = {1084-7529},
url = {http://dx.doi.org/10.1364/josaa.32.001581},
Abstract = {We provide a numerical tool to quantitatively study the
impact of nonlocality arising from free electrons in metals
on the optical properties of metallo-dielectric multilayers.
We found that scattering matrices are particularly well
suited to take into account the electron response through
the application of the hydrodynamic model. Though effects
due to nonlocality are, in general, quite small, they,
nevertheless, can be important for very thin (typically
below 10 nm) metallic layers, as in those used in
structures characterized by exotic dispersion curves. Such
structures include those with a negative refractive index,
hyperbolic metamaterials, and near-zero index materials.
Higher wave vectors mean larger nonlocal effects, so that it
is not surprising that subwavelength imaging capabilities of
hyperbolic metamaterials are found to be sensitive to
nonlocal effects. We find in all cases that the inclusion of
nonlocal effects leads to at least a 5% higher transmission
through the considered structure.},
Doi = {10.1364/josaa.32.001581},
Key = {fds269549}
}
@article{fds269551,
Author = {Lipworth, G and Ensworth, J and Seetharam, K and Lee, JS and Schmalenberg, P and Nomura, T and Reynolds, MS and Smith, DR and Urzhumov, Y},
Title = {Quasi-Static Magnetic Field Shielding Using Longitudinal
Mu-Near-Zero Metamaterials.},
Journal = {Scientific reports},
Volume = {5},
Pages = {12764},
Year = {2015},
Month = {August},
url = {http://dx.doi.org/10.1038/srep12764},
Abstract = {The control of quasi-static magnetic fields is of
considerable interest in applications including the
reduction of electromagnetic interference (EMI), wireless
power transfer (WPT), and magnetic resonance imaging (MRI).
The shielding of static or quasi-static magnetic fields is
typically accomplished through the use of inherently
magnetic materials with large magnetic permeability, such as
ferrites, used sometimes in combination with metallic sheets
and/or active field cancellation. Ferrite materials,
however, can be expensive, heavy and brittle. Inspired by
recent demonstrations of epsilon-, mu- and index-near-zero
metamaterials, here we show how a longitudinal mu-near-zero
(LMNZ) layer can serve as a strong frequency-selective
reflector of magnetic fields when operating in the
near-field region of dipole-like sources. Experimental
measurements with a fabricated LMNZ sheet constructed from
an artificial magnetic conductor - formed from non-magnetic,
conducting, metamaterial elements - confirm that the
artificial structure provides significantly improved
shielding as compared with a commercially available ferrite
of the same size. Furthermore, we design a structure to
shield simultaneously at the fundamental and first harmonic
frequencies. Such frequency-selective behavior can be
potentially useful for shielding electromagnetic sources
that may also generate higher order harmonics, while leaving
the transmission of other frequencies unaffected.},
Doi = {10.1038/srep12764},
Key = {fds269551}
}
@article{fds269550,
Author = {Hoang, TB and Akselrod, GM and Argyropoulos, C and Huang, J and Smith,
DR and Mikkelsen, MH},
Title = {Ultrafast spontaneous emission source using plasmonic
nanoantennas.},
Journal = {Nature communications},
Volume = {6},
Pages = {7788},
Year = {2015},
Month = {July},
url = {http://dx.doi.org/10.1038/ncomms8788},
Abstract = {Typical emitters such as molecules, quantum dots and
semiconductor quantum wells have slow spontaneous emission
with lifetimes of 1-10 ns, creating a mismatch with
high-speed nanoscale optoelectronic devices such as
light-emitting diodes, single-photon sources and lasers.
Here we experimentally demonstrate an ultrafast (<11 ps)
yet efficient source of spontaneous emission, corresponding
to an emission rate exceeding 90 GHz, using a hybrid
structure of single plasmonic nanopatch antennas coupled to
colloidal quantum dots. The antennas consist of silver
nanocubes coupled to a gold film separated by a thin polymer
spacer layer and colloidal core-shell quantum dots, a stable
and technologically relevant emitter. We show an increase in
the spontaneous emission rate of a factor of 880 and
simultaneously a 2,300-fold enhancement in the total
fluorescence intensity, which indicates a high radiative
quantum efficiency of ∼50%. The nanopatch antenna geometry
can be tuned from the visible to the near infrared,
providing a promising approach for nanophotonics based on
ultrafast spontaneous emission.},
Doi = {10.1038/ncomms8788},
Key = {fds269550}
}
@article{fds305681,
Author = {Liu, X and Larouche, S and Bowen, P and Smith, DR},
Title = {Clarifying the origin of third-harmonic generation from
film-coupled nanostripes.},
Journal = {Optics express},
Volume = {23},
Number = {15},
Pages = {19565-19574},
Year = {2015},
Month = {July},
url = {http://dx.doi.org/10.1364/oe.23.019565},
Abstract = {The resonance associated with plasmonic nanostructures
strongly enhances local optical fields, and can thus
dramatically enhance the nonlinear response of the composite
structure. However, the origin of the nonlinear signal
generated from hybrid nanostructures consisting of both
metallic and dielectric components can be ambiguous when all
constituents possess nonlinearities. In this paper, we
introduce a method for specifically identifying the third
harmonic generation (THG) originating from different
nonlinear sources in a film-coupled nanostripe. The
nanostripe consists of a metallic patch separated from a
metallic film by a dielectric spacer. By considering the THG
from each nonlinear source separately, we show that the
near- and far-field behaviors of the THG generated within
the various constituents of the nanostripe are
distinguishable due to fundamental differences in the THG
radiation properties. The THG signal from the metal is shown
to be suppressed by the structure itself, while the THG
signal from the spacer is enhanced by the gap plasmon modes
supported by the structure. The total THG signal is found to
be the sum of all nonlinear sources, with the far-field
radiation pattern determined by the ratio between the
third-order susceptibilities of the dielectric and the
metal.},
Doi = {10.1364/oe.23.019565},
Key = {fds305681}
}
@article{fds330963,
Author = {Thornton, J and Smith, D and Foti, SJ and Jiang, YY},
Title = {Reduced height Luneburg lens antennas for satellite
communications-on-the-move},
Journal = {Proceedings of 14th Conference on Microwave Techniques,
COMITE 2015},
Publisher = {IEEE},
Year = {2015},
Month = {June},
ISBN = {9781479981212},
url = {http://dx.doi.org/10.1109/COMITE.2015.7120325},
Abstract = {The hemispherical (or half-Luneburg) lens antenna is a
candidate type for satellite communications-on-the-move,
either singly or as an element in a small array. It offers
good aperture efficiency in a reduced height and excellent
scanning performance. This work describes the development of
half Luneburg lens antennas together with feeding
arrangements to provide highly directive antennas with good
scanning properties. The effects of the primary feed pattern
and other loss mechanisms are investigated and reported.
Measured gain for a 432mm diameter polymer lens at 30 GHz is
38.7 dBi.},
Doi = {10.1109/COMITE.2015.7120325},
Key = {fds330963}
}
@article{fds269553,
Author = {Fromenteze, T and Yurduseven, O and Imani, MF and Gollub, J and Decroze,
C and Carsenat, D and Smith, DR},
Title = {Computational imaging using a mode-mixing cavity at
microwave frequencies},
Journal = {Applied Physics Letters},
Volume = {106},
Number = {19},
Pages = {194104-194104},
Publisher = {AIP Publishing},
Year = {2015},
Month = {May},
ISSN = {0003-6951},
url = {http://dx.doi.org/10.1063/1.4921081},
Abstract = {We present a 3D computational imaging system based on a
mode-mixing cavity at microwave frequencies. The core
component of this system is an electrically large
rectangular cavity with one corner re-shaped to catalyze
mode mixing, often called a Sinai Billiard. The front side
of the cavity is perforated with a grid of periodic
apertures that sample the cavity modes and project them into
the imaging scene. The radiated fields are scattered by the
scene and are measured by low gain probe antennas. The
complex radiation patterns generated by the cavity thus
encode the scene information onto a set of frequency modes.
Assuming the first Born approximation for scattering
dynamics, the received signal is processed using
computational methods to reconstruct a 3D image of the scene
with resolution determined by the diffraction limit. The
proposed mode-mixing cavity is simple to fabricate, exhibits
low losses, and can generate highly diverse measurement
modes. The imaging system demonstrated in this letter can
find application in security screening and medical
diagnostic imaging.},
Doi = {10.1063/1.4921081},
Key = {fds269553}
}
@article{fds269554,
Author = {Baron, A and Hoang, TB and Fang, C and Mikkelsen, MH and Smith,
DR},
Title = {Ultrafast self-action of surface-plasmon polaritons at an
air/metal interface},
Journal = {Physical Review B - Condensed Matter and Materials
Physics},
Volume = {91},
Number = {19},
Publisher = {American Physical Society (APS)},
Year = {2015},
Month = {May},
ISSN = {1098-0121},
url = {http://dx.doi.org/10.1103/PhysRevB.91.195412},
Abstract = {We investigate both theoretically and experimentally the
nonlinear propagation of surface-plasmon polaritons (SPP) on
a single air/metal interface. Inspired by nonlinear
dielectric waveguide theory, we analytically derive a model
that describes the nonlinear propagation of SPPs, thus
bridging the description of plasmonic and dielectric
waveguides. The model, the numerical simulations, and the
experiments, which are carried out in the 100 fs regime,
reveal that the SPP undergoes strong ultrafast self-action
which manifests itself through self-induced absorption. Our
observations are consistent with a large, bulk, third-order
nonlinear susceptibility (χ(3)) of gold and provide a
self-consistent theory of self-action of SPPs at an
air/metal interface. Experimentally, we find
Im{χ-(3)}∼3×10-16m2/V2. These findings have important
implications in the nonlinear physics of plasmonics and
metamaterials as they provide evidence that nonlinear
absorption has a significant effect on the propagation of
SPPs excited by intense optical pulses. This self-action is
also expected to affect the anomalous absorption of light
near subwavelength structures as well as the strength of
desirable nonlinear processes such as third-harmonic
generation and four-wave mixing, which will inevitably
compete with nonlinear absorption.},
Doi = {10.1103/PhysRevB.91.195412},
Key = {fds269554}
}
@article{fds269555,
Author = {Ciracì, C and Scalora, M and Smith, DR},
Title = {Third-harmonic generation in the presence of classical
nonlocal effects in gap-plasmon nanostructures},
Journal = {Physical Review B - Condensed Matter and Materials
Physics},
Volume = {91},
Number = {20},
Publisher = {American Physical Society (APS)},
Year = {2015},
Month = {May},
ISSN = {1098-0121},
url = {http://dx.doi.org/10.1103/PhysRevB.91.205403},
Abstract = {Classical nonlocality in conducting nanostructures has been
shown to dramatically alter the linear optical response by
placing a fundamental limit on the maximum field enhancement
that can be achieved. This limit directly extends to all
nonlinear processes, which depend on field amplitudes. A
numerical study of third-harmonic generation in metal
film-coupled nanowires reveals that for subnanometer vacuum
gaps, the nonlocality may boost the effective nonlinearity
by 5 orders of magnitude as the field penetrates deeper
inside the metal than that predicted assuming a purely local
electronic response. We also study the impact of a nonlinear
dielectric placed in the gap region. In this case the effect
of nonlocality could be masked by the third-harmonic signal
generated by the spacer. By etching the dielectric
underneath the nanowire, however, it is possible to muffle
such contributions. Calculations are performed for both
silver and gold nanowire.},
Doi = {10.1103/PhysRevB.91.205403},
Key = {fds269555}
}
@article{fds269544,
Author = {Baron, A and Hoang, TB and Fang, C and Mikkelsen, MH and Smith,
DR},
Title = {Large and ultrafast nonlinear absorption of an air/gold
plasmonic waveguide},
Journal = {CLEO: QELS - Fundamental Science, CLEO_QELS
2015},
Pages = {1551p},
Publisher = {OSA},
Year = {2015},
Month = {May},
ISBN = {9781557529688},
url = {http://dx.doi.org/10.1364/CLEO_QELS.2015.FM3E.4},
Abstract = {We investigate theoretically and experimentally the
nonlinear propagation of surface plasmons on an air/gold
interface which reveals large and ultrafast (~100 fs)
self-induced absorption. The experiment enables a direct
measurement of the third-order nonlinear susceptibility. ©
OSA 2015.},
Doi = {10.1364/CLEO_QELS.2015.FM3E.4},
Key = {fds269544}
}
@article{fds269545,
Author = {Chandrasekar, R and Emani, NK and Lagutchev, A and Shalaev, VM and Ciraci, C and Smith, DR and Kildishev, AV},
Title = {Studying the interplay of electric and magnetic resonance-
enhanced second harmonic generation: Theory and
experiments},
Journal = {CLEO: QELS - Fundamental Science, CLEO_QELS
2015},
Pages = {1551p},
Publisher = {OSA},
Year = {2015},
Month = {May},
ISBN = {9781557529688},
url = {http://dx.doi.org/10.1364/CLEO_QELS.2015.FW3D.2},
Abstract = {We present an experimental study of a metasurface, which
exhibits electric and magnetic resonances, in order to
understand their independent contributions to
second-harmonic generation. A hydrodynamic model framework
is used to match experimental results. © OSA
2015.},
Doi = {10.1364/CLEO_QELS.2015.FW3D.2},
Key = {fds269545}
}
@article{fds269546,
Author = {Bowen, PT and Baron, A and Smith, DR},
Title = {Analytic modeling of metmaterial absorbers},
Journal = {CLEO: QELS - Fundamental Science, CLEO_QELS
2015},
Pages = {1551p},
Publisher = {OSA},
Year = {2015},
Month = {May},
ISBN = {9781557529688},
url = {http://dx.doi.org/10.1364/CLEO_QELS.2015.FW4C.5},
Abstract = {We present a fully analytical model that describes ideal
absorbing metasurfaces composed of film-coupled optical
nanoantennas. The model predicts the spectrum and the
angular dependence of the absorption and is compared to
full-wave numerical simulations. © 2014 Optical Society of
America.},
Doi = {10.1364/CLEO_QELS.2015.FW4C.5},
Key = {fds269546}
}
@article{fds269547,
Author = {Akselrod, GM and Argyropoulos, C and Hoang, TB and Ciracì, C and Fang,
C and Huang, J and Smith, DR and Mikkelsen, MH},
Title = {Plasmonic nanopatch antennas for large purcell
enhancement},
Journal = {CLEO: QELS - Fundamental Science, CLEO_QELS
2015},
Pages = {1551p},
Publisher = {OSA},
Year = {2015},
Month = {May},
ISBN = {9781557529688},
url = {http://dx.doi.org/10.1364/CLEO_QELS.2015.FW1E.2},
Abstract = {We demonstrate Purcell enhancements of ~1000 from
fluorescent molecules embedded in a plasmonic antenna with
sub-10 nm gap between metals. Simulations and experiments
reveal the high radiative efficiency and directionality of
the antenna. © OSA 2015.},
Doi = {10.1364/CLEO_QELS.2015.FW1E.2},
Key = {fds269547}
}
@article{fds269552,
Author = {Baron, A and Larouche, S and Gauthier, DJ and Smith,
DR},
Title = {Scaling of the nonlinear response of metal/dielectric
plasmonic waveguides},
Journal = {CLEO: QELS - Fundamental Science, CLEO_QELS
2015},
Pages = {1551p},
Publisher = {OSA},
Year = {2015},
Month = {May},
ISBN = {9781557529688},
url = {http://dx.doi.org/10.1364/CLEO_QELS.2015.FM3E.7},
Abstract = {The scaling of the nonlinear response of a single-interface
plasmonic waveguide is studied, where both the metal and
dielectric display nonlinearity. We introduce a
figure-of-merit that guides metal/dielectric nanophotonic
device design for specific applications. © OSA
2015.},
Doi = {10.1364/CLEO_QELS.2015.FM3E.7},
Key = {fds269552}
}
@article{fds335069,
Author = {Diallo, A and Groebner, RJ and Rhodes, TL and Battaglia, DJ and Smith,
DR and Osborne, TH and Canik, JM and Guttenfelder, W and Snyder,
PB},
Title = {Correlations between quasi-coherent fluctuations and the
pedestal evolution during the inter-edge localized modes
phase on DIII-D},
Journal = {Physics of Plasmas},
Volume = {22},
Number = {5},
Pages = {056111-056111},
Publisher = {AIP Publishing},
Year = {2015},
Month = {May},
url = {http://dx.doi.org/10.1063/1.4921148},
Abstract = {Direct measurements of the pedestal recovery during an
edge-localized mode cycle provide evidence that
quasi-coherent fluctuations (QCFs) play a role in the
inter-ELM pedestal dynamics. Using fast Thomson scattering
measurements, the pedestal density and temperature
evolutions are probed on sub-millisecond time scales to show
a fast recovery of the density gradient compared to the
temperature gradient. The temperature gradient appears to
provide a drive for the onset of quasi-coherent fluctuations
(as measured with the magnetic probe and the density
diagnostics) localized in the pedestal. The amplitude
evolution of these QCFs tracks the temperature gradient
evolution including its saturation. Such correlation
suggests that these QCFs play a key role in limiting the
pedestal temperature gradient. The saturation of the QCFs
coincides with the pressure gradient reaching the
kinetic-ballooning mode (KBM) critical gradient as predicted
by EPED1. Furthermore, linear microinstability analysis
using GS2 indicates that the steep gradient is near the KBM
threshold. Thus, the modeling and the observations together
suggest that QCFs are consistent with dominant KBMs,
although microtearing cannot be excluded as
subdominant.},
Doi = {10.1063/1.4921148},
Key = {fds335069}
}
@article{fds269556,
Author = {Akselrod, GM and Ming, T and Argyropoulos, C and Hoang, TB and Lin, Y and Ling, X and Smith, DR and Kong, J and Mikkelsen, MH},
Title = {Leveraging Nanocavity Harmonics for Control of Optical
Processes in 2D Semiconductors.},
Journal = {Nano letters},
Volume = {15},
Number = {5},
Pages = {3578-3584},
Year = {2015},
Month = {May},
ISSN = {1530-6984},
url = {http://dx.doi.org/10.1021/acs.nanolett.5b01062},
Abstract = {Optical cavities with multiple tunable resonances have the
potential to provide unique electromagnetic environments at
two or more distinct wavelengths--critical for control of
optical processes such as nonlinear generation, entangled
photon generation, or photoluminescence (PL) enhancement.
Here, we show a plasmonic nanocavity based on a nanopatch
antenna design that has two tunable resonant modes in the
visible spectrum separated by 350 nm and with line widths of
∼60 nm. The importance of utilizing two resonances
simultaneously is demonstrated by integrating monolayer
MoS2, a two-dimensional semiconductor, into the colloidally
synthesized nanocavities. We observe a 2000-fold enhancement
in the PL intensity of MoS2--which has intrinsically low
absorption and small quantum yield--at room temperature,
enabled by the combination of tailored absorption
enhancement at the first harmonic and PL quantum-yield
enhancement at the fundamental resonance.},
Doi = {10.1021/acs.nanolett.5b01062},
Key = {fds269556}
}
@article{fds335070,
Author = {Sechrest, Y and Smith, D and Stotler, DP and Munsat, T and Zweben,
SJ},
Title = {Comparison of beam emission spectroscopy and gas puff
imaging edge fluctuation measurements in National Spherical
Torus Experiment},
Journal = {Physics of Plasmas},
Volume = {22},
Number = {5},
Pages = {052310-052310},
Publisher = {AIP Publishing},
Year = {2015},
Month = {May},
url = {http://dx.doi.org/10.1063/1.4921215},
Abstract = {In this study, the close physical proximity of the Gas Puff
Imaging (GPI) and Beam Emission Spectroscopy (BES)
diagnostics on the National Spherical torus Experiment
(NSTX) is leveraged to directly compare fluctuation
measurements, and to study the local effects of the GPI
neutral deuterium puff during H-mode plasmas without large
Edge Localized Modes. The GPI and BES views on NSTX provide
partially overlapping coverage of the edge and scrape-off
layer (SOL) regions above the outboard midplane. The
separation in the toroidal direction is 16 °, and field
lines passing through diagnostic views are separated by ∼
20 cm in the direction perpendicular to the magnetic field.
Strong cross-correlation is observed, and strong
cross-coherence is seen for frequencies between 5 and 15
kHz. Also, probability distribution functions of
fluctuations measured ∼ 3 cm inside the separatrix exhibit
only minor deviations from a normal distribution for both
diagnostics, and good agreement between correlation length
estimates, decorrelation times, and structure velocities is
found at the ±40% level. While the two instruments agree
closely in many respects, some discrepancies are observed.
Most notably, GPI normalized fluctuation levels exceed BES
fluctuations by a factor of ∼ 9. BES mean intensity is
found to be sensitive to the GPI neutral gas puff, and BES
normalized fluctuation levels for frequencies between 1 and
10 kHz are observed to increase during the GPI
puff.},
Doi = {10.1063/1.4921215},
Key = {fds335070}
}
@article{fds330964,
Author = {Zheng, H and Smith, D and Elsdon, M and Livingstone, B and Ng, WP and Yurduseven, O},
Title = {Microwave inverse scattering using scalar indirect
holographic techniques},
Journal = {Mediterranean Microwave Symposium},
Volume = {2015-April},
Publisher = {IEEE},
Year = {2015},
Month = {April},
ISBN = {9781479973910},
url = {http://dx.doi.org/10.1109/MMS.2014.7088948},
Abstract = {This paper describes the use of indirect microwave
holographic together with inverse scattering techniques for
the reconstruction of the dielectric properties of unknown
objects. The use of indirect microwave holography enables
the complex field scattered from the object under imaging to
be recovered from intensity-only scalar microwave
measurements and therefore removes the requirement of using
expensive vector measurement equipment. This significantly
reduces the cost of the imaging system and simplifies the
hardware implementation. Following the successful
implementation of indirect holography method for shape and
position reconstruction, we have explored an algorithm which
combines indirect holography method and CSI method to solve
the phaseless data reconstruction problem. Results presented
here indicate that the material properties of composite
dielectric objects can be accurately reconstructed using
scalar measurements from indirect holography.},
Doi = {10.1109/MMS.2014.7088948},
Key = {fds330964}
}
@article{fds335068,
Author = {Kaye, SM and Abrams, T and Ahn, JW and Allain, JP and Andre, R and Andruczyk, D and Barchfeld, R and Battaglia, D and Bhattacharjee, A and Bedoya, F and Bell, RE and Belova, E and Berkery, J and Berry, L and Bertelli, N and Beiersdorfer, P and Bialek, J and Bilato, R and Boedo,
J and Bonoli, P and Boozer, A and Bortolon, A and Boyer, MD and Boyle, D and Brennan, D and Breslau, J and Brooks, J and Buttery, R and Capece, A and Canik, J and Chang, CS and Crocker, N and Darrow, D and Davis, W and Delgado-Aparicio, L and Diallo, A and D'Ippolito, D and Domier, C and Ebrahimi, F and Ethier, S and Evans, T and Ferraro, N and Ferron, J and Finkenthal, M and Fonck, R and Fredrickson, E and Fu, GY and Gates, D and Gerhardt, S and Glasser, A and Gorelenkov, N and Gorelenkova, M and Goumiri, I and Gray, T and Green, D and Guttenfelder, W and Harvey, R and Hassanein, A and Heidbrink, W and Hirooka, Y and Hooper, EB and Hosea,
J and Humphreys, D and Jaeger, EF and Jarboe, T and Jardin, S and Jaworski,
MA and Kaita, R and Kessel, C and Kim, K and Koel, B and Kolemen, E and Kramer, G and Ku, S and Kubota, S and Lahaye, RJ and Lao, L and Leblanc,
BP and Levinton, F and Liu, D and Lore, J and Lucia, M and Jr, NL and Maingi,
R and Majeski, R and Mansfield, D and Maqueda, R and McKee, G and Medley,
S and Meier, E and Menard, J and Mueller, D and Munsat, T and Muscatello,
C and Myra, J and Nelson, B and Nichols, J and Ono, M and Osborne, T and Park,
JK},
Title = {An overview of recent physics results from
NSTX},
Journal = {Nuclear Fusion},
Volume = {55},
Number = {10},
Pages = {104002-104002},
Publisher = {IOP Publishing},
Year = {2015},
Month = {March},
url = {http://dx.doi.org/10.1088/0029-5515/55/10/104002},
Abstract = {The National Spherical Torus Experiment (NSTX) is currently
being upgraded to operate at twice the toroidal field and
plasma current (up to 1T and 2MA), with a second, more
tangentially aimed neutral beam (NB) for current and
rotation control, allowing for pulse lengths up to 5s.
Recent NSTX physics analyses have addressed topics that will
allow NSTX-Upgrade to achieve the research goals critical to
a Fusion Nuclear Science Facility. These include producing
stable, 100% non-inductive operation in high-performance
plasmas, assessing plasma-material interface (PMI) solutions
to handle the high heat loads expected in the next-step
devices and exploring the unique spherical torus (ST)
parameter regimes to advance predictive capability.
Non-inductive operation and current profile control in
NSTX-U will be facilitated by co-axial helicity injection
(CHI) as well as radio frequency (RF) and NB heating. CHI
studies using NIMROD indicate that the reconnection process
is consistent with the 2D Sweet-Parker theory. Full-wave
AORSA simulations show that RF power losses in the
scrape-off layer (SOL) increase significantly for both NSTX
and NSTX-U when the launched waves propagate in the SOL.
Toroidal Alfvén eigenmode avalanches and higher frequency
Alfvén eigenmodes can affect NB-driven current through
energy loss and redistribution of fast ions. The inclusion
of rotation and kinetic resonances, which depend on
collisionality, is necessary for predicting experimental
stability thresholds of fast growing ideal wall and
resistive wall modes. Neutral beams and neoclassical
toroidal viscosity generated from applied 3D fields can be
used as actuators to produce rotation profiles optimized for
global stability. DEGAS-2 has been used to study the
dependence of gas penetration on SOL temperatures and
densities for the MGI system being implemented on the
Upgrade for disruption mitigation. PMI studies have focused
on the effect of ELMs and 3D fields on plasma detachment and
heat flux handling. Simulations indicate that snowflake and
impurity seeded radiative divertors are candidates for heat
flux mitigation in NSTX-U. Studies of lithium evaporation on
graphite surfaces indicate that lithium increases oxygen
surface concentrations on graphite, and deuterium-oxygen
affinity, which increases deuterium pumping and reduces
recycling. In situ and test-stand experiments of lithiated
graphite and molybdenum indicate temperature-enhanced
sputtering, although that test-stand studies also show the
potential for heat flux reduction through lithium vapour
shielding. Non-linear gyro kinetic simulations have
indicated that ion transport can be enhanced by a shear-flow
instability, and that non-local effects are necessary to
explain the observed rapid changes in plasma turbulence.
Predictive simulations have shown agreement between a
microtearing-based reduced transport model and the measured
electron temperatures in a microtearing unstable regime. Two
Alfvén eigenmode-driven fast ion transport models have been
developed and successfully benchmarked against NSTX data.
Upgrade construction is moving on schedule with initial
physics research operation of NSTX-U planned for
mid-2015.},
Doi = {10.1088/0029-5515/55/10/104002},
Key = {fds335068}
}
@article{fds330962,
Author = {Smith, D and Livingstone, B and Elsdon, M and Zheng, H and Schejbal, V and Yurduseven, O},
Title = {The development of indirect microwave holography for
measurement and imaging applications},
Journal = {Mediterranean Microwave Symposium},
Volume = {2015-January},
Publisher = {IEEE},
Year = {2015},
Month = {January},
ISBN = {9781467376020},
url = {http://dx.doi.org/10.1109/MMS.2015.7375501},
Abstract = {This work describes the development of indirect holographic
techniques for microwave measurements and imaging. It
outlines the basic theory of indirect holography and how it
relates to optical holographic techniques. It starts with a
description of the initial work using a single receiving
antenna for the determination of antenna radiation patterns
and the reconstruction of antenna aperture fields. This is
followed by a description of how these techniques can be
adapted for the imaging of passive objects. It also outlines
the techniques for the imaging of objects using indirect
holography. These techniques include simple back propagation
for the reconstruction of objects in free space and inverse
scattering techniques for objects in inhomogeneous
media.},
Doi = {10.1109/MMS.2015.7375501},
Key = {fds330962}
}
@article{fds269539,
Author = {Baron, A and Hoang, TB and Fang, C and Larouche, S and Gauthier, DJ and Mikkelsen, MH and Smith, DR},
Title = {Nonlinear Metal/Dielectric Plasmonic Interfaces},
Journal = {Nonlinear Optics, NLO 2015},
Publisher = {OSA},
Year = {2015},
Month = {January},
ISBN = {9781557520012},
url = {http://dx.doi.org/10.1364/NLO.2015.NTu2B.2},
Abstract = {We investigate theoretically and experimentally the optical
nonlinearity of metal/dielectric interfaces, which provides
a metric that predicts the scaling of self-action as well as
a means to measure χ(3)of gold using surface plasmon
polaritons.},
Doi = {10.1364/NLO.2015.NTu2B.2},
Key = {fds269539}
}
@article{fds335065,
Author = {Magnoni, L and Suthakar, U and Cordeiro, C and Georgiou, M and Andreeva,
J and Khan, A and Smith, DR},
Title = {Monitoring WLCG with lambda-architecture: A new scalable
data store and analytics platform for monitoring at petabyte
scale.},
Journal = {Journal of Physics: Conference Series},
Volume = {664},
Number = {5},
Pages = {052023-052023},
Publisher = {IOP Publishing},
Year = {2015},
Month = {January},
url = {http://dx.doi.org/10.1088/1742-6596/664/5/052023},
Abstract = {Monitoring the WLCG infrastructure requires the gathering
and analysis of a high volume of heterogeneous data (e.g.
data transfers, job monitoring, site tests) coming from
different services and experiment-specific frameworks to
provide a uniform and flexible interface for scientists and
sites. The current architecture, where relational database
systems are used to store, to process and to serve
monitoring data, has limitations in coping with the foreseen
increase in the volume (e.g. higher LHC luminosity) and the
variety (e.g. new data-transfer protocols and new
resource-types, as cloud-computing) of WLCG monitoring
events. This paper presents a new scalable data store and
analytics platform designed by the Support for Distributed
Computing (SDC) group, at the CERN IT department, which uses
a variety of technologies each one targeting specific
aspects of big-scale distributed data-processing (commonly
referred as lambda-architecture approach). Results of data
processing on Hadoop for WLCG data activities monitoring are
presented, showing how the new architecture can easily
analyze hundreds of millions of transfer logs in a few
minutes. Moreover, a comparison of data partitioning,
compression and file format (e.g. CSV, Avro) is presented,
with particular attention given to how the file structure
impacts the overall MapReduce performance. In conclusion,
the evolution of the current implementation, which focuses
on data storage and batch processing, towards a complete
lambda-architecture is discussed, with consideration of
candidate technology for the serving layer (e.g.
Elasticsearch) and a description of a proof of concept
implementation, based on Apache Spark and Esper, for the
real-time part which compensates for batch-processing
latency and automates problem detection and
failures.},
Doi = {10.1088/1742-6596/664/5/052023},
Key = {fds335065}
}
@article{fds335072,
Author = {Diallo, A and Groebner, RJ and Hughes, JW and Rhodes, TL and Baek, SG and LaBombard, B and Terry, JL and Cziegler, I and Walk, J and Hubbard, AE and Smith, D and Osborne, TH and Canik, JM and Guttenfelder, W and Snyder,
PB},
Title = {Inter-ELM pedestal evolution and the role of edge
fluctuations in the C-Mod and DIII-D tokamaks},
Journal = {42nd European Physical Society Conference on Plasma Physics,
EPS 2015},
Year = {2015},
Month = {January},
Key = {fds335072}
}
@article{fds335071,
Author = {Ruiz, JR and Ren, Y and Guttenfelder, W and White, AE and Kaye, SM and Leblanc, BP and Mazzucato, E and Lee, KC and Domier, CW and Smith, DR and Yuh, H},
Title = {Stabilization of electron-scale turbulence by electron
density gradient in NSTX},
Journal = {42nd European Physical Society Conference on Plasma Physics,
EPS 2015},
Year = {2015},
Month = {January},
Key = {fds335071}
}
@article{fds315571,
Author = {Marks, DL and Smith, DR},
Title = {Metamaterial resonators for dynamic spatial millimeter-wave
modulators},
Journal = {Proceedings of Frontiers in Optics 2015, FIO
2015},
Year = {2015},
Month = {January},
ISBN = {9781943580033},
Abstract = {© OSA 2015. Many phase spatial modulators exist at optical
frequencies such as liquid crystal cells. We present an
alternative for millimeter-waves based on metamaterial
resonators that produces strong phase modulation from a
small tuning range.},
Key = {fds315571}
}
@article{fds269558,
Author = {Baron, A and Larouche, S and Gauthier, DJ and Smith,
DR},
Title = {Scaling of the nonlinear response of the surface plasmon
polariton at a metal/dielectric interface},
Journal = {Journal of the Optical Society of America B: Optical
Physics},
Volume = {32},
Number = {1},
Pages = {9-14},
Publisher = {The Optical Society},
Year = {2015},
Month = {January},
ISSN = {0740-3224},
url = {http://dx.doi.org/10.1364/JOSAB.32.000009},
Abstract = {Plasmonic systems involve interfaces containing metal and
dielectric materials. In an effort to investigate the
scaling of the nonlinear response of the surface plasmon
polariton at a metal/dielectric interface, where the metal
and dielectric present optical nonlinearity, we introduce a
figure-of-merit that quantifies the contribution of the
metal and the dielectric to the nonlinear response in this
specific situation. In the case of self-action of the
surface plasmon polariton for the gold/dielectric interface,
we predict that the dielectric nonlinear response is
dominant for strongly nonlinear dielectrics such as
polydiacetylenes, chalcogenide glasses, or even
semiconductors. The gold nonlinear response is dominant only
in cases involving weakly nonlinear dielectrics such as
silicon dioxide or aluminum oxide. We verify the relevance
of the metric by investigating the process of optical
switching via the third-order nonlinear response and discuss
which gold/dielectric combinations have better switching
behaviors.},
Doi = {10.1364/JOSAB.32.000009},
Key = {fds269558}
}
@article{fds269559,
Author = {Larouche, S and Rose, A and Smith, DR},
Title = {A constitutive description of nonlinear metamaterials
through electric, magnetic, and magnetoelectric
nonlinearities},
Journal = {Springer Series in Materials Science},
Volume = {200},
Pages = {1-19},
Publisher = {Springer International Publishing},
Year = {2015},
Month = {January},
ISSN = {0933-033X},
url = {http://dx.doi.org/10.1007/978-3-319-08386-5_1},
Abstract = {Nonlinear metamaterials provide a host of interesting
phenomena which, like for their linear counterpart, can be
described using homogenized, effective properties. Following
the convention used in nonlinear optics, the response of
nonlinear metamaterials can be expressed as a power series
of the incident fields. However, contrarily to most
materials used in nonlinear optics that only possess an
electric nonlinear response, nonlinear metamaterials often
showelectric, magnetic, and magnetoelectric nonlinear
responses within a single unit cell. In this chapter, we
present two complementary approaches to determine all the
effective nonlinear susceptibilities of nonlinear
metamaterials. First we present a coupled-mode theory that
provides insight into the origin of the various nonlinear
susceptibilities that arise in nonlinear metamaterials
according to the symmetry of the unit cell. This approach
also leads to a description of the effect of the finite size
of the unit cells, often called spatial dispersion. Second,
we present a retrieval approach based on transfer matrices
that can be used to determine the effective nonlinear
susceptibilities from either simulated or experimental
results. We finally demonstrate how to use this approach by
applying it to the case of dual-gap varactor-loaded split
ring resonators.},
Doi = {10.1007/978-3-319-08386-5_1},
Key = {fds269559}
}
@article{fds269560,
Author = {Yurduseven, O and Imani, MF and Odabasi, H and Gollub, J and Lipworth,
G and Rose, A and Smith, DR},
Title = {Resolution of the frequency diverse metamaterial aperture
imager},
Journal = {Progress in Electromagnetics Research},
Volume = {150},
Pages = {97-107},
Publisher = {EMW Publishing},
Year = {2015},
Month = {January},
url = {http://dx.doi.org/10.2528/PIER14113002},
Abstract = {The resolution of a frequency diverse compressive
metamaterial aperture imager is investigated. The aperture
consists of a parallel plate waveguide, in which an array of
complementary, resonant metamaterial elements is patterned
into one of the plates. Microwaves injected into the
waveguide leak out through the resonant metamaterial
elements, forming a spatially diverse waveform at the scene.
As the frequency is scanned, the waveforms change, such that
scene information can be encoded onto a set of frequency
measurements. The compressive nature of the metamaterial
imager enables image reconstruction from a significantly
reduced number of measurements. We characterize the
resolution of this complex aperture by studying the
simulated point spread function (PSF) computed using
different image reconstruction techniques. We compare the
imaging performance of the system with that expected from
synthetic aperture radar (SAR) limits.},
Doi = {10.2528/PIER14113002},
Key = {fds269560}
}
@article{fds269561,
Author = {Chen, X and Ciracì, C and Smith, DR and Oh, S-H},
Title = {Nanogap-enhanced infrared spectroscopy with
template-stripped wafer-scale arrays of buried plasmonic
cavities.},
Journal = {Nano letters},
Volume = {15},
Number = {1},
Pages = {107-113},
Year = {2015},
Month = {January},
ISSN = {1530-6984},
url = {http://dx.doi.org/10.1021/nl503126s},
Abstract = {We have combined atomic layer lithography and template
stripping to produce a new class of substrates for
surface-enhanced infrared absorption (SEIRA) spectroscopy.
Our structure consists of a buried and U-shaped
metal-insulator-metal waveguide whose folded vertical arms
efficiently couple normally incident light. The insulator is
formed by atomic layer deposition (ALD) of Al2O3 and
precisely defines the gap size. The buried nanocavities are
protected from contamination by a silicon template until
ready for use and exposed by template stripping on demand.
The exposed nanocavity generates strong infrared resonances,
tightly confines infrared radiation into a gap that is as
small as 3 nm (λ/3300), and creates a dense array of
millimeter-long hotspots. After partial removal of the
insulators, the gaps are backfilled with benzenethiol
molecules, generating distinct Fano resonances due to strong
coupling with gap plasmons, and a SEIRA enhancement factor
of 10(5) is observed for a 3 nm gap. Because of the
wafer-scale manufacturability, single-digit-nanometer
control of the gap size via ALD, and long-term storage
enabled by template stripping, our buried plasmonic
nanocavity substrates will benefit broad applications in
sensing and spectroscopy.},
Doi = {10.1021/nl503126s},
Key = {fds269561}
}
@article{fds293134,
Author = {Chandrasekar, R and Emani, NK and Lagutchev, A and Shalaev, VM and Ciracì, C and Smith, DR and Kildishev, AV},
Title = {Second harmonic generation with plasmonic metasurfaces:
Direct comparison of electric and magnetic
resonances},
Journal = {Optical Materials Express},
Volume = {5},
Number = {11},
Pages = {2682-2691},
Publisher = {The Optical Society},
Year = {2015},
Month = {January},
url = {http://dx.doi.org/10.1364/OME.5.002682},
Abstract = {Plasmonic resonances in metallic nanostructures have been
shown to drastically enhance local electromagnetic fields,
and thereby increase the efficiency of nonlinear optical
phenomena, such as second harmonic generation (SHG). While
it has been experimentally observed that enhanced fields can
significantly boost SHG, to date it proved difficult to
probe electrical and magnetic resonance in one and the same
nanostructure. This however is necessary to directly compare
relative contributions of electrical and magnetic components
of SHG enhancement. In this paper we report an experimental
study of a metasurface capable of providing electrical and
magnetic resonant SHG enhancement for TM polarization. Our
metasurface could be engineered such that the peak
frequencies of electrical and magnetic resonances could be
adjusted independently. We used this feature to distinguish
their relative contributions. Experimentally it was observed
that the magnetic resonance provides only 50% as much
enhancement to SHG as compared to the electric resonance. In
addition aligning both resonances in frequency results in
conversion efficiency of 1.32 x 10-10.},
Doi = {10.1364/OME.5.002682},
Key = {fds293134}
}
@article{fds269557,
Author = {Lassiter, JB and Chen, X and Liu, X and Ciracì, C and Hoang, TB and Larouche, S and Oh, SH and Mikkelsen, MH and Smith,
DR},
Title = {Third-Harmonic Generation Enhancement by Film-Coupled
Plasmonic Stripe Resonators},
Journal = {ACS Photonics},
Volume = {1},
Number = {11},
Pages = {1212-1217},
Publisher = {American Chemical Society (ACS)},
Year = {2014},
Month = {November},
ISSN = {2330-4022},
url = {http://dx.doi.org/10.1021/ph500276v},
Abstract = {Because of their ability to strongly localize and enhance
optical fields, plasmonic nanostructures have the potential
to dramatically amplify the inherent nonlinear response of
materials. We illustrate the impact of this plasmonic
interaction by investigating the third-harmonic generation
(THG) from a system of film-coupled nanostripes operating at
1500 nm. Both the film and the stripes are gold, separated
by a nanoscale layer of aluminum oxide (Al2O3) grown using
atomic layer deposition. This nanoscale junction, with an
ultrasmooth interface, forms a waveguide cavity resonator
with a large and controllable electric field enhancement,
whose plasmon resonance can be tuned independently by
changing the stripe width. We study experimentally the
dependence of THG on the field enhancement by varying the
gap size between the stripe and the metal film while
simultaneously maintaining a fixed plasmon resonance. The
experiments are supported with numerical simulations in
which nonlinear contributions of the dielectric spacer layer
and the metal are considered. Enhancements of the THG of
nearly 5 orders of magnitude with respect to a bare metal
film are measured experimentally for the smallest gap sizes,
with a trend similar to that found in the numerical
simulations. (Chemical Equation Presented).},
Doi = {10.1021/ph500276v},
Key = {fds269557}
}
@article{fds269568,
Author = {Akselrod, GM and Argyropoulos, C and Hoang, TB and Ciracì, C and Fang,
C and Huang, J and Smith, DR and Mikkelsen, MH},
Title = {Probing the mechanisms of large Purcell enhancement in
plasmonic nanoantennas},
Journal = {Nature Photonics},
Volume = {8},
Number = {11},
Pages = {835-840},
Publisher = {Springer Nature},
Year = {2014},
Month = {November},
ISSN = {1749-4885},
url = {http://dx.doi.org/10.1038/nphoton.2014.228},
Abstract = {To move nanophotonic devices such as lasers and
single-photon sources into the practical realm, a
challenging list of requirements must be met, including
directional emission, room-temperature and broadband
operation, high radiative quantum efficiency and a large
spontaneous emission rate. To achieve these features
simultaneously, a platform is needed for which the various
decay channels of embedded emitters can be fully understood
and controlled. Here, we show that all these device
requirements can be satisfied by a film-coupled metal
nanocube system with emitters embedded in the dielectric gap
region. Fluorescence lifetime measurements on ensembles of
emitters reveal spontaneous emission rate enhancements
exceeding 1,000 while maintaining high quantum efficiency
(>0.5) and directional emission (84% collection efficiency).
Using angle-resolved fluorescence measurements, we
independently determine the orientations of emission dipoles
in the nanoscale gap. Incorporating this information with
the three-dimensional spatial distribution of dipoles into
full-wave simulations predicts time-resolved emission in
excellent agreement with experiments.},
Doi = {10.1038/nphoton.2014.228},
Key = {fds269568}
}
@article{fds269565,
Author = {Bowen, PT and Smith, DR},
Title = {Coupled-mode theory for film-coupled plasmonic
nanocubes},
Journal = {Physical Review B - Condensed Matter and Materials
Physics},
Volume = {90},
Number = {19},
Publisher = {American Physical Society (APS)},
Year = {2014},
Month = {November},
ISSN = {1098-0121},
url = {http://dx.doi.org/10.1103/PhysRevB.90.195402},
Abstract = {Planar metallic nanoparticles separated by nanoscale
distances from a metal film support unique plasmonic
resonances useful for controlling a wide range of
photodynamic processes. The fundamental resonance of a
film-coupled planar nanoparticle arises from a
transmission-line mode localized between nanoparticle and
film, whose properties can be roughly approximated by closed
form expressions similar to those used in patch antenna
theory. The insight provided by the analytical expressions,
and the potential of achieving similar closed-form
expressions for a range of plasmonic phenomenon such as
spasing, fluorescence enhancement, and perfect absorbers,
motivates a more detailed study of the film-coupled patch.
Here, we present an expanded analytical analysis of the
plasmonic patch geometry, applying an eigenmode expansion
method to arrive at a more accurate description of the field
distribution underneath a film-coupled plasmonic nanocube.
The fields corresponding to the inhomogeneous Maxwell's
equations are expanded in a set of lossless waveguide
eigenmodes. Radiation damping and Ohmic losses are then
perturbatively taken into account by considering an
equivalent surface impedance. We find that radiative loss
couples the lossless eigenmodes, leading to discernible
features in the scattering spectra of the nanocubes. The
method presented can be further applied to the case of point
source excitations, in which accounting for all potential
eigenmodes becomes essential.},
Doi = {10.1103/PhysRevB.90.195402},
Key = {fds269565}
}
@article{fds269564,
Author = {Ciracì, C and Rose, A and Argyropoulos, C and Smith,
DR},
Title = {Numerical studies of the modification of photodynamic
processes by film-coupled plasmonic nanoparticles},
Journal = {Journal of the Optical Society of America B: Optical
Physics},
Volume = {31},
Number = {11},
Pages = {2601-2607},
Publisher = {The Optical Society},
Year = {2014},
Month = {November},
ISSN = {0740-3224},
url = {http://dx.doi.org/10.1364/JOSAB.31.002601},
Abstract = {The local plasmon resonances of metallic nanostructures are
commonly associated with massive local field enhancements,
capable of increasing the photoexcitation of nearby quantum
emitters by orders of magnitude. However, these same
plasmonic structures support high densities of bound and
dissipative states, often quenching the nearby emitter or at
least offering competitive nonradiative channels. Thus,
finding a plasmonic platform that supports massive field
enhancements and a high proportion of radiating to
nonradiating states remains an active and promising area of
research. In this paper, we outline a simple method for
numerically studying plasmonic enhancements in fluorescence
and apply it to several variants of the film-coupled
nanoparticle platform. Filmcoupled nanoparticles make
excellent candidates for these investigations since the gap
dimension between nanoparticle and film-key to the
enhancement mechanism-can be precisely controlled in
experimental realizations. By correlating the properties of
embedded fluorophores with the resonances of the
film-coupled nanoparticles, we show quantum yield
engineering that is nearly independent of the fluorophore's
intrinsic quantum yield, yielding overall fluorescence
enhancements of over four orders of magnitude.},
Doi = {10.1364/JOSAB.31.002601},
Key = {fds269564}
}
@article{fds269562,
Author = {Chandrasekar, R and Emani, NK and Lagutchev, A and Shalaev, VM and Kildishev, AV and Ciraci, C and Smith, DR},
Title = {Second harmonic generation by metamagnetics: Interplay of
electric and magnetic resonances},
Journal = {Frontiers in Optics, FiO 2014},
Year = {2014},
Month = {October},
ISBN = {1557522863},
Abstract = {© OSA 2014. We present the first experimental study of the
interplay of electric and magnetic resonances in a
metamaterial to measure their independent contributions to
second-harmonic generation. Experiments indicate evident
contribution to SHG from fundamental magnetic
field.},
Key = {fds269562}
}
@article{fds269563,
Author = {Mikkelsen, MH and Rose, A and Hoang, TB and McGuire, F and Mock, JJ and Ciracì, C and Smith, DR},
Title = {Giant fluorescence enhancement of molecules coupled to
plasmonic nanoscale patch antennas},
Journal = {Frontiers in Optics, FiO 2014},
Year = {2014},
Month = {October},
ISBN = {1557522863},
Abstract = {© OSA 2014. We demonstrate a colloidally synthesized and
tunable plasmonic platform for giant fluorescence
enhancement and increased spontaneous emission rate of
embedded fluorophores. A transition between fluorescence
enhancement and quenching is revealed depending on the
plasmonic resonance.},
Key = {fds269563}
}
@article{fds330966,
Author = {Abadi, MM and Ghassemlooy, Z and Smith, D and Ng, WP and Khalighi, MA and Zvanovec, S},
Title = {Comparison of different combining methods for
space-diversity FSO systems},
Journal = {2014 9th International Symposium on Communication Systems,
Networks and Digital Signal Processing, CSNDSP
2014},
Pages = {1023-1028},
Publisher = {IEEE},
Year = {2014},
Month = {October},
ISBN = {9781479925810},
url = {http://dx.doi.org/10.1109/CSNDSP.2014.6923979},
Abstract = {This paper gives an overview of different signal combining
schemes for free space optical (FSO) communication systems
employing spatial diversity (SD) for the case of lognormal
weak turbulence atmospheric channels. The receiver
configurations are explained and categorized into two
domains, namely optical and electrical. Moreover, a new
combining scheme in the electrical domain, called 'logical'
domain combining, is introduced. We present closed-form
expressions of bit-error-rate for the combining schemes,
considering the typical case of a single-input
multiple-output (SIMO) system. Through some numerical
analyses, we show that depending on the number of receivers
and the turbulence strength, the proposed logical combining
method outperforms the other ones.},
Doi = {10.1109/CSNDSP.2014.6923979},
Key = {fds330966}
}
@article{fds269593,
Author = {Argyropoulos, C and Ciracì, C and Smith, DR},
Title = {Enhanced optical bistability with film-coupled plasmonic
nanocubes},
Journal = {Applied Physics Letters},
Volume = {104},
Number = {6},
Pages = {063108-063108},
Publisher = {AIP Publishing},
Year = {2014},
Month = {October},
ISSN = {0003-6951},
url = {http://dx.doi.org/10.1063/1.4866048},
Abstract = {Colloidally synthesized nanocubes strongly coupled to
conducting films hold great promise for enhancing different
nonlinear optical processes. They exhibit a robust and
sensitive scattering response that can be easily controlled
by their geometrical and material parameters. Strong local
field enhancement is generated at the gap regions between
the nanocubes and the metallic film. We show that strong
optical bistability and all-optical switching behavior can
be obtained by loading these nanogaps with Kerr nonlinear
materials. Relatively low input intensities are required to
obtain these nonlinear effects. The proposed design can lead
to efficient, low-power, and ultrafast all-optical memories
and scattering nanoswitches.},
Doi = {10.1063/1.4866048},
Key = {fds269593}
}
@article{fds269567,
Author = {Hill, RT and Kozek, KM and Hucknall, A and Smith, DR and Chilkoti,
A},
Title = {Nanoparticle-Film Plasmon Ruler Interrogated with
Transmission Visible Spectroscopy.},
Journal = {ACS photonics},
Volume = {1},
Number = {10},
Pages = {974-984},
Year = {2014},
Month = {October},
url = {http://dx.doi.org/10.1021/ph500190q},
Abstract = {The widespread use of plasmonic nanorulers (PNRs) in sensing
platforms has been plagued by technical challenges
associated with the development of methods to fabricate
precisely controlled nanostructures with high yield and
characterize them with high throughput. We have previously
shown that creating PNRs in a nanoparticle-film (NP-film)
format enables the fabrication of an extremely large
population of uniform PNRs with 100% yield using a
self-assembly approach, which facilitates high-throughput
PNR characterization using ensemble spectroscopic
measurements and eliminates the need for expensive
microscopy systems required by many other PNR platforms. We
expand upon this prior work herein, showing that the NP-film
PNR can be made compatible with aqueous sensing studies by
adapting it for use in a transmission localized surface
plasmon resonance spectroscopy format, where the coupled
NP-film resonance responsible for the PNR signal is directly
probed using an extinction measurement from a standard
spectrophotometer. We designed slide holders that fit inside
standard spectrophotometer cuvettes and position NP-film
samples so that the coupled NP-film resonance can be
detected in a collinear optical configuration. Once the
NP-film PNR samples are cuvette-compatible, it is
straightforward to calibrate the PNR in aqueous solution and
use it to characterize dynamic, angstrom-scale distance
changes resulting from pH-induced swelling of
polyelectrolyte (PE) spacer layers as thin as 1 PE layer and
also of a self-assembled monolayer of an amine-terminated
alkanethiol. This development is an important step toward
making PNR sensors more user-friendly and encouraging their
widespread use in various sensing schemes.},
Doi = {10.1021/ph500190q},
Key = {fds269567}
}
@article{fds269569,
Author = {Hunt, J and Gollub, J and Driscoll, T and Lipworth, G and Mrozack, A and Reynolds, MS and Brady, DJ and Smith, DR},
Title = {Metamaterial microwave holographic imaging
system.},
Journal = {Journal of the Optical Society of America. A, Optics, image
science, and vision},
Volume = {31},
Number = {10},
Pages = {2109-2119},
Year = {2014},
Month = {October},
ISSN = {1084-7529},
url = {http://dx.doi.org/10.1364/josaa.31.002109},
Abstract = {We demonstrate a microwave imaging system that combines
advances in metamaterial aperture design with emerging
computational imaging techniques. The flexibility inherent
to guided-wave, complementary metamaterials enables the
design of a planar antenna that illuminates a scene with
dramatically varying radiation patterns as a function of
frequency. As frequency is swept over the K-band
(17.5-26.5 GHz), a sequence of pseudorandom radiation
patterns interrogates a scene. Measurements of the return
signal versus frequency are then acquired and the scene is
reconstructed using computational imaging methods. The
low-cost, frequency-diverse static aperture allows
three-dimensional images to be formed without mechanical
scanning or dynamic beam-forming elements. The metamaterial
aperture is complementary to a variety of computational
imaging schemes, and can be used in conjunction with other
sensors to form a multifunctional imaging platform. We
illustrate the potential of multisensor fusion by
integrating an infrared structured-light and optical image
sensor to accelerate the microwave scene reconstruction and
to provide a simultaneous visualization of the
scene.},
Doi = {10.1364/josaa.31.002109},
Key = {fds269569}
}
@article{fds269566,
Author = {Ebadi, S and Landy, N and Perque, M and Driscoll, T and Smith,
D},
Title = {Wideband coaxial to substrate-integrated waveguide
transition in a multilayer reconfigurable antenna
configuration},
Journal = {IEEE Antennas and Propagation Society, AP-S International
Symposium (Digest)},
Pages = {454-455},
Publisher = {IEEE},
Year = {2014},
Month = {September},
ISSN = {1522-3965},
url = {http://dx.doi.org/10.1109/APS.2014.6904558},
Abstract = {A low-profile, wideband transition between a coaxial
waveguide and a substrate integrated waveguide (SIW) is
presented in this paper. The transition is designed for a
reconfigurable metamaterial antenna realized in multilayer
Printed Circuit Board at X-band. The transition achieves S11
below -15dB across a bandwidth of 19%, making it attractive
for many practical applications. Full wave simulation
results will be presented along with subtle details of the
fabrication such as effects of prepreg layers.},
Doi = {10.1109/APS.2014.6904558},
Key = {fds269566}
}
@article{fds335073,
Author = {Zweben, SJ and Stotler, DP and Bell, RE and Davis, WM and Kaye, SM and Leblanc, BP and Maqueda, RJ and Meier, ET and Munsat, T and Ren, Y and Sabbagh, SA and Sechrest, Y and Smith, DR and Soukhanovskii,
V},
Title = {Effect of a deuterium gas puff on the edge plasma in
NSTX},
Journal = {Plasma Physics and Controlled Fusion},
Volume = {56},
Number = {9},
Pages = {095010-095010},
Publisher = {IOP Publishing},
Year = {2014},
Month = {September},
url = {http://dx.doi.org/10.1088/0741-3335/56/9/095010},
Abstract = {This paper describes a detailed examination of the effects
of a relatively small pulsed deuterium gas puff on the edge
plasma and edge turbulence in NSTX. This gas puff caused
little or no change in the line-averaged plasma density or
total stored energy, or in the edge density and electron
temperature up to the time of the peak of the gas puff. The
radial profile of the Dα light emission and the edge
turbulence within this gas puff did not vary significantly
over its rise and fall, implying that these gas puffs did
not significantly perturb the local edge plasma or edge
turbulence. These measurements are compared with modeling by
DEGAS 2, UEDGE, and with simplified estimates for the
expected effects of this gas puff. © 2014 IOP Publishing
Ltd.},
Doi = {10.1088/0741-3335/56/9/095010},
Key = {fds335073}
}
@article{fds269579,
Author = {Rose, A and Hoang, TB and McGuire, F and Mock, JJ and Ciracì, C and Smith,
DR and Mikkelsen, MH},
Title = {Control of radiative processes using tunable plasmonic
nanopatch antennas.},
Journal = {Nano letters},
Volume = {14},
Number = {8},
Pages = {4797-4802},
Year = {2014},
Month = {August},
ISSN = {1530-6984},
url = {http://hdl.handle.net/10161/9254 Duke open
access},
Abstract = {The radiative processes associated with fluorophores and
other radiating systems can be profoundly modified by their
interaction with nanoplasmonic structures. Extreme
electromagnetic environments can be created in plasmonic
nanostructures or nanocavities, such as within the nanoscale
gap region between two plasmonic nanoparticles, where the
illuminating optical fields and the density of radiating
modes are dramatically enhanced relative to vacuum.
Unraveling the various mechanisms present in such coupled
systems, and their impact on spontaneous emission and other
radiative phenomena, however, requires a suitably reliable
and precise means of tuning the plasmon resonance of the
nanostructure while simultaneously preserving the
electromagnetic characteristics of the enhancement region.
Here, we achieve this control using a plasmonic platform
consisting of colloidally synthesized nanocubes
electromagnetically coupled to a metallic film. Each
nanocube resembles a nanoscale patch antenna (or nanopatch)
whose plasmon resonance can be changed independent of its
local field enhancement. By varying the size of the
nanopatch, we tune the plasmonic resonance by ∼ 200 nm,
encompassing the excitation, absorption, and emission
spectra corresponding to Cy5 fluorophores embedded within
the gap region between nanopatch and film. By sweeping the
plasmon resonance but keeping the field enhancements roughly
fixed, we demonstrate fluorescence enhancements exceeding a
factor of 30,000 with detector-limited enhancements of the
spontaneous emission rate by a factor of 74. The experiments
are supported by finite-element simulations that reveal
design rules for optimized fluorescence enhancement or large
Purcell factors.},
Doi = {10.1021/nl501976f},
Key = {fds269579}
}
@article{fds335074,
Author = {Gerhardt, SP and Canik, JM and Maingi, R and Battaglia, D and Bell, RE and Guttenfelder, W and Leblanc, BP and Smith, DR and Yuh, H and Sabbagh,
S},
Title = {Progress in understanding the enhanced pedestal H-mode in
NSTX},
Journal = {Nuclear Fusion},
Volume = {54},
Number = {8},
Pages = {083021-083021},
Publisher = {IOP Publishing},
Year = {2014},
Month = {August},
url = {http://dx.doi.org/10.1088/0029-5515/54/8/083021},
Abstract = {This paper describes the enhanced pedestal (EP) H-mode
observed in the National Spherical Torus Experiment (NSTX).
The defining characteristics of EP H-mode are given, namely
(i) transition after the L- to H-mode transition, (ii)
region of very steep ion temperature gradient, and (iii)
associated region of strong rotational shear. A newly
observed long-pulse EP H-mode example shows quiescent
behaviour for as long as the heating and current drive
sources are maintained. Cases are shown where the region of
steep ion temperature gradient is located at the very edge,
and cases where it is shifted up to 10cm inward from the
plasma edge; these cases are united by a common dependence
of the ion temperature gradient on the toroidal rotation
frequency shear. EP H-mode examples have been observed
across a wide range of q95 and pedestal collisionality. No
strong changes in the fluctuation amplitudes have been
observed following the EP H-mode transition, and transport
analysis indicates that the ion thermal transport is
comparable to or less than anticipated from a simple
neoclassical transport model. Cases are shown where EP
H-modes were reliably generated, though these low-q95
examples were difficult to sustain. A case where an
externally triggered edge localized mode (ELM) precipitates
the transition to EP H-mode is also shown, though an initial
experiment designed to trigger EP H-modes in this fashion
was unsuccessful. © 2014 IAEA, Vienna.},
Doi = {10.1088/0029-5515/54/8/083021},
Key = {fds335074}
}
@article{fds269571,
Author = {Landy, N and Smith, DR},
Title = {Two-dimensional metamaterial device design in the discrete
dipole approximation},
Journal = {Journal of Applied Physics},
Volume = {116},
Number = {4},
Pages = {044906-044906},
Publisher = {AIP Publishing},
Year = {2014},
Month = {July},
ISSN = {0021-8979},
url = {http://dx.doi.org/10.1063/1.4891295},
Abstract = {We extend the discrete dipole method to enable the analysis
and design of two-dimensional magnetoelectric metamaterial
devices based on transformation optics. Key to this method
is the evaluation of the dipole moments of the metamaterial
elements, which can be accomplished within the framework of
a rigorous Bloch wave model based on lattice sums.
Corrections to the polarizabilities for spatial dispersion
and magnetoelectric coupling are included in the formulation
of a generalized Clausius-Mossotti relationship. We
demonstrate the utility of the extended approach by
designing a cloaking structure that shows considerably
improved performance over that designed by assuming the
standard Clausius-Mossotti relationship between constitutive
parameter and polarizability. © 2014 AIP Publishing
LLC.},
Doi = {10.1063/1.4891295},
Key = {fds269571}
}
@article{fds269573,
Author = {Goldflam, MD and Liu, MK and Chapler, BC and Stinson, HT and Sternbach,
AJ and McLeod, AS and Zhang, JD and Geng, K and Royal, M and Kim, BJ and Averitt, RD and Jokerst, NM and Smith, DR and Kim, HT and Basov,
DN},
Title = {Voltage switching of a VO2 memory metasurface
using ionic gel},
Journal = {Applied Physics Letters},
Volume = {105},
Number = {4},
Pages = {041117-041117},
Publisher = {AIP Publishing},
Year = {2014},
Month = {July},
ISSN = {0003-6951},
url = {http://dx.doi.org/10.1063/1.4891765},
Abstract = {We demonstrate an electrolyte-based voltage tunable vanadium
dioxide (VO2) memory metasurface. Large spatial scale, low
voltage, non-volatile switching of terahertz (THz)
metasurface resonances is achieved through voltage
application using an ionic gel to drive the
insulator-to-metal transition in an underlying VO2 layer.
Positive and negative voltage application can selectively
tune the metasurface resonance into the "off" or "on" state
by pushing the VO2 into a more conductive or insulating
regime respectively. Compared to graphene based control
devices, the relatively long saturation time of resonance
modification in VO2 based devices suggests that this
voltage-induced switching originates primarily from
electrochemical effects related to oxygen migration across
the electrolyte-VO2 interface. © 2014 AIP Publishing
LLC.},
Doi = {10.1063/1.4891765},
Key = {fds269573}
}
@article{fds326629,
Author = {Baron, A and Hoang, TB and Fang, C and Mikkelsen, MH and Smith,
DR},
Title = {Ultrafast self-action in an air/gold plasmonic
waveguide},
Journal = {Optics InfoBase Conference Papers},
Year = {2014},
Month = {July},
ISBN = {9781467374750},
Key = {fds326629}
}
@article{fds326630,
Author = {Ciracì, C and Scalora, M and Smith, D},
Title = {Impact of nonlocal free-electron optical response on
third-harmonic generation in plasmonic nanostructures},
Journal = {Optics InfoBase Conference Papers},
Year = {2014},
Month = {July},
ISBN = {9781467374750},
Key = {fds326630}
}
@article{fds326631,
Author = {Bowen, PT and Baron, A and Smith, DR},
Title = {Analysis and modeling of metamaterial absorbers},
Journal = {Optics InfoBase Conference Papers},
Year = {2014},
Month = {July},
ISBN = {9781467374750},
Key = {fds326631}
}
@article{fds326243,
Author = {Baron, A and Hoang, TB and Fang, C and Mikkelsen, MH and Smith,
DR},
Title = {Ultrafast self-action in an air/gold plasmonic
waveguide},
Journal = {Optics InfoBase Conference Papers},
Volume = {Part F3-EQEC 2015},
Year = {2014},
Month = {July},
ISBN = {9781467374750},
Key = {fds326243}
}
@article{fds326244,
Author = {Ciracì, C and Scalora, M and Smith, D},
Title = {Impact of nonlocal free-electron optical response on
third-harmonic generation in plasmonic nanostructures},
Journal = {Optics InfoBase Conference Papers},
Volume = {Part F4-CLEO 2015},
Year = {2014},
Month = {July},
ISBN = {9781467374750},
Key = {fds326244}
}
@article{fds326245,
Author = {Bowen, PT and Baron, A and Smith, DR},
Title = {Analysis and modeling of metamaterial absorbers},
Journal = {Optics InfoBase Conference Papers},
Volume = {Part F3-EQEC 2015},
Year = {2014},
Month = {July},
ISBN = {9781467374750},
Key = {fds326245}
}
@article{fds269548,
Author = {Landy, N and Urzhumov, Y and Smith, DR},
Title = {Quasi-conformal approaches for two and three-dimensional
transformation optical media},
Volume = {9781447149965},
Pages = {1-32},
Booktitle = {Transformation Electromagnetics and Metamaterials:
Fundamental Principles and Applications},
Publisher = {Springer London},
Year = {2014},
Month = {July},
ISBN = {9781447149958},
url = {http://dx.doi.org/10.1007/978-1-4471-4996-5_1},
Abstract = {Transformation optical design is generally complicated by
the requirement for highly anisotropic and inhomogeneous
constituent materials. Quasi-conformal mappings have
appeared as an attractive subset of the general
transformation optics method because they only require
isotropic, dielectric-only materials. In this chapter, we
examine the quasi-conformal method as it applies to
transformation optics and show that while it does
significantly ease the burden of material design and
fabrication, it may also create severely aberrant behavior
unless caution is taken. We also show how to extend the
method to three dimensions, and examine the performance of
an optic designed with the quasi-conformal
method.},
Doi = {10.1007/978-1-4471-4996-5_1},
Key = {fds269548}
}
@article{fds269577,
Author = {Smith, DR},
Title = {Metamaterials. A cloaking coating for murky
media.},
Journal = {Science (New York, N.Y.)},
Volume = {345},
Number = {6195},
Pages = {384-385},
Year = {2014},
Month = {July},
ISSN = {0036-8075},
url = {http://dx.doi.org/10.1126/science.1256753},
Doi = {10.1126/science.1256753},
Key = {fds269577}
}
@article{fds335075,
Author = {Pozo, SD and Ribton, CN and Smith, DR},
Title = {A Novel RF Excited Plasma Cathode Electron Beam Gun
Design},
Journal = {IEEE Transactions on Electron Devices},
Volume = {61},
Number = {6},
Pages = {1890-1894},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2014},
Month = {June},
url = {http://dx.doi.org/10.1109/TED.2014.2299339},
Abstract = {© 2015 IEEE. This paper presents a new radio frequency (RF)
excited plasma cathode electron beam (EB) gun design and
experimental results at a frequency of 84 MHz. The design
offers the following benefits over thermionic cathode triode
EB guns: much longer cathode lifetime and as a result
improved reliability and reduced maintenance costs; no
requirement for a grid electrode, avoiding beam aberration,
and rapid beam pulsing. The construction of the diode gun
was completed and the results of this paper demonstrate that
the EB can be switched on in 200 ns and off within 800 ns.
Electrons were extracted from a plasma chamber and then
accelerated by an electric field applied in a vacuum chamber
at a pressure of 10-5 to 10-6 mbar, producing a collimated
EB. The ionized gas used was air at some 0.5 mbar pressure.
The EB gun has been operated at-60 kV accelerating potential
and has produced beams of up to 3.2 kW power continuous
wave. Modulation of the RF signal was used to control the
beam power. Details of the design features of the plasma
device are given and evidence of the advantages over
conventional EB guns is provided through empirical
results.},
Doi = {10.1109/TED.2014.2299339},
Key = {fds335075}
}
@article{fds269582,
Author = {Degiron, A and Smith, DR},
Title = {One-way glass for microwaves using nonreciprocal
metamaterials.},
Journal = {Physical review. E, Statistical, nonlinear, and soft matter
physics},
Volume = {89},
Number = {5},
Pages = {053203},
Publisher = {American Physical Society (APS)},
Year = {2014},
Month = {May},
ISSN = {1539-3755},
url = {http://dx.doi.org/10.1103/physreve.89.053203},
Abstract = {We introduce a class of nonreciprocal metamaterials based on
composite assemblies of metallic and biased ferrimagnetic
elements. We show that such structures act as ultrathin
one-way glasses due to the competition between two modes at
the surface of the ferrimagnetic elements--a low-loss
surface wave that transmits the signal on the other side of
the structure and a surface spin-wave resonance that
produces strong isolation levels. These findings can be
adapted to existing metamaterial geometries, offering a
blueprint to achieve unidirectional propagation in a variety
of artificial media at radio, microwave, and millimeter wave
frequencies.},
Doi = {10.1103/physreve.89.053203},
Key = {fds269582}
}
@article{fds335076,
Author = {Adey, D and Agarwalla, SK and Ankenbrandt, CM and Asfandiyarov, R and Back, JJ and Barker, G and Baussan, E and Bayes, R and Bhadra, S and Blackmore, V and Blondel, A and Bogacz, SA and Booth, C and Boyd, SB and Bramsiepe, SG and Bravar, A and Brice, SJ and Bross, AD and Cadoux, F and Cease, H and Cervera, A and Cobb, J and Colling, D and Coloma, P and Coney,
L and Dobbs, A and Dobson, J and Donini, A and Dornan, P and Dracos, M and Dufour, F and Edgecock, R and Geelhoed, M and Uchida, MA and Ghosh, T and Gómez-Cadenas, JJ and De Gouvêa and A and Haesler, A and Hanson, G and Harrison, PF and Hartz, M and Hernández, P and Hernando Morata and JA and Hodgson, P and Huber, P and Izmaylov, A and Karadzhov, Y and Kobilarcik,
T and Kopp, J and Kormos, L and Korzenev, A and Kuno, Y and Kurup, A and Kyberd, P and Lagrange, JB and Laing, A and Liu, A and Link, JM and Long,
K and Mahn, K and Mariani, C and Martin, C and Martin, J and McCauley, N and McDonald, KT and Mena, O and Mishra, SR and Mokhov, N and Morfín, J and Mori, Y and Murray, W and Neuffer, D and Nichol, R and Noah, E and Palmer,
MA and Parke, S and Pascoli, S and Pasternak, J and Plunkett, R and Popovic, M and Ratoff, P and Ravonel, M and Rayner, M and Ricciardi, S and Rogers, C and Rubinov, P and Santos, E and Sato, A and Sen, T and Scantamburlo, E and Sedgbeer, JK and Smith, DR and Smith, PJ and Sobczyk, JT and Søby, L and Soler, FJP and Sorel, M and Snopok, P and Stamoulis, P and Stanco, L},
Title = {Light sterile neutrino sensitivity at the nuSTORM
facility},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {89},
Number = {7},
Publisher = {American Physical Society (APS)},
Year = {2014},
Month = {April},
url = {http://dx.doi.org/10.1103/PhysRevD.89.071301},
Abstract = {A facility that can deliver beams of electron and muon
neutrinos from the decay of a stored muon beam has the
potential to unambiguously resolve the issue of the evidence
for light sterile neutrinos that arises in short-baseline
neutrino oscillation experiments and from estimates of the
effective number of neutrino flavors from fits to
cosmological data. In this paper, we show that the nuSTORM
facility, with stored muons of 3.8GeV/c±10%, will be able
to carry out a conclusive muon neutrino appearance search
for sterile neutrinos and test the LSND and MiniBooNE
experimental signals with 10σ sensitivity, even assuming
conservative estimates for the systematic uncertainties.
This experiment would add greatly to our knowledge of the
contribution of light sterile neutrinos to the number of
effective neutrino flavors from the abundance of primordial
helium production and from constraints on neutrino energy
density from the cosmic microwave background. The appearance
search is complemented by a simultaneous muon neutrino
disappearance analysis that will facilitate tests of various
sterile neutrino models. © 2014 American Physical
Society.},
Doi = {10.1103/PhysRevD.89.071301},
Key = {fds335076}
}
@article{fds269618,
Author = {Shin, D and Urzhumov, Y and Lim, D and Kim, K and Smith,
DR},
Title = {A versatile smart transformation optics device with auxetic
elasto-electromagnetic metamaterials.},
Journal = {Scientific reports},
Volume = {4},
Pages = {4084},
Year = {2014},
Month = {February},
url = {http://dx.doi.org/10.1038/srep04084},
Abstract = {Synergistic integration of electromagnetic (EM) and
mechanical properties of metamaterials, a concept known as
smart metamaterials, promises new applications across the
spectrum, from flexible waveguides to shape-conforming
cloaks. These applications became possible thanks to smart
transformation optics (STO), a design methodology that
utilizes coordinate transformations to control both EM wave
propagation and mechanical deformation of the device. Here,
we demonstrate several STO devices based on extremely
auxetic (Poisson ratio -1) elasto-electromagnetic
metamaterials, both of which exhibit enormous flexibility
and sustain efficient operation upon a wide range of
deformations. Spatial maps of microwave electric fields
across these devices confirm our ability to deform carpet
cloaks, bent waveguides, and potentially other
quasi-conformal TO-based devices operating at 7 ~ 8 GHz.
These devices are each fabricated from a single sheet of
initially uniform (double-periodic) square-lattice
metamaterial, which acquires the necessary distribution of
effective permittivity entirely from the mechanical
deformation of its boundary. By integrating transformation
optics and continuum mechanics theory, we provide analytical
derivations for the design of STO devices. Additionally, we
clarify an important point relating to two-dimensional STO
devices: the difference between plane stress and plane
strain assumptions, which lead to elastic metamaterials with
Poisson ratio -1 and -∞, respectively.},
Doi = {10.1038/srep04084},
Key = {fds269618}
}
@article{fds269616,
Author = {Ciracì, C and Chen, X and Mock, JJ and McGuire, F and Liu, X and Oh, SH and Smith, DR},
Title = {Film-coupled nanoparticles by atomic layer deposition:
Comparison with organic spacing layers},
Journal = {Applied Physics Letters},
Volume = {104},
Number = {2},
Pages = {023109-023109},
Publisher = {AIP Publishing},
Year = {2014},
Month = {January},
ISSN = {0003-6951},
url = {http://dx.doi.org/10.1063/1.4861849},
Abstract = {Film-coupled nanoparticle systems have proven a reliable
platform for exploring the field enhancement associated with
sub-nanometer sized gaps between plasmonic nanostructures.
In this Letter, we present a side-by-side comparison of the
spectral properties of film-coupled plasmon-resonant, gold
nanoparticles, with dielectric spacer layers fabricated
either using atomic layer deposition or using organic layers
(polyelectrolytes or self-assembled monolayers of
molecules). In either case, large area, uniform spacer
layers with sub-nanometer thicknesses can be accurately
deposited, allowing extreme coupling regimes to be probed.
The observed spectral shifts of the nanoparticles as a
function of spacer layer thickness are similar for the
organic and inorganic films and are consistent with
numerical calculations taking into account the nonlocal
response of the metal. © 2014 AIP Publishing
LLC.},
Doi = {10.1063/1.4861849},
Key = {fds269616}
}
@article{fds269543,
Author = {Mikkelsen, MH and Rose, A and Hoang, TB and McGuire, F and Mock, JJ and Ciracì, C and Smith, DR},
Title = {Tunable plasmonic platform for giant fluorescence
enhancement},
Journal = {Conference on Lasers and Electro-Optics Europe - Technical
Digest},
Volume = {2014-January},
Year = {2014},
Month = {January},
ISBN = {9781557529992},
Abstract = {We demonstrate a colloidally synthesized plasmonic platform
for giant fluorescence enhancement and increased spontaneous
emission rate of embedded fluorophores. A transition between
fluorescence enhancement and quenching is revealed depending
on the plasmonic resonance.},
Key = {fds269543}
}
@article{fds330967,
Author = {Yurduseven, O and Smith, D and Elsdon, M},
Title = {A transparent meshed solar monopole antenna for UWB
applications},
Journal = {8th European Conference on Antennas and Propagation, EuCAP
2014},
Pages = {2145-2149},
Publisher = {IEEE},
Year = {2014},
Month = {January},
ISBN = {9788890701849},
url = {http://dx.doi.org/10.1109/EuCAP.2014.6902233},
Abstract = {This paper demonstrates the integration of a transparent
meshed circular monopole antenna with a polycrystalline
silicon (poly-Si) solar cell operating as an RF ground plane
in addition to its photovoltaic function. While the meshed
circular monopole with the feed line printed on a clear
acrylic substrate placed upon the poly-Si solar cell offers
an optical transparency of 91%, it is demonstrated that the
meshed transparent monopole proposes similar radiation
characteristics in comparison with its conventional solid
counterpart and operates across a measured frequency band of
2.33-10.8 GHz covering UWB applications with an average
broadband gain of 4.1 dBi. The proposed meshed solar
monopole antenna generates a DC power output of 65.5 mW and
operates with a measured adequate solar efficiency of
13.1%.},
Doi = {10.1109/EuCAP.2014.6902233},
Key = {fds330967}
}
@article{fds330968,
Author = {Yurduseven, O and Smith, D and Elsdon, M},
Title = {A dual-polarized solar cell stacked microstrip patch antenna
with a λ/4 DC/RF isolation circuit for 5.8 GHz band WiMAX
networks},
Journal = {8th European Conference on Antennas and Propagation, EuCAP
2014},
Pages = {1382-1385},
Publisher = {IEEE},
Year = {2014},
Month = {January},
ISBN = {9788890701849},
url = {http://dx.doi.org/10.1109/EuCAP.2014.6902036},
Abstract = {In this paper, photovoltaic integration of a dual-polarized
microstrip patch antenna is demonstrated for 5.8 GHz band
WiMAX networks. The proposed antenna consists of a dual-fed
±45° dual-polarized square microstrip patch stacked with a
polycrystalline silicon (poly-Si) solar cell operating as an
RF parasitic patch element in addition to its photovoltaic
function. A DC/RF isolation circuit consisting of
quarter-wavelength microstrip transmission lines providing
RF open-circuit and DC short-circuit impedances at the DC
terminals of the stacked solar cell is used in order to
minimize the effect of solar operation on the RF response of
the antenna. It is demonstrated that the proposed solar
patch antenna operates across a measured frequency band of
5.66-5.91 GHz with a gain of 7.6 dBi at the resonance
frequency of 5.8 GHz.},
Doi = {10.1109/EuCAP.2014.6902036},
Key = {fds330968}
}
@article{fds330969,
Author = {Smith, D and Yurduseven, O and Livingstone, B and Zheng,
H},
Title = {An outline of indirect holographic methods for antenna
measurements and microwave imaging},
Journal = {2014 24th International Conference Radioelektronika,
RADIOELEKTRONIKA 2014 - Proceedings},
Publisher = {IEEE},
Year = {2014},
Month = {January},
ISBN = {9781479937158},
url = {http://dx.doi.org/10.1109/Radioelek.2014.6828403},
Abstract = {Indirect microwave holographic techniques offer a simple,
low cost technique for a range of microwave measurements
including the determination of antenna characteristics and
the ability to provide good quality images of passive
objects. This work provides a brief outline of the basic
theory of indirect microwave holography and how it can be
used for the reconstruction of scattered complex fields at
the measurement plane and how these results can be back
propagated to provide the scattered fields at any
preselected observation plane. It provides an outline of the
different techniques required for antenna measurement and
the imaging of passive objects. It demonstrates how indirect
holography can be used to determine the far field radiation
pattern of a high gain antenna and reconstruct the complex
antenna aperture fields. This work also demonstrates the use
of indirect holography for the imaging of passive objects.
The techniques described have been validated by experimental
results on a range of objects including buried objects. ©
2014 IEEE.},
Doi = {10.1109/Radioelek.2014.6828403},
Key = {fds330969}
}
@article{fds335077,
Author = {Del Pozo and S and Ribton, C and Smith, DR},
Title = {Characterisation of an RF excited argon plasma cathode
electron beam gun},
Journal = {2014 10th International Vacuum Electron Sources Conference,
IVESC 2014 and 2nd International Conference on Emission
Electronics, ICEE 2014 - Proceedings},
Publisher = {IEEE},
Year = {2014},
Month = {January},
ISBN = {9781479957729},
url = {http://dx.doi.org/10.1109/IVESC.2014.6892062},
Abstract = {This work describes the experimental set up used for
carrying out spectroscopic measurements in a plasma cathode
electron beam (EB) gun. Advantages of plasma cathode guns
over thermionic guns are described. The factors affecting
electron beam power such as plasma pressure, excitation
power and plasma chamber geometry are discussed. The maximum
beam current extracted was 53 mA from a 0.5 mm diameter
aperture in the plasma chamber. In this work, the electron
source is an argon plasma excited at 84 MHz. The pressure in
the plasma chamber was measured to be within 0.9 to 1.2 mbar
and was controlled by varying gas flow rates. The vacuum
chamber was at a pressure of 10-5 mbar.},
Doi = {10.1109/IVESC.2014.6892062},
Key = {fds335077}
}
@article{fds335078,
Author = {Del Pozo and S and Ribton, CN and Smith, DR},
Title = {Spectroscopic characterization of a novel RF excited plasma
cathode electron beam gun design},
Journal = {IEEE International Vacuum Electronics Conference, IVEC
2014},
Pages = {169-170},
Publisher = {IEEE},
Year = {2014},
Month = {January},
ISBN = {9781467301879},
url = {http://dx.doi.org/10.1109/IVEC.2014.6857544},
Abstract = {This work presents a radio frequency (RF) excited electron
beam (EB) gun design and experimental results obtained at a
frequency of 84 MHz. Details of the design features of the
plasma device are given and advantages over thermionic
cathode triode EB guns are demonstrated empirically.
Advantages include: longer cathode lifetime and reduced
maintenance costs; no requirement for a grid electrode,
avoiding beam aberration; and rapid beam pulsing. The EB gun
has been operated at -60 kV in a vacuum chamber at 10-5 to
10-6 mbar and an electron beam of a 3.2 kW power has been
extracted. This work gives details on the experimental setup
for carrying out emission spectroscopy measurements of the
plasma used as electron source and preliminary results on an
argon plasma cathode. © 2014 IEEE.},
Doi = {10.1109/IVEC.2014.6857544},
Key = {fds335078}
}
@article{fds376580,
Author = {Mikkelsen, MH and Rose, A and Hoang B. and TB and McGuire, F and Mock J.,
JJ and Cristian Ciracì, and Smith R. and DR},
Title = {Tunable plasmonic platform for giant fluorescence
enhancement},
Journal = {Optics InfoBase Conference Papers},
Year = {2014},
Month = {January},
ISBN = {9781557529992},
Abstract = {We demonstrate a colloidally synthesized plasmonic platform
for giant fluorescence enhancement and increased spontaneous
emission rate of embedded fluorophores. A transition between
fluorescence enhancement and quenching is revealed depending
on the plasmonic resonance. © 2014 OSA.},
Key = {fds376580}
}
@article{fds269570,
Author = {Machado, M and Ebadi, S and Driscoll, T and Smith,
D},
Title = {Experimental improvement of birefringence and response time
in Liquid Crystals using surface preparation of polyimide at
20GHz},
Journal = {IEEE MTT-S International Microwave Symposium
Digest},
Publisher = {IEEE},
Year = {2014},
Month = {January},
ISSN = {0149-645X},
url = {http://dx.doi.org/10.1109/MWSYM.2014.6848609},
Abstract = {This paper presents an experimental study analyzing the
effects of surface treated Polyimide (PI) on dielectric
anisotropy and response time of Liquid Crystal (LC) in an
In-Plane Switching (IPS) cell design. A Co-Planar Waveguide
(CPW) transmission line is used as an in-plane interrogation
architecture, with a layer of LC enclosed on top of the CPW.
By applying different surface preparations of PI, we are
able to derive an optimum condition to maximize
birefringence and minimize response times at 20GHz. Measured
phase change is increased from 28 deg to 72 deg for the same
length of the CPW line. At the same time, measurement
results show that fall time is decreased from 9.32s down to
4.1s. These improvements will facilitate realization of LC
in microwave devices in need of fast and tunable materials.
© 2014 IEEE.},
Doi = {10.1109/MWSYM.2014.6848609},
Key = {fds269570}
}
@article{fds269572,
Author = {Watts, CM and Shrekenhamer, D and Montoya, J and Lipworth, G and Hunt,
J and Sleasman, T and Krishna, S and Smith, DR and Padilla,
WJ},
Title = {Terahertz compressive imaging with metamaterial spatial
light modulators},
Journal = {Nature Photonics},
Volume = {8},
Number = {8},
Pages = {605-609},
Year = {2014},
Month = {January},
ISSN = {1749-4885},
url = {http://dx.doi.org/10.1038/nphoton.2014.139},
Abstract = {Imaging at long wavelengths, for example at terahertz and
millimetre-wave frequencies, is a highly sought-after goal
of researchers because of the great potential for
applications ranging from security screening and skin cancer
detection to all-weather navigation and biodetection. Here,
we design, fabricate and demonstrate active metamaterials
that function as real-time tunable, spectrally sensitive
spatial masks for terahertz imaging with only a single-pixel
detector. A modulation technique permits imaging with
negative mask values, which is typically difficult to
achieve with intensity-based components. We demonstrate
compressive techniques allowing the acquisition of
high-frame-rate, high-fidelity images. Our system is all
solid-state with no moving parts, yields improved
signal-to-noise ratios over standard raster-scanning
techniques, and uses a source orders of magnitude lower in
power than conventional set-ups. The demonstrated imaging
system establishes a new path for terahertz imaging that is
distinct from existing focal-plane-array-based cameras. ©
2014 Macmillan Publishers Limited. All rights
reserved.},
Doi = {10.1038/nphoton.2014.139},
Key = {fds269572}
}
@article{fds269581,
Author = {Watts, CM and Shrekenhamer, D and Montoya, J and Lipworth, G and Hunt,
J and Sleasman, T and Krishna, S and Smith, DR and Padilla,
WJ},
Title = {Coded and compressive THz imaging with metamaterials},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {8985},
Publisher = {SPIE},
Year = {2014},
Month = {January},
ISSN = {0277-786X},
url = {http://dx.doi.org/10.1117/12.2058082},
Abstract = {Imaging in long wavelength regimes holds huge potential in
many fields, from security to skin cancer detection.
However, it is often difficult to image at these frequencies
- the so called 'THz gap1' is no exception. Current
techniques generally involve mechanically raster scanning a
single detector to gain spatial information2, or utilization
of a THz focal plane array (FPA)3. However, raster scanning
results in slow image acquisition times and FPAs are
relatively insensitive to THz radiation, requiring the use
of high powered sources. In a different approach, a single
pixel detector can be used in which radiation from an object
is spatially modulated with a coded aperture to gain spatial
information. This multiplexing technique has not fully taken
off in the THz regime due to the lack of efficient coded
apertures, or spatial light modulators (SLMs), that operate
in this regime. Here we present the implementation of a
single pixel THz camera using an active SLM. We use
metamaterials to create an electronically controllable SLM,
permitting the acquisition of high-fidelity THz images. We
gain a signal-to-noise advantage over raster scanning
schemes through a multiplexing technique4. We also use a
source that is orders of magnitude lower in power than most
THz FPA implementations3,5. We are able to utilize
compressive sensing algorithms to reduce the number of
measurements needed to reconstruct an image, and hence
increase our frame rate to 1 Hz. This first generation
device represents a significant step towards the realization
of a single pixel THz camera.},
Doi = {10.1117/12.2058082},
Key = {fds269581}
}
@article{fds269619,
Author = {Lipworth, G and Ensworth, J and Seetharam, K and Huang, D and Lee, JS and Schmalenberg, P and Nomura, T and Reynolds, MS and Smith, DR and Urzhumov, Y},
Title = {Magnetic metamaterial superlens for increased range wireless
power transfer.},
Journal = {Scientific reports},
Volume = {4},
Pages = {3642},
Year = {2014},
Month = {January},
url = {http://www.ncbi.nlm.nih.gov/pubmed/24407490},
Abstract = {The ability to wirelessly power electrical devices is
becoming of greater urgency as a component of energy
conservation and sustainability efforts. Due to health and
safety concerns, most wireless power transfer (WPT) schemes
utilize very low frequency, quasi-static, magnetic fields;
power transfer occurs via magneto-inductive (MI) coupling
between conducting loops serving as transmitter and
receiver. At the "long range" regime - referring to
distances larger than the diameter of the largest loop - WPT
efficiency in free space falls off as (1/d)(6); power loss
quickly approaches 100% and limits practical implementations
of WPT to relatively tight distances between power source
and device. A "superlens", however, can concentrate the
magnetic near fields of a source. Here, we demonstrate the
impact of a magnetic metamaterial (MM) superlens on
long-range near-field WPT, quantitatively confirming in
simulation and measurement at 13-16 MHz the conditions under
which the superlens can enhance power transfer efficiency
compared to the lens-less free-space system.},
Doi = {10.1038/srep03642},
Key = {fds269619}
}
@article{fds330965,
Author = {Smith, D and Yurduseven, O and Livingstone, B and Schejbal,
V},
Title = {Microwave imaging using indirect holographic
techniques},
Journal = {IEEE Antennas and Propagation Magazine},
Volume = {56},
Number = {1},
Pages = {104-117},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2014},
Month = {January},
url = {http://dx.doi.org/10.1109/MAP.2014.6821762},
Abstract = {This work describes how indirect holographic techniques,
previously applied to the determination of antenna radiation
patterns, can be adapted for the imaging of passive objects.
It provides details of how complex scattered field values
can be obtained in a simple and inexpensive manner from
sampled scalar intensity measurements taken over a single
scanning aperture. This work provides a brief outline of the
basic theory of indirect microwave holography, and how the
transformation of the holographic intensity pattern into the
Fourier domain enables the isolation of the terms required
for complex field reconstruction to be isolated from the
remaining terms. The work is supported by a range of
experimental results, illustrating the reconstructed complex
fields for a number of simple test objects. Back-propagation
techniques have also been included to reconstruct complex
fields at the position of the scattering objects. ©
1990-2011 IEEE.},
Doi = {10.1109/MAP.2014.6821762},
Key = {fds330965}
}
@article{fds269580,
Author = {Watts, CM and Shrekenhamer, D and Montoya, J and Lipworth, G and Hunt,
J and Sleasman, T and Krishna, S and Smith, DR and Padilla,
WJ},
Title = {Terahertz compressive imaging with metamaterial spatial
light modulators},
Journal = {Nature Photonics},
Volume = {8},
Number = {8},
Pages = {605-609},
Publisher = {Springer Nature},
Year = {2014},
ISSN = {1749-4885},
url = {http://dx.doi.org/10.1038/nphoton.2014.139},
Doi = {10.1038/nphoton.2014.139},
Key = {fds269580}
}
@article{fds269617,
Author = {Lipworth, G and Hunt, J and Mrozack, A and Brady, D and Smith,
DR},
Title = {Simulations of 2D metamaterial apertures for coherent
computational imaging},
Journal = {2013 IEEE International Conference on Microwaves,
Communications, Antennas and Electronic Systems, COMCAS
2013},
Publisher = {IEEE},
Year = {2013},
Month = {December},
ISBN = {9781467357562},
url = {http://dx.doi.org/10.1109/COMCAS.2013.6685286},
Abstract = {A metamaterial aperture operating as a leaky waveguide with
resonating metamaterial irises can sweep its operation
frequency to modify its complex field pattern with no moving
parts. By randomly distributing the metamaterials' resonance
frequencies, we show the aperture can generate random
illumination patterns well suited for compressive sensing.
In this way the aperture utilizes the physical layer to
avoid redundant measurements in the image reconstruction
process. © 2013 IEEE.},
Doi = {10.1109/COMCAS.2013.6685286},
Key = {fds269617}
}
@article{fds269590,
Author = {Rose, A and Huang, D and Larouche, S and Smith, DR},
Title = {Effective nonlinearities in metamaterials},
Journal = {Optics InfoBase Conference Papers},
Pages = {cp},
Year = {2013},
Month = {December},
Abstract = {Clever structuring of dielectric and metallic composites can
lead to effective electric, magnetic and anisotropic
responses. When hybridized with nonlinear components, such
'metamaterials' can support a wide range of nonlinear
properties characterized by effective nonlinear
susceptibilities. © 2013 Optical Society of
America.},
Key = {fds269590}
}
@article{fds269592,
Author = {Ebadi, S and Driscoll, T and Smith, D},
Title = {Visual illustrations of microwave holographic beamforming
using a modulated surface-impedance metamaterial},
Journal = {IEEE Antennas and Propagation Society, AP-S International
Symposium (Digest)},
Pages = {2343-2344},
Publisher = {IEEE},
Year = {2013},
Month = {December},
ISSN = {1522-3965},
url = {http://dx.doi.org/10.1109/APS.2013.6711830},
Abstract = {We demonstrate the use of a metamaterial to transition
between a guided surface mode and a designed radiative
aperture distribution. Plots of the field distribution at
incremental distances removed from the aperture plane
illustrate the transformation from the reference mode to the
designed radiative aperture field - in this case a localized
plane-wave mode which produces a pencil beam at one angle.
© 2013 IEEE.},
Doi = {10.1109/APS.2013.6711830},
Key = {fds269592}
}
@article{fds269610,
Author = {Shin, D and Urzhumov, Y and Jung, Y and Kim, K and Smith,
DR},
Title = {Adjustable metamaterial cloaking using an elastic
crystal},
Journal = {Asia-Pacific Microwave Conference Proceedings,
APMC},
Pages = {331-332},
Publisher = {IEEE},
Year = {2013},
Month = {December},
url = {http://dx.doi.org/10.1109/APMC.2013.6695136},
Abstract = {We introduce a microwave cloak composed of smart
metamaterials whose electromagnetic properties can be
effectively changed by mechanical deformation. Against
mechanical deformations, our smart metamaterials self-adjust
own flexible elasto-electromagnetic crystal structure for
obeying transformation optics rules. With this idea, we
built microwave cloak made of flexible silicone rubber tube
array and experimentally demonstrated self-adjustable carpet
cloak in broadband ranges (8-12GHz) with variable
deformations. © 2013 IEEE.},
Doi = {10.1109/APMC.2013.6695136},
Key = {fds269610}
}
@article{fds269615,
Author = {Mrozack, A and Krishnamurthy, K and Lipworth, G and Smith, DR and Brady,
DJ},
Title = {Imaging of diffuse objects with dispersive
imagers},
Journal = {International Conference on Infrared, Millimeter, and
Terahertz Waves, IRMMW-THz},
Publisher = {IEEE},
Year = {2013},
Month = {December},
ISSN = {2162-2027},
url = {http://dx.doi.org/10.1109/IRMMW-THz.2013.6665888},
Abstract = {Dispersive imagers measure multiple speckle realizations of
the object to be estimated. This poses a challenge for
coherent imaging as classically objects are backpropagated
and then despeckled. We present initial findings on an
intensity based method for estimating the scattering
density. © 2013 IEEE.},
Doi = {10.1109/IRMMW-THz.2013.6665888},
Key = {fds269615}
}
@article{fds269621,
Author = {Poutrina, E and Rose, A and Brown, D and Urbas, A and Smith,
DR},
Title = {Forward and backward unidirectional scattering from
plasmonic coupled wires.},
Journal = {Optics express},
Volume = {21},
Number = {25},
Pages = {31138-31154},
Year = {2013},
Month = {December},
url = {http://dx.doi.org/10.1364/oe.21.031138},
Abstract = {We analyze the resonant electromagnetic response of
sub-wavelength plasmonic dimers formed by two silver strips
separated by a thin dielectric spacer and embedded in a
uniform dielectric media. We demonstrate that the
off-resonant electric and resonant, geometric
shape-leveraged, magnetic polarizabilities of the dimer
element can be designed to have close absolute values in a
certain spectral range, resulting in a predominantly
unidirectional scattering of the incident field due to
pronounced magneto-electric interference. Switching between
forward and backward directionality can be achieved with a
single element by changing the excitation wavelength, with
the scattering direction defined by the relative phases of
the polarizabilities. We extend the analysis to some
periodic configurations, including the specific case of a
perforated metal film, and discuss the differences between
the observed unidirectional scattering and the extraordinary
transmission effect. The unidirectional response can be
preserved and enhanced with periodic arrays of dimers and
can find applications in nanoantenna devices, integrated
optic circuits, sensors with nanoparticles, photovoltaic
systems, or perfect absorbers; while the option of switching
between forward and backward unidirectional scattering may
create interesting possibilities for manipulating optical
pressure forces.},
Doi = {10.1364/oe.21.031138},
Key = {fds269621}
}
@article{fds269622,
Author = {Rose, A and Powell, DA and Shadrivov, IV and Smith, DR and Kivshar,
YS},
Title = {Circular dichroism of four-wave mixing in nonlinear
metamaterials},
Journal = {Physical Review B - Condensed Matter and Materials
Physics},
Volume = {88},
Number = {19},
Publisher = {American Physical Society (APS)},
Year = {2013},
Month = {November},
ISSN = {1098-0121},
url = {http://dx.doi.org/10.1103/PhysRevB.88.195148},
Abstract = {Metamaterial engineering offers a route to combine unusual
and interesting optical phenomena in ways that are rare or
nonexistent in nature. As an exploration of this wide
parameter space, we experimentally demonstrate strong
cross-phase modulation and four-wave mixing in a chiral
metamaterial, highlighting the interplay of nonlinearity and
circular dichroism. Furthermore, we show that the magnitude
of the nonlinear parametric interaction follows certain
selection rules regarding the circular polarizations of the
various interacting waves. Using a coupled-mode analysis and
finite element simulations, we relate these selection rules
to the metamaterial's internal symmetries as well as its
circular dichroism in the linear regime. © 2013 American
Physical Society.},
Doi = {10.1103/PhysRevB.88.195148},
Key = {fds269622}
}
@article{fds269624,
Author = {Tsai, YJ and Tyler, T and Larouche, S and Llopis, A and Royal, M and Jokerst, NM and Smith, DR},
Title = {Metamaterial polarization multiplexed gratings},
Journal = {CLEO: QELS_Fundamental Science, CLEO:QELS FS
2013},
Pages = {QM4A.1},
Year = {2013},
Month = {November},
Abstract = {We demonstrate a metamaterial grating that has two
diffraction periods for two orthogonal linear polarization
states of illuminations. The proposed method will be useful
in free space optical communications and novel optical
imaging systems. © OSA 2013.},
Key = {fds269624}
}
@article{fds330972,
Author = {Yurduseven, O and Smith, D},
Title = {Solar cell stacked dual-polarised patch antenna for 5.8 GHz
band WiMAX network},
Journal = {Electronics Letters},
Volume = {49},
Number = {24},
Pages = {1514-1515},
Publisher = {Institution of Engineering and Technology
(IET)},
Year = {2013},
Month = {November},
url = {http://dx.doi.org/10.1049/el.2013.2451},
Abstract = {A novel combination of a two-port slant ± 45°
dual-polarised microstrip patch antenna with a
polycrystalline silicon (poly-Si) solar cell operating as an
RF stacked parasitic patch element is presented and
discussed for 5.8 GHz band polarisation diverse
multifunctional WiMAX systems. To minimise the effect of the
solar operation on the RF antenna performance, an effective
DC/RF isolation circuit consisting of quarter-wavelength
microstrip transmission lines is demonstrated. The proposed
solar patch provides identical E-plane and H-plane far-field
radiation patterns for +45° and -45° polarisations with a
gain of 7.8 dBi and operates at the frequency band of
5.66-5.91 GHz. © The Institution of Engineering and
Technology 2013.},
Doi = {10.1049/el.2013.2451},
Key = {fds330972}
}
@article{fds269620,
Author = {Landy, N and Hunt, J and Smith, DR},
Title = {Homogenization analysis of complementary waveguide
metamaterials},
Journal = {Photonics and Nanostructures - Fundamentals and
Applications},
Volume = {11},
Number = {4},
Pages = {453-467},
Year = {2013},
Month = {November},
ISSN = {1569-4410},
url = {http://dx.doi.org/10.1016/j.photonics.2013.07.004},
Abstract = {We analyze the properties of complementary metamaterials as
effective inclusions patterned into the conducting walls of
metal waveguide structures. We show that guided wave
metamaterials can be homogenized using the same retrieval
techniques used for volumetric metamaterials, leading to a
description in which a given complementary element is
conceptually replaced by a block of material within the
waveguide whose effective permittivity and permeability
result in equivalent scattering characteristics. The use of
effective constitutive parameters for waveguide materials
provides an alternative point-of-view for the design of
waveguide and microstrip based components, including planar
lenses and filters, as well as devices with derived from a
bulk material response. In addition to imparting effective
constitutive properties to the waveguide, complementary
metamaterials also couple energy from waveguide modes into
radiation. Thus, complementary waveguide metamaterials can
be used to modify and optimize a variety of antenna
structures. © 2013 Elsevier B.V.},
Doi = {10.1016/j.photonics.2013.07.004},
Key = {fds269620}
}
@article{fds269623,
Author = {Tsai, Y-J and Larouche, S and Tyler, T and Llopis, A and Royal, M and Jokerst, NM and Smith, DR},
Title = {Arbitrary birefringent metamaterials for holographic optics
at λ = 1.55 μm.},
Journal = {Optics express},
Volume = {21},
Number = {22},
Pages = {26620-26630},
Year = {2013},
Month = {November},
url = {http://www.ncbi.nlm.nih.gov/pubmed/24216883},
Abstract = {This paper presents an optical element capable of
multiplexing two diffraction patterns for two orthogonal
linear polarizations, based on the use of non-resonant
metamaterial cross elements. The metamaterial cross elements
provide unique building blocks for engineering arbitrary
birefringence. As a proof-of-concept demonstration, we
present the design and experimental characterization of a
polarization multiplexed blazed diffraction grating and a
polarization multiplexed computer-generated hologram, for
the telecommunication wavelength of λ = 1.55 μm. A
quantitative study of the polarization multiplexed grating
reveals that this approach yields a very large polarization
contrast ratio. The results show that metamaterials can form
the basis for a versatile and compact platform useful in the
design of multi-functional photonic devices.},
Doi = {10.1364/oe.21.026620},
Key = {fds269623}
}
@article{fds269626,
Author = {Liu, X and Rose, A and Poutrina, E and Ciracì, C and Larouche, S and Smith, DR},
Title = {Surfaces, films, and multilayers for compact nonlinear
plasmonics},
Journal = {Journal of the Optical Society of America B: Optical
Physics},
Volume = {30},
Number = {11},
Pages = {2999-3010},
Publisher = {The Optical Society},
Year = {2013},
Month = {November},
ISSN = {0740-3224},
url = {http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000326580500031&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=47d3190e77e5a3a53558812f597b0b92},
Abstract = {We present a step-by-step analysis of four-wave mixing (FWM)
in one-dimensional stacks of metallo-dielectric structures,
pointing out various channels of plasmonic and Fabry-Perot
enhancement. We start from the derivation of oblique
incidence FWM at a single interface and then extend these
expressions into a transfer-matrix-based formalism to
quantitatively study films and multilayer geometries.
Throughout our analysis, we consider typical examples, such
as a single silver interface, a thin silver film, and
Fabry-Perot multilayers. In this way, we offer an intuitive
view of the surprisingly rich dynamics supported by even the
simplest of nonlinear plasmonic systems. © 2013 Optical
Society of America.},
Doi = {10.1364/JOSAB.30.002999},
Key = {fds269626}
}
@article{fds335079,
Author = {Smith, DR and Parker, SE and Wan, W and Chen, Y and Diallo, A and Dudson,
BD and Fonck, RJ and Guttenfelder, W and McKee, GR and Kaye, SM and Thompson, DS and Bell, RE and Leblanc, BP and Podesta,
M},
Title = {Measurements and simulations of low-wavenumber pedestal
turbulence in the National Spherical Torus
Experiment},
Journal = {Nuclear Fusion},
Volume = {53},
Number = {11},
Pages = {113029-113029},
Publisher = {IOP Publishing},
Year = {2013},
Month = {November},
url = {http://dx.doi.org/10.1088/0029-5515/53/11/113029},
Abstract = {Previous pedestal turbulence measurements in the National
Spherical Torus Experiment assessed the spatial and temporal
properties of turbulence in the steep gradient region of
H-mode pedestals during edge localized mode (ELM)-free,
MHD-quiescent periods. Here, we extend the analysis to
fluctuation amplitudes and compare observations to pedestal
turbulence simulations. Measurements indicate normalized
fluctuation amplitudes are about 1-5% in the steep gradient
region. Regression analysis indicates fluctuation amplitudes
scale positively with electron density gradient,
collisionality, and poloidal beta, and scale negatively with
magnetic shear, electron density, ion temperature gradient
(ITG), toroidal flow and radial electric field. The scalings
are most consistent with trapped electron mode, kinetic
ballooning mode, or microtearing instabilities, but,
notably, least consistent with ITG turbulence. Gyrokinetic
simulations of pedestal turbulence with realistic pedestal
profiles show collisional instabilities with growth rates
that increase at higher density gradient and decrease at
higher ITG, in qualitative agreement with observed scalings.
Finally, Braginskii fluid simulations of pedestal turbulence
do not reproduce scalings from measurements and gyrokinetic
simulations, and suggest electron dynamics can be a critical
factor for accurate pedestal turbulence simulations. © 2013
IAEA, Vienna.},
Doi = {10.1088/0029-5515/53/11/113029},
Key = {fds335079}
}
@article{fds269625,
Author = {Ciracì, C and Britt Lassiter and J and Moreau, A and Smith,
DR},
Title = {Quasi-analytic study of scattering from optical plasmonic
patch antennas},
Journal = {Journal of Applied Physics},
Volume = {114},
Number = {16},
Pages = {163108-163108},
Publisher = {AIP Publishing},
Year = {2013},
Month = {October},
ISSN = {0021-8979},
url = {http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000326639200008&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=47d3190e77e5a3a53558812f597b0b92},
Abstract = {We present an analytical treatment of the optical scattering
from film-coupled nanocubes. Film-coupled nanoparticles are
a convenient platform for the demonstration of a variety of
fundamental plasmonic phenomena, including nonlocality and
field enhancement, and can also serve as the basis for
controlled reflectance surfaces. The nanocube geometry is
particularly amenable to analysis, since the cubes behave in
large part as plasmon resonant patch antennas, allowing the
well-known patch antenna equations to be applied with some
modifications. In particular, we make use of the plasmon
dispersion relation to avoid direct calculation of the
effective inductance per unit length - which would include
kinetic inductance contributions - instead calculating the
effective waveguide mode index to incorporate plasmonic
contributions. We compare the analytically derived field
enhancement and spectral characteristics of the film-coupled
nanoparticles with those obtained from full-wave
finite-element simulations. © 2013 AIP Publishing
LLC.},
Doi = {10.1063/1.4827185},
Key = {fds269625}
}
@article{fds269629,
Author = {Ciracì, C and Urzhumov, Y and Smith, DR},
Title = {Effects of classical nonlocality on the optical response of
three-dimensional plasmonic nanodimers},
Journal = {Journal of the Optical Society of America B: Optical
Physics},
Volume = {30},
Number = {10},
Pages = {2731-2736},
Publisher = {The Optical Society},
Year = {2013},
Month = {October},
ISSN = {0740-3224},
url = {http://dx.doi.org/10.1364/JOSAB.30.002731},
Abstract = {We examine the optical scattering from a variety of axially
symmetric plasmonic nanoparticle dimers separated by
nanoscale gaps, quantifying the role of classical
nonlocality on their optical properties. Due to the
rotational symmetry of the analyzed structures, a high
degree of accuracy is achieved using a computational
approach termed 2.5D modeling, in which a small number of
simulations on a two-dimensional domain can replace a
memory- and time-intensive simulation on a three-dimensional
domain. We find that scattered light from dimers consisting
of nanoparticles with flat surfaces, such as nanodisks,
exhibits pronounced spectral shifts due to the nonlocality
of the electron fluid; these significant shifts persist even
at relatively large (>1 nm) gap dimensions, where quantum
tunneling effects are believed to be negligible. The 2.5D
modeling technique accurately incorporates all responses due
to any nonaxially symmetric eigenmodes of the system, such
as dipolar and quadrupolar modes, thereby providing a
complete characterization of the system for any excitation.
© 2013 Optical Society of America.},
Doi = {10.1364/JOSAB.30.002731},
Key = {fds269629}
}
@article{fds335080,
Author = {Sabbagh, SA and Ahn, JW and Allain, J and Andre, R and Balbaky, A and Bastasz, R and Battaglia, D and Bell, M and Bell, R and Beiersdorfer, P and Belova, E and Berkery, J and Betti, R and Bialek, J and Bigelow, T and Bitter, M and Boedo, J and Bonoli, P and Boozer, A and Bortolon, A and Boyle, D and Brennan, D and Breslau, J and Buttery, R and Canik, J and Caravelli, G and Chang, C and Crocker, N and Darrow, D and Davis, B and Delgado-Aparicio, L and Diallo, A and Ding, S and D'Ippolito, D and Domier, C and Dorland, W and Ethier, S and Evans, T and Ferron, J and Finkenthal, M and Foley, J and Fonck, R and Frazin, R and Fredrickson,
E and Fu, G and Gates, D and Gerhardt, S and Glasser, A and Gorelenkov, N and Gray, T and Guo, Y and Guttenfelder, W and Hahm, T and Harvey, R and Hassanein, A and Heidbrink, W and Hill, K and Hirooka, Y and Hooper, EB and Hosea, J and Humphreys, D and Indireshkumar, K and Jaeger, F and Jarboe,
T and Jardin, S and Jaworski, M and Kaita, R and Kallman, J and Katsuro-Hopkins, O and Kaye, S and Kessel, C and Kim, J and Kolemen, E and Kramer, G and Krasheninnikov, S and Kubota, S and Kugel, H and La Haye,
RJ and Lao, L and Leblanc, B and Lee, W and Lee, K and Leuer, J and Levinton,
F and Liang, Y and Liu, D and Lore, J and Luhmann, N and Maingi, R and Majeski, R and Manickam, J and Mansfield, D and Maqueda, R and Mazzucato, E and McLean, A and McCune, D and McGeehan, B and McKee, G and Medley, S and Meier, E},
Title = {Overview of physics results from the conclusive operation of
the National Spherical Torus Experiment},
Journal = {Nuclear Fusion},
Volume = {53},
Number = {10},
Pages = {104007-104007},
Publisher = {IOP Publishing},
Year = {2013},
Month = {October},
url = {http://dx.doi.org/10.1088/0029-5515/53/10/104007},
Abstract = {Research on the National Spherical Torus Experiment, NSTX,
targets physics understanding needed for extrapolation to a
steady-state ST Fusion Nuclear Science Facility, pilot
plant, or DEMO. The unique ST operational space is leveraged
to test physics theories for next-step tokamak operation,
including ITER. Present research also examines implications
for the coming device upgrade, NSTX-U. An energy confinement
time, τE, scaling unified for varied wall conditions
exhibits a strong improvement of BTτE with decreased
electron collisionality, accentuated by lithium (Li) wall
conditioning. This result is consistent with nonlinear
microtearing simulations that match the experimental
electron diffusivity quantitatively and predict reduced
electron heat transport at lower collisionality.
Beam-emission spectroscopy measurements in the steep
gradient region of the pedestal indicate the poloidal
correlation length of turbulence of about ten ion gyroradii
increases at higher electron density gradient and lower Ti
gradient, consistent with turbulence caused by trapped
electron instabilities. Density fluctuations in the pedestal
top region indicate ion-scale microturbulence compatible
with ion temperature gradient and/or kinetic ballooning mode
instabilities. Plasma characteristics change nearly
continuously with increasing Li evaporation and edge
localized modes (ELMs) stabilize due to edge density
gradient alteration. Global mode stability studies show
stabilizing resonant kinetic effects are enhanced at lower
collisionality, but in stark contrast have almost no
dependence on collisionality when the plasma is
off-resonance. Combined resistive wall mode radial and
poloidal field sensor feedback was used to control n = 1
perturbations and improve stability. The disruption
probability due to unstable resistive wall modes (RWMs) was
surprisingly reduced at very high βN/li > 10 consistent
with low frequency magnetohydrodynamic spectroscopy
measurements of mode stability. Greater instability seen at
intermediate βN is consistent with decreased kinetic RWM
stabilization. A model-based RWM state-space controller
produced long-pulse discharges exceeding βN = 6.4 and
βN/li = 13. Precursor analysis shows 96.3% of disruptions
can be predicted with 10 ms warning and a false positive
rate of only 2.8%. Disruption halo currents rotate
toroidally and can have significant toroidal asymmetry.
Global kinks cause measured fast ion redistribution, with
full-orbit calculations showing redistribution from the core
outward and towards V∥/V = 1 where destabilizing
compressional Alfvén eigenmode resonances are expected.
Applied 3D fields altered global Alfvén eigenmode
characteristics. High-harmonic fast-wave (HHFW) power
couples to field lines across the entire width of the
scrape-off layer, showing the importance of the inclusion of
this phenomenon in designing future RF systems. The
snowflake divertor configuration enhanced by radiative
detachment showed large reductions in both steady-state and
ELM heat fluxes (ELMing peak values down from 19 MW m-2 to
less than 1.5 MW m-2). Toroidal asymmetry of heat deposition
was observed during ELMs or by 3D fields. The heating power
required for accessing H-mode decreased by 30% as the
triangularity was decreased by moving the X-point to larger
radius, consistent with calculations of the dependence of E
× B shear in the edge region on ion heat flux and X-point
radius. Co-axial helicity injection reduced the inductive
start-up flux, with plasmas ramped to 1 MA requiring 35%
less inductive flux. Non-inductive current fraction (NICF)
up to 65% is reached experimentally with neutral beam
injection at plasma current Ip = 0.7 MA and between 70-100%
with HHFW application at Ip = 0.3 MA. NSTX-U scenario
development calculations project 100% NICF for a large range
of 0.6 < Ip (MA) < 1.35. © 2013 IAEA, Vienna.},
Doi = {10.1088/0029-5515/53/10/104007},
Key = {fds335080}
}
@article{fds269630,
Author = {Grajower, M and Lerman, GM and Goykhman, I and Desiatov, B and Yanai, A and Smith, DR and Levy, U},
Title = {Subwavelength plasmonics for graded-index optics on a
chip.},
Journal = {Optics letters},
Volume = {38},
Number = {18},
Pages = {3492-3495},
Year = {2013},
Month = {September},
ISSN = {0146-9592},
url = {http://dx.doi.org/10.1364/ol.38.003492},
Abstract = {Planar plasmonic devices are becoming attractive for myriad
applications, owing to their potential compatibility with
standard microelectronics technology and the capability for
densely integrating a large variety of plasmonic devices on
a chip. Mitigating the challenges of using plasmonics in
on-chip configurations requires precise control over the
properties of plasmonic modes, in particular their shape and
size. Here we achieve this goal by demonstrating a planar
plasmonic graded-index lens focusing surface plasmons
propagating along the device. The plasmonic mode is
manipulated by carving subwavelength features into a
dielectric layer positioned on top of a uniform metal film,
allowing the local effective index of the plasmonic mode to
be controlled using a single binary lithographic step.
Focusing and divergence of surface plasmons is demonstrated
experimentally. The demonstrated approach can be used for
manipulating the propagation of surface plasmons, e.g., for
beam steering, splitting, cloaking, mode matching, and beam
shaping applications.},
Doi = {10.1364/ol.38.003492},
Key = {fds269630}
}
@article{fds335081,
Author = {Diallo, A and Canik, J and Göerler, T and Ku, SH and Kramer, GJ and Osborne, T and Snyder, P and Smith, DR and Guttenfelder, W and Bell, RE and Boyle, DP and Chang, CS and Leblanc, BP and Maingi, R and Podestà, M and Sabbagh, S},
Title = {Progress in characterization of the pedestal stability and
turbulence during the edge-localized-mode cycle on National
Spherical Torus Experiment},
Journal = {Nuclear Fusion},
Volume = {53},
Number = {9},
Pages = {093026-093026},
Publisher = {IOP Publishing},
Year = {2013},
Month = {September},
url = {http://dx.doi.org/10.1088/0029-5515/53/9/093026},
Abstract = {Progress in characterizing the edge stability and properties
of the microinstabilities responsible for enhanced transport
in the pedestal region is reported. The stability of the
pedestal is characterized in high performance discharges on
National Spherical Torus Experiment. These high performance
plasmas are found to be ideal kink-peeling and ideal
infinite-n ballooning unstable prior to the onset of
edge-localized modes (ELM). The spatial structure of
turbulence present during an ELM cycle in the pedestal
region indicates poloidal spatial scales propagating in the
ion diamagnetic drift direction at the pedestal top, and
radial spatial scales . These propagating spatial scales are
found to be poloidally elongated and consistent with
ion-scale microturbulence. Both global and local gyrokinetic
simulations have been performed to identify the
microturbulence structure. The local gyrokinetic analysis
indicates the presence of a linearly unstable hybrid kinetic
ballooning mode and trapped electron mode with spatial scale
and propagation direction consistent with experimental
observations. In the global gyrokinetic analysis, the
nonlinearly saturated potential fluctuations show radial and
poloidal correlation lengths in agreement with experimental
density fluctuation correlation length measurements. © 2013
IAEA, Vienna.},
Doi = {10.1088/0029-5515/53/9/093026},
Key = {fds335081}
}
@article{fds330974,
Author = {Yurduseven, O and Smith, D and Pearsall, N},
Title = {Solar cell stacked modified Z-double L-slot quad-band
PIFA},
Journal = {2013 7th European Conference on Antennas and Propagation,
EuCAP 2013},
Pages = {3721-3725},
Year = {2013},
Month = {August},
ISBN = {9788890701832},
Abstract = {This paper proposes a novel low-profile quad-band
multifunctional solar PIFA consisting of a polycrystalline
silicon (poly-Si) solar cell stacked suspended modified
radiating element with Z and double L-slots. The measured
return loss (S11) and E-plane/H-plane far-field radiation
patterns demonstrate that the fabricated solar PIFA has
quad-band radiation characteristics operating at the
frequency bands of 1.75-1.82 GHz, 2.38-2.61 GHz, 3.26-3.53
GHz and 4.66-4.83 GHz with measured impedance bandwidths of
3.91%, 9.38%, 7.94% and 3.58% and gains of 2.1, 6.4, 7.6 and
5.5 dBi, respectively. The proposed solar PIFA operates with
a measured solar efficiency of 13.9%, generating a DC power
output of 34 mW as a result of the photovoltaic effect. ©
2013 EurAAP.},
Key = {fds330974}
}
@article{fds330975,
Author = {Smith, D and Yurduseven, O and Livingstone, B},
Title = {The use of indirect holographic techniques for microwave
imaging},
Journal = {Proceedings of 13th Conference on Microwave Techniques,
COMITE 2013 - MAREW 2013: Microwave and Radio Electronics
Week 2013},
Pages = {16-21},
Publisher = {IEEE},
Year = {2013},
Month = {August},
ISBN = {9781467355124},
url = {http://dx.doi.org/10.1109/COMITE.2013.6545036},
Abstract = {The use of indirect holographic techniques for antenna
testing has been shown to offer a simple, low cost scalar
technique for the reconstruction of complex antenna aperture
fields. This work extends the use of indirect holography to
the imaging of objects. This work provides a brief outline
of the basic theory of indirect microwave holography and how
it can be used for the reconstruction of scattered complex
fields at the measurement plane and how these results can be
back propagated to provide images of the scattered fields at
the position of the original object. The techniques
described have been validated by experimental results on a
range of objects including buried objects. © 2013
IEEE.},
Doi = {10.1109/COMITE.2013.6545036},
Key = {fds330975}
}
@article{fds330976,
Author = {Yurduseven, O and Smith, D and Elsdon, M},
Title = {Cross-coax fed wideband solar patch antenna},
Journal = {Proceedings of 13th Conference on Microwave Techniques,
COMITE 2013 - MAREW 2013: Microwave and Radio Electronics
Week 2013},
Pages = {25-30},
Publisher = {IEEE},
Year = {2013},
Month = {August},
ISBN = {9781467355124},
url = {http://dx.doi.org/10.1109/COMITE.2013.6545037},
Abstract = {In this paper, a cross-coax fed low-profile short-circuited
suspended patch antenna combined with a polycrystalline
silicon (poly-Si) solar cell operating as a radiating patch
element is proposed for self-powered 2.4 GHz band WLAN and
2.3/2.5 GHz band WiMAX networks. The fabricated
multifunctional solar patch antenna has a measured wide
impedance bandwidth of 840 MHz, 35%, and offers a broadband
gain of 7.71 dBi. It operates with a measured solar
efficiency of 13.9%, generating a DC power output of 225 mW.
© 2013 IEEE.},
Doi = {10.1109/COMITE.2013.6545037},
Key = {fds330976}
}
@article{fds269632,
Author = {Lipworth, G and Mrozack, A and Hunt, J and Marks, DL and Driscoll, T and Brady, D and Smith, DR},
Title = {Metamaterial apertures for coherent computational imaging on
the physical layer.},
Journal = {Journal of the Optical Society of America. A, Optics, image
science, and vision},
Volume = {30},
Number = {8},
Pages = {1603-1612},
Year = {2013},
Month = {August},
ISSN = {1084-7529},
url = {http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000322591800017&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=47d3190e77e5a3a53558812f597b0b92},
Abstract = {We introduce the concept of a metamaterial aperture, in
which an underlying reference mode interacts with a designed
metamaterial surface to produce a series of complex field
patterns. The resonant frequencies of the metamaterial
elements are randomly distributed over a large bandwidth
(18-26 GHz), such that the aperture produces a rapidly
varying sequence of field patterns as a function of the
input frequency. As the frequency of operation is scanned,
different subsets of metamaterial elements become active, in
turn varying the field patterns at the scene. Scene
information can thus be indexed by frequency, with the
overall effectiveness of the imaging scheme tied to the
diversity of the generated field patterns. As the quality
(Q-) factor of the metamaterial resonators increases, the
number of distinct field patterns that can be generated
increases-improving scene estimation. In this work we
provide the foundation for computational imaging with
metamaterial apertures based on frequency diversity, and
establish that for resonators with physically relevant
Q-factors, there are potentially enough distinct
measurements of a typical scene within a reasonable
bandwidth to achieve diffraction-limited reconstructions of
physical scenes.},
Doi = {10.1364/josaa.30.001603},
Key = {fds269632}
}
@article{fds335082,
Author = {Ren, Y and Guttenfelder, W and Kaye, SM and Mazzucato, E and Bell, RE and Diallo, A and Domier, CW and Leblanc, BP and Lee, KC and Podesta, M and Smith, DR and Yuh, H},
Title = {Electron-scale turbulence spectra and plasma thermal
transport responding to continuous e × B shear ramp-up in a
spherical tokamak},
Journal = {Nuclear Fusion},
Volume = {53},
Number = {8},
Pages = {083007-083007},
Publisher = {IOP Publishing},
Year = {2013},
Month = {August},
url = {http://dx.doi.org/10.1088/0029-5515/53/8/083007},
Abstract = {Microturbulence is considered to be a major candidate in
driving anomalous transport in fusion plasmas, and the
equilibrium E × B shear generated by externally driven flow
can be a powerful tool to control microturbulence in future
fusion devices such as FNSF and ITER. Here we present the
first observation of the change in electron-scale turbulence
wavenumber spectrum (measured by a high-k scattering system)
and thermal transport responding to continuous E × B shear
ramp-up in an NSTX centre-stack limited and neutral beam
injection-heated L-mode plasma. It is found that while
linear stability analysis shows that the maximum electron
temperature gradient mode linear growth rate far exceeds the
observed E × B shearing rate in the measurement region of
the high-k scattering system, the unstable ion temperature
gradient (ITG) modes are susceptible to E × B shear
stabilization. We observed that as the E × B shearing rate
is continuously ramped up in the high-k measurement region,
the ratio between the E × B shearing rate and maximum ITG
mode growth rate continuously increases (from about 0.2 to
0.7) and the maximum power of the measured electron-scale
turbulence wavenumber spectra decreases. Meanwhile, electron
and ion thermal transport is also reduced in the outer half
of the plasmas as long as magnetohydrodynamic activities are
not important and the L-mode plasmas eventually reach
H-mode-like confinement. Linear and nonlinear gyrokinetic
simulations are presented to address the experimental
observations. © 2013 IAEA, Vienna.},
Doi = {10.1088/0029-5515/53/8/083007},
Key = {fds335082}
}
@article{fds269631,
Author = {Rose, A and Latterman, R and Smith, DR and Sullivan,
P},
Title = {Lower poling thresholds and enhanced Pockels coefficients in
nanoparticle-polymer composites},
Journal = {Applied Physics Letters},
Volume = {103},
Number = {3},
Pages = {031102-031102},
Publisher = {AIP Publishing},
Year = {2013},
Month = {July},
ISSN = {0003-6951},
url = {http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000322146300002&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=47d3190e77e5a3a53558812f597b0b92},
Abstract = {We investigate computationally the electromagnetic response
of composite media made from high-aspect ratio nanoparticle
arrays. The shape and local ordering of the nanoparticles
can be used to both confine and enhance the local electric
fields induced in response to static and propagating fields.
When such nanoparticle arrays are hybridized with
electrooptic polymers and subjected to a poling field, we
show that the nanoparticles can enable variant tensor
orientations and lower poling thresholds. From an effective
medium perspective, we find that the Pockels coefficients of
the nanoparticle-polymer composites can be enhanced by more
than an order of magnitude. © 2013 AIP Publishing
LLC.},
Doi = {10.1063/1.4813751},
Key = {fds269631}
}
@article{fds330977,
Author = {Yurduseven, O and Smith, D and Livingstone, B and Schejbal, V and You,
Z},
Title = {Investigations of resolution limits for indirect microwave
holographic imaging},
Journal = {International Journal of RF and Microwave Computer-Aided
Engineering},
Volume = {23},
Number = {4},
Pages = {410-416},
Publisher = {WILEY},
Year = {2013},
Month = {July},
url = {http://dx.doi.org/10.1002/mmce.20727},
Abstract = {This work describes how indirect holography which has
previously been applied to the determination of antenna
radiation patterns can be adapted for the imaging of passive
objects. It provides details of how complex scattered field
values can be obtained in a simple and inexpensive manner
from sampled scalar intensity measurements taken over a
single scanning aperture. This work uses indirect
holographic techniques to image a number of simple objects
including a rectangular metallic plate, a small metal plate
covered by a dielectric sheet and a small metallic circular
annulus. This work demonstrates that good quality images can
be reconstructed from simple scalar intensity patterns. It
demonstrates that clear outlines can be obtained in
particular from reconstructed phase patterns and that good
images can be obtained from objects with dimensions of the
order of a half wavelength. © 2013 Wiley Periodicals, Inc.
Int J RF and Microwave CAE, 2013. Copyright © 2013 Wiley
Periodicals, Inc.},
Doi = {10.1002/mmce.20727},
Key = {fds330977}
}
@article{fds269634,
Author = {Urzhumov, YA and Ciraci, C and Smith, DR},
Title = {Nanophotonics: Optical time reversal with
graphene},
Journal = {Nature Physics},
Volume = {9},
Number = {7},
Pages = {393-394},
Publisher = {Nature Publishing Group / Macmillan Publishers
Ltd.},
Year = {2013},
Month = {July},
ISSN = {1745-2473},
url = {http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000321113200009&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=47d3190e77e5a3a53558812f597b0b92},
Abstract = {Would you ever guess that a microscopic flake of graphite
could reverse the diffraction of light? An experiment that
demonstrates just such an effect highlights the exciting
optical applications of graphene — an atomic layer of
carbon with a two-dimensional honeycomb lattice.},
Doi = {10.1038/nphys2644},
Key = {fds269634}
}
@article{fds269635,
Author = {Goldflam, MD and Driscoll, T and Barnas, D and Khatib, O and Royal, M and Marie Jokerst and N and Smith, DR and Kim, BJ and Seo, G and Kim, HT and Basov, DN},
Title = {Two-dimensional reconfigurable gradient index memory
metasurface},
Journal = {Applied Physics Letters},
Volume = {102},
Number = {22},
Pages = {224103-224103},
Publisher = {AIP Publishing},
Year = {2013},
Month = {June},
ISSN = {0003-6951},
url = {http://dx.doi.org/10.1063/1.4809534},
Abstract = {Creation and control of spatial gradients in electromagnetic
properties is a central theme underlying optical device
design. In this work, we demonstrate that through
modification of the spatial and temporal distribution of
current, we can obtain increased control over the shape of
these gradients. We are able to write spatially sharp
gradients with ∼50% change in the index of refraction over
length scales of only a few wavelengths as observed through
diffraction limited terahertz spectroscopy. Furthermore, we
assess the potentials for such gradients for beam-steering
applications. © 2013 AIP Publishing LLC.},
Doi = {10.1063/1.4809534},
Key = {fds269635}
}
@article{fds269636,
Author = {Urzhumov, Y and Landy, N and Driscoll, T and Basov, D and Smith,
DR},
Title = {Thin low-loss dielectric coatings for free-space
cloaking.},
Journal = {Optics letters},
Volume = {38},
Number = {10},
Pages = {1606-1608},
Year = {2013},
Month = {May},
ISSN = {0146-9592},
url = {http://dx.doi.org/10.1364/ol.38.001606},
Abstract = {We report stereolithographic polymer-based fabrication and
experimental operation of a microwave X-band cloaking
device. The device is a relatively thin (about one
wavelength thick) shell of an air-dielectric composite, in
which the dielectric component has negligible loss and
dispersion. In a finite band (9.7-10.1 GHz), the shell
eliminates the shadow and strongly suppresses scattering
from a conducting cylinder of six-wavelength diameter for
TE-polarized free-space plane waves. The device does not
require an immersion liquid or conducting ground planes for
its operation. The dielectric constant of the polymer is low
enough (ε=2.45) to suggest that this cloaking technique
would be suitable for higher frequency radiation, including
visible light.},
Doi = {10.1364/ol.38.001606},
Key = {fds269636}
}
@article{fds335084,
Author = {Smith, DR and Fonck, RJ and McKee, GR and Thompson, DS and Bell, RE and Diallo, A and Guttenfelder, W and Kaye, SM and Leblanc, BP and Podesta,
M},
Title = {Characterization and parametric dependencies of low
wavenumber pedestal turbulence in the National Spherical
Torus Experiment},
Journal = {Physics of Plasmas},
Volume = {20},
Number = {5},
Pages = {055903-055903},
Publisher = {AIP Publishing},
Year = {2013},
Month = {May},
url = {http://dx.doi.org/10.1063/1.4803913},
Abstract = {The spherical torus edge region is among the most
challenging regimes for plasma turbulence simulations. Here,
we measure the spatial and temporal properties of ion-scale
turbulence in the steep gradient region of H-mode pedestals
during edge localized mode-free, MHD quiescent periods in
the National Spherical Torus Experiment. Poloidal
correlation lengths are about 10 ρ i, and decorrelation
times are about 5 a / c s. Next, we introduce a model
aggregation technique to identify parametric dependencies
among turbulence quantities and transport-relevant plasma
parameters. The parametric dependencies show the most
agreement with transport driven by trapped-electron mode,
kinetic ballooning mode, and microtearing mode turbulence,
and the least agreement with ion temperature gradient
turbulence. In addition, the parametric dependencies are
consistent with turbulence regulation by flow shear and the
empirical relationship between wider pedestals and larger
turbulent structures. © 2013 AIP Publishing
LLC.},
Doi = {10.1063/1.4803913},
Key = {fds335084}
}
@article{fds330978,
Author = {Yurduseven, O and Smith, D},
Title = {A solar cell stacked multi-slot quad-band PIFA for GSM, WLAN
and WiMAX networks},
Journal = {IEEE Microwave and Wireless Components Letters},
Volume = {23},
Number = {6},
Pages = {285-287},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2013},
Month = {April},
url = {http://dx.doi.org/10.1109/LMWC.2013.2258006},
Abstract = {This letter presents a novel low-profile quad-bandsolar PIFA
which has the potential to be employed in self-powered
low-power GSM 1800, 2.4 GHz band WLAN and 2.3/3.3/5.8 GHz
band WiMAX networks. The multi-slot loaded radiating PIFA
element consisting of W-L shaped slots stacked with a
polycrystalline silicon (poly-Si) solar cell operating as a
parasitic patch element enables the proposed solar PIFA to
operate at the center frequency bands of 1.8, 2.4, 3.4, and
5.8 GHz with measured impedance bandwidths of 16.7%, 9.16%,
7.65%, and 3.45%, respectively. By incorporating a stacked
poly-Si solar cell as a parasitic patch element an adequate
solar efficiency of 14.5% can be achieved, generating a dc
power output of 44 mW. © 2001-2012 IEEE.},
Doi = {10.1109/LMWC.2013.2258006},
Key = {fds330978}
}
@article{fds330979,
Author = {Yurduseven, O and Smith, D and Elsdon, M},
Title = {UWB meshed solar monopole antenna},
Journal = {Electronics Letters},
Volume = {49},
Number = {9},
Pages = {582-584},
Publisher = {Institution of Engineering and Technology
(IET)},
Year = {2013},
Month = {April},
url = {http://dx.doi.org/10.1049/el.2013.0478},
Abstract = {A novel combination of a parametrically optimised UWB meshed
circular disc monopole antenna with a polycrystalline
silicon (poly-Si) solar cell is presented and discussed. The
results indicate that the fabricated meshed solar monopole
antenna operates across the frequency band 2.33-10.8 GHz
with an average broadband gain of 4.1 dBi. It is
demonstrated that by meshing the monopole pattern an
adequate solar efficiency of 13.1% can be achieved. © The
Institution of Engineering and Technology
2013.},
Doi = {10.1049/el.2013.0478},
Key = {fds330979}
}
@article{fds269647,
Author = {Ciracì, C and Urzhumov, Y and Smith, DR},
Title = {Far-field analysis of axially symmetric three-dimensional
directional cloaks.},
Journal = {Optics express},
Volume = {21},
Number = {8},
Pages = {9397-9406},
Year = {2013},
Month = {April},
ISSN = {1094-4087},
url = {http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000318151600021&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=47d3190e77e5a3a53558812f597b0b92},
Abstract = {Axisymmetric radiating and scattering structures whose
rotational invariance is broken by non-axisymmetric
excitations present an important class of problems in
electromagnetics. For such problems, a cylindrical wave
decomposition formalism can be used to efficiently obtain
numerical solutions to the full-wave frequency-domain
problem. Often, the far-field, or Fraunhofer region is of
particular interest in scattering cross-section and
radiation pattern calculations; yet, it is usually
impractical to compute full-wave solutions for this region.
Here, we propose a generalization of the Stratton-Chu
far-field integral adapted for 2.5D formalism. The
integration over a closed, axially symmetric surface is
analytically reduced to a line integral on a meridional
plane. We benchmark this computational technique by
comparing it with analytical Mie solutions for a plasmonic
nanoparticle, and apply it to the design of a
three-dimensional polarization-insensitive
cloak.},
Doi = {10.1364/oe.21.009397},
Key = {fds269647}
}
@article{fds269649,
Author = {Ciracì, C and Pendry, JB and Smith, DR},
Title = {Hydrodynamic model for plasmonics: a macroscopic approach to
a microscopic problem.},
Journal = {Chemphyschem : a European journal of chemical physics and
physical chemistry},
Volume = {14},
Number = {6},
Pages = {1109-1116},
Year = {2013},
Month = {April},
url = {http://www.ncbi.nlm.nih.gov/pubmed/23512885},
Abstract = {In this concept, we present the basic assumptions and
techniques underlying the hydrodynamic model of electron
response in metals and demonstrate that the model can be
easily incorporated into computational models. We discuss
the role of the additional boundary conditions that arise
due to nonlocal terms in the modified equation of motion and
the ultimate impact on nanoplasmonic systems. The
hydrodynamic model captures much of the microscopic dynamics
relating to the fundamental quantum mechanical nature of the
electrons and reveals intrinsic limitations to the
confinement and enhancement of light around nanoscale
features. The presence of such limits is investigated
numerically for different configurations of plasmonic
nanostructures.},
Doi = {10.1002/cphc.201200992},
Key = {fds269649}
}
@article{fds335083,
Author = {Quinn, H and Graham, P and Morgan, K and Baker, Z and Caffrey, M and Smith,
D and Wirthlin, M and Bell, R},
Title = {Flight experience of the xilinx virtex-4},
Journal = {IEEE Transactions on Nuclear Science},
Volume = {60},
Number = {4},
Pages = {2682-2690},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2013},
Month = {March},
url = {http://dx.doi.org/10.1109/TNS.2013.2246581},
Abstract = {This paper provides information regarding the use of the
Xilinx Virtex-4 field-programmable gate array (FPGA) in a
spacecraft deployed to low-earth orbit. The results are
compared to pre-deployment accelerated single-event effects
(SEEs) and fault-injection testing. © 2013
IEEE.},
Doi = {10.1109/TNS.2013.2246581},
Key = {fds335083}
}
@article{fds269650,
Author = {Rose, A and Huang, D and Smith, DR},
Title = {Nonlinear interference and unidirectional wave mixing in
metamaterials.},
Journal = {Physical review letters},
Volume = {110},
Number = {6},
Pages = {063901},
Year = {2013},
Month = {February},
url = {http://www.ncbi.nlm.nih.gov/pubmed/23432242},
Abstract = {When both electric and magnetic mechanisms contribute to a
particular nonlinear optical process, there exists the
possibility for nonlinear interference, often characterized
by constructive or destructive interference in the radiation
pattern of harmonics and mix waves. However, observation of
a significant effect from nonlinear interference requires
careful balancing of the various contributions. For this
purpose, we propose an artificial metamaterial, using the
formalism of nonlinear magnetoelectric coupling to
simultaneously engineer the nonlinear polarization and
magnetization. We confirm our predictions of nonlinear
interference with both simulations and experiment,
demonstrating unidirectional wave mixing in two microwave
metamaterials. Our results point toward an ever wider range
of nonlinear properties, in which nonlinear interference is
just one of many potential applications.},
Doi = {10.1103/physrevlett.110.063901},
Key = {fds269650}
}
@article{fds269651,
Author = {Moreau, A and Ciracì, C and Smith, DR},
Title = {Impact of nonlocal response on metallodielectric multilayers
and optical patch antennas},
Journal = {Physical Review B - Condensed Matter and Materials
Physics},
Volume = {87},
Number = {4},
Publisher = {American Physical Society (APS)},
Year = {2013},
Month = {January},
ISSN = {1098-0121},
url = {http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000312999800008&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=47d3190e77e5a3a53558812f597b0b92},
Abstract = {We analyze the impact of nonlocality on the waveguide modes
of metallodielectric multilayers and optical patch antennas,
the latter formed from metal strips closely spaced above a
metallic plane. We model both the nonlocal effects
associated with the conduction electrons of the metal and
the previously overlooked response of bound electrons. We
show that the fundamental mode of a metal-dielectric-metal
waveguide, sometimes called the gap plasmon, is very
sensitive to nonlocality when the insulating, dielectric
layers are thinner than 5 nm. We suggest that optical patch
antennas, which can easily be fabricated with controlled
dielectric spacer layers and can be interrogated using
far-field scattering, can enable the measurement of
nonlocality in metals with good accuracy. © 2013 American
Physical Society.},
Doi = {10.1103/PhysRevB.87.045401},
Key = {fds269651}
}
@article{fds330980,
Author = {Abadi, MM and Ghassemlooy, Z and Smith, D and Ng,
WP},
Title = {A report on H-FSO/RF antenna measurement for outdoor
applications},
Journal = {Proceedings of the 2013 2nd International Workshop on
Optical Wireless Communications, IWOW 2013},
Pages = {118-122},
Publisher = {IEEE},
Year = {2013},
Month = {January},
url = {http://dx.doi.org/10.1109/IWOW.2013.6777790},
Abstract = {This paper presents a report on experimental set up and
results for a hybrid free space optics (FSO)/radio frequency
(RF) dual purpose antenna for outdoor applications. The
basic design of the antenna is discussed and we present two
sets of early experimental results for the signal to noise
ratio (SNR) and the Q-factor for the RF and FSO simplex link
at the far-field distance of RF antenna, respectively. Over
a link span of 15 m the measured SNR and the Q-factor are
45.68 dB and 15.69, respectively, demonstrating the
functioning transmission capability of the hybrid FSO/RF
link employing the proposed antenna. © 2013
IEEE.},
Doi = {10.1109/IWOW.2013.6777790},
Key = {fds330980}
}
@article{fds269578,
Author = {Tsai, YJ and Tyler, T and Larouche, S and Llopis, A and Royal, M and Jokerst, NM and Smith, DR},
Title = {Metamaterial polarization multiplexed gratings},
Journal = {2013 Conference on Lasers and Electro-Optics, CLEO
2013},
Year = {2013},
Month = {January},
url = {http://dx.doi.org/10.1364/cleo_qels.2013.qm4a.1},
Abstract = {We demonstrate a metamaterial grating that has two
diffraction periods for two orthogonal linear polarization
states of illuminations. The proposed method will be useful
in free space optical communications and novel optical
imaging systems. © 2013 The Optical Society.},
Doi = {10.1364/cleo_qels.2013.qm4a.1},
Key = {fds269578}
}
@article{fds269583,
Author = {Driscoll, T and Urzhumov, Y and Landy, N and Basov, D and Smith,
DR},
Title = {Dielectric metamaterials and composites in the age of 3D
printing, and directional cloaking},
Journal = {2013 7th International Congress on Advanced Electromagnetic
Materials in Microwaves and Optics, METAMATERIALS
2013},
Pages = {361-363},
Publisher = {IEEE},
Year = {2013},
Month = {January},
url = {http://dx.doi.org/10.1109/MetaMaterials.2013.6809053},
Abstract = {The rapid evolution of additive manufacturing techniques has
the potential to revolutionize a wide range of
fabrication-limited fields. In this article, we apply
plastic additive manufacturing to the creation of
radio-frequency electromagnetic devices, demonstrating a
metamaterial-like unidirectional cloak. Enabling this
all-dielectric cloak is a computational boundary-optimization
design approach significantly different from traditional
metamaterial design techniques. For a subset of
applications, the new all-dielectric cloak proves to work as
well as well as previous metal-inclusive designs. © 2013
IEEE.},
Doi = {10.1109/MetaMaterials.2013.6809053},
Key = {fds269583}
}
@article{fds269627,
Author = {Lassiter, JB and McGuire, F and Mock, JJ and Ciracì, C and Hill, RT and Wiley, BJ and Chilkoti, A and Smith, DR},
Title = {Plasmonic waveguide modes of film-coupled metallic
nanocubes.},
Journal = {Nano letters},
Volume = {13},
Number = {12},
Pages = {5866-5872},
Year = {2013},
Month = {January},
url = {http://www.ncbi.nlm.nih.gov/pubmed/24199752},
Abstract = {A metallic nanoparticle positioned over a metal film offers
great advantages as a highly controllable system relevant
for probing field-enhancement and other plasmonic effects.
Because the size and shape of the gap between the
nanoparticle and film can be controlled to subnanometer
precision using relatively simple, bottom-up fabrication
approaches, the film-coupled nanoparticle geometry has
recently been applied to enhancing optical fields, accessing
the quantum regime of plasmonics, and the design of surfaces
with controlled reflectance. In the present work, we examine
the plasmon modes associated with a silver nanocube
positioned above a silver or gold film, separated by an
organic, dielectric spacer layer. The film-coupled nanocube
is of particular interest due to the formation of waveguide
cavity-like modes between the nanocube and film. These modes
impart distinctive scattering characteristics to the system
that can be used in the creation of controlled reflectance
surfaces and other applications. We perform both
experimental spectroscopy and numerical simulations of
individual nanocubes positioned over a metal film, finding
excellent agreement between experiment and simulation. The
waveguide mode description serves as a starting point to
explain the optical properties observed.},
Doi = {10.1021/nl402660s},
Key = {fds269627}
}
@article{fds269652,
Author = {Hunt, J and Driscoll, T and Mrozack, A and Lipworth, G and Reynolds, M and Brady, D and Smith, DR},
Title = {Metamaterial apertures for computational
imaging.},
Journal = {Science (New York, N.Y.)},
Volume = {339},
Number = {6117},
Pages = {310-313},
Year = {2013},
Month = {January},
url = {http://www.ncbi.nlm.nih.gov/pubmed/23329043},
Abstract = {By leveraging metamaterials and compressive imaging, a
low-profile aperture capable of microwave imaging without
lenses, moving parts, or phase shifters is demonstrated.
This designer aperture allows image compression to be
performed on the physical hardware layer rather than in the
postprocessing stage, thus averting the detector, storage,
and transmission costs associated with full
diffraction-limited sampling of a scene. A guided-wave
metamaterial aperture is used to perform compressive image
reconstruction at 10 frames per second of two-dimensional
(range and angle) sparse still and video scenes at K-band
(18 to 26 gigahertz) frequencies, using frequency diversity
to avoid mechanical scanning. Image acquisition is
accomplished with a 40:1 compression ratio.},
Doi = {10.1126/science.1230054},
Key = {fds269652}
}
@article{fds269774,
Author = {Landy, N and Smith, DR},
Title = {A full-parameter unidirectional metamaterial cloak for
microwaves.},
Journal = {Nature materials},
Volume = {12},
Number = {1},
Pages = {25-28},
Year = {2013},
Month = {January},
ISSN = {1476-1122},
url = {http://www.ncbi.nlm.nih.gov/pubmed/23142840},
Abstract = {Invisibility is a notion that has long captivated the
popular imagination. However, in 2006, invisibility became a
practical matter for the scientific community as well, with
the suggestion that artificially structured metamaterials
could enable a new electromagnetic design paradigm, now
termed transformation optics. Since the advent of
transformation optics and subsequent initial demonstration
of the microwave cloak, the field has grown rapidly.
However, the complexity of the transformation optics
material prescription has continually forced researchers to
make simplifying approximations to achieve even a subset of
the desired functionality. These approximations place
profound limitations on the performance of transformation
optics devices in general, and cloaks especially. Here, we
design and experimentally characterize a two-dimensional,
unidirectional cloak that makes no approximations to the
underlying transformation optics formulation, yet is capable
of reducing the scattering of an object ten wavelengths in
size. We demonstrate that this approximation-free design
regains the performance characteristics promised by
transformation optics.},
Doi = {10.1038/nmat3476},
Key = {fds269774}
}
@article{fds335085,
Author = {Diallo, A and Kramer, GJ and Smith, DR and Maingi, R and Bell, RE and Guttenfelder, W and Leblanc, BP and Podestà, M and McKee, GJ and Fonck,
R},
Title = {Observation of ion scale fluctuations in the pedestal region
during the edge-localized-mode cycle on the National
Spherical Torus Experiment},
Journal = {Physics of Plasmas},
Volume = {20},
Number = {1},
Pages = {012505-012505},
Publisher = {AIP Publishing},
Year = {2013},
Month = {January},
url = {http://dx.doi.org/10.1063/1.4773402},
Abstract = {Characterization of the spatial structure of turbulence
fluctuations during the edge localized mode cycle in the
pedestal region is reported. Using the beam emission
spectroscopy and the correlation reflectometry systems,
measurements show spatial structure - k⊥ρiped - ranging
from 0.2 to 0.7 propagating in the ion diamagnetic drift
direction at the pedestal top. These propagating spatial
scales are found to be anisotropic and consistent with
ion-scale microturbulence of the type ion temperature
gradient and/or kinetic ballooning modes. © 2013 American
Institute of Physics.},
Doi = {10.1063/1.4773402},
Key = {fds335085}
}
@article{fds330971,
Author = {Elsdon, M and Yurduseven, O and Smith, D},
Title = {Early stage breast cancer detection using indirect microwave
holography},
Journal = {Progress in Electromagnetics Research},
Volume = {143},
Pages = {405-419},
Publisher = {EMW Publishing},
Year = {2013},
Month = {January},
url = {http://dx.doi.org/10.2528/PIER13091703},
Abstract = {A novel microwave imaging approach for early stage breast
cancer detection is described. The proposed technique
involves the use of an Indirect Microwave Holographic
technique employing a patented synthetic reference wave.
This approach offers benefits in terms of simplicity,
expense, comfort and safety when compared to current
mammography techniques. Experimental results using a
simulated breast phantom are included to demonstrate the
validity of this technique to obtain 2D images. The
technique is then extended to demonstrate the possibility of
obtaining 3D images by using indirect stereoscopic
holographic imaging.},
Doi = {10.2528/PIER13091703},
Key = {fds330971}
}
@article{fds330973,
Author = {Yurduseven, O and Smith, D and Pearsall, N and Forbes,
I},
Title = {A solar cell stacked slot-loaded suspended microstrip patch
antenna with multiband resonance characteristics for wlan
and WiMAX systems},
Journal = {Progress in Electromagnetics Research},
Volume = {142},
Pages = {321-332},
Publisher = {EMW Publishing},
Year = {2013},
Month = {January},
url = {http://dx.doi.org/10.2528/PIER13081502},
Abstract = {In this paper, a novel self-complementary shaped multiple- L
slot loaded suspended microstrip patch antenna stacked with
a polycrystalline silicon (poly-Si) solar cell is presented
for 2.4/5.2GHz band WLAN and 2.5/3.3/5.8 GHz band WiMAX
networks. While the proposed self-complementary shaped
multiple-L slot loaded suspended patch enables the
propagation of multiple TMmn modes to be present, the
poly-Si solar cell works as an RF parasitic patch element in
addition to its photovoltaic function. The proposed stacked
solar antenna combination topology enables the radiating
patch to be easily modified by slot-loading to achieve
multiband resonance characteristics and the poly-Si solar
cell to operate without being shaded by any RF components of
the antenna ensuring an optimum solar operation
performance.},
Doi = {10.2528/PIER13081502},
Key = {fds330973}
}
@article{fds330981,
Author = {Liu, L and Ghassemlooy, Z and Sambell, A and Danaher, S and Smith,
D},
Title = {Investigation of transformer turns ratio between feed and
slot of aperture coupled slot antenna by using
S11 parameter},
Journal = {IEEE Transactions on Antennas and Propagation},
Volume = {61},
Number = {11},
Pages = {5785-5787},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2013},
Month = {January},
url = {http://dx.doi.org/10.1109/TAP.2013.2275745},
Abstract = {This communication presents a simplified design approach to
obtain the turns ratio Nf which models the coupling between
the microstrip feed and slot line of an aperture coupled
slot antenna by using the S11 parameter. Equations are
derived using S11 parameter to determine Nf and simulations
are carried out at 2 GHz using substrates of PCB FR4, Duroid
5870, and Duroid 6010. Results indicate Nf is proportional
to the slot length from 0 to 20 mm increasing rapidly with
length. Over 20 mm slot length, the trend reduces and the
value of Nf tends towards 1. In addition, Nf varies with the
height of substrate but is little affected by dielectric
constant of substrate which could therefore be ignored to
simplify the design procedure. Measured results show good
agreement with the theoretical model. © 1963-2012
IEEE.},
Doi = {10.1109/TAP.2013.2275745},
Key = {fds330981}
}
@article{fds330970,
Author = {Yurduseven, O and Smith, D and Elsdon, M},
Title = {Printed slot loaded bow-tie antenna with super wideband
radiation characteristics for imaging applications},
Journal = {IEEE Transactions on Antennas and Propagation},
Volume = {61},
Number = {12},
Pages = {6206-6210},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2013},
Month = {January},
url = {http://dx.doi.org/10.1109/TAP.2013.2281353},
Abstract = {A super wideband printed modified bow-tie antenna loaded
with rounded-T shaped slots fed through amicrostrip balun is
proposed for microwave and millimeter-wave band imaging
applications. The modified slot-loaded bow-tie pattern
increases the electrical length of the bow-tie antenna
reducing the lower band to 3.1GHz. In addition, over the
investigated frequency band up to 40 GHz, the proposed
modified bow-tie pattern considerably flattens the input
impedance response of the bow-tie resulting in a smooth
impedance matching performance enhancing the reflection
coefficient (S11) characteristics. The introduction of the
modified ground plane printed underneath the bow-tie, on the
other hand, yields to directional far-field radiation
patterns with considerably enhanced gain performance. The S
11 and E-plane/H-plane far-field radiation pattern
measurements have been carried out and it is demonstrated
that the fabricated bow-tie antenna operates across a
measured frequency band of 3.1-40 GHz with an average
broadband gain of 7.1 dBi. © 2013 IEEE.},
Doi = {10.1109/TAP.2013.2281353},
Key = {fds330970}
}
@article{fds269633,
Author = {Landy, N and Hunt, J and Smith, DR},
Title = {Homogenization analysis of complementary waveguide
metamaterials},
Journal = {Photonics and Nanostructures - Fundamentals and
Applications},
Volume = {11},
Number = {4},
Pages = {453-467},
Publisher = {Elsevier BV},
Year = {2013},
ISSN = {1569-4410},
url = {http://dx.doi.org/10.1016/j.photonics.2013.07.004},
Abstract = {We analyze the properties of complementary metamaterials as
effective inclusions patterned into the conducting walls of
metal waveguide structures. We show that guided wave
metamaterials can be homogenized using the same retrieval
techniques used for volumetric metamaterials, leading to a
description in which a given complementary element is
conceptually replaced by a block of material within the
waveguide whose effective permittivity and permeability
result in equivalent scattering characteristics. The use of
effective constitutive parameters for waveguide materials
provides an alternative point-of-view for the design of
waveguide and microstrip based components, including planar
lenses and filters, as well as devices with derived from a
bulk material response. In addition to imparting effective
constitutive properties to the waveguide, complementary
metamaterials also couple energy from waveguide modes into
radiation. Thus, complementary waveguide metamaterials can
be used to modify and optimize a variety of antenna
structures. © 2013 Elsevier B.V. All rights
reserved.},
Doi = {10.1016/j.photonics.2013.07.004},
Key = {fds269633}
}
@article{fds335086,
Author = {Quinn, H and Graham, P and Morgan, K and Baker, Z and Caffrey, M and Smith,
D and Bell, R},
Title = {On-orbit results for the xilinx virtex-4
FPGA},
Journal = {IEEE Radiation Effects Data Workshop},
Publisher = {IEEE},
Year = {2012},
Month = {December},
ISBN = {9781467327312},
url = {http://dx.doi.org/10.1109/REDW.2012.6353715},
Abstract = {This paper provides information regarding the use of the
Xilinx Virtex-4 field-programmable gate array in a
spacecraft deployed to low-earth orbit. The results are
compared to pre-deployment accelerated and fault-injection
testing. Copyright © 2012 by the Institute of Electrical
and Electronic Engineers, Inc.},
Doi = {10.1109/REDW.2012.6353715},
Key = {fds335086}
}
@article{fds330982,
Author = {Yurduseven, O and Smith, D and Pearsall, N and Forbes,
I},
Title = {Design of a highly efficient wideband suspended solar array
antenna},
Journal = {IEEE Antennas and Propagation Society, AP-S International
Symposium (Digest)},
Publisher = {IEEE},
Year = {2012},
Month = {December},
ISBN = {9781467304627},
url = {http://dx.doi.org/10.1109/APS.2012.6348555},
Abstract = {This paper presents the design of a wideband suspended solar
patch array antenna for WLAN and ISM band applications. The
suspended silicon solar cells, which have been replaced with
traditional microstrip patches and work as antennas within
the design, are able to receive and transmit the EM signals
while producing a DC current as a result of the photovoltaic
effect. A unique and effective quarter-wave DC/AC decoupling
circuit, which enables the produced current to be withdrawn
from the system without affecting the RF performance of the
antenna, has been designed based on microwave circuit
topology. Experimental and full-wave simulation results of
the presented solar antenna operating within the frequency
band of 2.3-2.75 GHz, confirm the suitability of the
proposed design for wideband communication systems with a
wide impedance bandwidth of 18.36%, 450 MHz, and a high gain
of 12.2 dB. © 2012 IEEE.},
Doi = {10.1109/APS.2012.6348555},
Key = {fds330982}
}
@article{fds269756,
Author = {Grajower, M and Lerman, G and Goykhman, I and Desiatov, B and Yanai, A and Smith, DR and Levy, U},
Title = {Plasmonic graded-index planar lens based on subwavelength
features in the effective index regime},
Journal = {2012 Conference on Lasers and Electro-Optics, CLEO
2012},
Year = {2012},
Month = {December},
Abstract = {We experimentally demonstrate the planar focusing of Surface
Plasmon Polaritons using space variant PMMA subwavelength
features on top of a metallic film. Focusing is obtained by
creating an effective graded refractive index profile. ©
2012 OSA.},
Key = {fds269756}
}
@article{fds269757,
Author = {Smith, DR},
Title = {Defining new optics with metamaterials},
Journal = {2012 Conference on Lasers and Electro-Optics, CLEO
2012},
Year = {2012},
Month = {December},
Abstract = {Metamaterials provide resources for the development of
unconventional optical devices and the improvement of
conventional ones. We review the methods of analyzing,
constructing and characterizing metamaterials, and discuss
their extension to infrared and visible wavelengths. © 2012
OSA.},
Key = {fds269757}
}
@article{fds330983,
Author = {Yurduseven, O and Smith, D and Pearsall, N and Forbes,
I},
Title = {A triband short-circuited suspended solar patch
antenna},
Journal = {2012 10th International Symposium on Antennas, Propagation
and EM Theory, ISAPE 2012},
Pages = {294-297},
Publisher = {IEEE},
Year = {2012},
Month = {December},
ISBN = {9781467317993},
url = {http://dx.doi.org/10.1109/ISAPE.2012.6408767},
Abstract = {In this paper, a triband low-profile short-circuited
suspended patch antenna combined with a polycrystalline
silicon solar cell working as a radiating patch element is
proposed for 2.3/2.5/2.8/3.3/3.5 GHz band WiMAX and 2.4 GHz
band WLAN networks. The fabricated multifunctional solar
antenna offers measured impedance bandwidths of 230, 130 and
280 MHz at the resonance frequencies of 2.4, 2.8 and 3.45
GHz with measured gains of 7.4, 7.8 and 7.6 dBi
respectively. The proposed solar antenna generates a
measured open circuit voltage of 0.595 V with a short
circuit current of 602 mA as a result of the photovoltaic
effect, operating with a calculated solar efficiency of
13.22% and providing a DC power output of 0.238 W. © 2012
IEEE.},
Doi = {10.1109/ISAPE.2012.6408767},
Key = {fds330983}
}
@article{fds330984,
Author = {Yurduseven, O and Smith, D},
Title = {Symmetric/asymmetric H-plane horn fed offset parabolic
reflector antenna with switchable pencil/fan-beam radiation
characteristics},
Journal = {2012 10th International Symposium on Antennas, Propagation
and EM Theory, ISAPE 2012},
Pages = {82-85},
Publisher = {IEEE},
Year = {2012},
Month = {December},
ISBN = {9781467317993},
url = {http://dx.doi.org/10.1109/ISAPE.2012.6408713},
Abstract = {This paper presents a modified offset parabolic reflector
antenna design with easily switchable pencil/fan-beam
radiation patterns for X-band tracking, scanning and
surveillance microwave radar systems. The modified offset
parabolic reflector antenna, combined with an array of flat
aluminum plates at the bottom, is fed through
symmetric/asymmetric H-plane feed horn antennas. An
effective measured pencil-beam/fan-beam switching
performance has been achieved as a result of setting the
flares of the H-plane feed horn antenna symmetrically and
asymmetrically, without making any changes in the geometry
of the offset parabolic reflector antenna. © 2012
IEEE.},
Doi = {10.1109/ISAPE.2012.6408713},
Key = {fds330984}
}
@article{fds330985,
Author = {Yurduseven, O and Smith, D and Pearsall, N and Forbes, I and Johnston,
D},
Title = {A meshed multiband solar patch array antenna},
Journal = {LAPC 2012 - 2012 Loughborough Antennas and Propagation
Conference},
Publisher = {IEEE},
Year = {2012},
Month = {December},
ISBN = {9781467322195},
url = {http://dx.doi.org/10.1109/LAPC.2012.6403083},
Abstract = {In this paper, a meshed multiband solar patch array antenna,
consisting of a polycrystalline silicon solar panel working
as a ground plane whilst generating a DC power output of
1.48 W as a result of the photovoltaic effect with a
measured solar efficiency of 14.95%, is proposed for GSM
900/1800/1900, UMTS 1900, 3.5 GHz band WiMAX and C-band
applications. The proposed solar patch array antenna
introduces a further potential of solar cells to be
effectively used as embedded elements within communication
systems, raising the awareness of solar energy and offering
a practical solution to the requirement for the
incorporation of solar cells/panels with microwave antennas
within solar powered autonomous communication systems
suffering from increasing dimensions due to the separate
involvement of solar panels and microwave antennas. © 2012
IEEE.},
Doi = {10.1109/LAPC.2012.6403083},
Key = {fds330985}
}
@article{fds335087,
Author = {Baharin, R and Hobson, PR and Leslie, DE and Smith,
DR},
Title = {Effect of gamma radiation on potential ionising radiation
detectors and dosimeters based on quantum
dots},
Journal = {IEEE Nuclear Science Symposium Conference
Record},
Pages = {3228-3231},
Publisher = {IEEE},
Year = {2012},
Month = {December},
ISBN = {9781467320306},
url = {http://dx.doi.org/10.1109/NSSMIC.2012.6551737},
Abstract = {In this work, we report measured effects on the fluorescent
emission spectra of commercially produced core-shell
(CdSe/ZnS) quantum dots (QDs) of 2.5 nm, 3.3 nm and 6.3 nm
size in toluene, following exposure to 1 MeV gamma
irradiation in the range 0.1-110 Gy. We show that damage
depends on the size of the QDs, an effect seen in solutions
of a single type of QD as well as in a mixture, and that
increasing the concentration of QDs in the toluene decreases
the effect. Measurements have recently been made to
investigate and shift in peak wavelength following
irradiation and these are reported here. Recent work on the
production of a prototype 2D imaging dosimeter, by absorbing
a solution of green emitting QD in toluene into a sample of
porous 'Vycor' glass, has shown that QDs absorbed in the
Vycor fluoresce under several hours of continual
illumination and that the system continues to show
fluorescence for several days after the initial preparation.
Initial results of experiments to dynamically image the
Vycor during electron irradiation are presented as is
progress on the development of a second prototype device for
2D radiation dosimetry. © 2012 IEEE.},
Doi = {10.1109/NSSMIC.2012.6551737},
Key = {fds335087}
}
@article{fds335088,
Author = {Walker, TE and Smith, DR},
Title = {Development of a laboratory based XRF facility for measuring
elemental abundance ratios in planetary analogue powder
samples},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {8453},
Publisher = {SPIE},
Year = {2012},
Month = {December},
ISBN = {9780819491541},
url = {http://dx.doi.org/10.1117/12.926978},
Abstract = {This paper describes the use of a swept-charge device (SCD)
silicon X-ray detector in a laboratory based X-ray
fluorescence (XRF) facility for calculating elemental
abundance ratios from planetary analogue powder samples. The
facility was developed to support the Chandrayaan-1 X-ray
Spectrometer (C1XS) detector development and calibration
activities prior to the flight of the instrument onboard the
Indian Space Research Organisation (ISRO) Chandrayaan-1
mission to the Moon in 2008. The test facility has
subsequently been used to carry out XRF analysis of
homogenous samples made from mixtures of MgO, Al2O 3 and
SiO2 powders, all of grain size <44 μm, across a range of
mixture ratios and at a high level of X-ray flux data in
order to develop an algorithm which will allow the
calculation of elemental abundance ratios. This paper also
presents an analysis of XRF data collected from lunar
regolith simulant JSC-1A and an Etna Basalt powder sample to
enable calibration of various model parameters. The
operation of the SCD, the XRF test facility, the sample
preparation methodology and the process of obtaining
elemental abundance ratios from planetary analogue samples
using the test facility are discussed in this paper. © 2012
SPIE.},
Doi = {10.1117/12.926978},
Key = {fds335088}
}
@article{fds335089,
Author = {Walker, TE and Smith, DR},
Title = {The effects of radiation damage on the spectral resolution
of the Chandrayaan-1 X-ray Spectrometer over the full
mission duration},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {8453},
Publisher = {SPIE},
Year = {2012},
Month = {December},
ISBN = {9780819491541},
url = {http://dx.doi.org/10.1117/12.926983},
Abstract = {The Chandrayaan-1 X-ray Spectrometer (C1XS) was launched
onboard the Indian Space Research Organisation (ISRO)
Chandrayaan-1 lunar mission in October 2008. The instrument
consisted of 24 swept-charge device silicon X-ray detectors
providing a total collecting area of ∼24 cm2,
corresponding to a 14° field of view (FWHM), with the
ability to measure X-rays from 0.8 - 10 keV. During the 10
months the spacecraft was located in orbit around the Moon a
number of solar flare X-ray events were detected, along with
calibration data from X-ray sources housed inside the
movable door of the instrument. This paper presents a
further study of the degradation in spectral resolution of
the measured X-ray calibration lines, adding a final
calibration point towards the end of mission lifetime to the
known results from the midpoint of the mission, giving a
more detailed analysis of the extent of the radiation
damage. The radiation environment the detectors were
subjected to is discussed in light of the actual radiation
damage effects on the spectral resolution observed in
flight. © 2012 SPIE.},
Doi = {10.1117/12.926983},
Key = {fds335089}
}
@article{fds269608,
Author = {Smith, DR},
Title = {Defining new optics with metamaterials},
Journal = {Optics InfoBase Conference Papers},
Year = {2012},
Month = {December},
Abstract = {Metamaterials provide resources for the development of
unconventional optical devices and the improvement of
conventional ones. We review the methods of analyzing,
constructing and characterizing metamaterials, and discuss
their extension to infrared and visible wavelengths. © OSA
2012.},
Key = {fds269608}
}
@article{fds269609,
Author = {Grajower, M and Lerman, G and Goykhman, I and Desiatov, B and Yanai, A and Smith, DR and Levy, U},
Title = {Plasmonic graded-index planar lens based on subwavelength
features in the effective index regime},
Journal = {Optics InfoBase Conference Papers},
Year = {2012},
Month = {December},
Abstract = {We experimentally demonstrate the planar focusing of Surface
Plasmon Polaritons using space variant PMMA subwavelength
features on top of a metallic film. Focusing is obtained by
creating an effective graded refractive index profile. ©
OSA 2012.},
Key = {fds269609}
}
@article{fds269614,
Author = {Larouche, S and Tsai, YJ and Tyler, T and Jokerst, NM and Smith,
DR},
Title = {Infrared metamaterial hologram},
Journal = {Optics InfoBase Conference Papers},
Year = {2012},
Month = {December},
Abstract = {We designed, fabricated, and characterized an infrared
metamaterial hologram. The hologram correctly reproduces the
design image. This work demonstrates that metamate-rials can
be used to fabricate devices with arbitrary 2D refractive
index profiles. © 2011 Optical Society of
America.},
Key = {fds269614}
}
@article{fds269808,
Author = {Moreau, A and Ciracì, C and Mock, JJ and Hill, RT and Wang, Q and Wiley,
BJ and Chilkoti, A and Smith, DR},
Title = {Controlled-reflectance surfaces with film-coupled colloidal
nanoantennas.},
Journal = {Nature},
Volume = {492},
Number = {7427},
Pages = {86-89},
Year = {2012},
Month = {December},
url = {http://www.ncbi.nlm.nih.gov/pubmed/23222613},
Abstract = {Efficient and tunable absorption is essential for a variety
of applications, such as designing controlled-emissivity
surfaces for thermophotovoltaic devices, tailoring an
infrared spectrum for controlled thermal dissipation and
producing detector elements for imaging. Metamaterials based
on metallic elements are particularly efficient as absorbing
media, because both the electrical and the magnetic
properties of a metamaterial can be tuned by structured
design. So far, metamaterial absorbers in the infrared or
visible range have been fabricated using lithographically
patterned metallic structures, making them inherently
difficult to produce over large areas and hence reducing
their applicability. Here we demonstrate a simple method to
create a metamaterial absorber by randomly adsorbing
chemically synthesized silver nanocubes onto a
nanoscale-thick polymer spacer layer on a gold film, making
no effort to control the spatial arrangement of the cubes on
the film. We show that the film-coupled nanocubes provide a
reflectance spectrum that can be tailored by varying the
geometry (the size of the cubes and/or the thickness of the
spacer). Each nanocube is the optical analogue of a grounded
patch antenna, with a nearly identical local field structure
that is modified by the plasmonic response of the metal's
dielectric function, and with an anomalously large
absorption efficiency that can be partly attributed to an
interferometric effect. The absorptivity of large surface
areas can be controlled using this method, at scales out of
reach of lithographic approaches (such as electron-beam
lithography) that are otherwise required to manipulate
matter on the nanoscale.},
Doi = {10.1038/nature11615},
Key = {fds269808}
}
@article{fds335090,
Author = {Baharin, R and Hobson, PR and Leslie, DE and Smith,
DR},
Title = {Development of an ionising radiation detector based on
quantum dots absorbed in porous glass},
Journal = {Proceedings of the IEEE Conference on Nanotechnology},
Publisher = {IEEE},
Year = {2012},
Month = {November},
ISBN = {9781467321983},
url = {http://dx.doi.org/10.1109/NANO.2012.6322009},
Abstract = {In this work, we report measured effects on the fluorescent
emission spectra of commercially produced core-shell
(CdSe/ZnS) quantum dots (QDs). We report the effects on the
fluorescent emission spectra of commercially produced
CdSe/ZnS QDs of 2.5 nm, 3.3 nm and 6.3 nm size in toluene,
following exposure to 1 MeV gamma irradiation in the range
0.1-110 Gy. We show that damage depends on the size of the
QDs and that increasing the concentration of QDs in the
toluene decreases the effect. Recent work on the production
of a prototype 2D imaging dosimeter, by absorbing a solution
of green emitting QD in toluene into a sample of porous
Vycor glass, has shown that QDs absorbed in the Vycor
fluoresce under several hours of continual illumination and
that the system continues to show fluorescence for several
days after the initial preparation. Initial results of
experiments to dynamically image the Vycor during electron
irradiation are presented as is progress on the development
of a second prototype device for 2D radiation dosimetry. ©
2012 IEEE.},
Doi = {10.1109/NANO.2012.6322009},
Key = {fds335090}
}
@article{fds330986,
Author = {Bobor-Oyibo, F and Foti, SJ and Smith, D and Yurduseven,
O},
Title = {Modelling and analysis of a smart antenna system with
sub-sector dynamic capacity enhancement for mobile
telecommunication networks},
Journal = {Proceedings of the 2012 8th International Symposium on
Communication Systems, Networks and Digital Signal
Processing, CSNDSP 2012},
Publisher = {IEEE},
Year = {2012},
Month = {November},
ISBN = {9781457714733},
url = {http://dx.doi.org/10.1109/CSNDSP.2012.6292742},
Abstract = {This paper describes the modelling and analysis of a new
smart antenna concept. The paper outlines the rational for
the development of a dynamically reconfigurable smart
antenna system without greatly increasing the complexity of
the system. The subject smart antenna system is developed to
offer good coverage and capacity using multiple beams
throughout a cell sector and to be able to reconfigure the
beam to provide enhanced coverage and maintain capacity in
certain areas at reduced, but acceptable coverage throughout
the rest of the cell sector of a mobile telecommunication
network. The motivation behind the architecture and the
methodology used is discussed and then modelling and
analysis of the antenna system is presented. © 2012
IEEE.},
Doi = {10.1109/CSNDSP.2012.6292742},
Key = {fds330986}
}
@article{fds330987,
Author = {Yurduseven, O and Smith, D and Pearsall, N and Forbes, I and Bobor-Oyibo, F},
Title = {A solar parabolic reflector antenna design for digital
satellite communication systems},
Journal = {Proceedings of the 2012 8th International Symposium on
Communication Systems, Networks and Digital Signal
Processing, CSNDSP 2012},
Publisher = {IEEE},
Year = {2012},
Month = {November},
ISBN = {9781457714733},
url = {http://dx.doi.org/10.1109/CSNDSP.2012.6292741},
Abstract = {This paper introduces a compact solar parabolic reflector
antenna design, with an effective DC solar performance and
high gain / pencil beam antenna radiation characteristics,
as an alternative to the standalone use of home-based
autonomous solar panels and digital satellite antennas. The
proposed solar reflector antenna consists of 2 parabolic
shaped silicon solar panels with a diameter of 60 cm, each
constructed by connecting individual silicon solar cells
electrically in appropriate angles in order to create an
approximate parabolic surface. The solar panels within the
design have been connected in parallel in order to increase
the total DC output level for medium and high current
appliances. The bottom DC contact layer of the first silicon
solar panel, which collects the DC current generated by the
electrically connected solar cells within the panel as a
result of the photovoltaic effect, also works as a parabolic
reflector antenna with an average gain of 32.8 dB at the
digital satellite downlink frequency band of 10.70 - 12.75
GHz, allocated by the ITU to the Region 1, including Europe.
© 2012 IEEE.},
Doi = {10.1109/CSNDSP.2012.6292741},
Key = {fds330987}
}
@article{fds269770,
Author = {Larouche, S and Smith, DR},
Title = {Optics: Nanotube holograms.},
Journal = {Nature},
Volume = {491},
Number = {7422},
Pages = {47-48},
Year = {2012},
Month = {November},
ISSN = {0028-0836},
url = {http://dx.doi.org/10.1038/491047a},
Doi = {10.1038/491047a},
Key = {fds269770}
}
@article{fds269771,
Author = {Nguyen, V and Larouche, S and Landy, N and Lee, JS and Smith,
DR},
Title = {Quantitative comparison of gradient index and refractive
lenses.},
Journal = {Journal of the Optical Society of America. A, Optics, image
science, and vision},
Volume = {29},
Number = {11},
Pages = {2479-2497},
Year = {2012},
Month = {November},
url = {http://www.ncbi.nlm.nih.gov/pubmed/23201812},
Abstract = {We analyze the Seidel wavefront aberrations and spot sizes
of gradient index (GRIN) singlet lenses with Δn≈1. We
consider and compare curved and planar GRIN lenses with
F-numbers of 5 and 1 against equivalent refractive lenses.
We find that the planar GRIN lenses generally have larger
spot sizes compared to their refractive lens equivalents at
wide angles. This appears to be due to an inability to
correct for coma by adjusting the refractive index gradient
alone. We can correct for the coma by bending the GRIN lens.
This results in a singlet lens with performance close to but
not exceeding that of the equivalent refractive lens. We
also examine the impact of anisotropy on the planar GRIN
lenses. We find that fabricating the planar GRIN lenses from
a uniaxial medium has the potential to improve the
performance of the lenses.},
Doi = {10.1364/josaa.29.002479},
Key = {fds269771}
}
@article{fds269772,
Author = {Urzhumov, Y and Smith, DR},
Title = {Low-loss directional cloaks without superluminal velocity or
magnetic response.},
Journal = {Optics letters},
Volume = {37},
Number = {21},
Pages = {4471-4473},
Year = {2012},
Month = {November},
url = {http://www.ncbi.nlm.nih.gov/pubmed/23114333},
Abstract = {The possibility of making an optically large (many
wavelengths in diameter) object appear invisible has been a
subject of many recent studies. Exact invisibility scenarios
for large (relative to the wavelength) objects involve
(meta)materials with superluminal phase velocity [refractive
index (RI) less than unity] and/or magnetic response. We
introduce a new approximation applicable to certain device
geometries in the eikonal limit: piecewise-uniform scaling
of the RI. This transformation preserves the ray
trajectories but leads to a uniform phase delay. We show how
to take advantage of phase delays to achieve a limited
(directional and wavelength-dependent) form of invisibility
that does not require loss-ridden (meta)materials with
superluminal phase velocities.},
Doi = {10.1364/ol.37.004471},
Key = {fds269772}
}
@article{fds269773,
Author = {Urzhumov, YA and Smith, DR},
Title = {Flow stabilization with active hydrodynamic
cloaks.},
Journal = {Physical review. E, Statistical, nonlinear, and soft matter
physics},
Volume = {86},
Number = {5 Pt 2},
Pages = {056313},
Year = {2012},
Month = {November},
ISSN = {1539-3755},
url = {http://hdl.handle.net/10161/7574 Duke open
access},
Abstract = {We demonstrate that fluid flow cloaking solutions, based on
active hydrodynamic metamaterials, exist for two-dimensional
flows past a cylinder in a wide range of Reynolds numbers
(Re's), up to approximately 200. Within the framework of the
classical Brinkman equation for homogenized porous flow, we
demonstrate using two different methods that such cloaked
flows can be dynamically stable for Re's in the range of
5-119. The first highly efficient method is based on a
linearization of the Brinkman-Navier-Stokes equation and
finding the eigenfrequencies of the least stable
eigenperturbations; the second method is a direct numerical
integration in the time domain. We show that, by suppressing
the von Kármán vortex street in the weakly turbulent wake,
porous flow cloaks can raise the critical Reynolds number up
to about 120 or five times greater than for a bare uncloaked
cylinder.},
Doi = {10.1103/physreve.86.056313},
Key = {fds269773}
}
@article{fds335091,
Author = {Smith, DR and Fonck, RJ and McKee, GR and Thompson,
DS},
Title = {Diagnostic performance of the beam emission spectroscopy
system on the National Spherical Torus Experiment},
Journal = {Review of Scientific Instruments},
Volume = {83},
Number = {10},
Pages = {10D502-10D502},
Publisher = {AIP Publishing},
Year = {2012},
Month = {October},
url = {http://dx.doi.org/10.1063/1.4728094},
Abstract = {The beam emission spectroscopy system on the National
Spherical Torus Experiment measures localized density
fluctuations on the ion gyroscale. Optical sightlines
provide core to edge radial coverage, and the sightlines are
aligned to typical pitch angles to maximize cross-field
spatial resolution. Sightline images are 2-3 cm, and point
spread function calculations indicate image distortion from
pitch angle misalignment and atomic state finite lifetimes
is minor with a 15% increase in the image size. New
generation photodetectors achieve photon noise limited
measurements at frequencies up to 400 kHz with refrigerant
cooling at -20 °C. Measurements near the pedestal show
broadband turbulence up to 100 kHz, and poloidal correlation
lengths are about 10 cm. Plasma turbulence signals can be
2-3 orders of magnitude above photon noise and amplifier
thermal noise. © 2012 American Institute of
Physics.},
Doi = {10.1063/1.4728094},
Key = {fds335091}
}
@article{fds269807,
Author = {Hill, RT and Mock, JJ and Hucknall, A and Wolter, SD and Jokerst, NM and Smith, DR and Chilkoti, A},
Title = {Plasmon ruler with angstrom length resolution.},
Journal = {ACS nano},
Volume = {6},
Number = {10},
Pages = {9237-9246},
Year = {2012},
Month = {October},
url = {http://www.ncbi.nlm.nih.gov/pubmed/22966857},
Abstract = {We demonstrate a plasmon nanoruler using a coupled film
nanoparticle (film-NP) format that is well-suited for
investigating the sensitivity extremes of plasmonic
coupling. Because it is relatively straightforward to
functionalize bulk surface plasmon supporting films, such as
gold, we are able to precisely control plasmonic gap
dimensions by creating ultrathin molecular spacer layers on
the gold films, on top of which we immobilize plasmon
resonant nanoparticles (NPs). Each immobilized NP becomes
coupled to the underlying film and functions as a plasmon
nanoruler, exhibiting a distance-dependent resonance red
shift in its peak plasmon wavelength as it approaches the
film. Due to the uniformity of response from the film-NPs to
separation distance, we are able to use extinction and
scattering measurements from ensembles of film-NPs to
characterize the coupling effect over a series of very short
separation distances-ranging from 5 to 20 Å-and combine
these measurements with similar data from larger separation
distances extending out to 27 nm. We find that the film-NP
plasmon nanoruler is extremely sensitive at very short
film-NP separation distances, yielding spectral shifts as
large as 5 nm for every 1 Å change in separation distance.
The film-NP coupling at extremely small spacings is so
uniform and reliable that we are able to usefully probe gap
dimensions where the classical Drude model of the conducting
electrons in the metals is no longer descriptive; for gap
sizes smaller than a few nanometers, either quantum or
semiclassical models of the carrier response must be
employed to predict the observed wavelength shifts. We find
that, despite the limitations, large field enhancements and
extreme sensitivity persist down to even the smallest gap
sizes.},
Doi = {10.1021/nn3035809},
Key = {fds269807}
}
@article{fds269837,
Author = {Ciracì, C and Poutrina, E and Scalora, M and Smith,
DR},
Title = {Second-harmonic generation in metallic nanoparticles:
Clarification of the role of the surface},
Journal = {Physical Review B - Condensed Matter and Materials
Physics},
Volume = {86},
Number = {11},
Publisher = {American Physical Society (APS)},
Year = {2012},
Month = {September},
ISSN = {1098-0121},
url = {http://dx.doi.org/10.1103/PhysRevB.86.115451},
Abstract = {We present a numerical investigation of the second-order
nonlinear optical properties of metal-based metamaterial
nanoresonators. The nonlinear optical response of the metal
is described by a hydrodynamic model, with the effects of
electron pressure in the electron gas also taken into
account. We show that as the pressure term tends to zero the
amount of converted second-harmonic field tends to an
asymptotic value. In this limit it becomes possible to
rewrite the nonlinear surface contributions as functions of
the value of the polarization vector inside the bulk region.
Nonlocality thus can be incorporated into numerical
simulations without actually utilizing the nonlocal equation
of motion or solving for the rapidly varying fields that
occur near the metal surface. We use our model to
investigate the second-harmonic generation process with
three-dimensional gold nanoparticle arrays and show that
nanocrescents can easily attain conversion efficiencies of
∼6.0×10 -8 for pumping peak intensities of a few tens of
MW/cm2. ©2012 American Physical Society.},
Doi = {10.1103/PhysRevB.86.115451},
Key = {fds269837}
}
@article{fds269769,
Author = {Driscoll, T and Quinn, J and Di Ventra and M and Basov, DN and Seo, G and Lee,
YW and Kim, HT and Smith, DR},
Title = {Current oscillations in vanadium dioxide: Evidence for
electrically triggered percolation avalanches},
Journal = {Physical Review B - Condensed Matter and Materials
Physics},
Volume = {86},
Number = {9},
Publisher = {American Physical Society (APS)},
Year = {2012},
Month = {September},
ISSN = {1098-0121},
url = {http://dx.doi.org/10.1103/PhysRevB.86.094203},
Abstract = {In this work, we experimentally and theoretically explore
voltage-controlled oscillations occurring in microbeams of
vanadium dioxide. These oscillations are a result of the
reversible insulator-to-metal phase transition in vanadium
dioxide. By examining the structure of the observed
oscillations in detail, we propose a modified
percolative-avalanche model which allows for voltage
triggering. This model captures the periodicity and
waveshape of the oscillations as well as several other key
features. Importantly, our modeling shows that while
temperature plays a critical role in the vanadium dioxide
phase transition, electrically induced heating can not act
as the primary instigator of the oscillations in this
configuration. This realization leads us to identify the
electric field as the most likely candidate for driving the
phase transition. © 2012 American Physical
Society.},
Doi = {10.1103/PhysRevB.86.094203},
Key = {fds269769}
}
@article{fds269768,
Author = {Rose, A and Larouche, S and Poutrina, E and Smith,
DR},
Title = {Nonlinear magnetoelectric metamaterials: Analysis and
homogenization via a microscopic coupled-mode
theory},
Journal = {Physical Review A - Atomic, Molecular, and Optical
Physics},
Volume = {86},
Number = {3},
Publisher = {American Physical Society (APS)},
Year = {2012},
Month = {September},
ISSN = {1050-2947},
url = {http://dx.doi.org/10.1103/PhysRevA.86.033816},
Abstract = {Artificially structured metamaterials hybridized with
elements that respond nonlinearly to incident
electromagnetic fields can, from a macroscopic perspective,
support nonlinear responses that cannot be described by
purely electric or magnetic interactions. To investigate the
mechanisms and behaviors of such interactions, termed
nonlinear magnetoelectric coupling, we develop a set of
coupled-mode equations for describing three-wave mixing in a
metamaterial, using Bloch modes as the basis. By equating
these coupled-mode equations to those of a homogenized
system, we derive closed-form expressions for the
macroscopic nonlinear susceptibilities. From these
expressions, a great deal can be inferred about the nature
and construction of magnetoelectric nonlinearities in
metamaterials. As an example, we apply this method in the
analysis of a prototypical nonlinear magnetoelectric
metamaterial. In particular, we show that independent
control of the eight second-order susceptibility tensors
encompasses a massive parameter space from which new realms
of nonlinear interference and wave manipulation can be
accessed. © 2012 American Physical Society.},
Doi = {10.1103/PhysRevA.86.033816},
Key = {fds269768}
}
@article{fds269789,
Author = {Urzhumov, Y and Lee, JS and Tyler, T and Dhar, S and Nguyen, V and Jokerst,
NM and Schmalenberg, P and Smith, DR},
Title = {Electronically reconfigurable metal-on-silicon
metamaterial},
Journal = {Physical Review B - Condensed Matter and Materials
Physics},
Volume = {86},
Number = {7},
Publisher = {American Physical Society (APS)},
Year = {2012},
Month = {August},
ISSN = {1098-0121},
url = {http://hdl.handle.net/10161/7573 Duke open
access},
Abstract = {Reconfigurable metamaterial-based apertures can play a
unique role in both imaging and in beam-forming
applications, where current technology relies mostly on the
fabrication and integration of large detector or antenna
arrays. Here, we report the experimental demonstration of a
voltage-controlled, silicon-based electromagnetic
metamaterial operating in the W-band (75-110 GHz). In this
composite semiconductor metamaterial, patterned gold
metamaterial elements serve both to manage electromagnetic
wave propagation while simultaneously acting as electrical
Schottky contacts that control the local conductivity of the
semiconductor substrate. The active device layers consist of
a patterned metal on a 2-μm-thick n-doped silicon layer,
adhesively bonded to a transparent Pyrex wafer. The
transmittance of the composite metamaterial can be modulated
over a given frequency band as a function of bias voltage.
We demonstrate a quantitative understanding of the composite
device through the application of numerical approaches that
simultaneously treat the semiconductor junction physics as
well as wave propagation. © 2012 American Physical
Society.},
Doi = {10.1103/PhysRevB.86.075112},
Key = {fds269789}
}
@article{fds269806,
Author = {Ciracì, C and Hill, RT and Mock, JJ and Urzhumov, Y and Fernández-Domínguez, AI and Maier, SA and Pendry, JB and Chilkoti,
A and Smith, DR},
Title = {Probing the ultimate limits of plasmonic
enhancement.},
Journal = {Science (New York, N.Y.)},
Volume = {337},
Number = {6098},
Pages = {1072-1074},
Year = {2012},
Month = {August},
url = {http://www.ncbi.nlm.nih.gov/pubmed/22936772},
Abstract = {Metals support surface plasmons at optical wavelengths and
have the ability to localize light to subwavelength regions.
The field enhancements that occur in these regions set the
ultimate limitations on a wide range of nonlinear and
quantum optical phenomena. We found that the dominant
limiting factor is not the resistive loss of the metal, but
rather the intrinsic nonlocality of its dielectric response.
A semiclassical model of the electronic response of a metal
places strict bounds on the ultimate field enhancement. To
demonstrate the accuracy of this model, we studied optical
scattering from gold nanoparticles spaced a few angstroms
from a gold film. The bounds derived from the models and
experiments impose limitations on all nanophotonic
systems.},
Doi = {10.1126/science.1224823},
Key = {fds269806}
}
@article{fds269836,
Author = {Pendry, JB and Aubry, A and Smith, DR and Maier, SA},
Title = {Transformation optics and subwavelength control of
light.},
Journal = {Science (New York, N.Y.)},
Volume = {337},
Number = {6094},
Pages = {549-552},
Year = {2012},
Month = {August},
ISSN = {0036-8075},
url = {http://dx.doi.org/10.1126/science.1220600},
Abstract = {Our intuitive understanding of light has its foundation in
the ray approximation and is intimately connected with our
vision. As far as our eyes are concerned, light behaves like
a stream of particles. We look inside the wavelength and
study the properties of plasmonic structures with dimensions
of just a few nanometers, where at a tenth or even a
hundredth of the wavelength of visible light the ray picture
fails. We review the concept of transformation optics that
manipulates electric and magnetic field lines, rather than
rays; can provide an equally intuitive understanding of
subwavelength phenomena; and at the same time can be an
exact description at the level of Maxwell's
equations.},
Doi = {10.1126/science.1220600},
Key = {fds269836}
}
@article{fds269767,
Author = {Rose, A and Huang, D and Smith, DR},
Title = {Demonstration of nonlinear magnetoelectric coupling in
metamaterials},
Journal = {Applied Physics Letters},
Volume = {101},
Number = {5},
Pages = {051103-051103},
Publisher = {AIP Publishing},
Year = {2012},
Month = {July},
ISSN = {0003-6951},
url = {http://dx.doi.org/10.1063/1.4738774},
Abstract = {We demonstrate nonlinear magnetoelectric coupling in a
varactor-loaded metamaterial at microwave frequencies. The
nonlinear magnetoelectric coupling takes the form of
second-harmonic generation in which incident magnetic fields
at frequency ω drive an electric polarization at frequency
2ω. The magnitudes and phases of the generated signals from
two nonlinear metamaterials are measured, verifying the
dominant nonlinear process in each sample. We expect the
metamaterial design employed in this letter to form the
prototype for future investigations into nonlinear
magnetoelectric coupling. © 2012 American Institute of
Physics.},
Doi = {10.1063/1.4738774},
Key = {fds269767}
}
@article{fds269754,
Author = {Holloway, CL and Kuester, EF and Gordon, JA and O'Hara, J and Booth, J and Smith, DR},
Title = {An overview of the theory and applications of metasurfaces:
The two-dimensional equivalents of metamaterials},
Journal = {IEEE Antennas and Propagation Magazine},
Volume = {54},
Number = {2},
Pages = {10-35},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2012},
Month = {July},
ISSN = {1045-9243},
url = {http://dx.doi.org/10.1109/MAP.2012.6230714},
Abstract = {Metamaterials are typically engineered by arranging a set of
small scatterers or apertures in a regular array throughout
a region of space, thus obtaining some desirable bulk
electromagnetic behavior. The desired property is often one
that is not normally found naturally (negative refractive
index, near-zero index, etc.). Over the past ten years,
metamaterials have moved from being simply a theoretical
concept to a field with developed and marketed applications.
Three-dimensional metamaterials can be extended by arranging
electrically small scatterers or holes into a
two-dimensional pattern at a surface or interface. This
surface version of a metamaterial has been given the name
metasurface (the term metafilm has also been employed for
certain structures). For many applications, metasurfaces can
be used in place of metamaterials. Metasurfaces have the
advantage of taking up less physical space than do full
three-dimensional metamaterial structures; consequently,
metasurfaces offer the possibility of less-lossy structures.
In this overview paper, we discuss the theoretical basis by
which metasurfaces should be characterized, and discuss
their various applications. We will see how metasurfaces are
distinguished from conventional frequency-selective
surfaces. Metasurfaces have a wide range of potential
applications in electromagnetics (ranging from low microwave
to optical frequencies), including: (1) controllable smart
surfaces, (2) miniaturized cavity resonators, (3) novel
wave-guiding structures, (4) angular-independent surfaces,
(5) absorbers, (6) biomedical devices, (7) terahertz
switches, and (8) fluid-tunable frequency-agile materials,
to name only a few. In this review, we will see that the
development in recent years of such materials and/or
surfaces is bringing us closer to realizing the exciting
speculations made over one hundred years ago by the work of
Lamb, Schuster, and Pocklington, and later by Mandel'shtam
and Veselago. © 2012 IEEE.},
Doi = {10.1109/MAP.2012.6230714},
Key = {fds269754}
}
@article{fds335093,
Author = {Gow, JPD and Holland, AD and Pool, PJ and Smith, DR},
Title = {The effect of protons on the performance of second
generation Swept Charge Devices},
Journal = {Nuclear Instruments and Methods in Physics Research, Section
A: Accelerators, Spectrometers, Detectors and Associated
Equipment},
Volume = {680},
Pages = {86-89},
Publisher = {Elsevier BV},
Year = {2012},
Month = {July},
url = {http://dx.doi.org/10.1016/j.nima.2012.04.013},
Abstract = {The e2v technologies Swept Charge Device (SCD) was developed
as a large area detector for X-ray Fluorescence (XRF)
analysis, achieving near Fano-limited spectroscopy at -15
°C. The SCD was flown in the XRF instruments onboard the
European Space Agency's SMART-1 and the Indian Space
Research Organisation's Chandrayaan-1 lunar missions. The
second generation SCD, proposed for use in the soft X-ray
Spectrometer on the Chandrayaan-2 lunar orbiter and the soft
X-ray imager on China's HXMT mission, was developed, in
part, using the findings of the radiation damage studies
performed for the Chandrayaan-1 X-ray Spectrometer. This
paper discusses the factor of two improvements in radiation
tolerance achieved in the second generation SCD, the
different SCD sizes produced and their advantages for future
XRF instruments, for example through reduced shielding mass
or higher operating temperatures. © 2012 Elsevier B.V. All
rights reserved.},
Doi = {10.1016/j.nima.2012.04.013},
Key = {fds335093}
}
@article{fds330988,
Author = {Smith, D and Schejbal, V and Prouza, L},
Title = {A modified holographic technique for cylindrical near-field
antenna measurements},
Journal = {Proceedings of 6th European Conference on Antennas and
Propagation, EuCAP 2012},
Pages = {2528-2532},
Publisher = {IEEE},
Year = {2012},
Month = {July},
ISBN = {9781457709180},
url = {http://dx.doi.org/10.1109/EuCAP.2012.6205933},
Abstract = {A modification of the synthetic-cylindrical-wave-based
holographic technique for determining radiation patterns and
aperture fields of antennas is proposed. The modification is
based on using both the sum and difference of the near field
and reference signals to form the hologram via simple
low-cost amplitude-only near field measurements. This
approach when compared to the previous version, where only
the sum signal is used, allows increased sample spacing, and
also provides an improvement in quality of the final
results. That is validated by several numerical simulations.
Moreover, it allows cylindrical near-field antenna
measurements and probe corrections. © 2012
IEEE.},
Doi = {10.1109/EuCAP.2012.6205933},
Key = {fds330988}
}
@article{fds335092,
Author = {Walker, TE and Smith, DR},
Title = {The use of swept-charge devices in planetary analogue X-ray
fluorescence studies},
Journal = {Journal of Instrumentation},
Volume = {7},
Number = {7},
Pages = {C07004-C07004},
Publisher = {IOP Publishing},
Year = {2012},
Month = {July},
url = {http://dx.doi.org/10.1088/1748-0221/7/07/C07004},
Abstract = {The Chandrayaan-1 X-ray Spectrometer (C1XS) was launched
onboard the Indian Space Research Organisation (ISRO)
Chandrayaan-1 lunar mission in October 2008. The instrument
consisted of 24 swept-charge device (SCD) silicon X-ray
detectors providing a total collecting area of ∼ 24 cm2,
corresponding to a 14° field of view (FWHM), with the
ability to measure X-rays from 0.8-10 keV. One algorithm
used to analyse the C1XS flight data was developed at
Rutherford Appleton Laboratory (RAL) to convert the raw
X-ray flux data into elemental ratios and abundances to make
geological interpretations about the lunar surface.
Laboratory X-ray fluorescence (XRF) data were used to
validate the RAL algorithm, with previous studies
investigating how the measured XRF flux varies with target
surface characteristics including grain size and roughness.
Evidence for a grain-size effect was observed in the data,
the XRF line intensity generally decreasing with increasing
sample grain size, dependent on the relative abundance of
elemental components. This paper presents a subsequent study
using more homogeneous samples made from mixtures of MgO,
Al2O3 and SiO2 powders, all of grain size < 44μm, across a
broader range of mixture ratios and at a higher level of
X-ray flux data in order to further validate the RAL
algorithm. For the majority of the C1XS flight data analysed
so far with the RAL algorithm, the corresponding lunar
ground tracks have been generally basaltic, laboratory
verification of the algorithm having been primarily
conducted using basaltic lunar regolith simulant (JSC-1A)
XRF data. This paper also presents results from tests on a
terrestrial anorthosite sample, more relevant to the
anorthositic lunar highlands, from where the remaining C1XS
lunar dataset derives. The operation of the SCD, the XRF
test facility, sample preparation and collected XRF spectra
are discussed in this paper. © 2012 IOP Publishing Ltd and
Sissa Medialab srl.},
Doi = {10.1088/1748-0221/7/07/C07004},
Key = {fds335092}
}
@article{fds269766,
Author = {Paul, O and Urzhumov, Y and Elsen, C and Smith, D and Rahm,
M},
Title = {Construction of invisibility cloaks of arbitrary shape and
size using planar layers of metamaterials},
Journal = {Journal of Applied Physics},
Volume = {111},
Number = {12},
Pages = {123106-123106},
Publisher = {AIP Publishing},
Year = {2012},
Month = {June},
ISSN = {0021-8979},
url = {http://hdl.handle.net/10161/7570 Duke open
access},
Abstract = {Transformation optics (TO) is a powerful tool for the design
of electromagnetic and optical devices with novel
functionality derived from the unusual properties of the
transformation media. In general, the fabrication of TO
media is challenging, requiring spatially varying material
properties with both anisotropic electric and magnetic
responses. Though metamaterials have been proposed as a path
for achieving such complex media, the required properties
arising from the most general transformations remain
elusive, and cannot implemented by state-of-the-art
fabrication techniques. Here, we propose faceted
approximations of TO media of arbitrary shape in which the
volume of the TO device is divided into flat metamaterial
layers. These layers can be readily implemented by standard
fabrication and stacking techniques. We illustrate our
approximation approach for the specific example of a
two-dimensional, omnidirectional "invisibility cloak", and
quantify its performance using the total scattering cross
section as a practical figure of merit. © 2012 American
Institute of Physics.},
Doi = {10.1063/1.4729012},
Key = {fds269766}
}
@article{fds269764,
Author = {Driscoll, T and Lipworth, G and Hunt, J and Landy, N and Kundtz, N and Basov, DN and Smith, DR},
Title = {Performance of a three dimensional transformation-optical-flattened
Lüneburg lens.},
Journal = {Optics express},
Volume = {20},
Number = {12},
Pages = {13262-13273},
Year = {2012},
Month = {June},
url = {http://www.ncbi.nlm.nih.gov/pubmed/22714354},
Abstract = {We demonstrate both the beam-forming and imaging
capabilities of an X-band (8-12 GHz) operational Lüneburg
lens, one side of which has been flattened via a coordinate
transformation optimized using quasi-conformal
transformation optics (QCTO) procedures. Our experimental
investigation includes benchmark performance comparisons
between the QCTO Lüneburg lens and a commensurate
conventional Lüneburg lens. The QCTO Lüneburg lens is made
from a metamaterial comprised of inexpensive plastic and
fiberglass, and manufactured using fast and versatile
numerically controlled water-jet machining. Looking forward
towards the future and advanced TO designs, we discuss
inevitable design trade-offs between affordable scalable
manufacturing and rigorous adherence to the full TO
solution, as well as possible paths to mitigate performance
degradation in realizable designs.},
Doi = {10.1364/oe.20.013262},
Key = {fds269764}
}
@article{fds269765,
Author = {Larouche, S and Smith, DR},
Title = {Reconciliation of generalized refraction with diffraction
theory.},
Journal = {Optics letters},
Volume = {37},
Number = {12},
Pages = {2391-2393},
Year = {2012},
Month = {June},
url = {http://www.ncbi.nlm.nih.gov/pubmed/22739918},
Abstract = {When an electromagnetic wave is obliquely incident on the
interface between two homogeneous media with different
refractive indices, the requirement of phase continuity
across the interface generally leads to a shift in the
trajectory of the wave. When a linearly position-dependent
phase shift is imposed at the interface, the resulting
refraction may be described using a generalized version of
Snell's law. In this Letter, we establish a formal
equivalence between generalized refraction and blazed
diffraction gratings, further discussing the relative merits
of the two approaches.},
Doi = {10.1364/ol.37.002391},
Key = {fds269765}
}
@article{fds269763,
Author = {Ciracì, C and Poutrina, E and Scalora, M and Smith,
DR},
Title = {Origin of second-harmonic generation enhancement in optical
split-ring resonators},
Journal = {Physical Review B - Condensed Matter and Materials
Physics},
Volume = {85},
Number = {20},
Publisher = {American Physical Society (APS)},
Year = {2012},
Month = {May},
ISSN = {1098-0121},
url = {http://dx.doi.org/10.1103/PhysRevB.85.201403},
Abstract = {We present a study of the second-order nonlinear optical
properties of metal-based metamaterials. A hydrodynamic
model for electronic response is used, in which nonlinear
surface contributions are expressed in terms of the bulk
polarization. The model is in good agreement with published
experimental results, and clarifies the mechanisms
contributing to the nonlinear response. In particular, we
show that the reported enhancement of the second harmonic in
split-ring resonator based media is driven by the electric
rather than the magnetic properties of the structure. ©
2012 American Physical Society.},
Doi = {10.1103/PhysRevB.85.201403},
Key = {fds269763}
}
@article{fds330989,
Author = {Yurduseven, O and Smith, D and Bobor-Oyibo, F and Foti,
SJ},
Title = {Design of a highly efficient beam scanning asymmetric
H-plane horn antenna},
Journal = {2012 IEEE International Workshop on Antenna Technology, iWAT
2012},
Pages = {108-111},
Publisher = {IEEE},
Year = {2012},
Month = {May},
ISBN = {9781467300360},
url = {http://dx.doi.org/10.1109/IWAT.2012.6178410},
Abstract = {This paper presents the design and results of a novel
asymmetric H-plane horn antenna with an easily scanable,
highly efficient asymmetric radiation pattern. This design
offers a cost-effective and practical alternative to the
current beam scanning horn antennas used in surveillance
radars in which bulky and expensive switching and phase
shifting circuits and time consuming rotation mechanisms are
used for these antennas to feed the parabolic reflectors
asymmetrically to improve the air and coastal scanning
performance. In order to achieve that, the flares of the
proposed asymmetric H-plane horn antenna, which is
constructed from aluminum, are adjusted in a different way
from the traditional horn antennas so that it is possible to
shift the main lobe in a desired direction by setting the
flare angle s differently. The near and far-field
measurement results, which are in a good agreement with the
simulation results, demonstrate the beam scanning
performance of the proposed antenna through the use of
adjustable asymmetric flares throughout the paper. © 2012
IEEE.},
Doi = {10.1109/IWAT.2012.6178410},
Key = {fds330989}
}
@article{fds330990,
Author = {Bobor-Oyibo, F and Foti, SJ and Smith, D and Yurduseven,
O},
Title = {A smart antenna system with sub-sector dynamic capacity
enhancement for mobile telecommunication
networks},
Journal = {2012 IEEE International Workshop on Antenna Technology, iWAT
2012},
Pages = {100-103},
Publisher = {IEEE},
Year = {2012},
Month = {May},
ISBN = {9781467300360},
url = {http://dx.doi.org/10.1109/IWAT.2012.6178408},
Abstract = {Dynamic concentration of the users within a part of a cell
sector has placed pressure on network operators to find ways
to dynamically optimise the sector to increase capacity and
quality of service while maintaining coverage. Smart antenna
systems have been identified as being capable of dynamically
optimising the network. Network operators need to estimate
the actual performance gain that can be achieved with this
smart antenna system and a comprehensive knowledge of radio
propagation effects is an important factor for the
development and performance evaluation of mobile
telecommunication systems. This paper presents a performance
evaluation of this smart antenna concept within a realistic
radio environment. © 2012 IEEE.},
Doi = {10.1109/IWAT.2012.6178408},
Key = {fds330990}
}
@article{fds269753,
Author = {Chen, SY and Urzhumov, Y and Smith, DR and Lazarides,
AA},
Title = {Characterization of high order modes of plasmonic antenna
formed by nanoparticle/thin film hybrid structures},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {8269},
Publisher = {SPIE},
Year = {2012},
Month = {May},
ISSN = {0277-786X},
url = {http://hdl.handle.net/10161/5725 Duke open
access},
Abstract = {The plasmonic modes of a nano-antenna formed by a
nanoparticle/thin film hybrid system are investigated.
Plasmonic nano-antennas are well-known for their
capabilities to concentrate electromagnetic wave into
extreme small region and couple the emission from active
materials in proximity to the antennas into far-field
region. Previously, we have shown through direct measurement
of emission profile images that the nano-antennas not only
enhance Raman emission but also systematically direct
inelastic emission to the far-field through the dipole mode.
We also showed that high order modes of the hybrid structure
can be detected. Here, the higher order plasmonic modes are
characterized through imaging, variable angle linearly
polarized excitation, and simulation. Through spectral
simulation with improved resolution, two distinct modes are
found to contribute to the broad band high order mode. One
has dipole-like behavior and the other has quadrupole-like
behavior. The modes are characterized both through
near-field distribution and farfield scattering profiles.
The quadrupole-like mode can be excited by both p- and
s-polarized light whereas the dipolelike mode is only
excited by p-polarized light. These high order modes are not
as bright as the dipole mode in the farfield spectrum but
have substantial near field enhancement which can be
utilized for surface-enhancing spectroscopy and sensing. In
addition, characterization of high order modes may serve to
clarify the interaction between nano-antenna and active
materials and will lead to design rules for applications of
active plasmonic structures in integrated optical circuits.
© 2012 Copyright Society of Photo-Optical Instrumentation
Engineers (SPIE).},
Doi = {10.1117/12.907700},
Key = {fds269753}
}
@article{fds269790,
Author = {Poutrina, E and Ciracì, C and Gauthier, DJ and Smith,
DR},
Title = {Enhancing four-wave-mixing processes by nanowire arrays
coupled to a gold film.},
Journal = {Optics express},
Volume = {20},
Number = {10},
Pages = {11005-11013},
Year = {2012},
Month = {May},
url = {http://www.ncbi.nlm.nih.gov/pubmed/22565723},
Abstract = {We consider the process of four-wave mixing in an array of
gold nanowires strongly coupled to a gold film. Using
full-wave simulations, we perform a quantitative comparison
of the four-wave mixing efficiency associated with a bare
film and films with nanowire arrays. We find that the
strongly localized surface plasmon resonances of the coupled
nanowires provide an additional local field enhancement
that, along with the delocalized surface plasmon of the
film, produces an overall four-wave mixing efficiency
enhancement of up to six orders of magnitude over that of
the bare film. The enhancement occurs over a wide range of
excitation angles. The film-coupled nanowire array is easily
amenable to nanofabrication, and could find application as
an ultra-compact component for integrated photonic and
quantum optic systems.},
Doi = {10.1364/oe.20.011005},
Key = {fds269790}
}
@article{fds335094,
Author = {Ren, Y and Guttenfelder, W and Kaye, SM and Mazzucato, E and Bell, RE and Diallo, A and Domier, CW and Leblanc, BP and Lee, KC and Smith, DR and Yuh,
H},
Title = {Experimental study of parametric dependence of
electron-scale turbulence in a spherical
tokamak},
Journal = {Physics of Plasmas},
Volume = {19},
Number = {5},
Pages = {056125-056125},
Publisher = {AIP Publishing},
Year = {2012},
Month = {May},
url = {http://dx.doi.org/10.1063/1.4719689},
Abstract = {Electron-scale turbulence is predicted to drive anomalous
electron thermal transport. However, experimental study of
its relation with transport is still in its early stage. On
the National Spherical Tokamak Experiment (NSTX),
electron-scale density fluctuations are studied with a novel
tangential microwave scattering system with high radial
resolution of ±2 cm. Here, we report a study of parametric
dependence of electron-scale turbulence in NSTX H-mode
plasmas. The dependence on density gradient is studied
through the observation of a large density gradient
variation in the core induced by an edge localized mode
(ELM) event, where we found the first clear experimental
evidence of density gradient stabilization of electron-gyro
scale turbulence in a fusion plasma. This observation,
coupled with linear gyro-kinetic calculations, leads to the
identification of the observed instability as toroidal
electron temperature gradient (ETG) modes. It is observed
that longer wavelength ETG modes, k ⊥ ρs ≲ 10 (ρs is
the ion gyroradius at electron temperature and k is the
wavenumber perpendicular to local equilibrium magnetic
field), are most stabilized by density gradient, and the
stabilization is accompanied by about a factor of two
decrease in electron thermal diffusivity. Comparisons with
nonlinear ETG gyrokinetic simulations show ETG turbulence
may be able to explain the experimental electron heat flux
observed before the ELM event. The collisionality dependence
of electron-scale turbulence is also studied by
systematically varying plasma current and toroidal field, so
that electron gyroradius (ρe), electron beta (β e), and
safety factor (q95) are kept approximately constant. More
than a factor of two change in electron collisionality,
νe*, was achieved, and we found that the spectral power of
electron-scale turbulence appears to increase as νe* is
decreased in this collisonality scan. However, both linear
and nonlinear simulations show no or weak dependence with
the electron-ion collision frequency, νe/i. Instead, other
equilibrium parameters (safety factor, electron density
gradient, for example) affect ETG linear growth rate and
electron thermal transport more than νe/i does.
Furthermore, electron heat flux predicted by the simulations
is found to have an order-of-magnitude spatial variation in
the experimental measurement region and is also found to be
much smaller than experimental levels except at one radial
location we evaluated. The predicted electron heat flux is
shown to be strongly anti-correlated with density gradient,
which varies for a factor of three in the measurement
region, which is in agreement with the density gradient
dependence study reported in this paper. © 2012 American
Institute of Physics.},
Doi = {10.1063/1.4719689},
Key = {fds335094}
}
@article{fds335095,
Author = {Peterson, JL and Bell, R and Candy, J and Guttenfelder, W and Hammett,
GW and Kaye, SM and Leblanc, B and Mikkelsen, DR and Smith, DR and Yuh,
HY},
Title = {Suppressing electron turbulence and triggering internal
transport barriers with reversed magnetic shear in the
National Spherical Torus Experiment},
Journal = {Physics of Plasmas},
Volume = {19},
Number = {5},
Pages = {056120-056120},
Publisher = {AIP Publishing},
Year = {2012},
Month = {May},
url = {http://dx.doi.org/10.1063/1.4718456},
Abstract = {The National Spherical Torus Experiment (NSTX) [M. Ono,
Nucl. Fusion 40, 557 (2000)] can achieve high electron
plasma confinement regimes that are super-critically
unstable to the electron temperature gradient driven (ETG)
instability. These plasmas, dubbed electron internal
transport barriers (e-ITBs), occur when the magnetic shear
becomes strongly negative. Using the gyrokinetic code GYRO
[J. Candy and R. E. Waltz, J. Comput. Phys. 186, 545
(2003)], the first nonlinear ETG simulations of NSTX e-ITB
plasmas reinforce this observation. Local simulations
identify a strongly upshifted nonlinear critical gradient
for thermal transport that depends on magnetic shear. Global
simulations show e-ITB formation can occur when the magnetic
shear becomes strongly negative. While the ETG-driven
thermal flux at the outer edge of the barrier is large
enough to be experimentally relevant, the turbulence cannot
propagate past the barrier into the plasma interior. © 2012
American Institute of Physics.},
Doi = {10.1063/1.4718456},
Key = {fds335095}
}
@article{fds269805,
Author = {Mock, JJ and Hill, RT and Tsai, Y-J and Chilkoti, A and Smith,
DR},
Title = {Probing dynamically tunable localized surface plasmon
resonances of film-coupled nanoparticles by evanescent wave
excitation.},
Journal = {Nano letters},
Volume = {12},
Number = {4},
Pages = {1757-1764},
Year = {2012},
Month = {April},
url = {http://www.ncbi.nlm.nih.gov/pubmed/22429053},
Abstract = {The localized surface plasmon resonance (LSPR) spectrum
associated with a gold nanoparticle (NP) coupled to a gold
film exhibits extreme sensitivity to the nanogap region
where the fields are tightly localized. The LSPR of an
ensemble of film-coupled NPs can be observed using an
illumination scheme similar to that used to excite the
surface plasmon resonance (SPR) of a thin metallic film;
however, in the present system, the light is used to probe
the highly sensitive distance-dependent LSPR of the gaps
between NPs and film rather than the delocalized SPR of the
film. We show that the SPR and LSPR spectral contributions
can be readily distinguished, and we compare the
sensitivities of both modes to displacements in the average
gap between a collection of NPs and the gold film. The
distance by which the NPs are suspended in solution above
the gold film is fixed via a thin molecular spacer layer and
can be further modulated by subjecting the NPs to a
quasistatic electric field. The observed LSPR spectral
shifts triggered by the applied voltage can be correlated
with angstrom scale displacements of the NPs, suggesting the
potential for chip-scale or flow-cell plasmonic nanoruler
devices with extreme sensitivity.},
Doi = {10.1021/nl204596h},
Key = {fds269805}
}
@article{fds269762,
Author = {Huang, D and Urzhumov, Y and Smith, DR and Hoo Teo and K and Zhang,
J},
Title = {Magnetic superlens-enhanced inductive coupling for wireless
power transfer},
Journal = {Journal of Applied Physics},
Volume = {111},
Number = {6},
Pages = {064902-064902},
Publisher = {AIP Publishing},
Year = {2012},
Month = {March},
ISSN = {0021-8979},
url = {http://hdl.handle.net/10161/5722 Duke open
access},
Abstract = {We investigate numerically the use of a negative-permeability
perfect lens for enhancing wireless power transfer between
two current carrying coils. The negative permeability slab
serves to focus the flux generated in the source coil to the
receiver coil, thereby increasing the mutual inductive
coupling between the coils. The numerical model is compared
with an analytical theory that treats the coils as point
dipoles separated by an infinite planar layer of magnetic
material Urzhumov, Phys. Rev. B 19, 8312 (2011). In the
limit of vanishingly small radius of the coils, and large
width of the metamaterial slab, the numerical simulations
are in excellent agreement with the analytical model. Both
the idealized analytical and realistic numerical models
predict similar trends with respect to metamaterial loss and
anisotropy. Applying the numerical models, we further
analyze the impact of finite coil size and finite width of
the slab. We find that, even for these less idealized
geometries, the presence of the magnetic slab greatly
enhances the coupling between the two coils, including cases
where significant loss is present in the slab. We therefore
conclude that the integration of a metamaterial slab into a
wireless power transfer system holds promise for increasing
the overall system performance. © 2012 American Institute
of Physics.},
Doi = {10.1063/1.3692757},
Key = {fds269762}
}
@article{fds269759,
Author = {Bowen, PT and Driscoll, T and Kundtz, NB and Smith,
DR},
Title = {Using a discrete dipole approximation to predict complete
scattering of complicated metamaterials},
Journal = {New Journal of Physics},
Volume = {14},
Number = {3},
Pages = {033038-033038},
Publisher = {IOP Publishing},
Year = {2012},
Month = {March},
ISSN = {1367-2630},
url = {http://dx.doi.org/10.1088/1367-2630/14/3/033038},
Abstract = {We develop a numerical technique for simulating metamaterial
electromagnetic response based on an adaptation of the
discrete dipole approximation (DDA). Our approach reduces
each constituent metamaterial element within the composite
to a point dipole with electric and magnetic
polarizabilities, rather than assuming a homogenized
effective material. We first validate the approach by
computing the scattering cross-section for a collection of
densely spaced isotropic dipole moments arranged within a
cylindrical area, and compare with the known result from Mie
theory. The discrete dipole approach has considerable
advantages for the design of gradient and transformation
optical media based on metamaterials, since the absence of
local periodicity in other common design approaches leaves
them with questionable validity. Several variants of iconic
cloaking structures are investigated to illustrate the
method, in which we study the impact that different
configurations of dipolar elements can have on cloak
performance. The modeling of a complex medium as polarizable
dipoles provides a much closer connection to actual
metamaterial implementations, and can address key nonlocal
phenomena, such as magnetoelectric coupling, not accessible
to most current numerical metamaterial approaches. © IOP
Publishing Ltd and Deutsche Physikalische
Gesellschaft.},
Doi = {10.1088/1367-2630/14/3/033038},
Key = {fds269759}
}
@article{fds269760,
Author = {Arritt, BJ and Smith, DR and Khraishi, TA},
Title = {Analytically describing the temperature-dependent
constitutive parameters of an electromagnetic
metamaterial},
Journal = {Journal of Intelligent Material Systems and
Structures},
Volume = {23},
Number = {4},
Pages = {463-471},
Publisher = {SAGE Publications},
Year = {2012},
Month = {March},
ISSN = {1045-389X},
url = {http://dx.doi.org/10.1177/1045389X11433496},
Abstract = {Analogous to mechanical systems, modeling the
electromagnetic (EM) performance of large and complex
metamaterial structures requires the use of
effective-medium/constitutive properties. Constitutive
properties are critical for efficiently bridging the gap
between subwavelength geometry and performance at the
mesoscale. In this article, the temperature-dependent
effective medium properties for a metamaterial
electric-inductive-capacitive (ELC) resonator are described
analytically. ELC structures are commonly used in
metamaterial designs to provide a tailored electric response
to EM waves. An equivalent circuit model, coupled with
analytic expressions for the capacitances, inductance, and
resistance of the ELC resonator, is utilized to describe how
thermally induced mechanical strain and changes in material
properties manifest as temperature-dependent permittivity
and permeability curves for the metamaterial. The resulting
analytic expressions account for the effects of spatial
dispersion and losses. This article also details how the
process may be expanded to similarly describe the
temperature-dependent constitutive properties of
metamaterial magnetic resonators. © The Author(s)
2011.},
Doi = {10.1177/1045389X11433496},
Key = {fds269760}
}
@article{fds269761,
Author = {Urzhumov, Y and Landy, N and Smith, DR},
Title = {Isotropic-medium three-dimensional cloaks for acoustic and
electromagnetic waves},
Journal = {Journal of Applied Physics},
Volume = {111},
Number = {5},
Pages = {053105-053105},
Publisher = {AIP Publishing},
Year = {2012},
Month = {March},
ISSN = {0021-8979},
url = {http://hdl.handle.net/10161/5721 Duke open
access},
Abstract = {We propose a generalization of the two-dimensional
eikonal-limit cloak derived from a conformal transformation
to three dimensions. The proposed cloak is a spherical shell
composed of only isotropic media; it operates in the
transmission mode and requires no mirror or ground plane.
Unlike the well-known omnidirectional spherical cloaks, it
may reduce visibility of an arbitrary object only for a very
limited range of observation angles. In the short-wavelength
limit, this cloaking structure restores not only the
trajectories of incident rays, but also their phase, which
is a necessary ingredient to complete invisibility. Both
scalar-wave (acoustic) and transverse vector-wave
(electromagnetic) versions are presented. © 2012 American
Institute of Physics.},
Doi = {10.1063/1.3691242},
Key = {fds269761}
}
@article{fds269788,
Author = {Larouche, S and Tsai, Y-J and Tyler, T and Jokerst, NM and Smith,
DR},
Title = {Infrared metamaterial phase holograms.},
Journal = {Nature materials},
Volume = {11},
Number = {5},
Pages = {450-454},
Year = {2012},
Month = {March},
ISSN = {1476-1122},
url = {http://www.ncbi.nlm.nih.gov/pubmed/22426458},
Abstract = {As a result of advances in nanotechnology and the burgeoning
capabilities for fabricating materials with controlled
nanoscale geometries, the traditional notion of what
constitutes an optical device continues to evolve. The
fusion of maturing low-cost lithographic techniques with
newer optical design strategies has enabled the introduction
of artificially structured metamaterials in place of
conventional materials for improving optical components as
well as realizing new optical functionality. Here we
demonstrate multilayer, lithographically patterned,
subwavelength, metal elements, whose distribution forms a
computer-generated phase hologram in the infrared region
(10.6 μm). Metal inclusions exhibit extremely large
scattering and can be implemented in metamaterials that
exhibit a wide range of effective medium response, including
anomalously large or negative refractive index; optical
magnetism; and controlled anisotropy. This large palette of
metamaterial responses can be leveraged to achieve greater
control over the propagation of light, leading to more
compact, efficient and versatile optical
components.},
Doi = {10.1038/nmat3278},
Key = {fds269788}
}
@article{fds269758,
Author = {Urzhumov, Y and Chen, W and Bingham, C and Padilla, W and Smith,
DR},
Title = {Magnetic levitation of metamaterial bodies enhanced with
magnetostatic surface resonances},
Journal = {Physical Review B - Condensed Matter and Materials
Physics},
Volume = {85},
Number = {5},
Publisher = {American Physical Society (APS)},
Year = {2012},
Month = {February},
ISSN = {1098-0121},
url = {http://hdl.handle.net/10161/5723 Duke open
access},
Abstract = {We propose that macroscopic objects built from
negative-permeability metamaterials may experience
resonantly enhanced magnetic force in low-frequency magnetic
fields. Resonant enhancement of the time-averaged force
originates from magnetostatic surface resonances (MSRs),
which are analogous to the electrostatic resonances of
negative-permittivity particles, well known as surface
plasmon resonances in optics. We generalize the classical
problem of the MSR of a homogeneous object to include
anisotropic metamaterials and consider the most extreme case
of anisotropy, where the permeability is negative in one
direction but positive in the others. It is shown that
deeply subwavelength objects made of such indefinite
(hyperbolic) media exhibit a pronounced magnetic dipole
resonance that couples strongly to uniform or weakly
inhomogeneous magnetic field and provides strong enhancement
of the magnetic force, enabling applications such as
enhanced magnetic levitation. © 2012 American Physical
Society.},
Doi = {10.1103/PhysRevB.85.054430},
Key = {fds269758}
}
@article{fds335097,
Author = {Smith, DR},
Title = {Measuring plasma turbulence using low coherence microwave
radiation},
Journal = {Applied Physics Letters},
Volume = {100},
Number = {8},
Pages = {084107-084107},
Publisher = {AIP Publishing},
Year = {2012},
Month = {February},
url = {http://dx.doi.org/10.1063/1.3690922},
Abstract = {Low coherence backscattering (LCBS) is a proposed diagnostic
technique for measuring plasma turbulence and fluctuations.
LCBS is an adaptation of optical coherence tomography, a
biomedical imaging technique. Calculations and simulations
show LCBS measurements can achieve centimeter-scale spatial
resolution using low coherence microwave radiation. LCBS
measurements exhibit several advantages over standard plasma
turbulence measurement techniques including immunity to
spurious reflections and measurement access in hollow
density profiles. Also, LCBS is scalable for 1-D profile
measurements and 2-D turbulence imaging. © 2012 American
Institute of Physics.},
Doi = {10.1063/1.3690922},
Key = {fds335097}
}
@article{fds335099,
Author = {Weider, SZ and Kellett, BJ and Swinyard, BM and Crawford, IA and Joy,
KH and Grande, M and Howe, CJ and Huovelin, J and Narendranath, S and Alha,
L and Anand, M and Athiray, PS and Bhandari, N and Carter, JA and Cook, AC and Duston, LC and Fernandes, VA and Gasnault, O and Goswami, JN and Gow,
JPD and Holland, AD and Koschny, D and Lawrence, DJ and Maddison, BJ and Maurice, S and McKay, DJ and Okada, T and Pieters, C and Rothery, DA and Russell, SS and Shrivastava, A and Smith, DR and Wieczorek,
M},
Title = {The Chandrayaan-1 X-ray Spectrometer: First
results},
Journal = {Planetary and Space Science},
Volume = {60},
Number = {1},
Pages = {217-228},
Publisher = {Elsevier BV},
Year = {2012},
Month = {January},
url = {http://dx.doi.org/10.1016/j.pss.2011.08.014},
Abstract = {We present X-ray fluorescence observations of the lunar
surface, made by the Chandrayaan-1 X-ray Spectrometer during
two solar flare events early in the mission (12th December
2008 and 10th January 2009). Modelling of the X-ray spectra
with an abundance algorithm allows quantitative estimates of
the MgO/SiO 2 and Al 2O 3/SiO 2 ratios to be made for the
two regions, which are in mainly basaltic areas of the lunar
nearside. One of these ground tracks includes the Apollo 14
landing site on the Fra Mauro Formation. Within the 1σ
errors provided, the results are inside the range of
basaltic samples from the Apollo and Luna collections. The
Apollo 14 soil composition is in agreement with the results
from the January flare at the 1σ uncertainty level.
Discrepancies are observed between our results and
compositions derived for the same areas by the Lunar
Prospector gamma-ray spectrometer; some possible reasons for
this are discussed. © 2011 Elsevier Ltd. All rights
reserved.},
Doi = {10.1016/j.pss.2011.08.014},
Key = {fds335099}
}
@article{fds269755,
Author = {Shin, D and Urzhumov, Y and Jung, Y and Kang, G and Baek, S and Choi, M and Park, H and Kim, K and Smith, DR},
Title = {Broadband electromagnetic cloaking with smart
metamaterials.},
Journal = {Nature communications},
Volume = {3},
Pages = {1213},
Year = {2012},
Month = {January},
ISSN = {2041-1723},
url = {http://hdl.handle.net/10161/7571 Duke open
access},
Abstract = {The ability to render objects invisible with a cloak that
fits all objects and sizes is a long-standing goal for
optical devices. Invisibility devices demonstrated so far
typically comprise a rigid structure wrapped around an
object to which it is fitted. Here we demonstrate smart
metamaterial cloaking, wherein the metamaterial device not
only transforms electromagnetic fields to make an object
invisible, but also acquires its properties automatically
from its own elastic deformation. The demonstrated device is
a ground-plane microwave cloak composed of an elastic
metamaterial with a broad operational band (10-12 GHz) and
nearly lossless electromagnetic properties. The metamaterial
is uniform, or perfectly periodic, in its undeformed state
and acquires the necessary gradient-index profile, mimicking
a quasi-conformal transformation, naturally from a boundary
load. This easy-to-fabricate hybrid elasto-electromagnetic
metamaterial opens the door to implementations of a variety
of transformation optics devices based on quasi-conformal
maps.},
Doi = {10.1038/ncomms2219},
Key = {fds269755}
}
@article{fds269787,
Author = {Hunt, J and Tyler, T and Dhar, S and Tsai, Y-J and Bowen, P and Larouche,
S and Jokerst, NM and Smith, DR},
Title = {Planar, flattened Luneburg lens at infrared
wavelengths.},
Journal = {Optics express},
Volume = {20},
Number = {2},
Pages = {1706-1713},
Year = {2012},
Month = {January},
url = {http://www.ncbi.nlm.nih.gov/pubmed/22274513},
Abstract = {Employing artificially structured metamaterials provides a
means of circumventing the limits of conventional optical
materials. Here, we use transformation optics (TO) combined
with nanolithography to produce a planar Luneburg lens with
a flat focal surface that operates at telecommunication
wavelengths. Whereas previous infrared TO devices have been
transformations of free-space, here we implement a
transformation of an existing optical element to create a
new device with the same optical characteristics but a
user-defined geometry.},
Doi = {10.1364/oe.20.001706},
Key = {fds269787}
}
@article{fds335098,
Author = {Medley, SS and Kolesnichenko, YI and Yakovenko, YV and Bell, RE and Bortolon, A and Crocker, NA and Darrow, DS and Diallo, A and Domier, CW and Fonck, RJ and Fredrickson, ED and Gerhardt, SP and Gorelenkov, NN and Kramer, GJ and Kubota, S and Leblanc, BP and Lee, KC and Mazzucato, E and McKee, GR and Podestà, M and Ren, Y and Roquemore, AL and Smith, DR and Stutman, D and Tritz, K and White, RB},
Title = {Investigation of a transient energetic charge exchange flux
enhancement ('spike-on-tail') observed in
neutral-beam-heated H-mode discharges in the National
Spherical Torus Experiment},
Journal = {Nuclear Fusion},
Volume = {52},
Number = {1},
Pages = {013014-013014},
Publisher = {IOP Publishing},
Year = {2012},
Month = {January},
url = {http://dx.doi.org/10.1088/0029-5515/52/1/013014},
Abstract = {In the National Spherical Torus Experiment (NSTX), a large
increase in the charge exchange neutral flux localized
around the neutral beam (NB) injection full energy is
measured using a neutral particle analyser. Termed the
high-energy feature (HEF), it appears on the NB-injected
energetic-ion spectrum only in discharges where tearing or
kink-type modes (f < 50 kHz) are absent, toroidal Alfvén
eigenmode activity (f ∼ 50-150 kHz) is weak and global
Alfvén eigenmode (GAE) activity (f ∼ 400-1000 kHz) is
robust. Compressional Alfvén eigenmode activity (f > 1000
kHz) is usually sporadic or absent during the HEF event. The
HEF exhibits growth times of Δt ∼ 20-80 ms, durations
spanning 100-600 ms and peak-to-base flux ratios up to H = F
max/F min ∼ 10. In infrequent cases, a slowing-down
distribution below the HEF energy can develop that continues
to evolve over periods of order 100 ms, a time scale long
compared with the typical fast-ion equilibration times. HEFs
are observed only in H-mode (not L-mode) discharges with
injected power P b ≥ 4 MW and in the pitch range χ ≡ v
||/v ∼ 0.7-0.9; i.e. only for passing particles. Increases
of order 10-30% in the measured neutron yield and total
stored energy that are observed to coincide with the feature
appear to be driven by concomitant broadening of measured T
e(r), T i(r) and n e(r) profiles and not the HEF itself.
While the HEF has minimal impact on plasma performance, it
nevertheless poses a challenging wave-particle interaction
phenomenon to understand. Candidate mechanisms for HEF
formation are developed based on quasilinear (QL) theory of
wave-particle interaction. The only mechanism found to lead
to the large NPA flux ratios, H = F max/F min, observed in
NSTX is the QL evolution of the energetic-ion distribution,
F b(E, χ, r), in phase space. A concomitant loss of some
particles is observed due to interaction through cyclotron
resonance of the particles with destabilized modes having
sufficiently high frequencies, f ∼ 700-1000 kHz, in the
plasma frame that are tentatively identified as GAEs. ©
2012 IAEA, Vienna.},
Doi = {10.1088/0029-5515/52/1/013014},
Key = {fds335098}
}
@article{fds269602,
Author = {Smith, DR and Poutrina, E and Huang, D and Rose, A and Larouche,
S},
Title = {Controlling nonlinearity with structured
metamaterials},
Journal = {Optics InfoBase Conference Papers},
Year = {2011},
Month = {December},
Abstract = {Artificially structured media can exhibit a wider range of
both linear and nonlinear electromagnetic properties than
are supported in conventional media. We discuss the design
techniques and impact of these new emerging nonlinear
metamaterials. © 2011 OSA.},
Key = {fds269602}
}
@article{fds269603,
Author = {Rose, A and Smith, DR},
Title = {Quasi-phase matching in nonlinear metamaterials},
Journal = {Optics InfoBase Conference Papers},
Year = {2011},
Month = {December},
Abstract = {We employ nonlinear metamaterials to demonstrate alternative
quasi-phase matching (QPM) methods not feasible in natural
materials. Additionally, we propose a method for dynamic QPM
via resonance tuning, allowing for a tunable frequency of
operation. © OSA/CLEO 2011.},
Key = {fds269603}
}
@article{fds269604,
Author = {Huang, D and Poutrina, E and Rose, A and Larouche, S and Smith,
DR},
Title = {Three-wave mixing in microwave nonlinear
metamaterial},
Journal = {Optics InfoBase Conference Papers},
Year = {2011},
Month = {December},
Abstract = {We present a quantitative analysis of a three-wave mixing
process in a microwave nonlinear metamaterial showing a good
agreement between the analytical predictions and the
experiment. Strong resonant nonlinear response is observed.
© 2010 Optical Society of America.},
Key = {fds269604}
}
@article{fds269605,
Author = {Rose, A and Smith, DR},
Title = {Quasi-phase matching in nonlinear metamaterials},
Journal = {Optics InfoBase Conference Papers},
Year = {2011},
Month = {December},
Abstract = {We employ nonlinear metamaterials to demonstrate alternative
quasi-phase matching (QPM) methods not feasible in natural
materials. Additionally, we propose a method for dynamic QPM
via resonance tuning, allowing for a tunable frequency of
operation. © OSA/CLEO 2011.},
Key = {fds269605}
}
@article{fds269606,
Author = {Poutrina, E and Ciraci, C and Smith, DR},
Title = {Plasmonic nanocomposits for enhanced four-wave mixing
generation},
Journal = {Optics InfoBase Conference Papers},
Year = {2011},
Month = {December},
Abstract = {Third-order nonlinear response and strong field enhancement
in gold nanocomposites are utilized to analyze the enhanced
effective nonlinear susceptibility, subwavelength field
confinement and reduced bend radii in the evanescent and
propagating regimes of the generated four-wave-mixed light.
© 2008 Optical Society of America.},
Key = {fds269606}
}
@article{fds269607,
Author = {Rose, A and Smith, DR},
Title = {Quasi-phase matching in nonlinear metamaterials},
Journal = {Optics InfoBase Conference Papers},
Year = {2011},
Month = {December},
Abstract = {We employ nonlinear metamaterials to demonstrate alternative
quasi-phase matching (QPM) methods not feasible in natural
materials. Additionally, we propose a method for dynamic QPM
via resonance tuning, allowing for a tunable frequency of
operation. © OSA/CLEO 2011.},
Key = {fds269607}
}
@article{fds269612,
Author = {Chen, SY and Mock, JJ and Hill, RT and Chilkoti, A and Smith, DR and Lazarides, AA},
Title = {Raman antenna formed by molecule/plasmonic nanostructure
hybrid system},
Journal = {Optics InfoBase Conference Papers},
Year = {2011},
Month = {December},
Abstract = {A nano-antenna composed of a particle and a polarizable
surface provides control of the spatial distribution and
high enhancement of Raman scattering. This structure may
serve as a stable platform for single molecule detection. ©
2010 Optical Society of America.},
Key = {fds269612}
}
@article{fds269613,
Author = {Tsai, YJ and Larouche, S and Tyler, T and Lipworth, G and Mock, J and Jokerst, NM and Smith, DR},
Title = {Metamaterial blazed gratings},
Journal = {Optics InfoBase Conference Papers},
Year = {2011},
Month = {December},
Abstract = {We design, fabricate, and test a graded index diffractive
structure based on non-resonant I-beam metamaterials. The
measured diffraction spectrum is in good agreement with
simulation, and suggests a path toward metamaterial based
diffractive optics. © OSA/CLEO 2011.},
Key = {fds269613}
}
@article{fds269735,
Author = {Smith, DR and Tsai, YJ and Larouche, S},
Title = {Analysis of a gradient index metamaterial blazed diffraction
grating},
Journal = {IEEE Antennas and Wireless Propagation Letters},
Volume = {10},
Pages = {1605-1608},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2011},
Month = {December},
ISSN = {1536-1225},
url = {http://dx.doi.org/10.1109/LAWP.2011.2179632},
Abstract = {The equivalent of a blazed diffraction grating can be formed
from an array of metamaterial elements arranged so as to
produce a linear gradient in the effective refractive index.
By spreading the gradient over a multiwavelength distance,
and repeating the pattern many times, a gradient index
(GRIN) diffraction grating is formed. Using lithographically
patterned, metallic metamaterial elements, dozens of
distinguishable phase levels can be implemented by slightly
modifying the design of each successive metamaterial
element. We analyze here a multilayer metamaterial
diffraction grating designed for operation at 10.6 μm,
exploring the impact of material losses and impedance
mismatch on the diffraction efficiency. © 2006
IEEE.},
Doi = {10.1109/LAWP.2011.2179632},
Key = {fds269735}
}
@article{fds269834,
Author = {Schurig, D and Eleftheriades, GV and Smith, DR and Tretyakov,
SA},
Title = {Guest editorial: Special cluster on metamaterials},
Journal = {IEEE Antennas and Wireless Propagation Letters},
Volume = {10},
Pages = {1476-1479},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2011},
Month = {December},
ISSN = {1536-1225},
url = {http://dx.doi.org/10.1109/LAWP.2012.2183989},
Doi = {10.1109/LAWP.2012.2183989},
Key = {fds269834}
}
@article{fds269835,
Author = {Chen, WC and Mock, JJ and Smith, DR and Akalin, DR and Padilla,
WJ},
Title = {Controlling Gigahertz and Terahertz Surface
ElectromagneticWaves with Metamaterial Resonators},
Journal = {Physical Review X},
Volume = {1},
Number = {2},
Publisher = {American Physical Society (APS)},
Year = {2011},
Month = {December},
ISSN = {2160-3308},
url = {http://dx.doi.org/10.1103/PhysRevX.1.021016},
Abstract = {We computationally and experimentally investigate the use of
metamaterial resonators as bandpass filters and other
components that enable control of guided surface
electromagnetic waves. The guided surface electromagnetic
wave propagates on a planar Goubau line, launched via a
coplanar waveguide coupler with 50ω impedance. Experimental
samples targeted for either microwave or terahertz
frequencies are measured and shown to be in excellent
agreement with simulations. Metamaterial elements are
designed to absorb energy only of the planar Goubau line and
yield narrow-band resonances with relatively high quality
factors. Two independent configurations of coupled
metamaterial elements are demonstrated that modify the
otherwise flat transmission spectrum of the planar Goubau
line. By physically shunting the capacitive gaps of the
coupled metamaterial elements, we demonstrate the potential
for a large dynamic range in transmissivity, suggesting the
use of this configuration for highbandwidth terahertz
communications.},
Doi = {10.1103/PhysRevX.1.021016},
Key = {fds269835}
}
@article{fds269750,
Author = {Rose, A and Larouche, S and Smith, DR},
Title = {Quantitative study of the enhancement of bulk nonlinearities
in metamaterials},
Journal = {Physical Review A - Atomic, Molecular, and Optical
Physics},
Volume = {84},
Number = {5},
Publisher = {American Physical Society (APS)},
Year = {2011},
Month = {November},
ISSN = {1050-2947},
url = {http://dx.doi.org/10.1103/PhysRevA.84.053805},
Abstract = {Artificially structured metamaterials offer a means to
enhance the weak optical nonlinearities of natural
materials. The enhancement results from the inhomogeneous
nature of the metamaterial unit cell, over which the local
field distribution can likewise be strongly inhomogeneous,
with highly localized and concentrated field regions. We
investigate the nonlinear enhancement effect in
metamaterials through a numerical study of four nonlinear
metamaterial designs comprising arrays of metallic
structures embedded in nonlinear dielectrics and operating
around 10 THz. Through full-wave simulations and by
employing an extended version of the transfer-matrix-based
nonlinear parameter retrieval method, we confirm and
quantify the enhanced nonlinearities, showing bulk quadratic
nonlinear properties that are up to two orders of magnitude
larger, and cubic nonlinear properties that are up to four
orders of magnitude larger than the bulk nonlinear
dielectric alone. Furthermore, the proposed nonlinear
metamaterials support a variety of configurable nonlinear
properties and regimes, including electric, magnetic,
broadband, and low loss, depending on the particular
geometry chosen. Finally, we use the retrieved parameters in
a coupled-mode theory to predict the optimal crystal lengths
and conversion efficiencies of these structures, displaying
the possibility of efficient and subwavelength nonlinear
devices based on metamaterials. © 2011 American Physical
Society.},
Doi = {10.1103/PhysRevA.84.053805},
Key = {fds269750}
}
@article{fds269751,
Author = {Rose, A and Smith, DR},
Title = {Overcoming phase mismatch in nonlinear metamaterials
[Invited]},
Journal = {Optical Materials Express},
Volume = {1},
Number = {7},
Pages = {1232-1243},
Publisher = {The Optical Society},
Year = {2011},
Month = {November},
ISSN = {2159-3930},
url = {http://dx.doi.org/10.1364/OME.1.001232},
Abstract = {Nonlinear metamaterials have potentially interesting
applications in highly efficient wave-mixing and parametric
processes, owing to their ability to combine enhanced
nonlinearities with exotic and configurable linear
properties. However, the strong dispersion and
unconventional configurations typically associated with
metamaterials place strong demands on phase matching in such
structures. In this paper, we present an overview of
potential phase matching solutions for wave-mixing processes
in nonlinear metamaterials. Broadly speaking, we divide the
phase matching solutions into conventional techniques
(anomalous dispersion, birefringence, and quasi-phase
matching) and metamaterial-inspired techniques
(negative-index and index-near-zero phase matching),
offering numerical and experimental examples where possible.
We find that not only is phase matching feasible in
metamaterials, but metamaterials can support a wide range of
phase matching configurations that are otherwise impossible
in natural materials. These configurations have their most
compelling applications in those devices where at least one
of the interacting waves is counter-propagating, such as the
mirror-less optical parametric oscillator and the nonlinear
optical mirror. © 2011 Optical Society of
America.},
Doi = {10.1364/OME.1.001232},
Key = {fds269751}
}
@article{fds269785,
Author = {Tsai, Y-J and Larouche, S and Tyler, T and Lipworth, G and Jokerst, NM and Smith, DR},
Title = {Design and fabrication of a metamaterial gradient index
diffraction grating at infrared wavelengths.},
Journal = {Optics express},
Volume = {19},
Number = {24},
Pages = {24411-24423},
Year = {2011},
Month = {November},
url = {http://www.ncbi.nlm.nih.gov/pubmed/22109468},
Abstract = {We demonstrate the design, fabrication and characterization
of an artificially structured, gradient index metamaterial
with a linear index variation of Δn ~ 3.0. The linear
gradient profile is repeated periodically to form the
equivalent of a blazed grating, with the gradient occurring
across a spatial distance of 61 μm. The grating, which
operates at a wavelength of 10.6 μm, is composed of
non-resonant, progressively modified "I-beam" metamaterial
elements and approximates a linear phase shift gradient
using 61 distinguishable phase levels. The grating structure
consists of four layers of lithographically patterned
metallic I-beam elements separated by dielectric layers of
SiO(2). The index gradient is confirmed by comparing the
measured magnitudes of the -1, 0 and +1 diffracted orders to
those obtained from full wave simulations incorporating all
material properties of the metals and dielectrics of the
structures. The large index gradient has the potential to
enable compact infrared diffractive and gradient index
optics, as well as more exotic transformation optical
media.},
Doi = {10.1364/oe.19.024411},
Key = {fds269785}
}
@article{fds269749,
Author = {Urzhumov, YA and Smith, DR},
Title = {Erratum: Fluid flow control with transformation media
(Physical Review Letters (2011) 107 (074501))},
Journal = {Physical Review Letters},
Volume = {107},
Number = {18},
Publisher = {American Physical Society (APS)},
Year = {2011},
Month = {October},
ISSN = {0031-9007},
url = {http://dx.doi.org/10.1103/PhysRevLett.107.189902},
Doi = {10.1103/PhysRevLett.107.189902},
Key = {fds269749}
}
@article{fds335100,
Author = {Weider, SZ and Swinyard, BM and Kellett, BJ and Howe, CJ and Joy, KH and Crawford, IA and Gow, J and Smith, DR},
Title = {Planetary X-ray fluorescence analogue laboratory experiments
and an elemental abundance algorithm for
C1XS},
Journal = {Planetary and Space Science},
Volume = {59},
Number = {13},
Pages = {1393-1407},
Publisher = {Elsevier BV},
Year = {2011},
Month = {October},
url = {http://dx.doi.org/10.1016/j.pss.2011.05.005},
Abstract = {We have conducted laboratory experiments as an analogue to
planetary XRF (X-ray fluorescence) missions in order to
investigate the role of changing incidence (and phase) angle
geometry and sample grain-size on the intensity of XRF from
regolith-like samples. Our data provide evidence of a
grain-size effect, where XRF line intensity decreases with
increasing sample grain-size, as well as an almost
ubiquitous increase in XRF line intensity above incidence
angles of ∼60°. Data from a lunar regolith simulant are
also used to test the accuracy of an XRF abundance algorithm
developed at the Rutherford Appleton Laboratory (RAL), which
is used to estimate the major element abundance of the lunar
surface from Chandrayaan-1 X-ray Spectrometer (C1XS) XRF
data. In ideal situations (i.e.; when the input spectrum is
well defined and the XRF spectrum has a sufficient signal to
noise ratio) the algorithm can recover a known rock
composition to within 1.0 elemental wt% (1σ). © 2011
Elsevier Ltd. All rights reserved.},
Doi = {10.1016/j.pss.2011.05.005},
Key = {fds335100}
}
@article{fds269732,
Author = {Huang, D and Poutrina, E and Rose, A and Larouche, S and Smith,
DR},
Title = {Three-wave mixing in microwave nonlinear
metamaterial},
Journal = {2011 Conference on Lasers and Electro-Optics: Laser Science
to Photonic Applications, CLEO 2011},
Year = {2011},
Month = {September},
Abstract = {We present a quantitative analysis of a three-wave mixing
process in a microwave nonlinear metamaterial showing a good
agreement between the analytical predictions and the
experiment. Strong resonant nonlinear response is observed.
© 2011 OSA.},
Key = {fds269732}
}
@article{fds269733,
Author = {Rose, A and Smith, DR},
Title = {Quasi-phase matching in nonlinear metamaterials},
Journal = {2011 Conference on Lasers and Electro-Optics: Laser Science
to Photonic Applications, CLEO 2011},
Year = {2011},
Month = {September},
Abstract = {We employ nonlinear metamaterials to demonstrate alternative
quasi-phase matching (QPM) methods not feasible in natural
materials. Additionally, we propose a method for dynamic QPM
via resonance tuning, allowing for a tunable frequency of
operation. © 2011 OSA.},
Key = {fds269733}
}
@article{fds269747,
Author = {Dellagiacoma, C and Lasser, T and Martin, OJF and Degiron, A and Mock,
JJ and Smith, DR},
Title = {Simulation of complex plasmonic circuits including
bends.},
Journal = {Optics express},
Volume = {19},
Number = {20},
Pages = {18979-18988},
Year = {2011},
Month = {September},
ISSN = {1094-4087},
url = {http://dx.doi.org/10.1364/oe.19.018979},
Abstract = {Using a finite-element, full-wave modeling approach, we
present a flexible method of analyzing and simulating
dielectric and plasmonic waveguide structures as well as
their mode coupling. This method is applied to an integrated
plasmonic circuit where a straight dielectric waveguide
couples through a straight hybrid long-range plasmon
waveguide to a uniformly bent hybrid one. The hybrid
waveguide comprises a thin metal core embedded in a
two-dimensional dielectric waveguide. The performance of
such plasmonic circuits in terms of insertion losses is
discussed.},
Doi = {10.1364/oe.19.018979},
Key = {fds269747}
}
@article{fds269783,
Author = {Tsai, YJ and Larouche, S and Tyler, T and Lipworth, G and Mock, J and Jokerst, NM and Smith, DR},
Title = {Metamaterial blazed gratings},
Journal = {2011 Conference on Lasers and Electro-Optics: Laser Science
to Photonic Applications, CLEO 2011},
Year = {2011},
Month = {September},
Abstract = {We design, fabricate, and test a graded index diffractive
structure based on non-resonant I-beam metamaterials. The
measured diffraction spectrum is in good agreement with
simulation, and suggests a path toward metamaterial based
diffractive optics. © 2011 OSA.},
Key = {fds269783}
}
@article{fds269804,
Author = {Chen, SY and Mock, JJ and Hill, RT and Chilkoti, A and Smith, DR and Lazarides, AA},
Title = {Raman antenna formed by molecule/plasmonic nanostructure
hybrid system},
Journal = {2011 Conference on Lasers and Electro-Optics: Laser Science
to Photonic Applications, CLEO 2011},
Year = {2011},
Month = {September},
Abstract = {A nano-antenna composed of a particle and a polarizable
surface provides control of the spatial distribution and
high enhancement of Raman scattering. This structure may
serve as a stable platform for single molecule detection. ©
2011 OSA.},
Key = {fds269804}
}
@article{fds335101,
Author = {Raman, R and Ahn, JW and Allain, JP and Andre, R and Bastasz, R and Battaglia, D and Beiersdorfer, P and Bell, M and Bell, R and Belova, E and Berkery, J and Betti, R and Bialek, J and Bigelow, T and Bitter, M and Boedo, J and Bonoli, P and Boozer, A and Bortolon, A and Brennan, D and Breslau, J and Buttery, R and Canik, J and Caravelli, G and Chang, C and Crocker, NA and Darrow, D and Davis, W and Delgado-Aparicio, L and Diallo, A and Ding, S and D'Ippolito, D and Domier, C and Dorland, W and Ethier, S and Evans, T and Ferron, J and Finkenthal, M and Foley, J and Fonck, R and Frazin, R and Fredrickson, E and Fu, G and Gates, D and Gerhardt, S and Glasser, A and Gorelenkov, N and Gray, T and Guo, Y and Guttenfelder, W and Hahm, T and Harvey, R and Hassanein, A and Heidbrink, W and Hill, K and Hirooka, Y and Hooper, EB and Hosea, J and Hu,
B and Humphreys, D and Indireshkumar, K and Jaeger, F and Jarboe, T and Jardin, S and Jaworski, M and Kaita, R and Kallman, J and Katsuro-Hopkins, O and Kaye, S and Kessel, C and Kim, J and Kolemen, E and Krasheninnikov, S and Kubota, S and Kugel, H and La Haye and R and Lao, L and Leblanc, B and Lee, W and Lee, K and Leuer, J and Levinton, F and Liang, Y and Liu, D and Luhmann, N and Maingi, R and Majeski, R and Manickam, J and Mansfield, D and Maqueda, R and Mazzucato, E and McLean, A and McCune,
D and McGeehan, B and McKee, G and Medley, S and Menard, J and Menon, M and Meyer, H and Mikkelsen, D},
Title = {Overview of physics results from NSTX},
Journal = {Nuclear Fusion},
Volume = {51},
Number = {9},
Pages = {094011-094011},
Publisher = {IOP Publishing},
Year = {2011},
Month = {September},
url = {http://dx.doi.org/10.1088/0029-5515/51/9/094011},
Abstract = {In the last two experimental campaigns, the low aspect ratio
NSTX has explored physics issues critical to both toroidal
confinement physics and ITER. Experiments have made
extensive use of lithium coatings for wall conditioning,
correction of non-axisymmetric field errors and control of n
= 1 resistive wall modes (RWMs) to produce high-performance
neutral-beam heated discharges extending to 1.7 s in
duration with non-inductive current fractions up to 0.7. The
RWM control coils have been used to trigger repetitive ELMs
with high reliability, and they have also contributed to an
improved understanding of both neoclassical tearing mode and
RWM stabilization physics, including the interplay between
rotation and kinetic effects on stability. High harmonic
fast wave (HHFW) heating has produced plasmas with central
electron temperatures exceeding 6 keV. The HHFW heating was
used to show that there was a 20-40% higher power threshold
for the L-H transition for helium than for deuterium
plasmas. A new diagnostic showed a depletion of the fast-ion
density profile over a broad spatial region as a result of
toroidicity-induced Alfvén eigenmodes (TAEs) and
energetic-particle modes (EPMs) bursts. In addition, it was
observed that other modes (e.g. global Alfvén eigenmodes)
can trigger TAE and EPM bursts, suggesting that fast ions
are redistributed by high-frequency AEs. The momentum pinch
velocity determined by a perturbative technique decreased as
the collisionality was reduced, although the pinch to
diffusion ratio, Vpinch/χ, remained approximately constant.
The mechanisms of deuterium retention by graphite and
lithium-coated graphite plasma-facing components have been
investigated. To reduce divertor heat flux, a novel divertor
configuration, the 'snowflake' divertor, was tested in NSTX
and many beneficial aspects were found. A reduction in the
required central solenoid flux has been realized in NSTX
when discharges initiated by coaxial helicity injection were
ramped in current using induction. The resulting plasmas
have characteristics needed to meet the objectives of the
non-inductive start-up and ramp-up program of NSTX. © 2011
IAEA, Vienna.},
Doi = {10.1088/0029-5515/51/9/094011},
Key = {fds335101}
}
@article{fds335102,
Author = {Heidbrink, WW and McKee, GR and Smith, DR and Bortolon,
A},
Title = {"Beam-emission spectroscopy" diagnostics also measure edge
fast-ion light},
Journal = {Plasma Physics and Controlled Fusion},
Volume = {53},
Number = {8},
Pages = {085007-085007},
Publisher = {IOP Publishing},
Year = {2011},
Month = {August},
url = {http://dx.doi.org/10.1088/0741-3335/53/8/085007},
Abstract = {Beam-emission spectroscopy (BES) diagnostics normally detect
fluctuations in the light emitted by an injected neutral
beam. Under some circumstances, however, light from fast
ions that charge exchange in the high neutral-density region
at the edge of the plasma make appreciable contributions to
the BES signals. This 'passive' fast-ion Dα (FIDA) light
appears in BES signals from both the DIII-D tokamak and the
National Spherical Torus Experiment (NSTX). One type of
passive FIDA light is associated with classical orbits that
traverse the edge. Another type is caused by instabilities
that expel fast ions from the core; this light can
complicate measurement of the instability eigenfunction. ©
2011 IOP Publishing Ltd.},
Doi = {10.1088/0741-3335/53/8/085007},
Key = {fds335102}
}
@article{fds269745,
Author = {Rose, A and Huang, D and Smith, DR},
Title = {Controlling the second harmonic in a phase-matched
negative-index metamaterial.},
Journal = {Physical review letters},
Volume = {107},
Number = {6},
Pages = {063902},
Year = {2011},
Month = {August},
url = {http://www.ncbi.nlm.nih.gov/pubmed/21902325},
Abstract = {Nonlinear metamaterials have been predicted to support new
and exciting domains in the manipulation of light, including
novel phase-matching schemes for wave mixing. Most notable
is the so-called nonlinear-optical mirror, in which a
nonlinear negative-index medium emits the generated
frequency towards the source of the pump. In this Letter, we
experimentally demonstrate the nonlinear-optical mirror
effect in a bulk negative-index nonlinear metamaterial,
along with two other novel phase-matching configurations,
utilizing periodic poling to switch between the three
phase-matching domains.},
Doi = {10.1103/physrevlett.107.063902},
Key = {fds269745}
}
@article{fds269746,
Author = {Urzhumov, YA and Smith, DR},
Title = {Fluid flow control with transformation media.},
Journal = {Physical review letters},
Volume = {107},
Number = {7},
Pages = {074501},
Year = {2011},
Month = {August},
url = {http://www.ncbi.nlm.nih.gov/pubmed/21902398},
Abstract = {We introduce a new concept for the manipulation of fluid
flow around three-dimensional bodies. Inspired by
transformation optics, the concept is based on a
mathematical idea of coordinate transformations and
physically implemented with anisotropic porous media
permeable to the flow of fluids. In two situations-for an
impermeable object placed either in a free-flowing fluid or
in a fluid-filled porous medium-we show that the object can
be coated with an inhomogeneous, anisotropic permeable
medium, such as to preserve the flow that would have existed
in the absence of the object. The proposed fluid flow cloak
eliminates downstream wake and compensates viscous drag,
hinting at the possibility of novel propulsion
techniques.},
Doi = {10.1103/physrevlett.107.074501},
Key = {fds269746}
}
@article{fds269784,
Author = {Goldflam, MD and Driscoll, T and Chapler, B and Khatib, O and Marie
Jokerst, N and Palit, S and Smith, DR and Kim, BJ and Seo, G and Kim, HT and Ventra, MD and Basov, DN},
Title = {Reconfigurable gradient index using VO2 memory
metamaterials},
Journal = {Applied Physics Letters},
Volume = {99},
Number = {4},
Pages = {044103-044103},
Publisher = {AIP Publishing},
Year = {2011},
Month = {July},
ISSN = {0003-6951},
url = {http://dx.doi.org/10.1063/1.3615804},
Abstract = {We demonstrate tuning of a metamaterial device that
incorporates a form of spatial gradient control. Electrical
tuning of the metamaterial is achieved through a vanadium
dioxide layer which interacts with an array of split ring
resonators. We achieved a spatial gradient in the magnitude
of permittivity, writeable using a single transient
electrical pulse. This induced gradient in our device is
observed on spatial scales on the order of one wavelength at
1 THz. Thus, we show the viability of elements for use in
future devices with potential applications in beamforming
and communications. © 2011 American Institute of
Physics.},
Doi = {10.1063/1.3615804},
Key = {fds269784}
}
@article{fds269743,
Author = {Rose, A and Smith, DR},
Title = {Broadly tunable quasi-phase-matching in nonlinear
metamaterials},
Journal = {Physical Review A - Atomic, Molecular, and Optical
Physics},
Volume = {84},
Number = {1},
Publisher = {American Physical Society (APS)},
Year = {2011},
Month = {July},
ISSN = {1050-2947},
url = {http://dx.doi.org/10.1103/PhysRevA.84.013823},
Abstract = {The ability to tune the quasi-phase-matching (QPM) frequency
is a highly desirable though lacking feature of many
nonlinear devices. To this end, we consider QPM in a special
class of active nonlinear metamaterials (MMs), whose
properties can be controlled postfabrication. By application
of a tunable, periodic perturbation in the linear
susceptibility (magnetic or electric) of a MM, a single
nonlinear device can be constructed to operate over an
exceedingly broad bandwidth. We propose a nonlinear MM for
QPM second-order harmonic generation at terahertz
frequencies, predicted to have a tunable bandwidth of over
100%. © 2011 American Physical Society.},
Doi = {10.1103/PhysRevA.84.013823},
Key = {fds269743}
}
@article{fds269731,
Author = {Hunt, J and Kundtz, N and Sun, B and Smith, DR},
Title = {Transformation optics compressed rotman lens implemented
with complementary metamaterials},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {8021},
Publisher = {SPIE},
Year = {2011},
Month = {July},
ISSN = {0277-786X},
url = {http://dx.doi.org/10.1117/12.884319},
Abstract = {The solutions to the Rotman lens design equations constrain
the minimum size of the device. Here we use Transformation
Optics to compress a transmission line based Rotman lens by
27 percent along the optical axis while maintaining the beam
steering range, gain and side lobe amplitudes over the full
frequency range of the original lens. The transformation
applied requires an anisotropic magnetic response, which is
achieved in the transmission line context using
complementary electric dipole structures patterned into the
top conductor of the lens. The non-resonant complementary
metamaterial elements provide an anisotropic, effective
magnetic permeability with values that can be varied across
a spatial region by varying the geometry of each element. ©
2010 SPIE.},
Doi = {10.1117/12.884319},
Key = {fds269731}
}
@article{fds269741,
Author = {Allen, JW and Steyskal, H and Smith, DR},
Title = {Impedance and complex power of radiating elements under
electromagnetic source transformation},
Journal = {Microwave and Optical Technology Letters},
Volume = {53},
Number = {7},
Pages = {1524-1527},
Publisher = {WILEY},
Year = {2011},
Month = {July},
ISSN = {0895-2477},
url = {http://dx.doi.org/10.1002/mop.26077},
Abstract = {Transformation optics is a methodology that has proven
useful in the design of complex media used to alter and
control electromagnetic waves in either passive space or
regions that contain source distributions. Recently it has
been shown that the application of source transformations
can reshape field radiation patterns corresponding to
arbitrarily shaped sources. In the accompanying numerical
confirmations, the effect of source transformations on
fundamental quantities that are critical to the design and
evaluation of antenna based systems - such as complex power
and impedance, remain unexplored. In this paper, we present
results of theoretical analysis as well as full wave finite
element simulations, proving that the complex power and
impedance associated with an electromagnetic source are not
changed by source transformation methods. These results open
the door to the application of source transformations for
the design of practical antenna based systems, such as
conformal and phased array antenna design. Copyright © 2011
Wiley Periodicals, Inc.},
Doi = {10.1002/mop.26077},
Key = {fds269741}
}
@article{fds269742,
Author = {Urzhumov, Y and Smith, DR},
Title = {Metamaterial-enhanced coupling between magnetic dipoles for
efficient wireless power transfer},
Journal = {Physical Review B - Condensed Matter and Materials
Physics},
Volume = {83},
Number = {20},
Publisher = {American Physical Society (APS)},
Year = {2011},
Month = {May},
ISSN = {1098-0121},
url = {http://hdl.handle.net/10161/5076 Duke open
access},
Abstract = {Nonradiative coupling between conductive coils is a
candidate mechanism for wireless energy transfer
applications. In this paper we propose a power relay system
based on a near-field metamaterial superlens and present a
thorough theoretical analysis of this system. We use
time-harmonic circuit formalism to describe all interactions
between two coils attached to external circuits and a slab
of anisotropic medium with homogeneous permittivity and
permeability. The fields of the coils are found in the
point-dipole approximation using Sommerfeld integrals which
are reduced to standard special functions in the
long-wavelength limit. We show that, even with a realistic
magnetic loss tangent of order 0.1, the power transfer
efficiency with the slab can be an order of magnitude
greater than free-space efficiency when the load resistance
exceeds a certain threshold value. We also find that the
volume occupied by the metamaterial between the coils can be
greatly compressed by employing magnetic permeability with a
large anisotropy ratio. © 2011 American Physical
Society.},
Doi = {10.1103/PhysRevB.83.205114},
Key = {fds269742}
}
@article{fds269740,
Author = {Huang, D and Rose, A and Poutrina, E and Larouche, S and Smith,
DR},
Title = {Wave mixing in nonlinear magnetic metacrystal},
Journal = {Applied Physics Letters},
Volume = {98},
Number = {20},
Pages = {204102-204102},
Publisher = {AIP Publishing},
Year = {2011},
Month = {May},
ISSN = {0003-6951},
url = {http://dx.doi.org/10.1063/1.3592574},
Abstract = {We present experimental measurements of three- and four-wave
mixing phenomena in an artificially structured nonlinear
magnetic metacrystal at microwave frequencies. The sum
frequency generation signal for the varactor-loaded
split-ring resonator (VLSRR) metamaterial agrees
quantitatively with that predicted using an analytical
effective medium model describing the VLSRR medium. A
resonant enhancement of the nonlinear response is observed
near the metamaterial resonance. © 2011 American Institute
of Physics.},
Doi = {10.1063/1.3592574},
Key = {fds269740}
}
@article{fds335103,
Author = {Ren, Y and Kaye, SM and Mazzucato, E and Guttenfelder, W and Bell, RE and Domier, CW and Leblanc, BP and Lee, KC and Luhmann, NC and Smith, DR and Yuh, H},
Title = {Density gradient stabilization of electron temperature
gradient driven turbulence in a spherical
tokamak},
Journal = {Physical Review Letters},
Volume = {106},
Number = {16},
Publisher = {American Physical Society (APS)},
Year = {2011},
Month = {April},
url = {http://dx.doi.org/10.1103/PhysRevLett.106.165005},
Abstract = {In this Letter we report the first clear experimental
observation of density gradient stabilization of electron
temperature gradient driven turbulence in a fusion plasma.
It is observed that longer wavelength modes, kρs10, are
most stabilized by density gradient, and the stabilization
is accompanied by about a factor of 2 decrease in the plasma
effective thermal diffusivity. © 2011 American Physical
Society.},
Doi = {10.1103/PhysRevLett.106.165005},
Key = {fds335103}
}
@article{fds269738,
Author = {Arritt, BJ and Smith, DR and Khraishi, T},
Title = {Equivalent circuit analysis of metamaterial strain-dependent
effective medium parameters},
Journal = {Journal of Applied Physics},
Volume = {109},
Number = {7},
Pages = {073512-073512},
Publisher = {AIP Publishing},
Year = {2011},
Month = {April},
ISSN = {0021-8979},
url = {http://dx.doi.org/10.1063/1.3569742},
Abstract = {In this paper, we analytically describe the strain-dependent
effective medium properties for a metamaterial electric-LC
(ELC) resonator, commonly used in metamaterial designs to
provide a tailored electric response to electromagnetic
waves. Combining an equivalent circuit model of the ELC
resonator with existing analytic expressions for the
capacitive and inductive regions comprising the structure,
we obtain strain-dependent permittivity and permeability
curves for the metamaterial. The derived expressions account
for the effects of spatial dispersion and losses. © 2011
American Institute of Physics.},
Doi = {10.1063/1.3569742},
Key = {fds269738}
}
@article{fds269739,
Author = {Poutrina, E and Huang, D and Urzhumov, Y and Smith,
DR},
Title = {Nonlinear oscillator metamaterial model: numerical and
experimental verification.},
Journal = {Optics express},
Volume = {19},
Number = {9},
Pages = {8312-8319},
Year = {2011},
Month = {April},
url = {http://www.ncbi.nlm.nih.gov/pubmed/21643082},
Abstract = {We verify numerically and experimentally the accuracy of an
analytical model used to derive the effective nonlinear
susceptibilities of a varactor-loaded split ring resonator
(VLSRR) magnetic medium. For the numerical validation, a
nonlinear oscillator model for the effective magnetization
of the metamaterial is applied in conjunction with Maxwell
equations and the two sets of equations solved numerically
in the time-domain. The computed second harmonic generation
(SHG) from a slab of a nonlinear material is then compared
with the analytical model. The computed SHG is in excellent
agreement with that predicted by the analytical model, both
in terms of magnitude and spectral characteristics.
Moreover, experimental measurements of the power transmitted
through a fabricated VLSRR metamaterial at several power
levels are also in agreement with the model, illustrating
that the effective medium techniques associated with
metamaterials can accurately be transitioned to nonlinear
systems.},
Doi = {10.1364/oe.19.008312},
Key = {fds269739}
}
@article{fds269737,
Author = {Mock, JJ and Norton, SM and Chen, SY and Lazarides, AA and Smith,
DR},
Title = {Electromagnetic Enhancement Effect Caused by Aggregation on
SERS-Active Gold Nanoparticles},
Journal = {Plasmonics},
Volume = {6},
Number = {1},
Pages = {113-124},
Publisher = {Springer Nature},
Year = {2011},
Month = {March},
ISSN = {1557-1955},
url = {http://dx.doi.org/10.1007/s11468-010-9176-1},
Abstract = {We report a morphology-correlated surface-enhanced Raman
scattering (SERS) from molecules on the surface of
individual clusters of gold nanoparticles of two types and
compare the signal from clusters of two, three, four, and
five nanoparticles with the signal from single particles.
Cluster geometry and particle morphology are determined from
transmission electron microscopy for both clusters of 78- to
133-nm nanospheres and clusters of ~250-nm-etched
cylindrical particles with crevices and sharp edges, formed
in templates. Scattering from molecules on etched cylinders,
but not spheres, is sufficiently strong to allow spectra to
be collected from single particles illuminated at 632.8 nm.
SERS intensities from clusters of cylinders are found to
scale linearly with particle number, whereas, for
nanospheres, the scaling is non-linear. The linear scaling
of SERS from cylinders is a reflection of the high
enhancement provided by the sharp features of the individual
particles; whereas, the non-linear scaling of SERS from
clusters of spheres is found to be consistent with the
near-field enhancement from inter-particle coupling
simulated for clusters of spheres arranged in
representative-observed geometries. © 2010 Springer
Science+Business Media, LLC.},
Doi = {10.1007/s11468-010-9176-1},
Key = {fds269737}
}
@article{fds335104,
Author = {Smith, DR and Guttenfelder, W and Leblanc, BP and Mikkelsen,
DR},
Title = {Identification of microtearing modes below the ion gyroscale
in the National Spherical Torus Experiment},
Journal = {Plasma Physics and Controlled Fusion},
Volume = {53},
Number = {3},
Pages = {035013-035013},
Publisher = {IOP Publishing},
Year = {2011},
Month = {March},
url = {http://dx.doi.org/10.1088/0741-3335/53/3/035013},
Abstract = {Gyrokinetic calculations indicate microtearing modes below
the ion gyroscale are linearly unstable in a National
Spherical Torus Experiment (NSTX) plasma. The modes are
robustly unstable with respect to simulation parameters,
radial location and discharge time. The modes exist at
higher wavenumbers and exhibit narrower electric potential
mode structures than conventional microtearing modes, but
both modes extend to similar normalized radial wavenumbers.
Mode growth rates increase with higher electron temperature
gradients and higher collisionality. Finally, microtearing
modes below the ion gyroscale are the most unstable modes
near the magnetic axis, but electron temperature gradient
modes are the most unstable modes in the outer plasma
region. © 2011 IOP Publishing Ltd.},
Doi = {10.1088/0741-3335/53/3/035013},
Key = {fds335104}
}
@article{fds335105,
Author = {Yuh, HY and Kaye, SM and Levinton, FM and Mazzucato, E and Mikkelsen,
DR and Smith, DR and Bell, RE and Hosea, JC and Leblanc, BP and Peterson,
JL and Park, HK and Lee, W},
Title = {Suppression of electron temperature gradient turbulence via
negative magnetic shear in NSTX},
Journal = {Physical Review Letters},
Volume = {106},
Number = {5},
Publisher = {American Physical Society (APS)},
Year = {2011},
Month = {February},
url = {http://dx.doi.org/10.1103/PhysRevLett.106.055003},
Abstract = {Negative magnetic shear is found to suppress electron
turbulence and improve electron thermal transport for
plasmas in the National Spherical Torus Experiment (NSTX).
Sufficiently negative magnetic shear results in a transition
out of a stiff profile regime. Density fluctuation
measurements from high-k microwave scattering are verified
to be the electron temperature gradient (ETG) mode by
matching measured rest frequency and linear growth rate to
gyrokinetic calculations. Fluctuation suppression under
negligible E×B shear conditions confirm that negative
magnetic shear alone is sufficient for ETG suppression.
Measured electron temperature gradients can significantly
exceed ETG critical gradients with ETG mode activity reduced
to intermittent bursts, while electron thermal diffusivity
improves to below 0.1 electron gyro-Bohms. © 2011 American
Physical Society.},
Doi = {10.1103/PhysRevLett.106.055003},
Key = {fds335105}
}
@article{fds335096,
Author = {Hobson, PR and Leslie, DE and Smith, DR},
Title = {Effect of gamma radiation on potential ionising radiation
detectors and dosimeters based on quantum
dots},
Journal = {IEEE Nuclear Science Symposium Conference
Record},
Pages = {3015-3017},
Publisher = {IEEE},
Year = {2011},
Month = {January},
ISBN = {9781467301183},
url = {http://dx.doi.org/10.1109/NSSMIC.2011.6152542},
Abstract = {The fluorescent quantum yield of core-shell (CdSe/ZnS)
quantum dots (QDs) in hexane has recently been shown to
decrease with increasing gamma irradiation dose. Here we
report the effects on the fluorescent emission spectra of
commercially produced CdSe/ZnS QDs of 2.5 nm, 3.3 nm and 6.3
nm size in toluene, following exposure to 1 MeV gamma
irradiation in the range 0.1-110 Gy. We show that damage
depends on the size of the QDs and that increasing the
concentration of QDs in the toluene decreases the effect.
Recovery of fluorescence quantum yield one day after
irradiation has been seen, with full recovery noted for the
6.3 nm QDs. © 2011 IEEE.},
Doi = {10.1109/NSSMIC.2011.6152542},
Key = {fds335096}
}
@article{fds269734,
Author = {Hunt, J and Kundtz, N and Landy, N and Nguyen, V and Perram, T and Starr,
A and Smith, DR},
Title = {Broadband wide angle lens implemented with dielectric
metamaterials.},
Journal = {Sensors (Basel, Switzerland)},
Volume = {11},
Number = {8},
Pages = {7982-7991},
Year = {2011},
Month = {January},
url = {http://www.ncbi.nlm.nih.gov/pubmed/22164056},
Abstract = {The Luneburg lens is a powerful imaging device, exhibiting
aberration free focusing for parallel rays incident from any
direction. However, its advantages are offset by a focal
surface that is spherical and thus difficult to integrate
with standard planar detector and emitter arrays. Using the
recently developed technique of transformation optics, it is
possible to transform the curved focal surface to a flat
plane while maintaining the perfect focusing behavior of the
Luneburg over a wide field of view. Here we apply these
techniques to a lesser-known refractive Luneburg lens and
implement the design with a metamaterial composed of a
semi-crystalline distribution of holes drilled in a
dielectric. In addition, we investigate the aberrations
introduced by various approximations made in the
implementation of the lens. The resulting design approach
has improved mechanical strength with small aberrations and
is ideally suited to implementation at infrared and visible
wavelengths.},
Doi = {10.3390/s110807982},
Key = {fds269734}
}
@article{fds269736,
Author = {Urzhumov, YA and Kundtz, NB and Smith, DR and Pendry,
JB},
Title = {Cross-section comparisons of cloaks designed by
transformation optical and optical conformal mapping
approaches},
Journal = {Journal of Optics},
Volume = {13},
Number = {2},
Pages = {024002-024002},
Publisher = {IOP Publishing},
Year = {2011},
Month = {January},
ISSN = {2040-8978},
url = {http://hdl.handle.net/10161/5724 Duke open
access},
Abstract = {We review several approaches to optical invisibility
designed using transformation optics (TO) and optical
conformal mapping (CM) techniques. TO is a general framework
for solving inverse scattering problems based on mimicking
spatial coordinate transformations with distributions of
material properties. There are two essential steps in the
design of TO media: first, a coordinate transformation that
achieves some desired functionality, resulting in a
continuous spatial distribution of constitutive parameters
that are generally anisotropic; and, second, the reduction
of the derived continuous constitutive parameters to a
metamaterial that serves as a stepwise approximation. We
focus here on the first step, discussing the merits of
various TO strategies proposed for the long-sought
'invisibility cloak'-a structure that renders opaque objects
invisible. We also evaluate the cloaking capabilities of
structures designed by the related CM approach, which makes
use of conformal mapping to achieve index-only material
distributions. The performance of the various cloaks is
evaluated and compared using a universal measure-the total
(all-angle) scattering cross section. © 2011 IOP Publishing
Ltd.},
Doi = {10.1088/2040-8978/13/2/024002},
Key = {fds269736}
}
@article{fds269744,
Author = {Hunt, J and Jang, G and Smith, DR},
Title = {Perfect relay lens at microwave frequencies based on
flattening a Maxwell lens},
Journal = {Journal of the Optical Society of America B: Optical
Physics},
Volume = {28},
Number = {8},
Pages = {2025-2029},
Publisher = {The Optical Society},
Year = {2011},
Month = {January},
ISSN = {0740-3224},
url = {http://dx.doi.org/10.1364/JOSAB.28.002025},
Abstract = {We consider the design and implementation of a
two-dimensional metamaterial relay lens, conceptually formed
by flattening a Maxwell fisheye lens-a perfect imaging
device-through the use of a coordinate transformation.
Because Maxwell's equations are form-invariant under
coordinate transformations, the specifications for the
constitutive parameters of the device are obtained
immediately in a procedure that has now become known as
transformation optics. To obtain a more favorable
implementation of the lens, we seek a quasi-conformal
transformation optics transformation that minimizes the
required anisotropy, such that the resulting lens can be
formed using isotropic, dielectric-only media. We
demonstrate a flattened Maxwell lens at microwave
frequencies using a nonresonant metamaterial and confirm its
focusing and broad bandwidth behavior. Such planar,
dielectric-only structures can be readily implemented in
infrared and optical waveguides. © 2011 Optical Society of
America.},
Doi = {10.1364/JOSAB.28.002025},
Key = {fds269744}
}
@article{fds269748,
Author = {Kundtz, NB and Smith, DR and Pendry, JB},
Title = {Electromagnetic design with transformation
optics},
Journal = {Proceedings of the IEEE},
Volume = {99},
Number = {10},
Pages = {1622-1633},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2011},
Month = {January},
ISSN = {0018-9219},
url = {http://dx.doi.org/10.1109/JPROC.2010.2089664},
Abstract = {Transformation optics is an emerging technique for the
design of advanced electromagnetic media. Transformation
optical devices exploit the form invariance of Maxwell's
equations, allowing geometry to play the dominant role in
the design process rather than traditional wave or ray
optics. The use of coordinate transformations vastly eases
the burden of design for a large class of devices, though at
the expense of increasing the complexity of the underlying
materials used. Although the required constitutive
parameters of a transformation optical structure can be
challenginginherently anisotropic and spatially varying,
with both magnetic and electric responsenevertheless the
parameter requirements can often be met or approximated
through the use of artificially structured metamaterials.
Here, we review the basic concepts associated with
transformation optics and provide several examples to
illustrate its application. © 2011 IEEE.},
Doi = {10.1109/JPROC.2010.2089664},
Key = {fds269748}
}
@article{fds269752,
Author = {Huang, D and Poutrina, E and Zheng, H and Smith, DR},
Title = {Design and experimental characterization of nonlinear
metamaterials},
Journal = {Journal of the Optical Society of America B: Optical
Physics},
Volume = {28},
Number = {12},
Pages = {2925-2930},
Publisher = {The Optical Society},
Year = {2011},
Month = {January},
ISSN = {0740-3224},
url = {http://dx.doi.org/10.1364/JOSAB.28.002925},
Abstract = {We apply an analytic theory [New J. Phys. 12, 093010 (2010)]
toward the design of varactor-loaded split-ring resonator
metacrystals, having nonlinear electromagnetic properties on
demand. The design methodology here is shown to be efficient
and is validated by the excellent agreement between the
analytically predicted and experimentally measured harmonic
generation. The analytic formulas enable a path toward
optimization of nonlinear properties, which we demonstrate
by varying the spacing of the metamaterial elements to
maximize the second-order nonlinear susceptibility of the
system. © 2011 Optical Society of America.},
Doi = {10.1364/JOSAB.28.002925},
Key = {fds269752}
}
@article{fds330991,
Author = {Smith, D and Elsdon, M and Leach, MP and Fernando, M and Foti,
SJ},
Title = {The use of indirect holographic techniques for microwave
imaging},
Journal = {2010 10th Mediterranean Microwave Symposium, MMS
2010},
Pages = {192-195},
Publisher = {IEEE},
Year = {2010},
Month = {December},
ISBN = {9781424472437},
url = {http://dx.doi.org/10.1109/MMW.2010.5605192},
Abstract = {This work provides a brief outline of the basic theory of
indirect microwave holography. This is supported by
experimental work which illustrates how this technique can
be used successfully in a number of areas including antenna
measurements, concealed weapons detection and medical
imaging. © 2010 IEEE.},
Doi = {10.1109/MMW.2010.5605192},
Key = {fds330991}
}
@article{fds269594,
Author = {Cui, TJ and Smith, DR and Liu, R},
Title = {Preface},
Pages = {vii-ix},
Publisher = {Springer US},
Year = {2010},
Month = {December},
ISBN = {9781441905727},
url = {http://dx.doi.org/10.1007/978-1-4419-0573-4},
Doi = {10.1007/978-1-4419-0573-4},
Key = {fds269594}
}
@article{fds269589,
Author = {Poutrina, E and Huang, D and Smith, DR},
Title = {Analysis of nonlinear electromagnetic metamaterials},
Journal = {Optics InfoBase Conference Papers},
Year = {2010},
Month = {December},
Abstract = {We derive the expressions for the effective nonlinear
susceptibilities of a metacrystal formed from resonant
elements that couple strongly to the magnetic field. We
experimentally illus-trate the accuracy and validity of our
theoretical framework. © 2008 Optical Society of
America.},
Key = {fds269589}
}
@article{fds269595,
Author = {Chin, JY and Liu, R and Cui, TJ and Smith, DR},
Title = {Rapid design for metamaterials},
Pages = {61-85},
Publisher = {Springer US},
Year = {2010},
Month = {December},
url = {http://dx.doi.org/10.1007/978-1-4419-0573-4_4},
Abstract = {Metamaterials are generally composed of sub-wavelength
structures with designable geometries. The macroscopic
properties of metamaterials are harnessed by engineering the
geometric dimensions of the particles. During the past few
years, designing metamaterials has become increasingly
time-consuming due to the growing complexity of their
electromagnetic properties and the complexity has been
spurred by the arising interest in generating inhomogeneous
and anisotropic metamaterials. Motivated by accelerating the
design process for metamaterials with excellent accuracy,
rapid design for metamaterials is introduced in this
chapter. This method is based on full-wave simulation,
S-parameter retrieval technique, and the effective medium
theory for metamaterials. The rapid design algorithm for
metamaterials is widely applicable to all particles with or
without resonances from microwave to optical regime. Its
efficiency is validated and demonstrated by a few examples.
© Springer Science+Business Media, LLC 2010.},
Doi = {10.1007/978-1-4419-0573-4_4},
Key = {fds269595}
}
@article{fds269596,
Author = {Cui, TJ and Liu, R and Smith, DR},
Title = {Introduction to metamaterials},
Pages = {1-19},
Publisher = {Springer US},
Year = {2010},
Month = {December},
url = {http://dx.doi.org/10.1007/978-1-4419-0573-4_1},
Abstract = {There have been increasing interests in metamaterials in the
past 10 years in the scientific communities. However,
metamaterials are sometimes regarded as left-handed
materials or negative refractive index materials by a lot of
people including researchers. In fact, the rapid development
in this exciting area has shown that metamaterials are far
beyond left-handed materials. In this chapter, we will
clarify what metamaterial is and report the recent progress
on metamaterials. We also summarize the important issues for
the development and future of metamaterials, including the
optical transformation, effective medium theory for periodic
structures, broadband and low-loss metamaterials, rapid
design of metamaterials, and potential applications. The
impact of computational electromagnetics on metamaterials is
briefly discussed. © Springer Science+Business Media, LLC
2010.},
Doi = {10.1007/978-1-4419-0573-4_1},
Key = {fds269596}
}
@article{fds269597,
Author = {Liu, R and Chin, JY and Ji, C and Cui, TJ and Smith,
DR},
Title = {Experiment on cloaking devices},
Pages = {99-114},
Publisher = {Springer US},
Year = {2010},
Month = {December},
url = {http://dx.doi.org/10.1007/978-1-4419-0573-4_6},
Abstract = {In this chapter, we will discuss the approach of utilizing
transformation optic approach and metamaterial technology to
construct various cloaking devices in experiment. We take
the advantage of rapid design approach to demonstrate the
reduced cloaking device in free space. Then we discuss the
next-generation cloaking device of broadband and low-loss
feature. The experiment at microwave verifies the broadband
complex cloaking design. © Springer Science+Business Media,
LLC 2010.},
Doi = {10.1007/978-1-4419-0573-4_6},
Key = {fds269597}
}
@article{fds269598,
Author = {Cui, TJ and Smith, DR and Liu, R},
Title = {Metamaterials: Theory, design, and applications},
Journal = {Metamaterials: Theory, Design, and Applications},
Pages = {1-367},
Year = {2010},
Month = {December},
url = {http://dx.doi.org/10.1007/978-1-4419-0573-4},
Abstract = {Metamaterials: Theory, Design and Applications focuses on
the most recent research activity in metamaterials, taking a
reader beyond previously covered areas like left-handed
materials (LHM) and negative index materials (LIM). Some new
developments covered in the book include a rapid design
method for inhomogeneous metamaterials, microwave and RF
applications of metamaterials and dynamic metamaterial
systems. Editors Tie Jun Cui, David R. Smith and Ruopeng Liu
bring together the leading international minds focused on
metamaterials to provide an all-encompassing look at a
rapidly-developing field. This book stands alone as a
must-read for any engineer or researcher working with
metamaterials. Drawing on their years of experience in the
field, editors Tie Jun Cui, David R. Smith and Ruopeng Liu
present a breadth of research in metamaterials, covering
areas like: Optical transformation theory, including
invisible cloaks, concentrators, beam splitters and
antennas. Photonic metamaterials and the magnetic Plasmon
effect. Experimental verification techniques for invisible
cloaks. © Springer Science+Business Media, LLC 2010. All
rights reserved.},
Doi = {10.1007/978-1-4419-0573-4},
Key = {fds269598}
}
@article{fds269599,
Author = {Liu, R and Cui, TJ and Smith, DR},
Title = {General theory on artificial metamaterials},
Pages = {49-59},
Publisher = {Springer US},
Year = {2010},
Month = {December},
url = {http://dx.doi.org/10.1007/978-1-4419-0573-4_3},
Abstract = {In this chapter, we present a general theory of effective
media to establish the relationship between the local field
responses on metamaterial structure and the macroscopical
behaviors for artificial metamaterials composed of periodic
resonant structures. By treating the unit cell of the
periodic structure as a particle, we average the local field
to define the local average permittivity and permeability
for different unit structures and derive a general form of
discrete Maxwell's equations in macroscale. We obtain
different wave modes in metamaterials including propagation
mode, pure plasma mode, and resonant crystal bandgap mode.
The distortion in the electromagnetic parameters has been
well explained by the derived spatial dispersion model.
Thus, the unfamiliar behaviors of metamaterials from the
numerical S-parameter retrieval approach is further verified
and described. The excellent agreements between the
theoretical predictions and the numerical retrieval results
indicate that the new defined model and method of analysis
fit better to the physical structures and is thereafter a
more advanced form of fitting formula for the effective
electromagnetic parameters of metamaterials. © Springer
Science+Business Media, LLC 2010.},
Doi = {10.1007/978-1-4419-0573-4_3},
Key = {fds269599}
}
@article{fds269600,
Author = {Cheng, Q and Yang, XM and Ma, HF and Chin, JY and Cui, TJ and Liu, R and Smith, DR},
Title = {Experiments and applications of metamaterials in microwave
regime},
Pages = {321-355},
Publisher = {Springer US},
Year = {2010},
Month = {December},
url = {http://dx.doi.org/10.1007/978-1-4419-0573-4_14},
Abstract = {In this chapter some experiments and applications of
metamaterials in the microwave regime have been presented.
Although metamaterials are composed of structures with
finite periodicity, they can still be regarded as effective
medium when the periodicity is far smaller than the
wavelength. We discuss some interesting experiments such as
the tunneling structure and the partial focusing phenomenon
and investigate several applications like gradient index
circuit and the Luneberg lens antenna. The simulation and
experimental results show that metamaterials may have great
potentials in the design of microwave devices and antennas.
© Springer Science+Business Media, LLC 2010.},
Doi = {10.1007/978-1-4419-0573-4_14},
Key = {fds269600}
}
@article{fds269601,
Author = {Liu, R and Cheng, Q and Cui, TJ and Smith, DR},
Title = {Broadband and low-loss non-resonant metamaterials},
Pages = {87-97},
Publisher = {Springer US},
Year = {2010},
Month = {December},
url = {http://dx.doi.org/10.1007/978-1-4419-0573-4_5},
Abstract = {Loss and bandwidth have been major problems that limit the
potential applications on metamaterials for a long time. To
bring the ultimate opportunity to metamaterials, we analyze
and discuss, in this chapter, another type of metamaterials
that perform at low loss and broad bandwidth. Although the
range of structures is limited to those having only electric
response, with an electric permittivity always equal to or
greater than unity, there are still numerous metamaterial
design possibilities enabled by leveraging the non-resonant
elements. For example, a gradient, impedance matching layer
can be added that drastically reduces the return loss of the
optical elements, making them essentially reflectionless and
lossless. In microwave experiments, we demonstrate the
broadband design concepts with a gradient-index lens and a
beam-steering element, both of which are confirmed to
operate over the entire X-band (roughly 8-12∈GHz)
frequency spectrum. © Springer Science+Business Media, LLC
2010.},
Doi = {10.1007/978-1-4419-0573-4_5},
Key = {fds269601}
}
@article{fds269696,
Author = {Pryor, AD and Pappas, TN and Branch, MS},
Title = {Preface},
Journal = {Gastrointestinal Bleeding: A Practical Approach to Diagnosis
and Management},
Volume = {6},
Number = {1},
Pages = {1-2},
Publisher = {Elsevier BV},
Year = {2010},
Month = {December},
ISSN = {1569-4410},
url = {http://dx.doi.org/10.1007/978-1-4419-1693-8},
Doi = {10.1007/978-1-4419-1693-8},
Key = {fds269696}
}
@article{fds269713,
Author = {Ghezzo, F and Starr, AF and Smith, DR},
Title = {Integration of networks of sensors and electronics for
structural health monitoring of composite
materials},
Journal = {Advances in Civil Engineering},
Volume = {2010},
Pages = {1-13},
Publisher = {Hindawi Limited},
Year = {2010},
Month = {December},
ISSN = {1687-8086},
url = {http://dx.doi.org/10.1155/2010/598458},
Abstract = {The low-cost, widespread availability and robust nature of
current electronic devices suggest the feasibility of
creating a composite structure with integrated networked
sensors to monitor in real time the life of civil and
aerospace structures while in service conditions. For
structures that need to survive to high number of life
cycles under varying load-environmental conditions, it is of
crucial importance that the strength, stiffness, endurance,
and general load-bearing capabilities of the composite not
to be severely degraded by the integrated networked
components. Therefore, design tools must be developed to
achieve optimized, safe, and reliable structures. High
values of stress concentrations due to the presence of a
rigid device within a highly anisotropic material can
trigger the initiation of microcracks in the resin matrix.
To quantify these effects, the acoustic emission technique
is used to characterize the initiation of microfailures
within laminated composites with integrated electronics. ©
2010 Fabrizia Ghezzo et al.},
Doi = {10.1155/2010/598458},
Key = {fds269713}
}
@article{fds269730,
Author = {Driscoll, T and Smith, DR and Basov, DN},
Title = {Spectroscopic investigation of metamaterials across the
effective medium threshold},
Journal = {Metamaterials},
Volume = {4},
Number = {4},
Pages = {175-180},
Publisher = {Elsevier BV},
Year = {2010},
Month = {December},
ISSN = {1873-1988},
url = {http://dx.doi.org/10.1016/j.metmat.2010.06.002},
Abstract = {We spectroscopically investigate the scaling properties of a
metamaterial consisting of a square array of gold
cylindrical dots. The electromagnetic response of the
gold-dot array is found to scale in relation to the ratio of
the incident wavelength over the array spacing, in agreement
with general predictions of metamaterial theory. The
appropriateness of an effective medium description of the
array is analyzed in terms of the resonant polarizability of
the array components, and the onset of van der Hulst
backscattering at higher frequencies. © 2010 Elsevier
B.V.},
Doi = {10.1016/j.metmat.2010.06.002},
Key = {fds269730}
}
@article{fds269712,
Author = {Nguyen, VN and Yönak, SH and Smith, DR},
Title = {Multilayer W-band artificial dielectric on liquid crystal
polymer},
Journal = {IEEE Antennas and Wireless Propagation Letters},
Volume = {9},
Pages = {974-977},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2010},
Month = {November},
ISSN = {1536-1225},
url = {http://dx.doi.org/10.1109/LAWP.2010.2088104},
Abstract = {We present an artificial dielectric material designed to
operate at W-band millimeter-wave frequencies. The
artificial dielectric exhibits a wide range of variation in
its effective refractive index, making it suitable for use
in planar gradient index (GRIN) microwave lenses and other
quasi-optical devices. These devices include those designed
using recently developed transformation optics techniques.
Because the artificial materials are designed to be
nonresonant, their effective refractive indices display very
low dispersion with frequency; simulation and measurement
results for a number of test samples are presented that
confirm the expected broad bandwidth properties. A
comparison between the expected and experimentally
determined indices-of-refraction for these samples further
reveals close, quantitative agreement. © 2010
IEEE.},
Doi = {10.1109/LAWP.2010.2088104},
Key = {fds269712}
}
@article{fds330994,
Author = {Jiang, Y and Foti, SJ and Sambell, A and Smith, D},
Title = {A low profile radiating element with nearly hemispheric
coverage for satellite communications on-the-move hybrid
array antenna},
Journal = {2010 7th International Symposium on Communication Systems,
Networks and Digital Signal Processing, CSNDSP
2010},
Pages = {123-127},
Year = {2010},
Month = {November},
ISBN = {9781861353696},
Abstract = {A novel design solution of a dual-linearly-polarised Ku-band
low-profile radiating element for low elevation angle
coverage (down to 10° above horizon) is presented. Such an
element is suitable for full-duplex Satellite Communications
On-The-Move (SCOTM) hybrid scanned phased array antenna
applications. Standard-designed radiating elements for array
applications with low profile physical structure suffer poor
low elevation angle coverage as the element pattern reduces
by sine of the elevation angle. The element design
demonstrated in this paper features unique louvered array
element geometry incorporating a spatial "ray bending" lens
facilitates the shaping of the element pattern to increase
gain at low elevation angles. Preliminary modelling results
using ray-tracing analysis shows that the desired low angle
coverage can be achieved. Currently in progress full 3D
electromagnetic simulations which include the interaction
between the basic radiator and the spatial lens indicates
that using an ideal tilted element with novel louvered
reflector in addition with proposed lens, low angular
coverage can potentially be realised in a low profile
structure. © 2010 IEEE.},
Key = {fds330994}
}
@article{fds269646,
Author = {Arritt, B and Adomanis, B and Khraishi, T and Smith,
D},
Title = {Parametric analysis of the strain-dependent behavior of a
metamaterial electric resonator},
Journal = {Applied Physics Letters},
Volume = {97},
Number = {19},
Pages = {191907-191907},
Publisher = {AIP Publishing},
Year = {2010},
Month = {November},
ISSN = {0003-6951},
url = {http://dx.doi.org/10.1063/1.3507892},
Abstract = {In this paper, we describe the strain-dependent behavior of
an electric-LC (ELC) resonator unit cell, commonly used in
metamaterial designs. We leverage analytic expression to
understand the way strain manifests itself in a change in
electromagnetic (EM) response. We verify the simplified
physical models using full-wave simulations and generalize
the trends to accommodate the strain profile for any
arbitrary plane-stress loading scenario. © 2010 American
Institute of Physics.},
Doi = {10.1063/1.3507892},
Key = {fds269646}
}
@article{fds269729,
Author = {Landy, NI and Kundtz, N and Smith, DR},
Title = {Designing three-dimensional transformation optical media
using quasiconformal coordinate transformations.},
Journal = {Physical review letters},
Volume = {105},
Number = {19},
Pages = {193902},
Year = {2010},
Month = {November},
url = {http://www.ncbi.nlm.nih.gov/pubmed/21231170},
Abstract = {We introduce an approach to the design of three-dimensional
transformation optical (TO) media based on a generalized
quasiconformal mapping approach. The generalized
quasiconformal TO (QCTO) approach enables the design of
media that can, in principle, be broadband and low loss,
while controlling the propagation of waves with arbitrary
angles of incidence and polarization. We illustrate the
method in the design of a three-dimensional carpet ground
plane cloak and of a flattened Luneburg lens. Ray-trace
studies provide a confirmation of the performance of the
QCTO media, while also revealing the limited performance of
index-only versions of these devices.},
Doi = {10.1103/physrevlett.105.193902},
Key = {fds269729}
}
@article{fds269803,
Author = {Chen, S-Y and Mock, JJ and Hill, RT and Chilkoti, A and Smith, DR and Lazarides, AA},
Title = {Gold nanoparticles on polarizable surfaces as Raman
scattering antennas.},
Journal = {ACS nano},
Volume = {4},
Number = {11},
Pages = {6535-6546},
Year = {2010},
Month = {November},
url = {http://www.ncbi.nlm.nih.gov/pubmed/21038892},
Abstract = {Surface plasmons supported by metal nanoparticles are
perturbed by coupling to a surface that is polarizable.
Coupling results in enhancement of near fields and may
increase the scattering efficiency of radiative modes. In
this study, we investigate the Rayleigh and Raman scattering
properties of gold nanoparticles functionalized with cyanine
deposited on silicon and quartz wafers and on gold thin
films. Dark-field scattering images display red shifting of
the gold nanoparticle plasmon resonance and doughnut-shaped
scattering patterns when particles are deposited on silicon
or on a gold film. The imaged radiation patterns and
individual particle spectra reveal that the polarizable
substrates control both the orientation and brightness of
the radiative modes. Comparison with simulation indicates
that, in a particle-surface system with a fixed junction
width, plasmon band shifts are controlled quantitatively by
the permittivity of the wafer or the film. Surface-enhanced
resonance Raman scattering (SERRS) spectra and images are
collected from cyanine on particles on gold films. SERRS
images of the particles on gold films are doughnut-shaped as
are their Rayleigh images, indicating that the SERRS is
controlled by the polarization of plasmons in the antenna
nanostructures. Near-field enhancement and radiative
efficiency of the antenna are sufficient to enable Raman
scattering cyanines to function as gap field probes. Through
collective interpretation of individual particle Rayleigh
spectra and spectral simulations, the geometric basis for
small observed variations in the wavelength and intensity of
plasmon resonant scattering from individual antenna on the
three surfaces is explained.},
Doi = {10.1021/nn101644s},
Key = {fds269803}
}
@article{fds335106,
Author = {Poli, FM and Ethier, S and Wang, W and Hahm, TS and Mazzucato, E and Smith,
DR},
Title = {A synthetic diagnostic for validation of electron gyroradius
scale turbulence simulations against coherent scattering
measurements},
Journal = {Physics of Plasmas},
Volume = {17},
Number = {11},
Pages = {112514-112514},
Publisher = {AIP Publishing},
Year = {2010},
Month = {November},
url = {http://dx.doi.org/10.1063/1.3492715},
Abstract = {Comparison between spectra of short-scale density
fluctuations measured with coherent electromagnetic
scattering experiments and those extracted from
space-resolved numerical simulations is affected by a number
of systematic errors. These include the locality of
scattering measurements, the different domain covered
(space-resolved simulations versus wavenumber resolved
measurements), and the stationarity of simulated nonlinear
spectra. To bridge the gap between theory-simulations and
experiments, a synthetic diagnostic for high- k scattering
measurements has been developed. This synthetic scattering
predicts the propagation of the beam in an anisotropic,
inhomogeneous plasma and accounts for the spatial variation
of the instrumental transfer function. The latter, in
particular, is proven to provide an important calibration
factor not only for the simulated spectra, but also for the
measured ones, allowing the use of the synthetic diagnostic
in predictive mode. Results from a case study for National
Spherical Torus Experiment plasmas using high- k tangential
scattering system [Smith, Rev. Sci. Instrum. 75, 3840
(2004)] and the gyrokinetic tokamak simulation code [Wang,
Phys. Plasmas 13, 092505 (2006)] are presented. © 2010
American Institute of Physics.},
Doi = {10.1063/1.3492715},
Key = {fds335106}
}
@article{fds335108,
Author = {Schoenbeck, NL and Ellington, SD and Fonck, RJ and Jaehnig, K and McKee,
GR and Smith, D and Uzun-Kaymak, IU and Winz, G},
Title = {Low-noise, high-speed detector development for optical
turbulence fluctuation measurements for NSTX},
Journal = {Review of Scientific Instruments},
Volume = {81},
Number = {10},
Pages = {10D718-10D718},
Publisher = {AIP Publishing},
Year = {2010},
Month = {October},
url = {http://dx.doi.org/10.1063/1.3483196},
Abstract = {A new beam emission spectroscopy (BES) diagnostic is under
development. Photon-noise limited measurements of neutral
beam emissions are achieved using photoconductive
photodiodes with a novel frequency-compensated broadband
preamplifier. The new BES system includes a next-generation
preamplifier and upgraded optical coupling system. Notable
features of the design are surface-mount components,
minimized stray capacitance, a wide angular acceptance
photodiode, a differential output line driver, reduced input
capacitance, doubling of the frequency range, net reduced
electronic noise, and elimination of the need for a
cryogenic cooling system. The irreducible photon noise
dominates the noise up to 800 kHz for a typical input power
of 60 nW. This new assembly is being integrated into an
upgraded multichannel optical detector assembly for a new
BES system on the NSTX experiment. © 2010 American
Institute of Physics.},
Doi = {10.1063/1.3483196},
Key = {fds335108}
}
@article{fds335109,
Author = {Uzun-Kaymak, IU and Fonck, RJ and McKee, GR and Schoenbeck, N and Smith,
D and Winz, G and Yan, Z},
Title = {Ultrafast spectroscopy diagnostic to measure localized ion
temperature and toroidal velocity fluctuations},
Journal = {Review of Scientific Instruments},
Volume = {81},
Number = {10},
Pages = {10D714-10D714},
Publisher = {AIP Publishing},
Year = {2010},
Month = {October},
url = {http://dx.doi.org/10.1063/1.3479114},
Abstract = {A dual-channel high-efficiency, high-throughput custom
spectroscopic system has been designed and implemented at
DIII-D to measure localized ion thermal fluctuations
associated with drift wave turbulence. A large-area
prism-coupled transmission grating and high-throughput
collection optics are employed to observe C VI emission
centered near λ=529 nm. The diagnostic achieves 0.25 nm
resolution over a 2.0 nm spectral band via eight discrete
spectral channels. A turbulence-relevant time resolution of
1 μs is achieved using cooled high-speed avalanche
photodiodes and ultralow-noise preamplifiers. The system
sensitivity is designed to provide measurements of
normalized ion temperature fluctuations on the order of δ
Ti/Ti 1%. © 2010 American Institute of Physics.},
Doi = {10.1063/1.3479114},
Key = {fds335109}
}
@article{fds335107,
Author = {Smith, DR and Feder, H and Feder, R and Fonck, RJ and Labik, G and McKee,
GR and Schoenbeck, N and Stratton, BC and Uzun-Kaymak, I and Winz,
G},
Title = {Overview of the beam emission spectroscopy diagnostic system
on the National Spherical Torus Experiment},
Journal = {Review of Scientific Instruments},
Volume = {81},
Number = {10},
Pages = {10D717-10D717},
Publisher = {AIP Publishing},
Year = {2010},
Month = {October},
url = {http://dx.doi.org/10.1063/1.3478660},
Abstract = {A beam emission spectroscopy (BES) system has been installed
on the National Spherical Torus Experiment (NSTX) to study
ion gyroscale fluctuations. The BES system measures Dα
emission from a deuterium neutral heating beam. The system
includes two optical views centered at r/a≈0.45 and 0.85
and aligned to magnetic field pitch angles at the neutral
beam. f/1.5 collection optics produce 2-3 cm spot sizes at
the neutral beam. The initial channel layout includes radial
arrays, poloidal arrays, and two-dimensional grids. Radial
arrays provide coverage from r/a≈0.1 to beyond the
last-closed flux surface. Photodetectors and digital filters
provide high-sensitivity, low-noise measurements at
frequencies of up to 1 MHz. The BES system will be a
valuable tool for investigating ion gyroscale turbulence and
Alfv́n/energetic particle modes on NSTX. © 2010 American
Institute of Physics.},
Doi = {10.1063/1.3478660},
Key = {fds335107}
}
@article{fds269727,
Author = {Ghezzo, F and Smith, DR and Starr, TN and Perram, T and Starr, AF and Darlington, TK and Baldwin, RK and Oldenburg, SJ},
Title = {Erratum: Development and characterization of healable carbon
fiber composites with a reversibly cross linked polymer
(Journal of Composite Materials 44:13 (1587-1603))},
Journal = {Journal of Composite Materials},
Volume = {44},
Number = {22},
Pages = {2619},
Publisher = {SAGE Publications},
Year = {2010},
Month = {October},
ISSN = {0021-9983},
url = {http://dx.doi.org/10.1177/0021998310387033},
Doi = {10.1177/0021998310387033},
Key = {fds269727}
}
@article{fds269728,
Author = {Urzhumov, YA and Smith, DR},
Title = {Transformation optics with photonic band gap
media.},
Journal = {Physical review letters},
Volume = {105},
Number = {16},
Pages = {163901},
Year = {2010},
Month = {October},
url = {http://www.ncbi.nlm.nih.gov/pubmed/21230972},
Abstract = {We introduce a class of optical media based on adiabatically
modulated, dielectric-only, and potentially extremely
low-loss, photonic crystals (PC). The media we describe
represent a generalization of the eikonal limit of
transformation optics (TO). The basis of the concept is the
possibility to fit some equal frequency surfaces of certain
PCs with elliptic surfaces, allowing them to mimic the
dispersion relation of light in anisotropic effective media.
PC cloaks and other TO devices operating at visible
wavelengths can be constructed from optically transparent
substances such as glasses, whose attenuation coefficient
can be as small as 10 dB/km, suggesting the TO design
methodology can be applied to the development of optical
devices not limited by the losses inherent to metal-based,
passive metamaterials.},
Doi = {10.1103/physrevlett.105.163901},
Key = {fds269728}
}
@article{fds269802,
Author = {Hill, RT and Mock, JJ and Urzhumov, Y and Sebba, DS and Oldenburg, SJ and Chen, S-Y and Lazarides, AA and Chilkoti, A and Smith,
DR},
Title = {Leveraging nanoscale plasmonic modes to achieve reproducible
enhancement of light.},
Journal = {Nano letters},
Volume = {10},
Number = {10},
Pages = {4150-4154},
Year = {2010},
Month = {October},
url = {http://www.ncbi.nlm.nih.gov/pubmed/20804206},
Abstract = {The strongly enhanced and localized optical fields that
occur within the gaps between metallic nanostructures can be
leveraged for a wide range of functionality in nanophotonic
and optical metamaterial applications. Here, we introduce a
means of precise control over these nanoscale gaps through
the application of a molecular spacer layer that is
self-assembled onto a gold film, upon which gold
nanoparticles (NPs) are deposited electrostatically.
Simulations using a three-dimensional finite element model
and measurements from single NPs confirm that the gaps
formed by this process, between the NP and the gold film,
are highly reproducible transducers of surface-enhanced
resonant Raman scattering. With a spacer layer of roughly
1.6 nm, all NPs exhibit a strong Raman signal that decays
rapidly as the spacer layer is increased.},
Doi = {10.1021/nl102443p},
Key = {fds269802}
}
@article{fds269725,
Author = {Degiron, A and Smith, DR},
Title = {Nonlinear long-range plasmonic waveguides},
Journal = {Physical Review A - Atomic, Molecular, and Optical
Physics},
Volume = {82},
Number = {3},
Publisher = {American Physical Society (APS)},
Year = {2010},
Month = {September},
ISSN = {1050-2947},
url = {http://hdl.handle.net/10161/3309 Duke open
access},
Abstract = {We report on plasmonic waveguides made of a thin metal
stripe surrounded on one or both sides by a Kerr nonlinear
medium. Using an iterative numerical method, we investigate
the stationary long-range plasmons that exist for
self-focusing and self-defocusing Kerr-type nonlinearities.
The solutions are similar to the well-known case of
infinitely wide nonlinear waveguides-they are strongly
power-dependent and can experience symmetry-breaking
bifurcations under appropriate conditions. © 2010 The
American Physical Society.},
Doi = {10.1103/PhysRevA.82.033812},
Key = {fds269725}
}
@article{fds335110,
Author = {Walker, TE and Smith, DR and Howe, CJ and Kellett, BJ and Sreekumar, P and Grande, M},
Title = {The effects of radiation damage on the spectral resolution
of the Chandrayaan-1 x-ray spectrometer},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {7742},
Publisher = {SPIE},
Year = {2010},
Month = {September},
ISBN = {9780819482327},
url = {http://dx.doi.org/10.1117/12.858648},
Abstract = {The Chandrayaan-1 X-ray Spectrometer (C1XS) was launched
onboard the Indian Space Research Organisation (ISRO)
Chandrayaan-1 lunar mission in October 2008. The instrument
consisted of 24 swept-charge device silicon X-ray detectors
providing a total collecting area of ~24 cm2, corresponding
to a 14° field of view (FWHM), with the ability to measure
X-rays from 0.8 - 10 keV. During the 10 months the
spacecraft was located in orbit around the Moon a number of
solar flare X-ray events were detected, along with
calibration data from X-ray sources housed inside the
movable door of the instrument. This paper presents a study
of the degradation in spectral resolution of the measured
X-ray calibration lines, comparing those recorded mid way
through the mission lifetime with ground based calibration
data collected prior to the launch of the instrument. The
radiation environment the detectors were subjected to is
discussed in light of the actual radiation damage effects on
the spectral resolution observed in flight. © 2010
SPIE.},
Doi = {10.1117/12.858648},
Key = {fds335110}
}
@article{fds269723,
Author = {Poutrina, E and Huang, D and Smith, DR},
Title = {Analysis of nonlinear electromagnetic metamaterials},
Journal = {New Journal of Physics},
Volume = {12},
Number = {9},
Pages = {093010-093010},
Publisher = {IOP Publishing},
Year = {2010},
Month = {September},
ISSN = {1367-2630},
url = {http://dx.doi.org/10.1088/1367-2630/12/9/093010},
Abstract = {We analyze the properties of a nonlinear metamaterial formed
by integrating nonlinear components or materials into the
capacitive regions of metamaterial elements. A
straightforward homogenization procedure leads to general
expressions for the nonlinear susceptibilities of the
composite metamaterial medium. The expressions are
convenient, as they enable an inhomogeneous system of
scattering elements to be described as a continuous medium
using the standard notation of nonlinear optics. We
illustrate the validity and accuracy of our theoretical
framework by performing measurements on a fabricated
metamaterial sample composed of an array of split ring
resonators (SRRs) with packaged varactors embedded in the
capacitive gaps, in a manner similar to that of Wang et al
(2008 Opt. Express 16 16058). Because the SRRs exhibit a
predominantly magnetic response to electromagnetic fields,
the varactor-loaded SRR composite can be described as a
magnetic material with nonlinear terms in its effective
magnetic susceptibility. Treating the composite as a
nonlinear effective medium, we can quantitatively assess the
performance of the medium to enhance and facilitate
nonlinear processes, including second harmonic generation,
three-and four-wave mixing, selffocusing and other
well-known nonlinear phenomena. We illustrate the accuracy
of our approach by predicting the intensity-dependent
resonance frequency shift in the effective permeability of
the varactor-loaded SRR medium and comparing with
experimental measurements. © IOP Publishing Ltd and
Deutsche Physikalische Gesellschaft.},
Doi = {10.1088/1367-2630/12/9/093010},
Key = {fds269723}
}
@article{fds269724,
Author = {Smith, DR and Urzhumov, Y and Kundtz, NB and Landy,
NI},
Title = {Enhancing imaging systems using transformation
optics.},
Journal = {Optics express},
Volume = {18},
Number = {20},
Pages = {21238-21251},
Year = {2010},
Month = {September},
url = {http://www.ncbi.nlm.nih.gov/pubmed/20941020},
Abstract = {We apply the transformation optical technique to modify or
improve conventional refractive and gradient index optical
imaging devices. In particular, when it is known that a
detector will terminate the paths of rays over some surface,
more freedom is available in the transformation approach,
since the wave behavior over a large portion of the domain
becomes unimportant. For the analyzed configurations,
quasi-conformal and conformal coordinate transformations can
be used, leading to simplified constitutive parameter
distributions that, in some cases, can be realized with
isotropic index; index-only media can be low-loss and have
broad bandwidth. We apply a coordinate transformation to
flatten a Maxwell fish-eye lens, forming a near-perfect
relay lens; and also flatten the focal surface associated
with a conventional refractive lens, such that the system
exhibits an ultra-wide field-of-view with reduced
aberration.},
Doi = {10.1364/oe.18.021238},
Key = {fds269724}
}
@article{fds269726,
Author = {Rose, A and Larouche, S and Huang, D and Poutrina, E and Smith,
DR},
Title = {Nonlinear parameter retrieval from three- and four-wave
mixing in metamaterials.},
Journal = {Physical review. E, Statistical, nonlinear, and soft matter
physics},
Volume = {82},
Number = {3 Pt 2},
Pages = {036608},
Year = {2010},
Month = {September},
ISSN = {1539-3755},
url = {http://hdl.handle.net/10161/4289 Duke open
access},
Abstract = {We present a generalized nonlinear susceptibility retrieval
method for metamaterials based on transfer matrices and
valid in the nondepleted pump approximation. We construct a
general formalism to describe the transfer matrix method for
nonlinear media and apply it to the processes of three- and
four-wave mixing. The accuracy of this approach is verified
via finite element simulations. The method is then reversed
to give a set of equations for retrieving the nonlinear
susceptibility. Finally, we apply the proposed retrieval
operation to a three-wave mixing transmission experiment
performed on a varactor loaded split ring resonator
metamaterial sample and find quantitative agreement with an
analytical effective medium theory model.},
Doi = {10.1103/physreve.82.036608},
Key = {fds269726}
}
@article{fds269801,
Author = {Sajuyigbe, S and Ross, M and Geren, P and Cummer, SA and Tanielian, MH and Smith, DR},
Title = {Wide angle impedance matching metamaterials for
waveguide-fed phased-array antennas},
Journal = {IET Microwaves, Antennas and Propagation},
Volume = {4},
Number = {8},
Pages = {1063-1072},
Publisher = {Institution of Engineering and Technology
(IET)},
Year = {2010},
Month = {August},
ISSN = {1751-8725},
url = {http://dx.doi.org/10.1049/iet-map.2009.0543},
Abstract = {This work investigates the gains realisable through the use
of artificially structured materials, otherwise known as
metamaterials, in the wide angle impedance matching (WAIM)
of waveguide-fed phased-array antennas. The authors propose
that the anisotropic properties of a metamaterial layer,
when designed appropriately, can be employed to achieve
impedance matching at a wide contiguous range of
phased-array antenna transmission angles. Simulation and
numerical results show that an optimised impedance match
over a broad angular range can be readily achieved using a
doubly uniaxial (magnetic and electric) anisotropic layer,
an outcome not found accomplishable when an optimised
isotropic dielectric layer is used. The authors propose the
possibility of using metamaterials to achieve anisotropic
WAIM layer configurations, and the authors show, using two
simple uniaxial designs, that a metamaterial layer over the
phased-array gives performance characteristics similar to
its homogeneous anisotropic effective medium counterpart. ©
2010 The Institution of Engineering and Technology.},
Doi = {10.1049/iet-map.2009.0543},
Key = {fds269801}
}
@article{fds269721,
Author = {Hunt, J and Kundtz, N and Landy, N and Smith, DR},
Title = {Relaxation approach for the generation of inhomogeneous
distributions of uniformly sized particles},
Journal = {Applied Physics Letters},
Volume = {97},
Number = {2},
Pages = {024104-024104},
Publisher = {AIP Publishing},
Year = {2010},
Month = {July},
ISSN = {0003-6951},
url = {http://hdl.handle.net/10161/3238 Duke open
access},
Abstract = {For many applications in gradient index devices and photonic
crystals, it is necessary to be able to design
semicrystalline distributions of particles where the lattice
constant of the distribution is an arbitrary function of
position. We propose a method to generate such distributions
which is physically motivated by a system of interacting
particles, and apply it to the design and implementation of
a microwave gradient index lens. While the demonstration was
preformed at microwave wavelengths, this technique would
also be particularly useful for designing devices for
operation at IR and visible wavelengths where the
fabrication of distributions of uniformly sized holes or
columns is very easy. © 2010 American Institute of
Physics.},
Doi = {10.1063/1.3460914},
Key = {fds269721}
}
@article{fds269722,
Author = {Urzhumov, Y and Ghezzo, F and Hunt, J and Smith, DR},
Title = {Acoustic cloaking transformations from attainable material
properties},
Journal = {New Journal of Physics},
Volume = {12},
Number = {7},
Pages = {073014-073014},
Publisher = {IOP Publishing},
Year = {2010},
Month = {July},
ISSN = {1367-2630},
url = {http://hdl.handle.net/10161/5078 Duke open
access},
Abstract = {We propose a general methodology and a set of practical
recipes for the construction of ultra-broadband acoustic
cloaks-structures that can render themselves and a concealed
object undetectable by means of acoustic scattering. The
acoustic cloaks presented here are designed and function
analogously to electromagnetic cloaks. However, acoustic
cloaks in a fluid medium do not suffer the bandwidth
limitations imposed on their electromagnetic counterparts by
the finite speed of light in vacuum. In the absence of
specific metamaterials having arbitrary combinations of
quasi-static speed of sound and mass density, we explore the
flexibility of continuum transformations that produce
approximate cloaking solutions. We show that an imperfect,
eikonal acoustic cloak (that is, one which is not impedance
matched but is valid in the geometrical optics regime) with
negligible dispersion can be designed using a simple layered
geometry. Since a practical cloaking device will probably be
composed of combinations of solid materials rather than
fluids, it is necessary to consider the full elastic
properties of such media, which support shear waves in
addition to the compression waves associated with the
acoustic regime. We perform a systematic theoretical and
numerical investigation of the role of shear waves in
elastic cloaking devices. We find that for elastic
metamaterials with Poisson's ratio v > 0.49, shear waves do
not alter the cloaking effect. Such metamaterials can be
built from nearly incompressible rubbers (with v ≈ 0.499)
and fluids. We expect this finding to have applications in
other acoustic devices based on the form-invariance of the
scalar acoustic wave equation. © IOP Publishing Ltd and
Deutsche Physikalische Gesellschaft.},
Doi = {10.1088/1367-2630/12/7/073014},
Key = {fds269722}
}
@article{fds269718,
Author = {Larouche, S and Rose, A and Poutrina, E and Huang, D and Smith,
DR},
Title = {Experimental determination of the quadratic nonlinear
magnetic susceptibility of a varactor-loaded split ring
resonator metamaterial},
Journal = {Applied Physics Letters},
Volume = {97},
Number = {1},
Pages = {011109-011109},
Publisher = {AIP Publishing},
Year = {2010},
Month = {July},
ISSN = {0003-6951},
url = {http://hdl.handle.net/10161/3338 Duke open
access},
Abstract = {This letter presents a quantitative measurement of the
second harmonic generated by a slab of varactor loaded split
ring resonator metamaterial and the retrieval of the
effective quadratic nonlinear magnetic susceptibility
χ(2)musing an approach based on transfer matrices. The
retrieved value of χ(2)m is in excellent agreement with
that predicted by an analytical effective medium theory
model. © 2010 American Institute of Physics.},
Doi = {10.1063/1.3460919},
Key = {fds269718}
}
@article{fds269719,
Author = {Ghezzo, F and Smith, DR and Starr, TN and Perram, T and Starr, AF and Darlington, TK and Baldwin, RK and Oldenburg, SJ},
Title = {Development and characterization of healable carbon fiber
composites with a reversibly cross linked
polymer},
Journal = {Journal of Composite Materials},
Volume = {44},
Number = {13},
Pages = {1587-1603},
Publisher = {SAGE Publications},
Year = {2010},
Month = {June},
ISSN = {0021-9983},
url = {http://dx.doi.org/10.1177/0021998310363165},
Abstract = {Carbon fiber reinforced polymer (CFRP) laminates with
remendable cross-linked polymeric matrices were fabricated
using a modified resin transfer mold (RTM) technique. The
healable composite resin, bis-maleimide tetrafuran (2MEP4F),
was synthesized by mixing two monomers, furan (4F) and
maleimide (2MEP), at elevated temperatures. The fast kinetic
rate of the reaction of polymer constituents requires a fast
injection of the healable resin into the carbon fiber
preform. The polymer viscosity as a function of time and
temperature was experimentally quantified in order to
optimize the fabrication of the composite material and to
guarantee a uniform flow of the resin through the
reinforcement. The method was validated by characterizing
the thermo-mechanical properties of the polymerized 2MEP4F.
Additionally, the thermo-mechanical properties of the
remendable CFRP material were studied. © 2010 The
Author(s).},
Doi = {10.1177/0021998310363165},
Key = {fds269719}
}
@article{fds269782,
Author = {Dhar, S and Degiron, A and Smith, DR and Jokerst,
NM},
Title = {Planar integrated optical detection of a hybrid long-range
surface plasmon using an ingaas inverted-msm detector bonded
to silicon},
Journal = {IEEE Photonics Technology Letters},
Volume = {22},
Number = {11},
Pages = {841-843},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2010},
Month = {May},
ISSN = {1041-1135},
url = {http://dx.doi.org/10.1109/LPT.2010.2046402},
Abstract = {An InxGa1-x As thin-film inverted metalsemiconductormetal
photodetector has been integrated with a gold hybrid
long-range surface plasmon waveguide on silicon. This
integrated structure enables planar integrated optical
detection of a long-range surface plasmon wave at a
wavelength of 1.55℧ m. © 2010 IEEE.},
Doi = {10.1109/LPT.2010.2046402},
Key = {fds269782}
}
@article{fds269720,
Author = {Kundtz, N and Gaultney, D and Smith, DR},
Title = {Scattering cross-section of a transformation optics-based
metamaterial cloak},
Journal = {New Journal of Physics},
Volume = {12},
Number = {4},
Pages = {043039-043039},
Publisher = {IOP Publishing},
Year = {2010},
Month = {April},
ISSN = {1367-2630},
url = {http://dx.doi.org/10.1088/1367-2630/12/4/043039},
Abstract = {We present experimental quantitative scattering
cross-section (SCS) measurements for a metamaterial cloak.
The cloak is nearly identical to that reported in 2006;
however, quantitative experimental measurements have not yet
been reported for such a structure. This cylindrically
symmetric cloak is designed to operate at a frequency of 10
GHz and to reduce the SCS of a cylinder 50 mm in diameter.
Despite being only a crude approximation of the ideal
transformation optical design, the fabricated metamaterial
cloak is shown to reduce the SCS of the cylinder over the
frequency range from 9.91 to 10.14GHz, a span of 230MHz or a
2.3% bandwidth. The maximum reduction in the SCS is 24%.
This result provides a useful experimental, quantitative
benchmark that can form the basis for comparison of the
performances of future improved cloaking structures. © IOP
Publishing Ltd and Deutsche Physikalische
Gesellschan.},
Doi = {10.1088/1367-2630/12/4/043039},
Key = {fds269720}
}
@article{fds269715,
Author = {Larouche, S and Smith, DR},
Title = {A retrieval method for nonlinear metamaterials},
Journal = {Optics Communications},
Volume = {283},
Number = {8},
Pages = {1621-1627},
Publisher = {Elsevier BV},
Year = {2010},
Month = {April},
ISSN = {0030-4018},
url = {http://dx.doi.org/10.1016/j.optcom.2009.10.107},
Abstract = {Metamaterials are engineered periodic structures for which
it is possible to assign effective homogenized constitutive
properties. In recent years, metamaterials in which the
constituent elements are integrated with inherently
nonlinear materials or electronic components have been
considered for their potential impact on nonlinear wave
propagation. As is the case with their linear counterparts,
nonlinear metamaterials can also be assigned homogenized
effective properties. The effective constitutive parameters
of a metamaterial can be determined by a retrieval method
applied to full-wave numerical simulations of a single layer
of the structure. In this work, we present a transfer matrix
approach that extends the retrieval of metamaterial
properties to include the effective nonlinear
susceptibilities. Comparisons with time-domain finite
element simulations of continuous nonlinear slabs confirm
the validity of this approach. The proposed approach is also
applied to determine the nonlinear susceptibility of a
simple nonlinear metamaterial. © 2009 Elsevier
B.V.},
Doi = {10.1016/j.optcom.2009.10.107},
Key = {fds269715}
}
@article{fds269716,
Author = {Poutrina, E and Larouche, S and Smith, DR},
Title = {Parametric oscillator based on a single-layer resonant
metamaterial},
Journal = {Optics Communications},
Volume = {283},
Number = {8},
Pages = {1640-1646},
Publisher = {Elsevier BV},
Year = {2010},
Month = {April},
ISSN = {0030-4018},
url = {http://dx.doi.org/10.1016/j.optcom.2009.11.037},
Abstract = {We perform numerical simulations demonstrating parametric
generation and oscillation processes in a single-layer of
metamaterial composed of split ring resonators (SRRs). In
general, a parametric resonance is achieved by introducing a
time-modulation of one of the energy-storing parameters of a
resonant system. An individual SRR is a resonant system that
can be modeled as an RLC-circuit inductively coupled to an
applied time-varying magnetic field. The relatively simple
circuit model can be employed to establish the range of
parameters providing the growth of parametric oscillations
within the SRR medium. We relate the numerically predicted
circuit parameters that ensure the buildup of parametric
oscillations to those parameters expected to be available in
a modified SRR medium, in which lumped element varactors
integrated into the SRRs are used as modulable capacitance
elements. © 2009 Elsevier B.V. All rights
reserved.},
Doi = {10.1016/j.optcom.2009.11.037},
Key = {fds269716}
}
@article{fds269710,
Author = {Huang, D and Poutrina, E and Smith, DR},
Title = {Analysis of the power dependent tuning of a varactor-loaded
metamaterial at microwave frequencies},
Journal = {Applied Physics Letters},
Volume = {96},
Number = {10},
Pages = {104104-104104},
Publisher = {AIP Publishing},
Year = {2010},
Month = {March},
ISSN = {0003-6951},
url = {http://hdl.handle.net/10161/3339 Duke open
access},
Abstract = {We present an analysis of the nonlinear, power-dependent
resonance frequency shift for two metamaterial mediums
consisting of arrays of varactor-loaded split ring
resonators (VLSRRs). We confirm that, over a limited range
of power, a VLSRR medium can be described by its second and
third order nonlinear susceptibilities, making it a useful
analog medium for the quantitative investigation of other
nonlinear phenomena that might be achieved using inherently
nonlinear materials integrated into metamaterials.
Experimental measurements of the resonance frequency shift
with power from fabricated VLSRR samples are found to be in
excellent agreement with the analytical model. © 2010
American Institute of Physics.},
Doi = {10.1063/1.3356223},
Key = {fds269710}
}
@article{fds269717,
Author = {Smith, DR},
Title = {Analytic expressions for the constitutive parameters of
magnetoelectric metamaterials.},
Journal = {Physical review. E, Statistical, nonlinear, and soft matter
physics},
Volume = {81},
Number = {3 Pt 2},
Pages = {036605},
Publisher = {American Physical Society (APS)},
Year = {2010},
Month = {March},
ISSN = {1539-3755},
url = {http://hdl.handle.net/10161/4286 Duke open
access},
Abstract = {Electromagnetic metamaterials are artificially structured
media typically composed of arrays of resonant
electromagnetic circuits, the dimension and spacing of which
are considerably smaller than the free-space wavelengths of
operation. The constitutive parameters for metamaterials,
which can be obtained using full-wave simulations in
conjunction with numerical retrieval algorithms, exhibit
artifacts related to the finite size of the metamaterial
cell relative to the wavelength. Liu [R. Liu, T. J. Cui, D.
Huang, B. Zhao, and D. R. Smith, Phys. Rev. E 76, 026606
(2007)] showed that the complicated, frequency-dependent
forms of the constitutive parameters can be described by a
set of relatively simple analytical expressions. These
expressions provide useful insight and can serve as the
basis for more intelligent interpolation or optimization
schemes. Here, we show that the same analytical expressions
can be obtained using a transfer-matrix formalism applied to
a one-dimensional periodic array of thin, resonant,
dielectric, or magnetic sheets. The transfer-matrix
formalism breaks down, however, when both electric and
magnetic responses are present in the same unit cell, as it
neglects the magnetoelectric coupling between unit cells [C.
R. Simovski, Metamaterials 1, 62 (2007)]. We show that an
alternative analytical approach based on the same physical
model must be applied for such structures. Furthermore, in
addition to the intercell coupling, electric and magnetic
resonators within a unit cell may also exhibit
magnetoelectric coupling. For such cells, we find an
analytical expression for the effective index, which
displays markedly characteristic dispersion features that
depend on the strength of the coupling coefficient. We
illustrate the applicability of the derived expressions by
comparing to full-wave simulations on magnetoelectric unit
cells. We conclude that the design of metamaterials with
tailored simultaneous electric and magnetic response-such as
negative index materials-will generally be complicated by
potentially unwanted magnetoelectric coupling.},
Doi = {10.1103/physreve.81.036605},
Key = {fds269717}
}
@article{fds269714,
Author = {Kundtz, N and Smith, DR},
Title = {Extreme-angle broadband metamaterial lens.},
Journal = {Nature materials},
Volume = {9},
Number = {2},
Pages = {129-132},
Year = {2010},
Month = {February},
ISSN = {1476-1122},
url = {http://www.ncbi.nlm.nih.gov/pubmed/20023631},
Abstract = {For centuries, the conventional approach to lens design has
been to grind the surfaces of a uniform material in such a
manner as to sculpt the paths that rays of light follow as
they transit through the interfaces. Refractive lenses
formed by this procedure of bending the surfaces can be of
extremely high quality, but are nevertheless limited by
geometrical and wave aberrations that are inherent to the
manner in which light refracts at the interface between two
materials. Conceptually, a more natural--but usually less
convenient--approach to lens design would be to vary the
refractive index throughout an entire volume of space. In
this manner, far greater control can be achieved over the
ray trajectories. Here, we demonstrate how powerful emerging
techniques in the field of transformation optics can be used
to harness the flexibility of gradient index materials for
imaging applications. In particular we design and
experimentally demonstrate a lens that is broadband (more
than a full decade bandwidth), has a field-of-view
approaching 180 degrees and zero f-number. Measurements on a
metamaterial implementation of the lens illustrate the
practicality of transformation optics to achieve a new class
of optical devices.},
Doi = {10.1038/nmat2610},
Key = {fds269714}
}
@article{fds335111,
Author = {Baharin, R and Hobson, PR and Smith, DR},
Title = {Simulation of MeV electron energy deposition in CdS quantum
dots absorbed in silicate glass for radiation
dosimetry},
Journal = {Journal of Physics: Conference Series},
Volume = {244},
Number = {1},
Pages = {012007-012007},
Publisher = {IOP Publishing},
Year = {2010},
Month = {January},
url = {http://dx.doi.org/10.1088/1742-6596/244/1/012007},
Abstract = {We are currently developing 2D dosimeters with optical
readout based on CdS or CdS/CdSe core-shell quantum-dots
using commercially available materials. In order to
understand the limitations on the measurement of a 2D
radiation profile the 3D deposited energy profile of MeV
energy electrons in CdS quantum-dot-doped silica glass have
been studied by Monte Carlo simulation using the CASINO and
PENELOPE codes. Profiles for silica glass and CdS
quantum-dot-doped silica glass were then compared. © 2010
IOP Publishing Ltd.},
Doi = {10.1088/1742-6596/244/1/012007},
Key = {fds335111}
}
@article{fds330992,
Author = {Fernando, M and Busawon, K and Elsdon, M and Smith,
D},
Title = {Fundamental issues in antenna design for microwave medical
imaging applications},
Journal = {2010 7th International Symposium on Communication Systems,
Networks and Digital Signal Processing, CSNDSP
2010},
Pages = {795-800},
Year = {2010},
Month = {January},
ISBN = {9781861353696},
url = {http://dx.doi.org/10.1109/csndsp16145.2010.5580323},
Abstract = {This paper surveys the development of microwave medical
imaging and the fundamental challenges associated with
microwave antennas design for medical imaging applications.
Different microwave antennas used in medical imaging
applications such as monopoles, bow-tie, vivaldi and
pyramidal horn antennas are discussed. The challenges faced
when the latter used in medical imaging environment are
detailed. The paper provides the possible solutions for the
challenges at hand and also provides insight into the
modelling work which will help the microwave engineering
community to understand the behaviour of the microwave
antennas in coupling media. © 2010 IEEE.},
Doi = {10.1109/csndsp16145.2010.5580323},
Key = {fds330992}
}
@article{fds330993,
Author = {Bobor-Oyibo, F and Smith, D and Foti, SJ},
Title = {The effects of a finite ground plane on the characteristics
of printed patch antennas with and without a suspended
patch},
Journal = {2010 7th International Symposium on Communication Systems,
Networks and Digital Signal Processing, CSNDSP
2010},
Pages = {111-114},
Year = {2010},
Month = {January},
ISBN = {9781861353696},
url = {http://dx.doi.org/10.1109/csndsp16145.2010.5580447},
Abstract = {In most analyses of microstrip patch antennas the effects of
a finite ground plane are neglected because it is assumed
infinite. However, in mobile communication systems the
ground plane of antennas must be finite. Therefore, the
effect of the finite ground plane on the characteristics of
printed patch antenna elements is worth investigation. In
this paper a stacked patch antenna has been proposed and the
effects of a finite ground plane on the total radiation
pattern are investigated. In fact, we have shown that a
truncated ground plane of width approximately one wavelength
will produce a 3dB beam width for the patch of approximately
65 degrees in contrast to the 90 degrees which occurs for an
infinite ground plane. A physical description of the reason
for this is included. © 2010 IEEE.},
Doi = {10.1109/csndsp16145.2010.5580447},
Key = {fds330993}
}
@article{fds330995,
Author = {Fernando, MJ and Elsdon, M and Busawon, K and Smith,
D},
Title = {A Novel simplified mathematical model for antennas used in
medical imaging applications},
Journal = {Journal of Physics: Conference Series},
Volume = {255},
Number = {1},
Pages = {012001-012001},
Publisher = {IOP Publishing},
Year = {2010},
Month = {January},
url = {http://dx.doi.org/10.1088/1742-6596/255/1/012001},
Abstract = {In this paper a new technique is proposed to model the
current across a monopole antenna and thereby the radiation
fields of the antenna can be calculated. Generally, the
Method of Moments (MOM) technique is used for this purpose
whereby the integral equations are discretised to find the
fields of an antenna. The proposed model requires only the
knowledge of three parameters (Initial Current I0, Damping
coefficient a and the radial parameter τ) and hence
considerably reduces the computational time and space as its
results do not depend on the number of functions involved.
The new technique is also developed to take account of the
conductivity property of the surrounding medium. Hence this
technique can be used in field prediction for antennas
employed in medical imaging applications. Initial results
obtained from the new technique show good correlation in
comparison with the MOM technique. © 2010 IOP Publishing
Ltd.},
Doi = {10.1088/1742-6596/255/1/012001},
Key = {fds330995}
}
@article{fds335112,
Author = {Griffin, MJ and Abergel, A and Abreu, A and Ade, PAR and André, P and Augueres, JL and Babbedge, T and Bae, Y and Baillie, T and Baluteau, JP and Barlow, MJ and Bendo, G and Benielli, D and Bock, JJ and Bonhomme, P and Brisbin, D and Brockley-Blatt, C and Caldwell, M and Cara, C and Castro-Rodriguez, N and Cerulli, R and Chanial, P and Chen, S and Clark,
E and Clements, DL and Clerc, L and Coker, J and Communal, D and Conversi,
L and Cox, P and Crumb, D and Cunningham, C and Daly, F and Davis, GR and DeAntoni, P and Delderfield, J and Devin, N and Di Giorgio and A and Didschuns, I and Dohlen, K and Donati, M and Dowell, A and Dowell, CD and Duband, L and Dumaye, L and Emery, RJ and Ferlet, M and Ferrand, D and Fontignie, J and Fox, M and Franceschini, A and Frerking, M and Fulton,
T and Garcia, J and Gastaud, R and K.Gear, W and Glenn, J and Goizel, A and Griffin, DK and Grundy, T and Guest, S and Guillemet, L and Hargrave,
PC and Harwit, M and Hastings, P and Hatziminaoglou, E and Herman, M and Hinde, B and Hristov, V and Huang, M and Imhof, P and Isaak, KJ and Israelsson, U and Ivison, RJ and Jennings, D and Kiernan, B and King,
KJ and Lange, AE and Latter, W and Laurent, G and Laurent, P and Leeks, SJ and Lellouch, E and Levenson, L and Li, B and Li, J and Lilienthal, J and Lim,
T and Liu, SJ and Lu, N and Madden, S and Mainetti, G and Marliani, P and McKay, D and Mercier, K and Molinari, S and Morris, H and Moseley, H and Mulder, J and Mur, M},
Title = {The Herschel -SPIRE instrument and its in-flight
performance},
Journal = {Astronomy and Astrophysics},
Volume = {518},
Number = {4},
Pages = {L3-L3},
Publisher = {E D P SCIENCES},
Year = {2010},
Month = {January},
url = {http://dx.doi.org/10.1051/0004-6361/201014519},
Abstract = {The Spectral and Photometric Imaging REceiver (SPIRE), is
the Herschel Space Observatory's submillimetre camera and
spectrometer. It contains a three-band imaging photometer
operating at 250, 350 and 500 μm, and an imaging
Fourier-transform spectrometer (FTS) which covers
simultaneously its whole operating range of 194-671 μm
(447-1550 GHz). The SPIRE detectors are arrays of
feedhorn-coupled bolometers cooled to 0.3 K. The photometer
has a field of view of 4′ × 8′, observed simultaneously
in the three spectral bands. Its main operating mode is
scan-mapping, whereby the field of view is scanned across
the sky to achieve full spatial sampling and to cover large
areas if desired. The spectrometer has an approximately
circular field of view with a diameter of 2.6′. The
spectral resolution can be adjusted between 1.2 and 25 GHz
by changing the stroke length of the FTS scan mirror. Its
main operating mode involves a fixed telescope pointing with
multiple scans of the FTS mirror to acquire spectral data.
For extended source measurements, multiple position offsets
are implemented by means of an internal beam steering mirror
to achieve the desired spatial sampling and by rastering of
the telescope pointing to map areas larger than the field of
view. The SPIRE instrument consists of a cold focal plane
unit located inside the Herschel cryostat and warm
electronics units, located on the spacecraft Service Module,
for instrument control and data handling. Science data are
transmitted to Earth with no on-board data compression, and
processed by automatic pipelines to produce calibrated
science products. The in-flight performance of the
instrument matches or exceeds predictions based on
pre-launch testing and modelling: the photometer sensitivity
is comparable to or slightly better than estimated
pre-launch, and the spectrometer sensitivity is also better
by a factor of 1.5-2. © ESO 2010.},
Doi = {10.1051/0004-6361/201014519},
Key = {fds335112}
}
@article{fds335113,
Author = {Lee, W and Mazzucato, E and Smith, DR and Park, HK and Domier, CW and Luhmann, NC},
Title = {Calibration of the collective scattering system on
NSTX},
Journal = {34th International Conference on Infrared, Millimeter, and
Terahertz Waves, IRMMW-THz 2009},
Publisher = {IEEE},
Year = {2009},
Month = {December},
ISBN = {9781424454174},
url = {http://dx.doi.org/10.1109/ICIMW.2009.5325541},
Abstract = {A multichannel 280-GHz collective scattering system has been
employed to investigate electron gyro-scale density
fluctuations in National Spherical Torus Experiment (NSTX)
plasmas. The longitudinal scattering volume length, which is
the spatial resolution of the scattering measurement, was
calculated in tokamak geometry since the targeting
wavenumber is greatly affected by the configuration of the
magnetic field. An absolute power calibration was performed
to determine the power response of the detection system. The
results of the scattering length calculation and the power
calibration were applied to estimate the density fluctuation
levels from the scattering signals measured on NSTX plasmas.
© 2009 IEEE.},
Doi = {10.1109/ICIMW.2009.5325541},
Key = {fds335113}
}
@article{fds335114,
Author = {Smith, DR and Kaye, SM and Lee, W and Mazzucato, E and Park, HK and Bell,
RE and Domier, CW and Leblanc, BP and Levinton, FM and Luhmann, NC and Menard, JE and Yuh, H},
Title = {Electron gyroscale fluctuation measurements in National
Spherical Torus Experiment H-mode plasmas},
Journal = {Physics of Plasmas},
Volume = {16},
Number = {11},
Pages = {112507},
Publisher = {AIP Publishing},
Year = {2009},
Month = {December},
url = {http://dx.doi.org/10.1063/1.3262530},
Abstract = {A collective scattering system has measured electron
gyroscale fluctuations in National Spherical Torus
Experiment [M. Ono, Nucl. Fusion 40, 557 (2000)] H-mode
plasmas to investigate electron temperature gradient (ETG)
turbulence. Observations and results pertaining to
fluctuation measurements in ETG-stable regimes, the toroidal
field scaling of fluctuation amplitudes, the relation
between fluctuation amplitudes and transport quantities, and
fluctuation magnitudes and k -spectra are presented.
Collectively, the measurements provide insight and guidance
for understanding ETG turbulence and anomalous electron
thermal transport. © 2009 American Institute of
Physics.},
Doi = {10.1063/1.3262530},
Key = {fds335114}
}
@article{fds330996,
Author = {Jiang, Y and Foti, SJ and Sambell, A and Smith, D},
Title = {A new low profile antenna with improved performance for
satellite on-the-move communications},
Journal = {Proceedings - 2009 3rd IEEE International Symposium on
Microwave, Antenna, Propagation and EMC Technologies for
Wireless Communications, MAPE 2009},
Pages = {59-62},
Publisher = {IEEE},
Year = {2009},
Month = {December},
ISBN = {9781424440740},
url = {http://dx.doi.org/10.1109/MAPE.2009.5355557},
Abstract = {A novel design solution for a low-profile full-duplex
Satellite-On-The-Move Communications hybrid scanned phased
array antenna for low elevation angle coverage (down to 10°
) is described. The antenna is operated at Ku-Band. The
unique louvered array element geometry in combination with a
spatial filter/ "ray bending" lens facilitates the shaping
of the element pattern to increase gain at low elevation
angles. Preliminary modelling results using simple
ray-tracing and 3D E simulation indicate that the desired
low angle coverage can be achieved. ©2009
IEEE.},
Doi = {10.1109/MAPE.2009.5355557},
Key = {fds330996}
}
@article{fds269611,
Author = {Dhar, S and Degiron, A and Smith, DR and Jokerst,
NM},
Title = {Planar integration of a long range surface plasmon waveguide
with an inverted metal-semiconductor-metal photodetector on
silicon},
Journal = {Optics InfoBase Conference Papers},
Year = {2009},
Month = {December},
Abstract = {A long range surface plasmon polariton (LR-SPP)
insulator-metal-insulator waveguide was integrated with a
thin film InxGa1-xAs-based photodetector (PD) on silicon for
planar detection of LR-SPPs, and demonstrated coupling from
the LR-SPP to the PD. © 2009 Optical Society of
America.},
Key = {fds269611}
}
@article{fds269704,
Author = {Sajuyigbe, S and Justice, BJ and Starr, AF and Smith,
DR},
Title = {Design and analysis of three-dimensionalized ELC
metamaterial unit cell},
Journal = {IEEE Antennas and Wireless Propagation Letters},
Volume = {8},
Pages = {1268-1271},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2009},
Month = {December},
ISSN = {1536-1225},
url = {http://dx.doi.org/10.1109/LAWP.2009.2036572},
Abstract = {The use of a three-dimensional electric-LC (3D-ELC)
resonator to obtain a minimally refractive and strongly
transmissive composite metamaterial is explored. The 3D-ELC
repeated unit cell consists of two ELC elements that, when
put together, may be used to generate responding electric
dipole moments in the x̧, y̧, and z̧ directions. When
embedded inside a host material whose permittivity is
significantly greater than unity, the repeated 3D-ELC
metamaterial can be used to depress the effective dielectric
constant of the resulting composite material to a nearunity
value in all Cartesian directions. The concept of designing
a unity-index metamaterial-with the properties of free
space-may prove useful in creating mechanically durable
materials for use as radomes or other enclosures for
radiating structures. © 2009 IEEE.},
Doi = {10.1109/LAWP.2009.2036572},
Key = {fds269704}
}
@article{fds269705,
Author = {Ghezzo, F and Starr, TN and Perram, T and Darlington, TK and Starr, AF and Smith, DR},
Title = {Development of self healing composite materials: Fabrication
and micro-structural analyses},
Journal = {ICCM International Conferences on Composite
Materials},
Year = {2009},
Month = {December},
Abstract = {A custom resin transfer molding (RTM) method for the
fabrication of carbon fiber composites using thermally
reversible highly cross linked polymeric matrices was
developed. The resulting material quality and healing
efficiency was assessed using X-ray phase contrast
micro-tomography. The X-ray investigations revealed that
partial healing of extended cracks occurred in samples that
were kept at 90°C for 2 hours.},
Key = {fds269705}
}
@article{fds269707,
Author = {Arritt, BJ and Starr, AF and Smith, DR},
Title = {Electromagnetic performance of mechanically loaded composite
metamaterials},
Journal = {ICCM International Conferences on Composite
Materials},
Year = {2009},
Month = {December},
Abstract = {The field of metamaterials has seen tremendous advancements
in the design, modeling, and development of structures with
novel ElectroMagnetic (EM) properties. However, nothing had
been done to characterize how those EM properties change
when a metamaterial structure is transitioned into a
relevant environment (i.e. mechanical and thermal loading).
This research seeks to understand the linkage between the
mechanical loading of these multi-component,
inclusion-intensive structures, and their resultant changes
in EM performance; thus laying the foundation for the
eventual operational use of these novel multifunctional
structures.},
Key = {fds269707}
}
@article{fds269703,
Author = {Poutrina, E and Smith, DR},
Title = {High-frequency active metamaterials},
Journal = {2009 Conference on Lasers and Electro-Optics and 2009
Conference on Quantum Electronics and Laser Science
Conference, CLEO/QELS 2009},
Year = {2009},
Month = {November},
Abstract = {We present a systematic numerical study of metamaterials
integrated with gain media to achieve composite
metamaterials at terahertz and infrared wavelength with
reduced losses. The impact of spatial dispersion on the
effective permeability resonance restoration is emphasized.
© 2008 Optical Society of America.},
Key = {fds269703}
}
@article{fds269777,
Author = {Dhar, S and Degiron, A and Smith, DR and Jokerst,
NM},
Title = {Planar integration of a long range surface plasmon waveguide
with an inverted metal-semiconductor-metal photodetector on
silicon},
Journal = {2009 Conference on Lasers and Electro-Optics and 2009
Conference on Quantum Electronics and Laser Science
Conference, CLEO/QELS 2009},
Year = {2009},
Month = {November},
Abstract = {A long range surface plasmon polariton (LR-SPP)
insulator-metal-insulator waveguide was integrated with a
thin film InxGa1-xAs-based photodetector (PD) on silicon for
planar detection of LR-SPPs, and demonstrated coupling from
the LR-SPP to the PD. ©2009 Optical Society of
America.},
Key = {fds269777}
}
@article{fds269800,
Author = {Sajuyigbe, S and Cummer, SA and Smith, DR},
Title = {Utilization of metamaterials for wide angle impedance
matching (WAIM) in phased array antennas},
Journal = {IEEE Antennas and Propagation Society, AP-S International
Symposium (Digest)},
Publisher = {IEEE},
Year = {2009},
Month = {November},
ISSN = {1522-3965},
url = {http://dx.doi.org/10.1109/APS.2009.5172272},
Doi = {10.1109/APS.2009.5172272},
Key = {fds269800}
}
@article{fds269701,
Author = {Liu, R and Cheng, Q and Chin, JY and Mock, JJ and Cui, TJ and Smith,
DR},
Title = {Broadband gradient index microwave quasi-optical elements
based on non-resonant metamaterials.},
Journal = {Optics express},
Volume = {17},
Number = {23},
Pages = {21030-21041},
Year = {2009},
Month = {November},
url = {http://www.ncbi.nlm.nih.gov/pubmed/19997341},
Abstract = {Utilizing non-resonant metamaterial elements, we demonstrate
that complex gradient index optics can be constructed
exhibiting low material losses and large frequency
bandwidth. Although the range of structures is limited to
those having only electric response, with an electric
permittivity always equal to or greater than unity, there
are still numerous metamaterial design possibilities enabled
by leveraging the non-resonant elements. For example, a
gradient, impedance matching layer can be added that
drastically reduces the return loss of the optical elements
due to reflection. In microwave experiments, we demonstrate
the broadband design concepts with a gradient index lens and
a beam-steering element, both of which are confirmed to
operate over the entire X-band (roughly 8-12 GHz) frequency
spectrum.},
Doi = {10.1364/oe.17.021030},
Key = {fds269701}
}
@article{fds269702,
Author = {Nguyen, VN and Yönak, SH and Smith, DR},
Title = {Millimeter-wave artificial dielectric gradient index
lenses},
Journal = {European Conference on Antennas and Propagation, EuCAP 2009,
Proceedings},
Pages = {1886-1890},
Year = {2009},
Month = {October},
Abstract = {We present an artificial dielectric gradient index lens
designed to operate at millimeter-wave frequencies. Finite
element simulations are used in conjunction with material
parameter retrieval techniques to design an artificial
dielectric unit cell with an optimum refractive index range.
This refractive index range is then used with ray-tracing
software to arrive at an optimized index profile. A lens
with this index profile is realized using multilayer printed
wiring boards (PWBs) and tested.},
Key = {fds269702}
}
@article{fds335115,
Author = {Delgado-Aparicio, L and Stutman, D and Tritz, K and Finkenthal, M and Kaye, S and Bell, R and Kaita, R and Leblanc, B and Levinton, F and Menard,
J and Paul, S and Smith, D and Yuh, H},
Title = {Impurity transport studies in NSTX neutral beam heated
H-mode plasmas},
Journal = {Nuclear Fusion},
Volume = {49},
Number = {8},
Pages = {085028-085028},
Publisher = {IOP Publishing},
Year = {2009},
Month = {September},
url = {http://dx.doi.org/10.1088/0029-5515/49/8/085028},
Abstract = {The first experimental assessment of low-Z impurity
transport in a neutral beam heated, high-confinement H-mode
plasma sustained in a low-field, low-aspect ratio spherical
tokamak, was performed at the National Spherical Torus
Experiment (NSTX). The injected impurities penetrate to the
core on a hundred millisecond time scale, indicating a low
core particle diffusivity (≲1 m2 s-1) in good agreement
with the values predicted by neoclassical transport theory.
In addition, a fixed q-profile magnetic field scan that
showed reduced impurity penetration at high fields is also
reported. This result suggests that anomalous ion particle
transport associated with turbulent long-wavelength
electrostatic instabilities must be largely suppressed in
the NSTX core. © 2009 IAEA, Vienna.},
Doi = {10.1088/0029-5515/49/8/085028},
Key = {fds335115}
}
@article{fds269711,
Author = {Roberts, DA and Kundtz, N and Smith, DR},
Title = {Optical lens compression via transformation
optics.},
Journal = {Optics express},
Volume = {17},
Number = {19},
Pages = {16535-16542},
Year = {2009},
Month = {September},
url = {http://www.ncbi.nlm.nih.gov/pubmed/19770868},
Abstract = {Transformation optics is widely associated with the design
of unconventional electromagnetic devices, such as
electromagnetic cloaks or concentrators. However, a wide
range of conventional optical devices with potentially
advantageous properties can be designed by the
transformation optical approach. For example, a coordinate
transformation can be introduced that compresses a region of
space, resulting in an overall decrease in the thickness of
an optical instrument such as a lens. The optical properties
of a transformed lens, such as Fresnel reflection or
aberration profile, are equivalent to those of the original
lens, while the transformed lens and the bounding
transformation optical material are thinner than the
original lens. This approach to flattening the profile of a
lens represents an advantage over the use of a higher
dielectric material because it does not introduce greater
Fresnel reflections or require a redesign of the basic
optic. Though transformation optical media are generally
anisotropic, with both electric and magnetic response, it is
possible to arrive at a dielectric-only transformation
optical distribution for a lens interacting with
transverse-magnetic (TM) polarized light. The
dielectric-only distribution can be implemented using
broad-band, low-loss metamaterials. Lens designs for both a
full transformation and a dielectric-only implementation are
discussed and confirmed via finite-element
simulations.},
Doi = {10.1364/oe.17.016535},
Key = {fds269711}
}
@article{fds269778,
Author = {Driscoll, T and Kim, H-T and Chae, B-G and Kim, B-J and Lee, Y-W and Jokerst, NM and Palit, S and Smith, DR and Di Ventra and M and Basov,
DN},
Title = {Memory metamaterials.},
Journal = {Science (New York, N.Y.)},
Volume = {325},
Number = {5947},
Pages = {1518-1521},
Year = {2009},
Month = {September},
url = {http://www.ncbi.nlm.nih.gov/pubmed/19696311},
Abstract = {The resonant elements that grant metamaterials their
distinct properties have the fundamental limitation of
restricting their useable frequency bandwidth. The
development of frequency-agile metamaterials has helped to
alleviate these bandwidth restrictions by allowing real-time
tuning of the metamaterial frequency response. We
demonstrate electrically controlled persistent frequency
tuning of a metamaterial, which allows the lasting
modification of its response by using a transient stimulus.
This work demonstrates a form of memory capacitance that
interfaces metamaterials with a class of devices known
collectively as memory devices.},
Doi = {10.1126/science.1176580},
Key = {fds269778}
}
@article{fds269781,
Author = {Tsai, Y-J and Degiron, A and Jokerst, NM and Smith,
DR},
Title = {Plasmonic multi-mode interference couplers.},
Journal = {Optics express},
Volume = {17},
Number = {20},
Pages = {17471-17482},
Year = {2009},
Month = {September},
url = {http://www.ncbi.nlm.nih.gov/pubmed/19907531},
Abstract = {Plasmonic multi-mode interference (MMI) couplers have been
investigated both numerically and experimentally at the
telecommunication wavelength of 1.55 mum. In this study, the
couplers are implemented using thin Au stripes that support
long-range surface plasmons. We first detail the operation
principle of these devices with numerical simulations and
show that useful effects can be obtained despite the high
material losses inherent to metallic structures. A series of
MMI couplers is subsequently fabricated and experimentally
characterized, showing a quantitative agreement with our
numerical predictions. We conclude by discussing some of the
possible applications for these structures.},
Doi = {10.1364/oe.17.017471},
Key = {fds269781}
}
@article{fds335122,
Author = {Mazzucato, E and Bell, RE and Ethier, S and Hosea, JC and Kaye, SM and Leblanc, BP and Lee, WW and Ryan, PM and Smith, DR and Wang, WX and Wilson,
JR and Yuh, H},
Title = {Study of turbulent fluctuations driven by the electron
temperature gradient in the National spherical torus
experiment},
Journal = {Nuclear Fusion},
Volume = {49},
Number = {5},
Pages = {055001-055001},
Publisher = {IOP Publishing},
Year = {2009},
Month = {July},
url = {http://dx.doi.org/10.1088/0029-5515/49/5/055001},
Abstract = {Various theories and numerical simulations support the
conjecture that the ubiquitous problem of anomalous electron
transport in tokamaks may arise from a short-scale
turbulence driven by the electron temperature gradient. To
check whether this turbulence is present in plasmas of the
National Spherical Torus Experiment, measurements of
turbulent fluctuations were performed with coherent
scattering of electromagnetic waves. Results from plasmas
heated by high harmonic fast waves show the existence of
density fluctuations in the range of wave numbers k⊥ρe =
0.1-0.4, corresponding to a turbulence scale length of the
order of the collisionless skin depth. Experimental
observations and agreement with numerical results from the
linear gyro-kinetic GS2 code indicate that the observed
turbulence is driven by the electron temperature gradient.
These turbulent fluctuations were not observed at the
location of an internal transport barrier driven by a
negative magnetic shear. © 2009 IAEA, Vienna.},
Doi = {10.1088/0029-5515/49/5/055001},
Key = {fds335122}
}
@article{fds269798,
Author = {Allen, J and Kundtz, N and Roberts, DA and Cummer, SA and Smith,
DR},
Title = {Electromagnetic source transformations using superellipse
equations},
Journal = {Applied Physics Letters},
Volume = {94},
Number = {19},
Pages = {194101-194101},
Publisher = {AIP Publishing},
Year = {2009},
Month = {June},
ISSN = {0003-6951},
url = {http://dx.doi.org/10.1063/1.3130182},
Abstract = {Transformation optics can be used to design media with
unique properties that alter the behavior of electromagnetic
waves in passive space and recently in space containing
source distributions. We present source transformations
where current from a linear radiator is spread over a
cylindrical shell with various cross sections. The
semianalytic transformations are based on superellipse
equations. Finite-element full-wave simulations of
transformations from a dipole to a cylinder, diamond-shaped
cylinder, and flattened cylinder are presented. The
radiation pattern of the dipole seen by an outside observer
is replicated in all cases demonstrating the potential
applicability of source transformations to conformal antenna
design. © 2009 American Institute of Physics.},
Doi = {10.1063/1.3130182},
Key = {fds269798}
}
@article{fds335123,
Author = {Yuh, HY and Levinton, FM and Bell, RE and Hosea, JC and Kaye, SM and Leblanc, BP and Mazzucato, E and Peterson, JL and Smith, DR and Candy,
J and Waltz, RE and Domier, CW and Luhmann, NC and Lee, W and Park,
HK},
Title = {Internal transport barriers in the National Spherical Torus
Experiment},
Journal = {Physics of Plasmas},
Volume = {16},
Number = {5},
Pages = {056120-056120},
Publisher = {AIP Publishing},
Year = {2009},
Month = {June},
url = {http://dx.doi.org/10.1063/1.3129163},
Abstract = {In the National Spherical Torus Experiment [M. Ono, Nucl.
Fusion 41, 1435 (2001)], internal transport barriers (ITBs)
are observed in reversed (negative) shear discharges where
diffusivities for electron and ion thermal channels and
momentum are reduced. While neutral beam heating can produce
ITBs in both electron and ion channels, high harmonic fast
wave heating can also produce electron ITBs (e-ITBs) under
reversed magnetic shear conditions without momentum input.
Interestingly, the location of the e-ITB does not
necessarily match that of the ion ITB (i-ITB). The e-ITB
location correlates best with the magnetic shear minima
location determined by motional Stark effect constrained
equilibria, whereas the i-ITB location better correlates
with the location of maximum E×B shearing rate. Measured
electron temperature gradients in the e-ITB can exceed
critical gradients for the onset of electron thermal
gradient microinstabilities calculated by linear gyrokinetic
codes. A high- k microwave scattering diagnostic shows
locally reduced density fluctuations at wave numbers
characteristic of electron turbulence for discharges with
strongly negative magnetic shear versus weakly negative or
positive magnetic shear. Reductions in fluctuation amplitude
are found to be correlated with the local value of magnetic
shear. These results are consistent with nonlinear
gyrokinetic simulations predicting a reduction in electron
turbulence under negative magnetic shear conditions despite
exceeding critical gradients. © 2009 American Institute of
Physics.},
Doi = {10.1063/1.3129163},
Key = {fds335123}
}
@article{fds335121,
Author = {Smith, DR and Kaye, SM and Lee, W and Mazzucato, E and Park, HK and Bell,
RE and Domier, CW and Leblanc, BP and Levinton, FM and Luhmann, NC and Menard, JE and Yuh, H},
Title = {Observations of reduced electron gyroscale fluctuations in
national spherical torus experiment H-mode plasmas with
large E×B flow shear},
Journal = {Physical Review Letters},
Volume = {102},
Number = {22},
Publisher = {American Physical Society (APS)},
Year = {2009},
Month = {June},
url = {http://dx.doi.org/10.1103/PhysRevLett.102.225005},
Abstract = {Electron gyroscale fluctuation measurements in National
Spherical Torus Experiment H-mode plasmas with large
toroidal rotation reveal fluctuations consistent with
electron temperature gradient (ETG) turbulence. Large
toroidal rotation in National Spherical Torus Experiment
plasmas with neutral beam injection generates E×B flow
shear rates comparable to ETG linear growth rates. Enhanced
fluctuations occur when the electron temperature gradient is
marginally stable with respect to the ETG linear critical
gradient. Fluctuation amplitudes decrease when the E×B flow
shear rate exceeds ETG linear growth rates. The observations
indicate that E×B flow shear can be an effective
suppression mechanism for ETG turbulence. © 2009 The
American Physical Society.},
Doi = {10.1103/PhysRevLett.102.225005},
Key = {fds335121}
}
@article{fds335120,
Author = {Grande, M and Maddison, BJ and Howe, CJ and Kellett, BJ and Sreekumar,
P and Huovelin, J and Crawford, IA and Duston, CL and Smith, D and Anand,
M and Bhandari, N and Cook, A and Fernandes, V and Foing, B and Gasnaut, O and Goswami, JN and Holland, A and Joy, KH and Kochney, D and Lawrence, D and Maurice, S and Okada, T and Narendranath, S and Pieters, C and Rothery,
D and Russell, SS and Shrivastava, A and Swinyard, B and Wilding, M and Wieczorek, M},
Title = {The C1XS X-ray Spectrometer on Chandrayaan-1},
Journal = {Planetary and Space Science},
Volume = {57},
Number = {7},
Pages = {717-724},
Publisher = {Elsevier BV},
Year = {2009},
Month = {June},
url = {http://dx.doi.org/10.1016/j.pss.2009.01.016},
Abstract = {The Chandrayaan-1 X-ray Spectrometer (C1XS) is a compact
X-ray spectrometer for the Indian Space Research
Organisation (ISRO) Chandrayaan-1 lunar mission. It exploits
heritage from the D-CIXS instrument on ESA's SMART-1
mission. As a result of detailed developments to all aspects
of the design, its performance as measured in the laboratory
greatly surpasses that of D-CIXS. In comparison with
SMART-1, Chandrayaan-1 is a science-oriented rather than a
technology mission, leading to far more favourable
conditions for science measurements. C1XS is designed to
measure absolute and relative abundances of major
rock-forming elements (principally Mg, Al, Si, Ca and Fe) in
the lunar crust with spatial resolution ≤25 FWHM km, and
to achieve relative elemental abundances of better than 10%.
© 2009 Elsevier Ltd.},
Doi = {10.1016/j.pss.2009.01.016},
Key = {fds335120}
}
@article{fds335116,
Author = {Hall, DJ and Holland, A and Smith, DR},
Title = {The use of automatic scale selection to improve the spatial
and spectral resolution of a scintillator-coupled
EMCCD},
Journal = {Nuclear Instruments and Methods in Physics Research, Section
A: Accelerators, Spectrometers, Detectors and Associated
Equipment},
Volume = {604},
Number = {1-2},
Pages = {207-210},
Publisher = {Elsevier BV},
Year = {2009},
Month = {June},
url = {http://dx.doi.org/10.1016/j.nima.2009.01.075},
Abstract = {The technology behind the Electron-Multiplying Charge
Coupled Device (EMCCD) was successfully exploited by e2v
technologies in the late 1990s. Since then, many uses have
been found for these low light level (L3) devices including
surveillance and many scientific applications. The EMCCD
increases or 'multiplies' the charge signal by the
phenomenon of impact ionisation (or avalanche
multiplication) allowing the detection of low signal events
of only a few photons. When coupled with a scintillator,
this low light capability can be used to image photon
flashes from individual X-ray interaction events. The
combination of depth of interaction effects in the
scintillator, shot noise on the signal and the
multiplication noise factor lead to large variations in the
profile of the detected signal from a constant energy X-ray
source. This variation leads to reduced spectral performance
and can have adverse effects on the centering techniques
used in photon-counting imagers. The concept of scale-space
is similar in many ways to the Fourier or wavelet
transforms. Automatic scale selection can be implemented
through the scale-space transform as a method of fitting a
known profile to the observed photon flash. The process is
examined here in the context of the photon-counting EMCCD
detector and the results obtained in both simulated and
experimental data compared. Through the analysis of the
fitting process and the results achieved, the implications
on imaging performance and spectral resolution are
discussed. © 2008 Elsevier B.V. All rights
reserved.},
Doi = {10.1016/j.nima.2009.01.075},
Key = {fds335116}
}
@article{fds335117,
Author = {Murray, NJ and Holland, AD and Smith, DR and Gow, JP and Pool, PJ and Burt,
DJ},
Title = {The X-ray quantum efficiency measurement of high resistivity
CCDs},
Journal = {Nuclear Instruments and Methods in Physics Research, Section
A: Accelerators, Spectrometers, Detectors and Associated
Equipment},
Volume = {604},
Number = {1-2},
Pages = {180-182},
Publisher = {Elsevier BV},
Year = {2009},
Month = {June},
url = {http://dx.doi.org/10.1016/j.nima.2009.01.052},
Abstract = {The CCD247 is the second generation of high-resistivity
device to be manufactured in e2v technologies plc
development programme. Intended for infrared astronomy, the
latest devices are fabricated on high resistivity (∼8 kΩ
cm) bulk silicon, allowing for a greater device thickness
whilst maintaining full depletion when 'thinned' to a
thickness of 150 μm. In the case of the front illuminated
variant, depletion of up to 300 μm is achievable by
applying a gate to substrate potential of up to 120 V,
whilst retaining adequate spectral performance. The
increased depletion depth of high-resistivity CCDs greatly
improves the quantum efficiency (QE) for incident X-ray
photons of energies above 5 keV, making such a device
beneficial in future X-ray astronomy missions and other
applications. Here we describe the experimental setup and
present results of X-ray QE measurements taken in the energy
range 2-20 keV for a front illuminated CCD247, showing QE in
excess of 80% at 10 keV. Results for the first generation
CCD217 and swept-charge device (1500 Ω cm epitaxial
silicon) are also presented. © 2009 Elsevier B.V. All
rights reserved.},
Doi = {10.1016/j.nima.2009.01.052},
Key = {fds335117}
}
@article{fds335118,
Author = {Smith, DR and Gow, J},
Title = {The effect of protons on the performance of swept-charge
devices},
Journal = {Nuclear Instruments and Methods in Physics Research, Section
A: Accelerators, Spectrometers, Detectors and Associated
Equipment},
Volume = {604},
Number = {1-2},
Pages = {177-179},
Publisher = {Elsevier BV},
Year = {2009},
Month = {June},
url = {http://dx.doi.org/10.1016/j.nima.2009.01.051},
Abstract = {The e2v technologies CCD54, or swept-charge device (SCD) has
been extensively radiation tested for use in the
Chandrayaan-1 X-ray Spectrometer (C1XS) instrument, to be
launched as a part of the Indian Space Research Organisation
(ISRO) Chandrayaan-1 payload in 2008. The principle use of
the SCD is in X-ray fluorescence (XRF) applications, the
device providing a relatively large collecting area of 1.1
cm2, and achieving near Fano-limited spectroscopy at -15
°C, a temperature that is easily obtained using a
thermoelectric cooler (TEC). This paper describes the
structure and operation of the SCD and details the
methodology and results obtained from two proton irradiation
studies carried out in 2006 and 2008, respectively to
quantify the effects of proton irradiation on the
operational characteristics of the device. The analysis
concentrates on the degradation of the measured FWHM of
various elemental lines and quantifies the effects of proton
fluence on the observed X-ray fluorescence spectra from
mineralogical target samples. © 2009 Elsevier B.V. All
rights reserved.},
Doi = {10.1016/j.nima.2009.01.051},
Key = {fds335118}
}
@article{fds335119,
Author = {Howe, CJ and Drummond, D and Edeson, R and Maddison, B and Parker, DJ and Parker, R and Shrivastava, A and Spencer, J and Kellett, BJ and Grande,
M and Sreekumar, P and Huovelin, J and Smith, DR and Gow, J and Narendranath. K.C. and S and d'Uston, L},
Title = {Chandrayaan-1 X-ray Spectrometer (C1XS)-Instrument design
and technical details},
Journal = {Planetary and Space Science},
Volume = {57},
Number = {7},
Pages = {735-743},
Publisher = {Elsevier BV},
Year = {2009},
Month = {June},
url = {http://dx.doi.org/10.1016/j.pss.2009.01.011},
Abstract = {The UK-built Chandrayaan-1 X-ray Spectrometer (C1XS) is
flying as an ESA instrument on India's Chandrayaan-1 mission
to the Moon. The Chandrayaan-1 mission launched on the 22nd
October 2008 and entered a 100 km polar lunar orbit on the
12th November 2008. C1XS builds on experience gained with
the earlier D-CIXS instrument on SMART-1, but will be a
technically much more capable instrument. Here we describe
the instrument design. © 2009 Elsevier Ltd. All rights
reserved.},
Doi = {10.1016/j.pss.2009.01.011},
Key = {fds335119}
}
@article{fds269709,
Author = {Chin, JY and Gollub, JN and Mock, JJ and Liu, R and Harrison, C and Smith,
DR and Cui, TJ},
Title = {An efficient broadband metamaterial wave
retarder.},
Journal = {Optics express},
Volume = {17},
Number = {9},
Pages = {7640-7647},
Year = {2009},
Month = {April},
ISSN = {1094-4087},
url = {http://dx.doi.org/10.1364/oe.17.007640},
Abstract = {Metamaterials with anisotropic electromagnetic properties
have the capability to manipulate the polarization states of
electromagnetic waves. We describe a method to design a
broadband, low-loss wave retarder with graded constitutive
parameter distributions based on non-resonant metamaterial
elements. A structured metamaterial half-wave retarder that
converts one linear polarization to its cross polarization
is designed and its performance is characterized
experimentally.},
Doi = {10.1364/oe.17.007640},
Key = {fds269709}
}
@article{fds269779,
Author = {Landy, NI and Bingham, CM and Tyler, T and Jokerst, N and Smith, DR and Padilla, WJ},
Title = {Design, theory, and measurement of a polarization-insensitive
absorber for terahertz imaging},
Journal = {Physical Review B - Condensed Matter and Materials
Physics},
Volume = {79},
Number = {12},
Publisher = {American Physical Society (APS)},
Year = {2009},
Month = {March},
ISSN = {1098-0121},
url = {http://dx.doi.org/10.1103/PhysRevB.79.125104},
Abstract = {We present the theory, design, and realization of a
polarization- insensitive metamaterial absorber for
terahertz frequencies. Effective-medium theory is used to
describe the absorptive properties of the metamaterial in
terms of optical constants-a description that has been thus
far lacking. From our theoretical approach, we construct a
device that yields over 95% absorption in simulation. Our
fabricated design consists of a planar single unit-cell
layer of metamaterial and reaches an absorptivity of 77% at
1.145 THz. © 2009 The American Physical
Society.},
Doi = {10.1103/PhysRevB.79.125104},
Key = {fds269779}
}
@article{fds335124,
Author = {Ingley, R and Smith, DR and Holland, AD},
Title = {Life testing of EMCCD gain characteristics},
Journal = {Nuclear Instruments and Methods in Physics Research, Section
A: Accelerators, Spectrometers, Detectors and Associated
Equipment},
Volume = {600},
Number = {2},
Pages = {460-465},
Publisher = {Elsevier BV},
Year = {2009},
Month = {March},
url = {http://dx.doi.org/10.1016/j.nima.2008.10.041},
Abstract = {Two electron-multiplication, charge-coupled devices (e2v
CCD97) were operated continuously for 52 days to assess
their avalanche gain stability. This work was part of an
evaluation study into their suitability for the radial
velocity spectrometer (RVS) instrument on the European Space
Agency's Gaia cornerstone mission. After one day the device
gain was stable to within 10%, and at the end of the test
both devices reached the required multiplication gain of 8
with an avalanche electrode voltage of less than 36 V. ©
2008 Elsevier B.V. All rights reserved.},
Doi = {10.1016/j.nima.2008.10.041},
Key = {fds335124}
}
@article{fds269700,
Author = {Liu, R and Yang, XM and Gollub, JG and Mock, JJ and Cui, TJ and Smith,
DR},
Title = {Gradient index circuit by waveguided metamaterials},
Journal = {Applied Physics Letters},
Volume = {94},
Number = {7},
Pages = {073506-073506},
Publisher = {AIP Publishing},
Year = {2009},
Month = {February},
ISSN = {0003-6951},
url = {http://dx.doi.org/10.1063/1.3081399},
Abstract = {Metamaterials are artificially structured materials that
provide considerable flexibility for control of
electromagnetic waves. The metamaterial concept can also be
applied to the design of planar waveguiding structures.
Here, we illustrate this design approach with the
development of two-dimensional (2D) planar gradient index
(GRIN) circuits. To form the structure, we make use of a 2D
complementary split ring resonator, which exhibits an
electric response to guided transverse-electric waves. To
confirm the properties of the planar GRIN structure
predicted from numerical simulations, we present
experimental results for a beam-steering and a focusing GRIN
circuit. These examples illustrate the versatility of the
metamaterial approach in the design of complex waveguiding
structures. © 2009 American Institute of
Physics.},
Doi = {10.1063/1.3081399},
Key = {fds269700}
}
@article{fds269699,
Author = {Garcia-Pomar, JL and Gollub, JN and Mock, JJ and Smith, DR and Nieto-Vesperinas, M},
Title = {Experimental two-dimensional field mapping of total internal
reflection lateral beam shift in a self-collimated photonic
crystal},
Journal = {Applied Physics Letters},
Volume = {94},
Number = {6},
Pages = {061121-061121},
Publisher = {AIP Publishing},
Year = {2009},
Month = {February},
ISSN = {0003-6951},
url = {http://dx.doi.org/10.1063/1.3085768},
Abstract = {A lateral beam shift is demonstrated both theoretically and
in microwave experiments when total internal reflection
takes place at the boundary of a self-collimating
two-dimensional photonic crystal consisting of an array of
high index dielectric cylinders. We further show the
dependence of this shift on the cut of the last row of
cylinders that defines the crystal interface. © 2009
American Institute of Physics.},
Doi = {10.1063/1.3085768},
Key = {fds269699}
}
@article{fds269708,
Author = {Gollub, JN and Chin, JY and Cui, TJ and Smith, DR},
Title = {Hybrid resonant phenomena in a SRR/YIG metamaterial
structure.},
Journal = {Optics express},
Volume = {17},
Number = {4},
Pages = {2122-2131},
Year = {2009},
Month = {February},
url = {http://www.ncbi.nlm.nih.gov/pubmed/19219116},
Abstract = {We consider the hybridization of the resonance of a SRR
metamaterial with the gyromagnetic material resonance of
yittrium iron garnet (YIG) inclusions. The combination of an
artificial structural resonance and natural material
resonance generates a unique hybrid resonance that can be
harnessed to make tunable metamaterials and further extend
the range of achievable electromagnetic materials. A
predictive analytic model is applied that accurately
describes the characteristics of this SRR/YIG hybridization.
We suggest that this hybridization has been observed in
experimental data presented by Kang et al. [Opt. Express,
16, 8825 (2008)] and present numerical simulations to
support this assertion. In addition, we investigate a design
for optimizing the SRR/YIG structure that shows strong
hybridization with a minimum amount of YIG
material.},
Doi = {10.1364/oe.17.002122},
Key = {fds269708}
}
@article{fds335125,
Author = {Grande, M and Maddison, BJ and Sreekumar, P and Huovelin, J and Kellett,
BJ and Howe, CJ and Crawford, IA and Smith, DR},
Title = {The Chandrayaan-1 X-ray spectrometer},
Journal = {Current Science},
Volume = {96},
Number = {4},
Pages = {517-519},
Year = {2009},
Month = {February},
Abstract = {The Chandrayaan-1 X-ray Spectrometer (C1XS) is a compact
X-ray spectrometer for the Chandrayaan-1 lunar mission. It
exploits heritage from the D-C1XS instrument on ESA's
SMART-1 mission. C1XS is designed to measure absolute and
relative abundances of major rock-forming elements
(principally Mg, Al, Si, Ti, Ca and Fe) over the lunar
surface. The baseline design consists of 24 nadir pointing
Swept Charge Device detectors, which provide high detection
efficiency in the 1-7 keV range, which contains the X-ray
fluorescence lines of the above elements of interest.
Micromachined collimators provide a 14 degree FWHM FOV,
equivalent to 25 km from 100 km altitude. A deployable door
protects the instrument during launch and cruise, and also
provides a 55Fe calibration X-ray source for detector
calibration. Additional refinements compared to D-C1XS will
result in a significantly improved energy resolution. To
record the incident solar X-ray flux at the Moon, C1XS
carries an X-ray Solar Monitor (XSM). C1XS will arrive at
the Moon in the run up to the maximum of the solar cycle 24,
and the expected high incident X-ray flux coupled to a 100
km circular polar orbit, will provide composition data
accurate to better than 10% of major elemental abundances
over the lunar surface.},
Key = {fds335125}
}
@article{fds269780,
Author = {Degiron, A and Cho, SY and Tyler, T and Jokerst, NM and Smith,
DR},
Title = {Directional coupling between dielectric and long-range
plasmon waveguides},
Journal = {New Journal of Physics},
Volume = {11},
Number = {1},
Pages = {015002-015002},
Publisher = {IOP Publishing},
Year = {2009},
Month = {January},
ISSN = {1367-2630},
url = {http://dx.doi.org/10.1088/1367-2630/11/1/015002},
Abstract = {We have designed, fabricated and characterized integrated
directional couplers capable of converting the mode of an
optical dielectric waveguide into a long-range plasmon
propagating along a thin metal stripe. We demonstrate that
the coupling between the two types of waveguides is
generally very weak unless specific conditions are met. This
sensitivity could be potentially exploited in sensing
applications or for developing novel active photonic
components. © IOP Publishing Ltd and Deutsche Physikalische
Gesellschaft.},
Doi = {10.1088/1367-2630/11/1/015002},
Key = {fds269780}
}
@article{fds269588,
Author = {Poutrina, E and Smith, DR},
Title = {High-frequency active metamaterials},
Journal = {Optics InfoBase Conference Papers},
Year = {2009},
Month = {January},
Abstract = {We present a systematic numerical study of metamaterials
integrated with gain media to achieve composite
metamaterials at terahertz and infrared wavelength with
reduced losses. The impact of spatial dispersion on the
effective permeability resonance restoration is emphasized.
© 2008 Optical Society of America.},
Key = {fds269588}
}
@article{fds269706,
Author = {Liu, R and Ji, C and Mock, JJ and Chin, JY and Cui, TJ and Smith,
DR},
Title = {Broadband ground-plane cloak.},
Journal = {Science (New York, N.Y.)},
Volume = {323},
Number = {5912},
Pages = {366-369},
Year = {2009},
Month = {January},
url = {http://www.ncbi.nlm.nih.gov/pubmed/19150842},
Abstract = {The possibility of cloaking an object from detection by
electromagnetic waves has recently become a topic of
considerable interest. The design of a cloak uses
transformation optics, in which a conformal coordinate
transformation is applied to Maxwell's equations to obtain a
spatially distributed set of constitutive parameters that
define the cloak. Here, we present an experimental
realization of a cloak design that conceals a perturbation
on a flat conducting plane, under which an object can be
hidden. To match the complex spatial distribution of the
required constitutive parameters, we constructed a
metamaterial consisting of thousands of elements, the
geometry of each element determined by an automated design
process. The ground-plane cloak can be realized with the use
of nonresonant metamaterial elements, resulting in a
structure having a broad operational bandwidth (covering the
range of 13 to 16 gigahertz in our experiment) and
exhibiting extremely low loss. Our experimental results
indicate that this type of cloak should scale well toward
optical wavelengths.},
Doi = {10.1126/science.1166949},
Key = {fds269706}
}
@article{fds269692,
Author = {Leonhardt, U and Smith, DR},
Title = {Focus on cloaking and transformation optics},
Journal = {New Journal of Physics},
Volume = {10},
Number = {11},
Pages = {115019-115019},
Publisher = {IOP Publishing},
Year = {2008},
Month = {December},
ISSN = {1367-2630},
url = {http://dx.doi.org/10.1088/1367-2630/10/11/115019},
Doi = {10.1088/1367-2630/10/11/115019},
Key = {fds269692}
}
@article{fds269795,
Author = {Hand, TH and Gollub, J and Sajuyigbe, S and Smith, DR and Cummer,
SA},
Title = {Characterization of complementary electric field coupled
resonant surfaces},
Journal = {Applied Physics Letters},
Volume = {93},
Number = {21},
Pages = {212504-212504},
Publisher = {AIP Publishing},
Year = {2008},
Month = {December},
ISSN = {0003-6951},
url = {http://dx.doi.org/10.1063/1.3037215},
Abstract = {We present angle-resolved free-space transmission and
reflection measurements of a surface composed of
complementary electric inductive-capacitive (CELC)
resonators. By measuring the reflection and transmission
coefficients of a CELC surface with different polarizations
and particle orientations, we show that the CELC only
responds to in-plane magnetic fields. This confirms the
Babinet particle duality between the CELC and its
complement, the electric field coupled LC resonator.
Characterization of the CELC structure serves to expand the
current library of resonant elements metamaterial designers
can draw upon to make unique materials and surfaces. © 2008
American Institute of Physics.},
Doi = {10.1063/1.3037215},
Key = {fds269795}
}
@article{fds335126,
Author = {Gow, J and Smith, DR and Holland, AD and Maddison, B and Howe, C and Grande, M and Sreekumar, P and Huovelin, J},
Title = {Radiation study of swept-charge devices for the
Chandrayaan-1 X-ray spectrometer (C1XS) instrument},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {7021},
Publisher = {SPIE},
Year = {2008},
Month = {December},
ISBN = {9780819472311},
url = {http://dx.doi.org/10.1117/12.791732},
Abstract = {The Chandrayaan-1 X-ray Spectrometer (C1XS) will be launched
as part of the Indian Space Research Organisation (ISRO)
Chandrayaan-1 payload in September 2008, arriving at the
Moon within 7 days to begin a two year mission in lunar
orbit conducting mineralogical surface mapping over the
range of 1 - 10 keV. The detector plane of the instrument
consists of twenty four e2v technologies CCD54 swept-charge
devices (SCDs). Such devices were first flown in the
Demonstration of a Compact Imaging X-ray Spectrometer
(D-CIXS) instrument onboard SMART-1 irradiation on SCD
operational performance.},
Doi = {10.1117/12.791732},
Key = {fds335126}
}
@article{fds335127,
Author = {Hall, DJ and Holland, A and Smith, DR},
Title = {Imaging and spectroscopy using a scintillator-coupled
EMCCD},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {7021},
Publisher = {SPIE},
Year = {2008},
Month = {December},
ISBN = {9780819472311},
url = {http://dx.doi.org/10.1117/12.790965},
Abstract = {The CCD97 is a low light level (L3) device from e2v
technologies range of electron multiplying CCDs (EMCCDs).
The device uses e2v's patented extended gain register and
through the use of appropriately designed electrodes can be
used to maximise the signal whilst keeping the impact of the
noise to a minimum. The nature of this device makes it ideal
for use with a scintillator in order to see individual
flashes of light from single X-ray photons. Through the
examination of individual X-ray events, it is possible to
analyse each interaction in the scintillator to determine
the sub-pixel position of the interaction. Using the
modelling capabilities of the Geant4 toolkit it is possible
to simulate X-ray events and thus examine interactions with
known energy and point of interaction. Through bringing
together the experimental and simulated results, the
spectral capabilities of such a device are
discussed.},
Doi = {10.1117/12.790965},
Key = {fds335127}
}
@article{fds330997,
Author = {Smith, D and Skobelev, SP and Leach, MP},
Title = {A modified holographic technique for antenna
measurements},
Journal = {ISAPE 2008 - The 8th International Symposium on Antennas,
Propagation and EM Theory Proceedings},
Pages = {46-49},
Publisher = {IEEE},
Year = {2008},
Month = {December},
ISBN = {9781424421923},
url = {http://dx.doi.org/10.1109/ISAPE.2008.4735136},
Abstract = {This work describes an extension to the use of indirect
holographic techniques for antenna measurements. Previous
versions of this work have been restricted to the
measurement of high gain antennas without reducing sample
spacing and increasing measurement times. This work
describes a technique whereby using both sum and difference
signals from the complex near field and the reference signal
cancellation of the unwanted term in the Fourier domain is
achieved enabling measurements to be made on medium gain
antennas. Measured results are compared to simulation
results for a small pyramidal horn antenna and are shown to
provide good agreement. © 2008 IEEE.},
Doi = {10.1109/ISAPE.2008.4735136},
Key = {fds330997}
}
@article{fds330998,
Author = {Bobor-Oyibo, F and Foti, SJ and Smith, D},
Title = {A multiple switched beam smart antenna with beam shaping for
dynamic optimisation of capacity & coverage in mobile
telecommunication networks},
Journal = {ISAPE 2008 - The 8th International Symposium on Antennas,
Propagation and EM Theory Proceedings},
Pages = {356-359},
Publisher = {IEEE},
Year = {2008},
Month = {December},
ISBN = {9781424421923},
url = {http://dx.doi.org/10.1109/ISAPE.2008.4735219},
Abstract = {A four column Smart antenna array fed by a 4×4 Butler
matrix augmented by a variable beam shaping network has been
designed and simulated. It is demonstrated that using only
three phase shifters within the beam shaping network
provides dynamic beam flexibility including: four narrow
switched beams, a right shaped beam, a left shaped beam and
a broad broadcast channel beam. The shaped beams concentrate
coverage at high capacity in either the right or left half
of a sector while maintaining coverage at lower capacity
over the reminder of the sector. The resultant antenna
system represents an improvement in performance over a
single multiple switched beam smart antenna without the cost
and complexity of a fully adaptive smart antenna. Simulated
radiation patterns over the full 3G frequency band show that
useful dynamic coverage & capacity enhancement can be
implemented with the proposed antenna system. © 2008
IEEE.},
Doi = {10.1109/ISAPE.2008.4735219},
Key = {fds330998}
}
@article{fds269693,
Author = {Liu, R and Ji, C and Mock, JJ and Tiejun, C and Smith,
DR},
Title = {Random gradient index metamaterials},
Journal = {META08 - Proceedings of the 2008 International Workshop on
Metamaterials},
Pages = {248-250},
Publisher = {IEEE},
Year = {2008},
Month = {December},
url = {http://dx.doi.org/10.1109/META.2008.4723589},
Abstract = {We report a broadband reflectionless gradient random medium
design and experimental implementation by using metamaterial
technology. This gradient random medium matches the
impedance of the air and gradually change its refraction
index randomly, creating a puzzle for wave propagation in
front of a metal conductor. Thus, such type of coating is
expected to diffuse the reflection waves from a conductor
metal. The implementation of such device needs, in our
experiment, more than 30,000 different unit cells.
Obviously, such large scale design and fabrication mask
generation have been out of the scope of traditional manual
production. We propose an automatical metamaterial design
system, which made the implementation of gradient random
medium possible and provide the technique of large scale
metamaterial unit-cell design. The design is verified by the
2D near field scanning mapper measurement and the angular
measurement. The measurement results show that the designed
sample works well as we expected. © 2008
IEEE.},
Doi = {10.1109/META.2008.4723589},
Key = {fds269693}
}
@article{fds269694,
Author = {Liu, R and Ji, C and Tiejun, C and Smith, DR},
Title = {Progress of metamaterials at microwave frequencies},
Journal = {META08 - Proceedings of the 2008 International Workshop on
Metamaterials},
Pages = {47-49},
Publisher = {IEEE},
Year = {2008},
Month = {December},
url = {http://dx.doi.org/10.1109/META.2008.4723528},
Abstract = {Metamaterials have been rapidly explored for a few years and
attracted tremendous attentions. This paper discussed the
latest progress in metamaterials at microwave frequencies.
The ability of designing and building the complex medium has
been dramatically enlarged via the development of various
types of metamaterial configuration, rapid design system and
sophisticated fabrication technique. © 2008
IEEE.},
Doi = {10.1109/META.2008.4723528},
Key = {fds269694}
}
@article{fds269695,
Author = {Roberts, DA and Rahm, M and Pendry, JB and Smith,
DR},
Title = {Transformation-optical design of sharp waveguide bends and
corners},
Journal = {Applied Physics Letters},
Volume = {93},
Number = {25},
Pages = {251111-251111},
Publisher = {AIP Publishing},
Year = {2008},
Month = {December},
ISSN = {0003-6951},
url = {http://dx.doi.org/10.1063/1.3055604},
Abstract = {Transformation optics is a recently appreciated approach for
designing complex electromagnetic media. Here, we describe
the extension of transformation optical techniques to
include waveguide boundary conditions. We illustrate the use
of finite embedded coordinate transformations to design a
medium that can be incorporated into a waveguide bend or
corner, rendering the structure reflectionless. The expected
behavior of the waveguide bends is confirmed with numerical
simulations. © 2008 American Institute of
Physics.},
Doi = {10.1063/1.3055604},
Key = {fds269695}
}
@article{fds269799,
Author = {Kundtz, N and Roberts, DA and Allen, J and Cummer, S and Smith,
DR},
Title = {Optical source transformations.},
Journal = {Optics express},
Volume = {16},
Number = {26},
Pages = {21215-21222},
Year = {2008},
Month = {December},
url = {http://www.ncbi.nlm.nih.gov/pubmed/19104551},
Abstract = {Transformation optics is a recently appreciated methodology
for the design of complex media that control the propagation
of electromagnetic and other types of waves. The
transformation optical technique involves the use of
coordinate transformations applied to some region of space,
providing a conceptual means to redirect the flow of waves.
Successfully designed devices to date have made use of
transformations acting on passive space only; however, the
technique can also be applied when source distributions
(e.g., current and charge) are included within the space
being transformed. In this paper we present examples of
source transformations that illustrate the potential of
these expanded transformation optical methods. In
particular, using finite-element full-wave simulations, we
confirm the restoration of dipole radiation patterns from
both a distorted 'pin-wheel' antenna and a bent dipole
partially occluded by a cylindrical scatterer. We propose
the technique of source transformations as a powerful
approach for antenna design, especially in relation to
conformal antennas.},
Doi = {10.1364/oe.16.021215},
Key = {fds269799}
}
@article{fds335128,
Author = {Smith, DR and Mazzucato, E and Lee, W and Park, HK and Domier, CW and Luhmann, NC},
Title = {A collective scattering system for measuring electron
gyroscale fluctuations on the National Spherical Torus
Experiment},
Journal = {Review of Scientific Instruments},
Volume = {79},
Number = {12},
Pages = {123501-123501},
Publisher = {AIP Publishing},
Year = {2008},
Month = {December},
url = {http://dx.doi.org/10.1063/1.3039415},
Abstract = {A collective scattering system has been installed on the
National Spherical Torus Experiment (NSTX) to measure
electron gyroscale fluctuations in NSTX plasmas. The system
measures fluctuations with k⊥ ρ e 0.6 and k⊥ 20 cm-1.
Up to five distinct wavenumbers are measured simultaneously,
and the large toroidal curvature of NSTX plasmas provides
enhanced spatial localization. Steerable optics can position
the scattering volume throughout the plasma from the
magnetic axis to the outboard edge. Initial measurements
indicate rich turbulent dynamics on the electron gyroscale.
The system will be a valuable tool for investigating the
connection between electron temperature gradient turbulence
and electron thermal transport in NSTX plasmas. © 2008
American Institute of Physics.},
Doi = {10.1063/1.3039415},
Key = {fds335128}
}
@article{fds269691,
Author = {Jiang, WX and Cui, TJ and Yang, XM and Cheng, Q and Liu, R and Smith,
DR},
Title = {Invisibility cloak without singularity},
Journal = {Applied Physics Letters},
Volume = {93},
Number = {19},
Pages = {194102-194102},
Publisher = {AIP Publishing},
Year = {2008},
Month = {November},
ISSN = {0003-6951},
url = {http://dx.doi.org/10.1063/1.3026532},
Abstract = {An elliptical invisible cloak is proposed using a coordinate
transformation in the elliptical-cylindrical coordinate
system, which crushes the cloaked object to a line segment
instead of a point. The elliptical cloak is reduced to a
nearly circular cloak if the elliptical focus becomes very
small. The advantage of the proposed invisibility cloak is
that none of the parameters is singular and the changing
range of all parameters is relatively small. © 2008
American Institute of Physics.},
Doi = {10.1063/1.3026532},
Key = {fds269691}
}
@article{fds330999,
Author = {Leach, MP and Smith, D and Skobelev, SP},
Title = {A modified holographic technique for planar near-field
antenna measurements},
Journal = {IEEE Transactions on Antennas and Propagation},
Volume = {56},
Number = {10},
Pages = {3342-3345},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2008},
Month = {October},
url = {http://dx.doi.org/10.1109/TAP.2008.929522},
Abstract = {A modification of the synthetic-plane-wave-based holographic
technique for determining radiation patterns and aperture
fields of medium-gain horn antennas is proposed. The
modification is based on using both the sum and difference
of the near field and reference signals to form the hologram
via simple low-cost amplitude-only near field measurements.
This approach when compared to the previous version, where
only the sum signal is used, allows increased sample
spacing, and also provides an improvement in quality of the
final results. The effectiveness of the modified technique
is confirmed by both calculated and measured results
obtained for pyramidal and conical horn antennas at 10 GHz
frequency. © 2008 IEEE.},
Doi = {10.1109/TAP.2008.929522},
Key = {fds330999}
}
@article{fds269792,
Author = {Hand, TH and Yu, Y and Palit, S and Bingham, C and Rahm, M and Smith, DR and Padilla, WJ and Jokerst, N and Cummer, SA},
Title = {Dual-band planar electric THz metamaterial with resonator
yield analysis},
Journal = {2008 Conference on Quantum Electronics and Laser Science
Conference on Lasers and Electro-Optics,
CLEO/QELS},
Year = {2008},
Month = {September},
url = {http://dx.doi.org/10.1109/CLEO.2008.4552339},
Abstract = {THz radiation transmission through a dual-band electric
metamaterial is presented, where we analyze manufacturing
defects in the metamaterial. Removing different resonator
percentages allows us to quantify the effects of
manufacturing defects on the material response. ©2008
IEEE.},
Doi = {10.1109/CLEO.2008.4552339},
Key = {fds269792}
}
@article{fds269793,
Author = {Hand, TH and Yuan, Y and Palit, S and Bingham, C and Rahm, M and Smith, DR and Padilla, WJ and Jokerst, N and Cummer, SA},
Title = {Dual-band planar electric THz metamaterial with resonator
yield analysis},
Journal = {Conference on Quantum Electronics and Laser Science (QELS) -
Technical Digest Series},
Year = {2008},
Month = {September},
url = {http://dx.doi.org/10.1109/QELS.2008.4552848},
Abstract = {THz radiation transmission through a dual-band electric
metamaterial is presented, where we analyze manufacturing
defects in the metamaterial. Removing different resonator
percentages allows us to quantify the effects of
manufacturing defects on the material response. © 2008
IEEE.},
Doi = {10.1109/QELS.2008.4552848},
Key = {fds269793}
}
@booklet{Chen08,
Author = {Chen, HT and Palit, S and Tyler, T and Bingham, CM and Zide, JMO and O'Hara, JF and Smith, DR and Gossard, AC and Averitt, RD and Padilla,
WJ and Jokerst, NM and Taylor, AJ},
Title = {Hybrid metamaterials enable fast electrical modulation of
freely propagating terahertz waves},
Journal = {Applied Physics Letters},
Volume = {93},
Number = {9},
Pages = {091117-091117},
Publisher = {AIP Publishing},
Year = {2008},
Month = {September},
ISSN = {0003-6951},
url = {http://dx.doi.org/10.1063/1.2978071},
Abstract = {We demonstrate fast electrical modulation of freely
propagating terahertz waves at room temperature using hybrid
metamaterial devices. The devices are planar metamaterials
fabricated on doped semiconductor epitaxial layers, which
form hybrid metamaterial-Schottky diode structures. With an
applied ac voltage bias, we show modulation of terahertz
radiation at inferred frequencies over 2 MHz. The modulation
speed is limited by the device depletion capacitance which
may be reduced for even faster operation. © 2008 American
Institute of Physics.},
Doi = {10.1063/1.2978071},
Key = {Chen08}
}
@article{fds269698,
Author = {Cheng, Q and Liu, R and Mock, JJ and Cui, TJ and Smith,
DR},
Title = {Partial focusing by indefinite complementary
metamaterials},
Journal = {Physical Review B - Condensed Matter and Materials
Physics},
Volume = {78},
Number = {12},
Publisher = {American Physical Society (APS)},
Year = {2008},
Month = {September},
ISSN = {1098-0121},
url = {http://dx.doi.org/10.1103/PhysRevB.78.121102},
Abstract = {We have experimentally realized a two-dimensional partial
focusing within a planar waveguide using complementary
indefinite metamaterials. When the electric fields emitted
from the dipole are TE polarized, the focusing condition
requires negative magnetic response in the propagation
direction of the waveguide, which can be achieved by the
complementary electric resonator (CELC) structures. We have
carefully designed the experimental configurations and the
dimensions for the CELC structures. The experimental result
is consistent with the theoretical prediction, which
validates the partial focusing phenomenon. © 2008 The
American Physical Society.},
Doi = {10.1103/PhysRevB.78.121102},
Key = {fds269698}
}
@article{fds269690,
Author = {Nguyen, VN and Justice, BJ and Yönak, SH and Smith,
DR},
Title = {Electrically coupled graded index metamaterial},
Journal = {Conference Proceedings 2008 IEEE International Workshop on
Antenna Technology: Small Antennas and Novel Metamaterials,
IWAT 2008},
Pages = {119-122},
Publisher = {IEEE},
Year = {2008},
Month = {September},
url = {http://dx.doi.org/10.1109/IWAT.2008.4511304},
Doi = {10.1109/IWAT.2008.4511304},
Key = {fds269690}
}
@booklet{Mock08,
Author = {Mock, JJ and Hill, RT and Degiron, A and Zauscher, S and Chilkoti, A and Smith, DR},
Title = {Distance-dependent plasmon resonant coupling between a gold
nanoparticle and gold film.},
Journal = {Nano letters},
Volume = {8},
Number = {8},
Pages = {2245-2252},
Year = {2008},
Month = {August},
ISSN = {1530-6984},
url = {http://www.ncbi.nlm.nih.gov/pubmed/18590340},
Abstract = {We present an experimental analysis of the plasmonic
scattering properties of gold nanoparticles controllably
placed nanometers away from a gold metal film. We show that
the spectral response of this system results from the
interplay between the localized plasmon resonance of the
nanoparticle and the surface plasmon polaritons of the gold
film, as previously predicted by theoretical studies. In
addition, we report that the metal film induces a
polarization to the single nanoparticle light scattering,
resulting in a doughnut-shaped point spread function when
imaged in the far-field. Both the spectral response and the
polarization effects are highly sensitive to the
nanoparticle-film separation distance. Such a system shows
promise in potential biometrology and diagnostic
devices.},
Doi = {10.1021/nl080872f},
Key = {Mock08}
}
@article{fds335129,
Author = {Brew, CAJ and Wilson, FF and Castelli, G and Adye, T and Roethel, W and Luppi, E and Andreotti, D and Smith, D and Khan, A and Barrett, M and Barlow, R and Bailey, D},
Title = {Production of BABAR skimmed analysis
datasets using the grid},
Journal = {Journal of Physics: Conference Series},
Volume = {119},
Number = {6},
Pages = {062018-062018},
Publisher = {IOP Publishing},
Year = {2008},
Month = {July},
url = {http://dx.doi.org/10.1088/1742-6596/119/6/062018},
Abstract = {The BABAR Collaboration, based at Stanford Linear
Accelerator Center (SLAC), Stanford, US, has been performing
physics reconstruction, simulation studies and data analysis
for 8 years using a number of compute farms around the
world. Recent developments in Grid technologies could
provide a way to manage the distributed resources in a
single coherent structure. We describe enhancements to the
BABAR experiment's distributed skimmed dataset production
system to make use of European Grid resources and present
the results with regard to B ABAR's latest cycle of skimmed
dataset production. We compare the benefits of a local and
Grid-based systems, the ease with which the system is
managed and the challenges of integrating the Grid with
legacy software. We compare job success rates and
manageability issues between Grid and non-Grid production.
© 2008 IOP Publishing Ltd.},
Doi = {10.1088/1742-6596/119/6/062018},
Key = {fds335129}
}
@booklet{Driscoll08,
Author = {Driscoll, T and Palit, S and Qazilbash, MM and Brehm, M and Keilmann, F and Chae, BG and Yun, SJ and Kim, HT and Cho, SY and Jokerst, NM and Smith, DR and Basov, DN},
Title = {Dynamic tuning of an infrared hybrid-metamaterial resonance
using vanadium dioxide},
Journal = {Applied Physics Letters},
Volume = {93},
Number = {2},
Pages = {024101-024101},
Publisher = {AIP Publishing},
Year = {2008},
Month = {July},
ISSN = {0003-6951},
url = {http://dx.doi.org/10.1063/1.2956675},
Abstract = {We demonstrate a metamaterial device whose far-infrared
resonance frequency can be dynamically tuned. Dynamic tuning
should alleviate many bandwidth-related roadblocks to
metamaterial application by granting a wide matrix of
selectable electromagnetic properties. This tuning effect is
achieved via a hybrid-metamaterial architecture;
intertwining split ring resonator metamaterial elements with
vanadium dioxide (VO2)-a material whose optical properties
can be strongly and quickly changed via external stimulus.
This hybrid structure concept opens a fresh dimension in
both exploring and exploiting the intriguing electromagnetic
behavior of metamaterials. (C) 2008 American Institute of
Physics.},
Doi = {10.1063/1.2956675},
Key = {Driscoll08}
}
@booklet{Rahm08,
Author = {Rahm, M and Roberts, DA and Pendry, JB and Smith,
DR},
Title = {Transformation-optical design of adaptive beam bends and
beam expanders.},
Journal = {Optics express},
Volume = {16},
Number = {15},
Pages = {11555-11567},
Year = {2008},
Month = {July},
ISSN = {1094-4087},
url = {http://www.ncbi.nlm.nih.gov/pubmed/18648477},
Abstract = {We describe the design of adaptive beam bends and beam
splitters with arbitrary bend and split angles by use of
finite embedded coordinate transformations. The devices do
not exhibit reflection at the entrance or exit surfaces. It
is shown that moderate and practically achievable values of
the relative permittivity and permeability can be obtained
for beam bends and splitters with both small and large bend
radius. The devices are also discussed in the context of
reconfigurable metamaterials, in which the bend and split
angles can be dynamically tuned. The performance of adaptive
beam bends and splitters is demonstrated in full wave
simulations based on a finite-element method. Furthermore,
the design of an adaptively adjustable transformation-optical
beam expander/compressor is presented. It is observed that a
pure transformation-optical design cannot result in a
reflectionless beam expander/compressor.},
Doi = {10.1364/oe.16.011555},
Key = {Rahm08}
}
@booklet{Sebba08,
Author = {Sebba, DS and Mock, JJ and Smith, DR and Labean, TH and Lazarides,
AA},
Title = {Reconfigurable core-satellite nanoassemblies as
molecularly-driven plasmonic switches},
Journal = {Nano Letters},
Volume = {8},
Number = {7},
Pages = {1803-1808},
Year = {2008},
Month = {July},
ISSN = {1530-6984},
url = {http://www.ncbi.nlm.nih.gov/pubmed/18540653},
Abstract = {Molecular control of plasmon coupling is investigated in
sub-100 nm assemblies composed of 13 nm gold "satellite"
particles tethered by reconfigurable DNA nanostructures to a
50 nm gold "core" particle. Reconfiguration of the DNA
nanostructures from a compact to an extended state results
in blue shifting of the assembly plasmon resonance,
indicating reduced interparticle coupling and lengthening of
the core-satellite tether. Scattering spectra of the
core-satellite assemblies before and after reconfiguration
are compared with spectra calculated using a structural
model that incorporates the core/satellite ratio determined
by TEM imaging and estimates of tether length based upon
prior measurements of interparticle separation in DNA linked
nanoparticle networks. A strong correspondence between
measured and simulated difference spectra validates the
structural models that link the observed plasmon modulation
with DNA nanostructure reconfiguration.},
Doi = {10.1021/nl080029h},
Key = {Sebba08}
}
@booklet{Jiang08,
Author = {Jiang, WX and Cui, TJ and Cheng, Q and Chin, JY and Yang, XM and Liu, RP and Smith, DR},
Title = {Design of arbitrarily shaped concentrators based on
conformally optical transformation of nonuniform rational
B-spline surfaces},
Journal = {Applied Physics Letters},
Volume = {92},
Number = {26},
Pages = {264101-264101},
Publisher = {AIP Publishing},
Year = {2008},
Month = {June},
ISSN = {0003-6951},
url = {http://dx.doi.org/10.1063/1.2951485},
Abstract = {We study the design of arbitrarily shaped electromagnetic
(EM) concentrators and their potential applications. To
obtain closed-form formulas of EM parameters for an
arbitrarily shaped concentrator, we employ nonuniform
rational B-spline (NURBS) to represent the geometrical
boundary. Using the conformally optical transformation of
NURBS surfaces, we propose the analytical design of
arbitrarily shaped concentrators, which are composed of
anisotropic and inhomogeneous metamaterials with closed-form
constitutive tensors. The designed concentrators are
numerically validated by full-wave simulations, which show
perfectly directed EM behaviors. As one of the potential
applications, we demonstrate a way to amplify plane waves
using a rectangular concentrator, which is much more
efficient and easier than the existing techniques. Using
NURBS expands the generality of the transformation optics
and could lead toward making a very general tool that would
interface with commercial softwares such as 3D STUDIOMAX and
MAYA. (c) 2008 American Institute of Physics.},
Doi = {10.1063/1.2951485},
Key = {Jiang08}
}
@booklet{Yuan08,
Author = {Yuan, Y and Bingham, C and Tyler, T and Palit, S and Hand, TH and Padilla,
WJ and Smith, DR and Jokerst, NM and Cummer, SA},
Title = {Dual-band planar electric metamaterial in the terahertz
regime.},
Journal = {Optics express},
Volume = {16},
Number = {13},
Pages = {9746-9752},
Year = {2008},
Month = {June},
ISSN = {1094-4087},
url = {http://www.ncbi.nlm.nih.gov/pubmed/18575543},
Abstract = {We present the design, fabrication, and measurement of a
dual-band planar metamaterial with two distinct electric
resonances at 1.0 and 1.2 THz, as a step towards the
development of frequency agile or broadband THz materials
and devices. A method of defining the effective thickness of
the metamaterial layer is introduced to simplify the
material design and characterization. Good agreement between
the simulated and measured transmission is obtained for the
fabricated sample by treating the sample as multi-layer
system, i. e. the effective metamaterial layer plus the rest
of the substrate, as well as properly modeling the loss of
the substrate. The methods introduced in this paper can be
extended to planar metamaterial structures operating in
infrared and optical frequency ranges.},
Doi = {10.1364/oe.16.009746},
Key = {Yuan08}
}
@booklet{Landy08,
Author = {Landy, NI and Sajuyigbe, S and Mock, JJ and Smith, DR and Padilla,
WJ},
Title = {Perfect metamaterial absorber.},
Journal = {Physical review letters},
Volume = {100},
Number = {20},
Pages = {207402},
Year = {2008},
Month = {May},
ISSN = {0031-9007},
url = {http://dx.doi.org/10.1103/physrevlett.100.207402},
Abstract = {We present the design for an absorbing metamaterial (MM)
with near unity absorbance A(omega). Our structure consists
of two MM resonators that couple separately to electric and
magnetic fields so as to absorb all incident radiation
within a single unit cell layer. We fabricate, characterize,
and analyze a MM absorber with a slightly lower predicted
A(omega) of 96%. Unlike conventional absorbers, our MM
consists solely of metallic elements. The substrate can
therefore be optimized for other parameters of interest. We
experimentally demonstrate a peak A(omega) greater than 88%
at 11.5 GHz.},
Doi = {10.1103/physrevlett.100.207402},
Key = {Landy08}
}
@article{fds269628,
Author = {Smith, DR and Soukoulis, CM},
Title = {Preface},
Journal = {Photonics and Nanostructures - Fundamentals and
Applications},
Volume = {6},
Number = {1},
Pages = {1-2},
Publisher = {Elsevier BV},
Year = {2008},
Month = {April},
ISSN = {0029-5493},
url = {http://dx.doi.org/10.1016/j.photonics.2008.01.003},
Doi = {10.1016/j.photonics.2008.01.003},
Key = {fds269628}
}
@booklet{Rahm08a,
Author = {Rahm, M and Schurig, D and Roberts, DA and Cummer, SA and Smith, DR and Pendry, JB},
Title = {Design of electromagnetic cloaks and concentrators using
form-invariant coordinate transformations of Maxwell's
equations},
Journal = {Photonics and Nanostructures - Fundamentals and
Applications},
Volume = {6},
Number = {1},
Pages = {87-95},
Publisher = {Elsevier BV},
Year = {2008},
Month = {April},
ISSN = {1569-4410},
url = {http://dx.doi.org/10.1016/j.photonics.2007.07.013},
Abstract = {The technique of applying form-invariant, spatial coordinate
transformations of Maxwell's equations can facilitate the
design of structures with unique electromagnetic or optical
functionality. Here, we illustrate the transformation-optical
approach in the designs of a square electromagnetic cloak
and an omni-directional electromagnetic field concentrator.
The transformation equations are described and the
functionality of the devices is numerically confirmed by
two-dimensional finite element simulations. The two devices
presented demonstrate that the transformation optic approach
leads to the specification of complex, anisotropic and
inhomogeneous materials with well directed and distinct
electromagnetic behavior. © 2007 Elsevier B.V. All rights
reserved.},
Doi = {10.1016/j.photonics.2007.07.013},
Key = {Rahm08a}
}
@booklet{Degiron08,
Author = {Degiron, A and Cho, SY and Harrison, C and Jokerst, NM and Dellagiacoma,
C and Martin, OJF and Smith, DR},
Title = {Experimental comparison between conventional and hybrid
long-range surface plasmon waveguide bends},
Journal = {Physical Review A - Atomic, Molecular, and Optical
Physics},
Volume = {77},
Number = {2},
Publisher = {American Physical Society (APS)},
Year = {2008},
Month = {February},
ISSN = {1050-2947},
url = {http://dx.doi.org/10.1103/PhysRevA.77.021804},
Abstract = {We report on the characterization of long-range surface
plasmon waveguide bends at telecom wavelengths (λ=1550
nm). The structures consist of a thin Au stripe embedded in
a transparent polymer film. When the polymer thickness is
larger than the lateral extension of the plasmon, the stripe
sustains a conventional long-range mode; in the opposite
case, the mode is hybrid because its field distribution is
confined by total internal reflection in the dielectric
cladding. This hybridization increases the damping by
absorption but dramatically reduces the radiation loss that
occurs for curved geometries, such as bends. Our results are
supported quantitatively by full-wave finite-element
simulations. © 2008 The American Physical
Society.},
Doi = {10.1103/PhysRevA.77.021804},
Key = {Degiron08}
}
@article{fds304083,
Author = {Rahm, M and Cummer, SA and Schurig, D and Pendry, JB and Smith,
DR},
Title = {Optical design of reflectionless complex media by finite
embedded coordinate transformations.},
Journal = {Physical review letters},
Volume = {100},
Number = {6},
Pages = {063903},
Year = {2008},
Month = {February},
url = {http://arxiv.org/abs/0711.1846v2},
Abstract = {Transformation optics offers an unconventional approach to
the control of electromagnetic fields. The transformation
optical structures proposed to date, such as electromagnetic
"invisibility" cloaks and concentrators, are inherently
reflectionless and leave the transmitted wave undisturbed.
Here, we expand the class of transformation optical
structures by introducing finite, embedded coordinate
transformations, which allow the electromagnetic waves to be
steered or focused. We apply the method to the design of
several devices, including a parallel beam shifter and a
beam splitter, both of which are reflectionless and exhibit
unusual electromagnetic behavior as confirmed by 2D
full-wave simulations.},
Doi = {10.1103/physrevlett.100.063903},
Key = {fds304083}
}
@article{fds269586,
Author = {Hand, TH and Yuan, Y and Palit, S and Bingham, C and Rahm, M and Smith, DR and Padilla, WJ and Jokerst, N and Cummer, SA},
Title = {Dual-band planar electric THz metamaterial with resonator
yield analysis},
Journal = {Optics InfoBase Conference Papers},
Year = {2008},
Month = {January},
Abstract = {THz radiation transmission through a dual-band electric
metamaterial is presented, where we analyze manufacturing
defects in the metamaterial. Removing different resonator
percentages allows us to quantify the effects of
manufacturing defects on the material response. © 2008 OSA
/ CLEO/QELS 2008.},
Key = {fds269586}
}
@article{fds269587,
Author = {Hand, TH and Yuan, Y and Palit, S and Bingham, C and Rahm, M and Smith, DR and Padilla, WJ and Jokerst, N and Cummer, SA},
Title = {Dual-band planar electric THz metamaterial with resonator
yield analysis},
Journal = {Optics InfoBase Conference Papers},
Year = {2008},
Month = {January},
Abstract = {THz radiation transmission through a dual-band electric
metamaterial is presented, where we analyze manufacturing
defects in the metamaterial. Removing different resonator
percentages allows us to quantify the effects of
manufacturing defects on the material response. © 2008 OSA
/ CLEO/QELS 2008.},
Key = {fds269587}
}
@article{fds269697,
Author = {Degiron, A and Berini, P and Smith, DR},
Title = {Guiding light with long-range plasmons},
Journal = {Optics and Photonics News},
Volume = {19},
Number = {7-8},
Pages = {28-34},
Publisher = {The Optical Society},
Year = {2008},
Month = {January},
ISSN = {1047-6938},
url = {http://dx.doi.org/10.1364/OPN.19.7.000028},
Abstract = {Long-range surface plasmons can be implemented, to develop
integrated optical circuits and other chip-scale photonic
applications. Long-range surface plasmons are optical modes
propagating along metallic circuits at optical and
near-infrared wavelengths that are characterized by specific
electromagnetic properties. It is also a coupled mode of
metal films, arising when its thickness is small, to allow
it on each metal-dielectric interface to interact. These
modes are less confined and less affected by absorption in
the metal. The electromagnetic fields associated with these
plasmons are evanescent in the direction transverse to their
propagation, due to interaction between plasmons and
electrons. A simple way to guide a long-range surface
plasmon is, to restrict the width of the thin metal film
along which it propagates.},
Doi = {10.1364/OPN.19.7.000028},
Key = {fds269697}
}
@booklet{Cummer08,
Author = {Cummer, SA and Popa, BI and Schurig, D and Smith, DR and Pendry, J and Rahm, M and Starr, A},
Title = {Scattering theory derivation of a 3D acoustic cloaking
shell},
Journal = {Physical Review Letters},
Volume = {1},
Number = {2},
Pages = {024301},
Year = {2008},
Month = {January},
ISSN = {0031-9007},
url = {http://www.ncbi.nlm.nih.gov/pubmed/18232873},
Abstract = {Through acoustic scattering theory we derive the mass
density and bulk modulus of a spherical shell that can
eliminate scattering from an arbitrary object in the
interior of the shell-in other words, a 3D acoustic cloaking
shell. Calculations confirm that the pressure and velocity
fields are smoothly bent and excluded from the central
region as for previously reported electromagnetic cloaking
shells. The shell requires an anisotropic mass density with
principal axes in the spherical coordinate directions and a
radially dependent bulk modulus. The existence of this 3D
cloaking shell indicates that such reflectionless solutions
may also exist for other wave systems that are not
isomorphic with electromagnetics.},
Doi = {10.1103/PhysRevLett.100.024301},
Key = {Cummer08}
}
@booklet{Liu08,
Author = {Liu, R and Cheng, Q and Hand, T and Mock, JJ and Cui, TJ and Cummer, SA and Smith, DR},
Title = {Experimental demonstration of electromagnetic tunneling
through an epsilon-near-zero metamaterial at microwave
frequencies},
Journal = {Physical Review Letters},
Volume = {1},
Number = {2},
Pages = {023903},
Year = {2008},
Month = {January},
ISSN = {0031-9007},
url = {http://www.ncbi.nlm.nih.gov/pubmed/18232869},
Abstract = {Silveirinha and Engheta have recently proposed that
electromagnetic waves can tunnel through a material with an
electric permittivity (epsilon) near zero (ENZ). An ENZ
material of arbitrary geometry can thus serve as a perfect
coupler between incoming and outgoing waveguides with
identical cross-sectional area, so long as one dimension of
the ENZ is electrically small. In this Letter we present an
experimental demonstration of microwave tunneling between
two planar waveguides separated by a thin ENZ channel. The
ENZ channel consists of a planar waveguide in which
complementary split ring resonators are patterned on the
lower surface. A tunneling passband is found in transmission
measurements, while a two-dimensional spatial map of the
electric field distribution reveals a uniform phase
variation across the channel-both measurements in agreement
with theory and numerical simulations.},
Doi = {10.1103/PhysRevLett.100.023903},
Key = {Liu08}
}
@article{fds304903,
Author = {Cummer, SA and Popa, B-I and Schurig, D and Smith, DR and Pendry, J and Rahm, M and Starr, A},
Title = {Scattering theory derivation of a 3D acoustic cloaking
shell.},
Journal = {Physical review letters},
Volume = {100},
Number = {2},
Pages = {024301},
Year = {2008},
Month = {January},
ISSN = {0031-9007},
url = {http://www.ncbi.nlm.nih.gov/pubmed/18232873},
Abstract = {Through acoustic scattering theory we derive the mass
density and bulk modulus of a spherical shell that can
eliminate scattering from an arbitrary object in the
interior of the shell--in other words, a 3D acoustic
cloaking shell. Calculations confirm that the pressure and
velocity fields are smoothly bent and excluded from the
central region as for previously reported electromagnetic
cloaking shells. The shell requires an anisotropic mass
density with principal axes in the spherical coordinate
directions and a radially dependent bulk modulus. The
existence of this 3D cloaking shell indicates that such
reflectionless solutions may also exist for other wave
systems that are not isomorphic with electromagnetics.},
Doi = {10.1103/physrevlett.100.024301},
Key = {fds304903}
}
@article{fds304904,
Author = {Liu, R and Cheng, Q and Hand, T and Mock, JJ and Cui, TJ and Cummer, SA and Smith, DR},
Title = {Experimental demonstration of electromagnetic tunneling
through an epsilon-near-zero metamaterial at microwave
frequencies.},
Journal = {Physical review letters},
Volume = {100},
Number = {2},
Pages = {023903},
Year = {2008},
Month = {January},
ISSN = {0031-9007},
url = {http://www.ncbi.nlm.nih.gov/pubmed/18232869},
Abstract = {Silveirinha and Engheta have recently proposed that
electromagnetic waves can tunnel through a material with an
electric permittivity (epsilon) near zero (ENZ). An ENZ
material of arbitrary geometry can thus serve as a perfect
coupler between incoming and outgoing waveguides with
identical cross-sectional area, so long as one dimension of
the ENZ is electrically small. In this Letter we present an
experimental demonstration of microwave tunneling between
two planar waveguides separated by a thin ENZ channel. The
ENZ channel consists of a planar waveguide in which
complementary split ring resonators are patterned on the
lower surface. A tunneling passband is found in transmission
measurements, while a two-dimensional spatial map of the
electric field distribution reveals a uniform phase
variation across the channel--both measurements in agreement
with theory and numerical simulations.},
Doi = {10.1103/physrevlett.100.023903},
Key = {fds304904}
}
@article{fds335131,
Author = {Smith, DR and Gow, J and Holland, AD},
Title = {Proton irradiation of swept-charge devices for the
Chandrayaan-1 X-ray Spectrometer (C1XS)},
Journal = {Nuclear Instruments and Methods in Physics Research, Section
A: Accelerators, Spectrometers, Detectors and Associated
Equipment},
Volume = {583},
Number = {2-3},
Pages = {270-277},
Publisher = {Elsevier BV},
Year = {2007},
Month = {December},
url = {http://dx.doi.org/10.1016/j.nima.2007.09.050},
Abstract = {This paper presents work carried out in support of
swept-charge device (SCD) characterisation for the
Chandrayaan-1 X-ray Spectrometer (C1XS) instrument. A brief
overview of the C1XS instrument is presented, followed by a
description of SCD structure and operation. The SCD test
facility and method of device characterisation using two
different drive sequencers to assess leakage current and
spectroscopy performance (FWHM and noise at Mn Kα) are then
described. The expected end-of-life (EOL) 10 MeV equivalent
proton fluence for the SCDs of C1XS was modelled using Monte
Carlo simulation software and used in a subsequent proton
irradiation study involving eight SCDs. The irradiation
study was carried out at the Kernfysisch Versneller
Instituut (KVI) in the Netherlands and characterised the
impact of 50% and 100% of the expected Chandrayaan-1 EOL
proton fluence on the SCD operational characteristics. The
radiation environment modelling, irradiation methodology and
post-irradiation characterisation of the devices are
presented in this paper and recommendations about the
planned C1XS operational temperature and shielding are
given. © 2007 Elsevier B.V. All rights reserved.},
Doi = {10.1016/j.nima.2007.09.050},
Key = {fds335131}
}
@booklet{Cheng07,
Author = {Cheng, Q and Liu, R and Huang, D and Cui, TJ and Smith,
DR},
Title = {Circuit verification of tunneling effect in zero
permittivity medium},
Journal = {Applied Physics Letters},
Volume = {91},
Number = {23},
Year = {2007},
Month = {December},
ISSN = {0003-6951},
url = {http://dx.doi.org/10.1063/1.2822444},
Abstract = {We demonstrate the tunneling effect in zero permittivity
medium using the multilayered printed circuit, where
complementary split ring resonators have been used to
produce the resonant electric response and achieve the
effective zero permittivity near the plasma frequency. We
have shown experimentally the existence of the transmission
peak near the zero permittivity frequency. The application
of such a structure as a circuit bend has been investigated,
which shows the potential usage in the design of microwave
and millimeter-wave integrated circuits in the future. ©
2007 American Institute of Physics.},
Doi = {10.1063/1.2822444},
Key = {Cheng07}
}
@article{fds335130,
Author = {Gow, J and Smith, DR and Holland, AD and Maddison, B and Howe, C and Sreekumar, P and Huovelin, J and Grande, M},
Title = {Characterisation of swept-charge devices for the
Chandrayaan-1 X-ray Spectrometer (C1XS) instrument},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {6686},
Publisher = {SPIE},
Year = {2007},
Month = {December},
ISBN = {9780819468345},
url = {http://dx.doi.org/10.1117/12.734062},
Abstract = {The Indian Space Research Organisation (ISRO) Chandrayaan-1
mission is India's first lunar spacecraft, containing a
suite of instruments to carry out high-resolution remote
sensing of the Moon at visible, near infrared and X-ray
wavelengths. Due for launch in early 2008, the spacecraft
will carry out its two year mission in a polar orbit around
the Moon at an altitude of 100 km. One of the eleven
instruments in the spacecraft payload is the Chandrayaan-1
X-ray Spectrometer (C1XS), a descendant of the successful
D-CIXS instrument that flew on the European Space Agency
SMART-1 lunar mission launched in 2003. C1XS consists of 24
swept-charge device (SCD) silicon X-ray detectors arranged
in 6 modules that will carry out high quality X-ray
spectroscopic mapping of the Moon using the technique of
X-ray fluorescence. This paper presents an overview of the
Chandrayaan-1 mission and specifically the C1XS instrument
and describes the development of an SCD test facility,
proton irradiation characterisation and screening of
candidate SCD devices for the mission.},
Doi = {10.1117/12.734062},
Key = {fds335130}
}
@article{fds331000,
Author = {Leach, MP and Smith, D and Skobelev, SP and Elsdont,
M},
Title = {An improved holographic technique for medium-gain antenna
near field measurements},
Journal = {IET Seminar Digest},
Volume = {2007},
Number = {11961},
Publisher = {Institution of Engineering and Technology},
Year = {2007},
Month = {December},
ISBN = {9780863418426},
url = {http://dx.doi.org/10.1049/ic.2007.1091},
Abstract = {A modification of the holographic technique based on
synthetic plane wave for determining radiation patterns and
aperture fields of medium-gain horn antennas is proposed.
The modification is based on using both the sum and
difference of the near field and reference signals to form
the hologram via simple low-cost amplitude-only near field
measurements. This approach when compared to the previous
version, where only the sum signal is used, allows increased
sample spacing, and also provides an improvement in quality
of the final results. The effectiveness of the modified
technique is confirmed by both calculated and measured
results obtained for a conical horn antenna operating at 10
GHz frequency.},
Doi = {10.1049/ic.2007.1091},
Key = {fds331000}
}
@article{fds331002,
Author = {Leach, MP and Elsdon, M and Smith, D and Skobelev,
SP},
Title = {Initial results on X-polar far-field radiation patterns
prediction using indirect holographic measurements},
Journal = {IEEE Antennas and Propagation Society, AP-S International
Symposium (Digest)},
Pages = {585-588},
Publisher = {IEEE},
Year = {2007},
Month = {December},
ISBN = {9781424408771},
url = {http://dx.doi.org/10.1109/APS.2007.4395561},
Doi = {10.1109/APS.2007.4395561},
Key = {fds331002}
}
@article{fds331003,
Author = {Leach, MP and Skobelev, SP and Elsdon, M and Smith,
D},
Title = {A modified holographic technique for antenna
measurements},
Journal = {2007 International Conference on Electromagnetics in
Advanced Applications, ICEAA'07},
Pages = {776-779},
Publisher = {IEEE},
Year = {2007},
Month = {December},
ISBN = {9781424407675},
url = {http://dx.doi.org/10.1109/ICEAA.2007.4387418},
Abstract = {A modification of the synthetic-plane-wave-based holographic
technique for determining radiation patterns and aperture
fields of medium-gain horn antennas is proposed. The
modification is based on using both the sum and difference
of the near field and reference signals to form the hologram
via simple low-cost amplitude-only near field measurements.
This approach when compared to the previous version, where
only the sum signal is used, allows increased sample
spacing, and also provides an improvement in quality of the
final results. The effectiveness of the modified technique
is confirmed by both calculated and measured results
obtained for some horn antennas at 10 GHz frequency. © 2007
IEEE.},
Doi = {10.1109/ICEAA.2007.4387418},
Key = {fds331003}
}
@article{fds269688,
Author = {Smith, DR},
Title = {The role of metamaterials and plasmons for novel sensing
applications},
Journal = {Proceedings of IEEE Sensors},
Pages = {1},
Publisher = {IEEE},
Year = {2007},
Month = {December},
url = {http://dx.doi.org/10.1109/ICSENS.2007.4388317},
Abstract = {The past ten years have seen a tremendous acceleration in
the exploration of metals for photonic applications. This
exploration has been common to both the metamaterials and
the plasmonics fields, which leverage the strong resonances
of structured metals to produce desired electromagnetic
response. However, the unique electromagnetic properties of
metal components and composite materials come at a price:
while a seemingly limitless palette of electromagnetic
behavior can be coaxed out of carefully designed metal
structures - negative refractive index and optical magnetism
being two striking examples - material losses and dispersion
place heavy constraints on the ultimate usability of these
properties. Despite their drawbacks, metamaterials based on
metals and plasmonic structures also exhibit unique
phenomena that are distinct from other systems and
materials. Both structures possess the capability to
localize electromagnetic fields to regions much smaller than
the wavelength of light, and to strongly enhance the local
fields. This focusing of light naturally brings about an
extreme sensitivity to the local environment, which can be
used to implement sensing or modulation functionality. By
exploiting the benefits of metals - field localization,
field enhancement and sensitivity to local environment -
while minimizing their disadvantages, we hope to develop an
array of unique and competitive devices across the
electromagnetic spectrum. In this talk we describe the
amazing electromagnetic response that can be achieved in
engineered metamaterial composites with metal inclusions,
including negative index materials and the recently reported
"invisibility" cloaks. © 2007 IEEE.},
Doi = {10.1109/ICSENS.2007.4388317},
Key = {fds269688}
}
@article{fds269689,
Author = {Degiron, A and Mock, JJ and Smith, DR},
Title = {Optical control of metamaterial unit cells at microwave
frequencies},
Journal = {Conference Proceedings of the International Symposium on
Signals, Systems and Electronics},
Pages = {209-212},
Year = {2007},
Month = {December},
url = {http://dx.doi.org/10.1109/ISSSE.2007.4294450},
Abstract = {We have developed metamaterial unit cells whose properties
can be controlled dynamically using near-infrared light. The
structures consist of split ring resonators (SRRs) operating
at microwave frequencies that contain a piece of low-doped
silicon in their gap. We show that the SRR response strongly
depends on the silicon resistivity and exploit this property
to modulate the amplitude or tune the frequency of the SRR
resonance by photodoping the semiconductor with an 815 nm
laser diode. We present several designs and experimental
demonstrations of elementary active photonic devices based
on this approach. © 2007 IEEE.},
Doi = {10.1109/ISSSE.2007.4294450},
Key = {fds269689}
}
@article{fds269791,
Author = {Parazzoli, CG and Greegor, RB and Tanielian, MH and Smith, DR and Cummer, S and Schurig, D and Ziolkowski, R},
Title = {Applications of metamaterials in the GHz frequency
domain},
Journal = {IEEE Antennas and Propagation Society, AP-S International
Symposium (Digest)},
Pages = {1152-1155},
Publisher = {IEEE},
Year = {2007},
Month = {December},
ISSN = {1522-3965},
url = {http://dx.doi.org/10.1109/APS.2007.4395703},
Doi = {10.1109/APS.2007.4395703},
Key = {fds269791}
}
@booklet{Baena07,
Author = {Baena, JD and Jelinek, L and Marqús, R and Mock, JJ and Gollub, J and Smith, DR},
Title = {Isotropic frequency selective surfaces made of cubic
resonators},
Journal = {Applied Physics Letters},
Volume = {91},
Number = {19},
Year = {2007},
Month = {November},
ISSN = {0003-6951},
url = {http://dx.doi.org/10.1063/1.2806915},
Abstract = {Isotropic frequency selective surface (FSS) made of cubic
arrangements of split ring resonators (SRRs) is proposed and
analyzed. For this purpose, a suitable isotropic
modification of the SRR was used in the design of a cubic
unit element invariant under the tetrahedral point symmetry
group. It was experimentally demonstrated that the
transmission through such a FSS is angle and polarization
independent. For comparison, another FSS, whose unit
elements do not satisfy necessary symmetries, was measured,
showing clearly anisotropic behavior. We feel then that
symmetries play an important role. Potential device
applications are envisioned for antenna technology at
microwave and terahertz frequencies. © 2007 American
Institute of Physics.},
Doi = {10.1063/1.2806915},
Key = {Baena07}
}
@booklet{Gollub07,
Author = {Gollub, J and Hand, T and Sajuyigbe, S and Mendonca, S and Cummer, S and Smith, DR},
Title = {Characterizing the effects of disorder in metamaterial
structures},
Journal = {Applied Physics Letters},
Volume = {91},
Number = {16},
Pages = {162907-162907},
Publisher = {AIP Publishing},
Year = {2007},
Month = {October},
ISSN = {0003-6951},
url = {http://dx.doi.org/10.1063/1.2801391},
Abstract = {We investigate the effects of disorder on metamaterial
samples composed of split ring resonators with randomly
introduced variation in their geometrical dimensions. We
demonstrate that disorder broadens the negative permeability
band and introduces effective losses into the system.
Transmission measurements on samples with varying degrees of
disorder are found to be in excellent agreement with
predictions based on standard homogenization theories. ©
2007 American Institute of Physics.},
Doi = {10.1063/1.2801391},
Key = {Gollub07}
}
@booklet{Schurig07,
Author = {Schurig, D and Pendry, JB and Smith, DR},
Title = {Transformation-designed optical elements.},
Journal = {Optics express},
Volume = {15},
Number = {22},
Pages = {14772-14782},
Year = {2007},
Month = {October},
ISSN = {1094-4087},
url = {http://dx.doi.org/10.1364/oe.15.014772},
Abstract = {We describe transformation design of optical elements which,
in addition to image transfer, perform useful operations.
For one class of operations, including translation,
rotation, mirroring and inversion, an image can be generated
that is ideal in the sense of the perfect lens (combining
both near- and far-field components in a flat, unit transfer
function, up to the limits imposed by material
imperfection). We also describe elements that perform
magnification, free from geometric aberrations, even while
providing free-space working distance on both the input and
output sides. These magnifying elements also operate in the
near- and far-field, allowing them to transfer near field
information into the far field, as with the hyper lens and
other related devices, however in contrast to those devices,
insertion loss can be much lower, due to the matching
properties accessible with transformation design. The
devices here described inherently require dispersive
materials, thus chromatic aberration will be present, and
the bandwidth limited.},
Doi = {10.1364/oe.15.014772},
Key = {Schurig07}
}
@article{fds269687,
Author = {Degiron, A and Smith, DR},
Title = {Numerical simulations of long-range plasmonic transmission
lines},
Journal = {Springer Series in Optical Sciences},
Volume = {131},
Pages = {55-71},
Publisher = {Springer Netherlands},
Year = {2007},
Month = {September},
ISSN = {0342-4111},
url = {http://dx.doi.org/10.1007/978-1-4020-4333-8_5},
Abstract = {Structures that guide waves can be found in almost every
optoelectronic or photonic device. Yet, the basic principles
of guided waves in practical realizations have not evolved
substantially over the past several decades. At microwave or
radio frequencies (RF), waveguides typically comprise
metal-enclosed volumes with or without a central conductor;
in the latter case, the lateral dimensions of the waveguide
dictate the frequencies of operation. At optical
wavelengths, metals are comparatively poor conductors and
have traditionally been excluded as optical components.
Instead, dielectric waveguides are employed in which the
mismatch between a higher dielectric region and free space
or a lower dielectric cladding constrains light in a plane
perpendicular to propagation. Because of the low losses in
insulating dielectrics, optical waveguides (such as fiber
optics) can support propagating modes with extraordinarily
low absorption attenuation-often less than 1 dB per
kilometer. © 2007 Springer.},
Doi = {10.1007/978-1-4020-4333-8_5},
Key = {fds269687}
}
@booklet{Yao07,
Author = {Yao, YH and Cui, TJ and Cheng, Q and Liu, RP and Huang, D and Smith,
DR},
Title = {Realization of a super waveguide for high-power-density
generation and transmission using right- and left-handed
transmission-line circuits},
Journal = {Physical Review E},
Volume = {76},
Number = {3},
Pages = {036602},
Year = {2007},
Month = {September},
ISSN = {1539-3755},
url = {http://dx.doi.org/10.1103/physreve.76.036602},
Abstract = {In an earlier work [Cheng and Cui, Phys. Rev. B 72, 113112
(2005)], we have shown theoretically that extremely high
power densities can be generated and transmitted in a super
waveguide which is filled with homogeneous bilayers of
right- and left-handed materials. In this paper, we realize
such a super waveguide using right-handed transmission-line
(RHTL) and left-handed transmission-line (LHTL) circuits.
After a rigorous design of the RHTL-LHTL structure, we
observe the generation and transmission of high-power
densities in the super circuit waveguide from accurate
simulation results. Both lossless and lossy cases have been
studied for the LHTL circuit. From the simulation results
and the rigorous analysis of energy speeds, we show that
high-power flows with opposite directions are excited in the
RHTL and LHTL parts of the super waveguide, which form the
energy vortices in the waveguide cross section.},
Doi = {10.1103/physreve.76.036602},
Key = {Yao07}
}
@booklet{Driscoll07,
Author = {Driscoll, T and Andreev, GO and Basov, DN and Palit, S and Cho, SY and Jokerst, NM and Smith, DR},
Title = {Tuned permeability in terahertz split-ring resonators for
devices and sensors},
Journal = {Applied Physics Letters},
Volume = {91},
Number = {6},
Pages = {062511-062511},
Publisher = {AIP Publishing},
Year = {2007},
Month = {August},
ISSN = {0003-6951},
url = {http://dx.doi.org/10.1063/1.2768300},
Abstract = {A process is demonstrated for tuning the magnetic resonance
frequency of a fixed split-ring resonator array, by way of
adding material near the split-ring elements. Applying drops
of a silicon-nanospheres/ethanol solution to the surface of
the sample decreases the magnetic resonance frequency of the
split-ring array in incremental steps of 0.03 THz. This fine
tuning is done post fabrication and is demonstrated to be
reversible. The exhibited sensitivity of the split-ring
resonance frequency to the presence of silicon nanospheres
also suggests further application possibilities as a sensor
device. © 2007 American Institute of Physics.},
Doi = {10.1063/1.2768300},
Key = {Driscoll07}
}
@booklet{Liu07a,
Author = {Liu, R and Degiron, A and Mock, JJ and Smith, DR},
Title = {Negative index material composed of electric and magnetic
resonators},
Journal = {Applied Physics Letters},
Volume = {90},
Number = {26},
Pages = {263504-263504},
Publisher = {AIP Publishing},
Year = {2007},
Month = {August},
ISSN = {0003-6951},
url = {http://dx.doi.org/10.1063/1.2752120},
Abstract = {Negative index-of-refraction materials (NIMs) require both
the electric permittivity and the magnetic permeability of
the material to be negative. Most reported NIMs have
combined conducting split ring resonators (SRRs) to realize
the magnetic response and nonresonant wires to realize the
electric response. Here, however, the authors demonstrate an
impedance-matched, relatively broadband NIM which makes use
of SRRs and electric resonators, tuned such that they
resonate at the same frequency and with nearly the same
frequency dispersion. The NIM properties are confirmed by
direct measurements of the phase variation and field
distributions, obtained by field mapping. © 2007 American
Institute of Physics.},
Doi = {10.1063/1.2752120},
Key = {Liu07a}
}
@booklet{Liu07,
Author = {Liu, R and Cui, TJ and Huang, D and Zhao, B and Smith,
DR},
Title = {Description and explanation of electromagnetic behaviors in
artificial metamaterials based on effective medium
theory.},
Journal = {Physical review. E, Statistical, nonlinear, and soft matter
physics},
Volume = {76},
Number = {2 Pt 2},
Pages = {026606},
Year = {2007},
Month = {August},
ISSN = {1539-3755},
url = {http://dx.doi.org/10.1103/physreve.76.026606},
Abstract = {We present a general theory of effective media to set up the
relationship between the particle responses and the
macroscopic system behaviors for artificial metamaterials
composed of periodic resonant structures. By treating the
unit cell of the periodic structure as a particle, we define
the average permittivity and permeability for different unit
structures and derive a general form of discrete Maxwell's
equations on the macroscale, from which we obtain different
wave modes in metamaterials including the propagation mode,
pure plasma mode, and resonant crystal band-gap mode. We
explain unfamiliar behaviors of metamaterials from the
numerical S parameter retrieval approach. The excellent
agreement between theoretical predictions and retrieval
results indicates that the defined model and method of
analysis fit the physical structures very well. Thereafter,
we propose a more advanced form of the fitting formulas for
the effective electromagnetic parameters of
metamaterials.},
Doi = {10.1103/physreve.76.026606},
Key = {Liu07}
}
@booklet{Degiron07a,
Author = {Degiron, A and Dellagiacoma, C and McIlhargey, JG and Shvets, G and Martin, OJF and Smith, DR},
Title = {Simulations of hybrid long-range plasmon modes with
application to 90 degree bends.},
Journal = {Optics letters},
Volume = {32},
Number = {16},
Pages = {2354-2356},
Year = {2007},
Month = {August},
ISSN = {0146-9592},
url = {http://www.ncbi.nlm.nih.gov/pubmed/17700783},
Abstract = {We perform rigorous simulations of hybrid long-range modes
guided by a central metal core and a two-dimensional
dielectric slab. We show that these modes are subject to
fewer limitations than conventional long-range plasmon modes
in terms of field confinement and guiding performance. These
hybrid modes may offer substantial improvements for
integrated plasmonic components, as illustrated here by the
consideration of 90 degrees bends.},
Doi = {10.1364/ol.32.002354},
Key = {Degiron07a}
}
@booklet{Degiron07,
Author = {A. Degiron and D. R. Smith and J. J. Mock and B. J. Justice and J. Gollub},
Title = {Negative index and indefinite media waveguide
couplers},
Journal = {Applied Physics A-materials Science \& Processing},
Volume = {87},
Number = {2},
Pages = {321 -- 328},
Year = {2007},
Month = {May},
ISSN = {0947-8396},
Abstract = {We study the coupling interaction between dielectric
waveguides and coupling elements made from
negative-refracting media. The coupling configuration
consists of a length of dielectric waveguide, which
terminates either directly into or near a planar layer
composed of the negative-refracting medium, and is followed
by a second waveguide. Radiation output from the first
waveguide is refocused at the position of the second
waveguide, so that the negative-refracting layer serves as a
coupler between the waveguides. Because both isotropic
negative-index layers and bilayers of indefinite media can
recover the near-field, evanescent components of a source
field distribution, the coupling between the input and
output waveguides can be highly efficient - in principle
providing perfect, lossless coupling. We present simulations
and some initial experimental results illustrating the
coupling effect, and speculate on the potential for optical
fiber couplers and integrated modulators.},
Key = {Degiron07}
}
@article{071210498773,
Author = {Degiron, A and Smith, DR and Mock, JJ and Justice, BJ and Gollub,
J},
Title = {Negative index and indefinite media waveguide
couplers},
Journal = {Applied Physics A: Materials Science and
Processing},
Volume = {87},
Number = {2},
Pages = {321-328},
Publisher = {Springer Nature},
Year = {2007},
Month = {May},
ISSN = {0947-8396},
url = {http://dx.doi.org/10.1007/s00339-006-3835-2},
Keywords = {Computer simulation;Dielectric waveguides;Modulators;Planar
waveguides;Refractive index;},
Abstract = {We study the coupling interaction between dielectric
waveguides and coupling elements made from
negative-refracting media. The coupling configuration
consists of a length of dielectric waveguide, which
terminates either directly into or near a planar layer
composed of the negative-refracting medium, and is followed
by a second waveguide. Radiation output from the first
waveguide is refocused at the position of the second
waveguide, so that the negative-refracting layer serves as a
coupler between the waveguides. Because both isotropic
negative-index layers and bilayers of indefinite media can
recover the near-field, evanescent components of a source
field distribution, the coupling between the input and
output waveguides can be highly efficient - in principle
providing perfect, lossless coupling. We present simulations
and some initial experimental results illustrating the
coupling effect, and speculate on the potential for optical
fiber couplers and integrated modulators. © Springer-Verlag
2007.},
Doi = {10.1007/s00339-006-3835-2},
Key = {071210498773}
}
@booklet{Driscoll07a,
Author = {Driscoll, T and Basov, DN and Padilla, WJ and Mock, JJ and Smith,
DR},
Title = {Electromagnetic characterization of planar metamaterials by
oblique angle spectroscopic measurements},
Journal = {Physical Review B - Condensed Matter and Materials
Physics},
Volume = {75},
Number = {11},
Publisher = {American Physical Society (APS)},
Year = {2007},
Month = {March},
ISSN = {1098-0121},
url = {http://dx.doi.org/10.1103/PhysRevB.75.115114},
Abstract = {Artificially structured metamaterials with unit-cell
dimensions on the order of 1 10th of a wavelength (λ 10)
have been shown to be well approximated by an effective
medium description which mimics a continuous material. In
this paper we present data for transmission and reflection
from a planar array of split-ring resonators (SRRs) at
varying angles of incidence. We attempt to model the form of
the angle-dependent response of the SRRs using the Fresnel
equations formulated from effective medium theory-treating
the array as a thin continuous anisotropic crystal. This
model is then fit to experimental data taken on a planar
array of split rings to gauge the model accuracy, and to
produce values for the frequency-dependent permeability and
permittivity of the experimental SRR array. Simultaneous
fitting of the transmission and reflection at multiple
angles helps to avoid multiple solutions for the
permittivity and permeability. This forward fitting approach
using multiple angles is advantageous, as it enables a
characterization of the optical constants without the need
for phase information, and it avoids many of the branch
problems inherent in the numerical inversion methods used so
far on metamaterials. The work presented here shows the
feasibility of this method. A refined procedure will be
particularly advantageous for experimental characterization
of higher frequency structures (i.e., THz and above), where
phase information is difficult or impossible to obtain. ©
2007 The American Physical Society.},
Doi = {10.1103/PhysRevB.75.115114},
Key = {Driscoll07a}
}
@booklet{Liu07b,
Author = {Liu, R and Cui, TJ and Zhao, B and Lin, XQ and Ma, HF and Huang, D and Smith,
DR},
Title = {Resonant crystal band gap metamaterials in the microwave
regime and their exotic amplification of evanescent
waves},
Journal = {Applied Physics Letters},
Volume = {90},
Number = {9},
Pages = {091912-091912},
Publisher = {AIP Publishing},
Year = {2007},
Month = {March},
ISSN = {0003-6951},
url = {http://dx.doi.org/10.1063/1.2709897},
Abstract = {The authors realize resonant crystal band gap metamaterials
(CBMs) using circuit structures in the microwave regime,
which behave quite differently from the conventional
photonic band gap structures. They show that a periodic
array of series inductor and shunt capacitor is equivalent
to a CBM similar to a magnetic plasma at higher frequency
band, and a periodic array of series capacitor and shunt
inductor behaves like a CBM similar to an electric plasma at
lower frequency band. The equivalent medium parameters have
been derived in both cases, which show the existence of
conjugate loss in imaginary parts. When two such structures
are cascaded together, the authors demonstrate that
evanescent waves are amplified and transmitted in a very
narrow frequency band under the antimatching condition. Such
a feature can be used to design extremely narrow band
filters. Theoretical predictions, circuit simulations, and
experimental results are presented to validate their
conclusions. © 2007 American Institute of
Physics.},
Doi = {10.1063/1.2709897},
Key = {Liu07b}
}
@booklet{Degiron07b,
Author = {A. Degiron and J. J. Mock and D. R. Smith},
Title = {Modulating and tuning the response of metamaterials at the
unit cell level},
Journal = {Optics Express},
Volume = {15},
Number = {3},
Pages = {1115 -- 1127},
Year = {2007},
Month = {February},
ISSN = {1094-4087},
Abstract = {We perform a series of simulations and experiments at
microwave frequencies where we dynamically alter the
magnetic resonance of one individual split ring resonator by
photodoping a piece of low-doped semiconductor positioned
within the gap of the resonator. We predict and
experimentally achieve a complete suppression of the
resonance amplitude using an 815 nm laser source and then
briefly consider the problem of tuning the frequency of an
SRR by the same method. We also illustrate the metamaterial
approach to active electromagnetic devices by implementing a
simple yet efficient optical modulator and a three channel
dynamical filter. (c) 2007 Optical Society of
America.},
Key = {Degiron07b}
}
@booklet{Driscoll07b,
Author = {T. Driscoll and G. O. Andreev and D. N. Basov and S. Palit and T. Ren and J. Mock and S. Y. Cho and N. M. Jokerst and D. R. Smith},
Title = {Quantitative investigation of a terahertz artificial
magnetic resonance using oblique angle spectroscopy},
Journal = {Applied Physics Letters},
Volume = {90},
Number = {9},
Year = {2007},
Month = {February},
ISSN = {0003-6951},
Abstract = {The authors present a spectroscopic analysis of a planar
split-ring-resonator (SRR) medium at terahertz frequencies,
quantitatively characterizing the associated magnetic
resonance. Experimental quantification at terahertz and
infrared frequencies of metamaterial optical constants has
been primarily absent, largely due to the difficulty of
collecting phase information at these frequencies. In this
letter, the authors circumvent the need for phase
information in the characterization by acquiring the power
transmitted through the metamaterial at a series of oblique
angles, and relating the multiangle data set to the
effective permittivity and permeability through the Fresnel
expressions. The resulting measurements reveal the expected
resonant permeability of the SRR which exhibits a range of
negative values, the minimum value being mu=-0.8 at 1.1 THz.
(c) 2007 American Institute of Physics.},
Key = {Driscoll07b}
}
@booklet{Greegor07,
Author = {Greegor, RB and Parazzoli, CG and Nielsen, JA and Thompson, MA and Tanielian, MH and Vier, DC and Schultz, S and Smith, DR and Schurig,
D},
Title = {Microwave focusing and beam collimation using negative index
of refraction lenses},
Journal = {IET Microwaves, Antennas and Propagation},
Volume = {1},
Number = {1},
Pages = {108-115},
Publisher = {Institution of Engineering and Technology
(IET)},
Year = {2007},
Month = {February},
ISSN = {1751-8725},
url = {http://dx.doi.org/10.1049/iet-map:20060071},
Abstract = {Negative index of refraction materials (NIMs) were first
postulated by Veselago in 1968 and have recently been
realised using structures formed with rings and wires
deposited on printed circuit boards. The proof of the
existence of negative index of refraction was established
using a Snell's law experiment with a wedge. The predicted
and measured refraction angles were found to be consistent
for a negative index material and in excellent agreement
with the theoretical expectations. For microwave lenses NIMs
have the advantage of being lighter, having better focusing
properties and potentially lower aberrations. Simulation and
experimental results on NIM configurations including
gradient index of refraction and spherical 3D lenses are
presented. Both focusing and beam collimating applications
will be considered. These results will be compared to normal
positive index of refraction material lenses. © 2007 The
Institution of Engineering and Technology.},
Doi = {10.1049/iet-map:20060071},
Key = {Greegor07}
}
@article{070710426144,
Author = {Degiron, A and Mock, JJ and Smith, DR},
Title = {Modulating and tuning the response of metamaterials at the
unit cell level.},
Journal = {Optics express},
Volume = {15},
Number = {3},
Pages = {1115-1127},
Year = {2007},
Month = {February},
ISSN = {1094-4087},
url = {http://dx.doi.org/10.1364/OE.15.001115},
Keywords = {Light modulators;Light sources;Magnetic resonance;Microwaves;Natural
frequencies;Semiconductor materials;},
Abstract = {We perform a series of simulations and experiments at
microwave frequencies where we dynamically alter the
magnetic resonance of one individual split ring resonator by
photodoping a piece of low-doped semiconductor positioned
within the gap of the resonator. We predict and
experimentally achieve a complete suppression of the
resonance amplitude using an 815 nm laser source and then
briefly consider the problem of tuning the frequency of an
SRR by the same method. We also illustrate the metamaterial
approach to active electromagnetic devices by implementing a
simple yet efficient optical modulator and a three channel
dynamical filter.},
Doi = {10.1364/oe.15.001115},
Key = {070710426144}
}
@article{fds331004,
Author = {Smith, D and Leach, M and Elsdon, M and Foti, SJ},
Title = {Indirect holographic techniques for determining antenna
radiation characteristics and imaging aperture
fields},
Journal = {IEEE Antennas and Propagation Magazine},
Volume = {49},
Number = {1},
Pages = {54-67},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2007},
Month = {February},
url = {http://dx.doi.org/10.1109/MAP.2007.370982},
Abstract = {Indirect holographic techniques offer the potential of using
simple and inexpensive near-field intensity-pattern
measurements for the determination of the radiation
characteristics of microwave antennas, and for the
reconstruction of complex aperture fields. This work
describes a practical method of applying indirect
holographic techniques to microwave antennas. It describes
how a technique originally developed at optical frequencies
can be adapted to enable measurements to be taken on
microwave antennas. The major difference is the replacement
of a radiated reference signal by an electronically
generated reference signal. This has enabled previous
practical limitations to be overcome. Computer simulations
and practical results are included for a large dish antenna
at a sample spacing similar to those employed in direct
holographic techniques. This work also describes how
reducing the sample spacing significantly below a half
wavelength enables the radiation characteristics of smaller
antennas to be determined. © 2007 IEEE.},
Doi = {10.1109/MAP.2007.370982},
Key = {fds331004}
}
@article{fds331005,
Author = {Maniam, J and Selvanathan, N and Abu-Bakar, M and Smith, D and Elgabroun, HM and Yeong, PM and Senthil Kumar,
S},
Title = {Microwave holographic imaging technique for tumour
detection},
Journal = {IFMBE Proceedings},
Volume = {15},
Pages = {275-277},
Year = {2007},
Month = {January},
ISBN = {9783540680161},
url = {http://dx.doi.org/10.1007/978-3-540-68017-8_71},
Abstract = {Early, accurate and efficient screening of tumour will go a
long way to improve the life expectancy and quality of life.
Microwave holographic technique uses nonionising radiation
which has the potential to screen patients for tumour at low
cost. It offers high contrast between healthy and malignant
tissues and assists in forming image of the location and the
extent of the malignant tissue. This technique exploits the
advantages of holography without requiring the direct
measurement which uses an expensive network analyser. This
paper will investigate the use of an alternative microwave
imaging technique using indirect holographic method. The use
of continuous wave signal for imaging avoids the problems
associated with pulsed systems. The use of two stage
holographic technique requires recording of a holographic
interference pattern as stage one and reconstruction of
original image of the object as stage two. As a preliminary
study, the transmitted microwave signal is bombarded on a
suitable phantom and the scattered signals are measured. The
significance of this technique is that it offers real time
imaging possibility which can be used as intra operative
imaging tool during the surgery to remove
tumour.},
Doi = {10.1007/978-3-540-68017-8_71},
Key = {fds331005}
}
@article{fds331007,
Author = {Elsdon, M and Leach, M and Skobelev, S and Smith,
D},
Title = {Microwave holographic imaging of breast cancer},
Journal = {IEEE 2007 International Symposium on Microwave, Antenna,
Propagation and EMC Technologies for Wireless
Communications, MAPE},
Pages = {966-969},
Publisher = {IEEE},
Year = {2007},
Month = {January},
ISBN = {9781424410446},
url = {http://dx.doi.org/10.1109/MAPE.2007.4393791},
Abstract = {Breast cancer is one of the most common forms of cancer in
women. X-ray mammography is the most widely used technique
for early detection but has limitations. In this paper, an
alternative approach for breast cancer detection using
microwave imaging is presented. This is based upon a
microwave holographic approach, central to which is the use
of a synthetic reference beam. This approach has benefits in
terms of simplicity and expense. Experimental results using
a breast phantom are included to demonstrate the potential
of this approach. © 2007 IEEE.},
Doi = {10.1109/MAPE.2007.4393791},
Key = {fds331007}
}
@article{fds269775,
Author = {Justice, BJ and Nguyen, VN and Yönak, SH and Kim, J and Smith,
DR},
Title = {Electric-field-coupled metamaterials for microwave beam
formation},
Journal = {IEEE Antennas and Propagation Society, AP-S International
Symposium (Digest)},
Pages = {2566-2569},
Publisher = {IEEE},
Year = {2007},
ISSN = {1522-3965},
url = {http://dx.doi.org/10.1109/APS.2007.4396058},
Abstract = {Microwave propagation through an eleetrie-field-coupled
metamaterial lens with a refractive index gradient is
experimentally investigated. A gradient in the refractive
index of the metamaterial is introduced by continuous tuning
of a single parameter in the metamaterial elements.
Experimental field maps, acquired in a planar waveguide,
demonstrate that the planar gradient index lens can be used
to collimate radiation from a line source, thereby forming a
beam. © 2007 IEEE.},
Doi = {10.1109/APS.2007.4396058},
Key = {fds269775}
}
@article{071010476427,
Author = {Driscoll, T and Andreev, GO and Basov, DN and Palit, S and Ren, T and Mock,
J and Cho, S-Y and Jokerst, NM and Smith, DR},
Title = {Quantitative investigation of a terahertz artificial
magnetic resonance using oblique angle spectroscopy},
Journal = {Applied Physics Letters},
Volume = {90},
Number = {9},
Pages = {092508},
Publisher = {AIP Publishing},
Year = {2007},
ISSN = {0003-6951},
url = {http://dx.doi.org/10.1063/1.2679766},
Keywords = {Magnetic permeability;Natural frequencies;Optical
constants;Permittivity;Power transmission;Spectroscopic
analysis;},
Abstract = {The authors present a spectroscopic analysis of a planar
split-ring-resonator (SRR) medium at terahertz frequencies,
quantitatively characterizing the associated magnetic
resonance. Experimental quantification at terahertz and
infrared frequencies of metamaterial optical constants has
been primarily absent, largely due to the difficulty of
collecting phase information at these frequencies. In this
letter, the authors circumvent the need for phase
information in the characterization by acquiring the power
transmitted through the metamaterial at a series of oblique
angles, and relating the multiangle data set to the
effective permittivity and permeability through the Fresnel
expressions. The resulting measurements reveal the expected
resonant permeability of the SRR which exhibits a range of
negative values, the minimum value being μ=-0.8 at 1.1
THz. © 2007 American Institute of Physics.},
Doi = {10.1063/1.2679766},
Key = {071010476427}
}
@article{fds331006,
Author = {Smith, D and Elsdon, M and Leach, M and Fernando, M and Foti,
SJ},
Title = {3D Microwave imaging for medical and security
applications},
Journal = {2006 International RF and Microwave Conference, (RFM)
Proceedings},
Pages = {233-237},
Publisher = {IEEE},
Year = {2006},
Month = {December},
ISBN = {9780780397446},
url = {http://dx.doi.org/10.1109/RFM.2006.331076},
Abstract = {The use of microwaves for imaging applications is currently
of much research interest particularly in the areas of
security imaging and medical imaging. Microwaves have been
shown to be able to image objects concealed beneath clothing
and recent research work has indicated that microwaves could
offer a new low cost non-ionising technique for the
detection and imaging of breast cancer tumours. Traditional
intensity only measurements have only been able to provide
2D images of objects. This work will describe how our
indirect holographic approach can be used to reconstruct 3D
images of objects from a single scalar 2D holographic
intensity pattern. ©2006 IEEE.},
Doi = {10.1109/RFM.2006.331076},
Key = {fds331006}
}
@article{fds269683,
Author = {Smith, DR and Park, DF},
Title = {A novel organic fiber for fiber reinforced structural
composites},
Journal = {6th Annual SPE Automotive Composites Conference
2006},
Volume = {2},
Pages = {830-839},
Year = {2006},
Month = {December},
Abstract = {A novel fiber technology is being developed for the fiber
reinforced composites industry. The fiber is a form of poly
vinyl alcohol (PVOH). When added to conventional fiber
reinforced composite PVOH fiber gives exceptional impact
resistance, surface finish and improved recycling properties
to fiber reinforced composites. PVOH is highly chemical and
UV light resistant compared to other commercially available
reinforcing fibers. PVOH is also economical compared to many
high performance reinforcing fibers. PVOH can be used in
combination with existing fibers (such as fiberglass,
polyester, Kevlar) or as a stand alone fiber in both
thermoset and thermoplastic resins. PVOH requires distinct
surface modification to make the fiber compatible with each
commercial polymer resin system. PVOH is commercially
available for polyester and epoxy resins with vinyl ester,
phenolic, polyolefin, silicone and urethane resins in
development. Advanced resin systems have been demonstrated
that create a bond that is stronger between fiber and resin
than the fiber itself, giving a moldable composite with true
isotropic properties. PVOH fiber is being targeted toward a
broad array of applications and markets. Applications
include molding compounds (bulk and sheet), pre-pregs, mats
(woven, non-woven and uni-directional), braided structures,
and chopped fiber (including wet laid). Markets include
aerospace, automotive, construction, consumer, electronics,
marine and the chemical industry. PVOH has a fit wherever
molded composites require a lightweight reinforcing fiber
with excellent impact, chemical and environmental
properties.},
Key = {fds269683}
}
@booklet{Driscoll06,
Author = {Driscoll, T and Basov, DN and Rye, PM and Nemat-Nasser, S and Schurig,
D and Smith, DR},
Title = {Free space microwave focusing by a negative-index gradient
lens},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {6320},
Number = {8},
Year = {2006},
Month = {November},
ISSN = {0277-786X},
url = {http://dx.doi.org/10.1117/12.680752},
Abstract = {Metamaterial structures designed to have simultaneously
negative permittivity and permeability are known as
left-handed materials. Their complexity and our
understanding of their properties have advanced rapidly to
the point where direct applications are now viable. We
present a radial gradient-index (GRIN) lens with an
index-of-refraction ranging from -2.67(edge) to
-0.97(center). Experimentally, we find the lens can produce
field intensities at the focus that are greater than that of
the incident plane wave. These results are obtained at 10.45
GHz and in excellent agreement with full-wave simulations.
This lens is a demonstrate an newly pioneered advanced
fabrication technique using conventional printed circuit
board (PCB) technology which offers significant design,
mechanical, and cost advantages over other microwave lens
constructions.},
Doi = {10.1117/12.680752},
Key = {Driscoll06}
}
@article{9187001,
Author = {Schurig, D and Mock, JJ and Justice, BJ and Cummer, SA and Pendry, JB and Starr, AF and Smith, DR},
Title = {Metamaterial electromagnetic cloak at microwave
frequencies.},
Journal = {Science (New York, N.Y.)},
Volume = {314},
Number = {5801},
Pages = {977-980},
Year = {2006},
Month = {November},
url = {http://www.ncbi.nlm.nih.gov/pubmed/17053110},
Keywords = {copper;metamaterials;microwave propagation;},
Abstract = {A recently published theory has suggested that a cloak of
invisibility is in principle possible, at least over a
narrow frequency band. We describe here the first practical
realization of such a cloak; in our demonstration, a copper
cylinder was "hidden" inside a cloak constructed according
to the previous theoretical prescription. The cloak was
constructed with the use of artificially structured
metamaterials, designed for operation over a band of
microwave frequencies. The cloak decreased scattering from
the hidden object while at the same time reducing its
shadow, so that the cloak and object combined began to
resemble empty space.},
Doi = {10.1126/science.1133628},
Key = {9187001}
}
@article{fds335133,
Author = {Smith, DR and Holland, AD and Martin, A and Burt, D and Eaton, T and Steward, R},
Title = {Development and testing of a 2-D transfer
CCD},
Journal = {IEEE Transactions on Electron Devices},
Volume = {53},
Number = {11},
Pages = {2748-2754},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2006},
Month = {November},
url = {http://dx.doi.org/10.1109/TED.2006.884072},
Abstract = {This paper describes the development, operation, and
characterization of charge-coupled devices (CCDs) that
feature an electrode structure that allows the transfer of
charge both horizontally and vertically through the image
area. Such devices have been termed two-dimensional (2-D)
transfer CCDs (2DT CCDs), as opposed to the conventional
devices, which might be called one-dimensional transfer
CCDs, but in other respects are the same as conventional CCD
devices. Batches of two different 2DT CCD test devices,
featuring different electrode structures but with identical
clocking operation in each case, were produced and tested.
The methodology of 2-D charge transfer in each of the device
types is described, followed by a presentation of test
results from the new CCDs. The ability of both 2DT CCD
transfer electrode schemes to successfully transfer charge
in both horizontal and vertical directions in the image
section of the devices has been proven, opening up potential
new applications for 2DT CCD use. © 2006
IEEE.},
Doi = {10.1109/TED.2006.884072},
Key = {fds335133}
}
@article{fds335134,
Author = {Smith, DR and Walton, DM and Ingley, R and Holland, AD and Cropper, M and Pool, P},
Title = {EMCCDs for space applications},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {6276},
Publisher = {SPIE},
Year = {2006},
Month = {October},
ISBN = {9780819463418},
url = {http://dx.doi.org/10.1117/12.671368},
Abstract = {This paper describes a qualification programme for
Electron-Multiplication Charge Coupled Devices (EMCCDs) for
use in space applications. While the presented results are
generally applicable, the programme was carried out in the
context of CCD development for the Radial Velocity
Spectrometer (RVS) instrument on the European Space Agency's
cornerstone Gaia mission. We discuss the issues of device
radiation tolerance, charge transfer efficiency at low
signal levels and life time effects on the
electron-multiplication gain. The development of EMCCD
technology to allow operation at longer wavelengths using
high resistivity silicon, and the cryogenic characterisation
of EMCCDs are also described.},
Doi = {10.1117/12.671368},
Key = {fds335134}
}
@article{fds335135,
Author = {Lim, T and Swinyard, B and Griffin, M and Aramburu, A and Baluteau, JP and Bock, J and Ferlet, M and Fulton, T and Griffin, D and Guest, S and Hargrave, P and King, K and Leeks, S and Naylor, D and Polehampton, E and Rizzo, D and Sawyer, E and Schulz, B and Sidher, S and Spencer, L and Smith, D and Nguen, HT and Valtchanov, I and Waskett, T and Woodcraft,
A},
Title = {Preliminary results from herschel-SPIRE flight instrument
testing},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {6265 I},
Publisher = {SPIE},
Year = {2006},
Month = {October},
ISBN = {9780819463302},
url = {http://dx.doi.org/10.1117/12.672752},
Abstract = {The Spectral and Photometric Imaging REceiver (SPIRE) is one
of the three scientific instruments to fly on the European
Space Agency's Herschel Space Observatory, and contains a
three-band imaging submillimetre photometer and an imaging
Fourier transform spectrometer. The flight model of the
SPIRE cold focal plane unit has been built up in stages with
a cold test campaign associated with each stage. The first
campaign focusing on the spectrometer took place in early
2005 and the second campaign focusing on the photometer was
in Autumn 2005. SPIRE is currently undergoing its third cold
test campaign following cryogenic vibration testing. Test
results to date show that the instrument is performing very
well and in general meets not only its requirements but also
most of its performance goals. We present an overview of the
instrument tests performed to date, and the preliminary
results.},
Doi = {10.1117/12.672752},
Key = {fds335135}
}
@article{fds331008,
Author = {Smith, D and Elsdon, M and Leach, M and Fdo, M and Foti,
SJ},
Title = {A microwave indirect holographic system for security and
medical imaging applications},
Journal = {European Space Agency, (Special Publication) ESA
SP},
Volume = {626 SP},
Year = {2006},
Month = {October},
ISBN = {9789290929376},
Abstract = {This work details how an indirect microwave holographic
technique originally developed for antenna measurements can
be extended to imaging applications. It outlines how complex
field patterns can be reconstructed from holographic
intensity patterns. It also outlines how images of both
metallic and non-metallic objects can be obtained from these
patterns. Results are presented to demonstrate how this
technique ca b be applied in the areas of concealed weapons
detection and medical imaging.},
Key = {fds331008}
}
@booklet{Schurig06,
Author = {Schurig, D and Pendry, JB and Smith, DR},
Title = {Calculation of material properties and ray tracing in
transformation media.},
Journal = {Optics express},
Volume = {14},
Number = {21},
Pages = {9794-9804},
Year = {2006},
Month = {October},
ISSN = {1094-4087},
url = {http://dx.doi.org/10.1364/oe.14.009794},
Abstract = {Complex and interesting electromagnetic behavior can be
found in spaces with non-flat topology. When considering the
properties of an electromagnetic medium under an arbitrary
coordinate transformation an alternative interpretation
presents itself. The transformed material property tensors
may be interpreted as a different set of material properties
in a flat, Cartesian space. We describe the calculation of
these material properties for coordinate transformations
that describe spaces with spherical or cylindrical holes in
them. The resulting material properties can then implement
invisibility cloaks in flat space. We also describe a method
for performing geometric ray tracing in these materials
which are both inhomogeneous and anisotropic in their
electric permittivity and magnetic permeability.},
Doi = {10.1364/oe.14.009794},
Key = {Schurig06}
}
@article{fds331009,
Author = {Leach, M and Elsdon, M and Foti, SJ and Smith, D},
Title = {Imaging dielectric objects using a novel synthetic off-axis
holographic technique},
Journal = {Microwave and Optical Technology Letters},
Volume = {48},
Number = {10},
Pages = {1957-1961},
Publisher = {WILEY},
Year = {2006},
Month = {October},
url = {http://dx.doi.org/10.1002/mop.21826},
Abstract = {Original results are presented for the imaging of dielectric
objects using an indirect planar microwave imaging system
that employs an off-axis holographic concept. The ability of
this intensity only planar recording technique to recover
phase information about the object under test proves to be
significant in the imaging of dielectrics. © 2006 Wiley
Periodicals, Inc.},
Doi = {10.1002/mop.21826},
Key = {fds331009}
}
@booklet{Justice06,
Author = {B. J. Justice and J. J. Mock and L. H. Guo and A. Degiron and D. Schurig and D. R. Smith},
Title = {Spatial mapping of the internal and external electromagnetic
fields of negative index metamaterials},
Journal = {Optics Express},
Volume = {14},
Number = {19},
Pages = {8694 -- 8705},
Year = {2006},
Month = {September},
ISSN = {1094-4087},
Abstract = {We perform an experimental study of the phase and amplitude
of microwaves interacting with and scattered by
two-dimensional negative index metamaterials. The
measurements are performed in a parallel plate waveguide
apparatus at X-band frequencies (8-12 GHz), thus
constraining the electromagnetic fields to two dimensions. A
detection antenna is fixed to one of the plates, while a
second plate with a fixed source antenna or waveguide is
translated relative to the first plate. The detection
antenna is inserted into, but not protruding below, the
stationary plate so that fields internal to the metamaterial
samples can be mapped. From the measured mappings of the
electric field, the interplay between the microstructure of
the metamaterial lattice and the macroscopic averaged
response is revealed. For example, the mapped phase fronts
within a metamaterial having a negative refractive index are
consistent with a macroscopic phase-in accordance with the
effective medium predictions-which travels in a direction
opposite to the direction of propagation. The field maps are
in excellent agreement with finite element numerical
simulations performed assuming homogeneous metamaterial
structures. (c) 2006 Optical Society of America},
Key = {Justice06}
}
@booklet{Cummer06,
Author = {S. A. Cummer and B. I. Popa and D. Schurig and D. R. Smith and J. Pendry},
Title = {Full-wave simulations of electromagnetic cloaking
structures},
Journal = {Physical Review E},
Volume = {74},
Number = {3},
Year = {2006},
Month = {September},
ISSN = {1539-3755},
Abstract = {Pendry have reported electromagnetically anisotropic and
inhomogeneous shells that, in theory, completely shield an
interior structure of arbitrary size from electromagnetic
fields without perturbing the external fields. Neither the
coordinate transformation-based analytical formulation nor
the supporting ray-tracing simulation indicate how material
perturbations and full-wave effects might affect the
solution. We report fully electromagnetic simulations of the
cylindrical version of this cloaking structure using ideal
and nonideal (but physically realizable) electromagnetic
parameters that show that the low-reflection and power-flow
bending properties of the electromagnetic cloaking structure
are not especially sensitive to modest permittivity and
permeability variations. The cloaking performance degrades
smoothly with increasing loss, and effective low-reflection
shielding can be achieved with a cylindrical shell composed
of an eight- (homogeneous) layer approximation of the ideal
continuous medium. An imperfect but simpler version of the
cloaking material is derived and is shown to reproduce the
ray bending of the ideal material in a manner that may be
easier to experimentally realize.},
Key = {Cummer06}
}
@booklet{Smith06,
Author = {D. R. Smith and D. Schurig and J. J. Mock},
Title = {Characterization of a planar artificial magnetic
metamaterial surface},
Journal = {Physical Review E},
Volume = {74},
Number = {3},
Year = {2006},
Month = {September},
ISSN = {1539-3755},
Abstract = {We explore the electromagnetic characterization of a planar
artificial magnetic metamaterial. Because the composite
structure is two- rather than three-dimensional, it does not
form a medium with assignable bulk properties, such as the
electric permittivity and magnetic permeability. However, we
find that it is possible to characterize the expected bulk
response of a structure composed of repeated layers of
metamaterial planes, from a reflectance measurement of a
single metamaterial surface made at an oblique angle. We
present an analytical theory that relates the reflectance of
a single plane to the expected bulk permeability and
permeability of the composite, as well as supporting
experiments and numerical simulations. Our results show that
the recent use of reflectance measurements to characterize
planar split ring resonator samples can reveal the presence
of circulating currents in a sample-the precursor to
artificial magnetism-but are insufficient to provide
quantitative results unless the symmetry of the underlying
metamaterial elements is carefully specified.},
Key = {Smith06}
}
@article{9337862,
Author = {Smith, DR and Schurig, D and Mock, JJ},
Title = {Characterization of a planar artificial magnetic
metamaterial surface.},
Journal = {Physical review. E, Statistical, nonlinear, and soft matter
physics},
Volume = {74},
Number = {3 Pt 2},
Pages = {036604},
Year = {2006},
Month = {September},
ISSN = {1539-3755},
url = {http://dx.doi.org/10.1103/PhysRevE.74.036604},
Keywords = {magnetic materials;metamaterials;permeability;permittivity;photonic
crystals;reflectivity;},
Abstract = {We explore the electromagnetic characterization of a planar
artificial magnetic metamaterial. Because the composite
structure is two- rather than three-dimensional, it does not
form a medium with assignable bulk properties, such as the
electric permittivity and magnetic permeability. However, we
find that it is possible to characterize the expected bulk
response of a structure composed of repeated layers of
metamaterial planes, from a reflectance measurement of a
single metamaterial surface made at an oblique angle. We
present an analytical theory that relates the reflectance of
a single plane to the expected bulk permeability and
permeability of the composite, as well as supporting
experiments and numerical simulations. Our results show that
the recent use of reflectance measurements to characterize
planar split ring resonator samples can reveal the presence
of circulating currents in a sample--the precursor to
artificial magnetism--but are insufficient to provide
quantitative results unless the symmetry of the underlying
metamaterial elements is carefully specified.},
Doi = {10.1103/physreve.74.036604},
Key = {9337862}
}
@article{9324139,
Author = {Justice, BJ and Mock, JJ and Guo, L and Degiron, A and Schurig, D and Smith, DR},
Title = {Spatial mapping of the internal and external electromagnetic
fields of negative index metamaterials.},
Journal = {Optics express},
Volume = {14},
Number = {19},
Pages = {8694-8705},
Year = {2006},
Month = {September},
ISSN = {1094-4087},
url = {http://dx.doi.org/10.1364/oe.14.008694},
Keywords = {finite element analysis;metamaterials;microwave
propagation;refractive index;},
Abstract = {We perform an experimental study of the phase and amplitude
of microwaves interacting with and scattered by
two-dimensional negative index metamaterials. The
measurements are performed in a parallel plate waveguide
apparatus at X-band frequencies (8-12 GHz), thus
constraining the electromagnetic fields to two dimensions. A
detection antenna is fixed to one of the plates, while a
second plate with a fixed source antenna or waveguide is
translated relative to the first plate. The detection
antenna is inserted into, but not protruding below, the
stationary plate so that fields internal to the metamaterial
samples can be mapped. From the measured mappings of the
electric field, the interplay between the microstructure of
the metamaterial lattice and the macroscopic averaged
response is revealed. For example, the mapped phase fronts
within a metamaterial having a negative refractive index are
consistent with a macroscopic phase-in accordance with the
effective medium predictions-which travels in a direction
opposite to the direction of propagation. The field maps are
in excellent agreement with finite element numerical
simulations performed assuming homogeneous metamaterial
structures.},
Doi = {10.1364/oe.14.008694},
Key = {9324139}
}
@article{064110158839,
Author = {Cummer, SA and Popa, B-I and Schurig, D and Smith, DR and Pendry,
J},
Title = {Full-wave simulations of electromagnetic cloaking
structures.},
Journal = {Physical review. E, Statistical, nonlinear, and soft matter
physics},
Volume = {74},
Number = {3 Pt 2},
Pages = {036621},
Year = {2006},
Month = {September},
ISSN = {1539-3755},
url = {http://dx.doi.org/10.1103/PhysRevE.74.036621},
Keywords = {Computer simulation;Electromagnetic fields;Ray
tracing;Perturbation techniques;Approximation
theory;},
Abstract = {Pendry et al. have reported electromagnetically anisotropic
and inhomogeneous shells that, in theory, completely shield
an interior structure of arbitrary size from electromagnetic
fields without perturbing the external fields. Neither the
coordinate transformation-based analytical formulation nor
the supporting ray-tracing simulation indicate how material
perturbations and full-wave effects might affect the
solution. We report fully electromagnetic simulations of the
cylindrical version of this cloaking structure using ideal
and nonideal (but physically realizable) electromagnetic
parameters that show that the low-reflection and power-flow
bending properties of the electromagnetic cloaking structure
are not especially sensitive to modest permittivity and
permeability variations. The cloaking performance degrades
smoothly with increasing loss, and effective low-reflection
shielding can be achieved with a cylindrical shell composed
of an eight- (homogeneous) layer approximation of the ideal
continuous medium. An imperfect but simpler version of the
cloaking material is derived and is shown to reproduce the
ray bending of the ideal material in a manner that may be
easier to experimentally realize.},
Doi = {10.1103/physreve.74.036621},
Key = {064110158839}
}
@article{063210058628,
Author = {Smith, DR and Gollub, J and Mock, JJ and Padilla, WJ and Schurig,
D},
Title = {Calculation and measurement of bianisotropy in a split ring
resonator metamaterial},
Journal = {Journal of Applied Physics},
Volume = {100},
Number = {2},
Pages = {024507-024507},
Publisher = {AIP Publishing},
Year = {2006},
Month = {August},
ISSN = {0021-8979},
url = {http://dx.doi.org/10.1063/1.2218033},
Keywords = {Electromagnetic waves;Magnetic moments;Magnetic field
effects;Magnetic couplings;Polarization;Composite
structures;},
Abstract = {A medium that exhibits artificial magnetism can be formed by
assembling an array of split ring resonators (SRRs) - planar
conducting elements that exhibit a resonant response to
electromagnetic radiation. The SRR exhibits a large magnetic
dipole moment when excited by a magnetic field directed
along its axis. However, the SRR also exhibits an electric
response that can be quite large depending on the symmetry
of the SRR and the orientation of the SRR with respect to
the electric component of the field. So, while the SRR
medium can be considered as having a predominantly magnetic
response for certain orientations with respect to the
incident wave, it is generally the case that the SRR
exhibits magnetoelectric coupling, and hence a medium of
SRRs arranged so as to break mirror symmetry about one of
the axes will exhibit bianisotropy. We present here a method
of directly calculating the magnetoelectric coupling terms
using averages over the fields computed from full-wave
finite-element based numerical simulations. We confirm the
predicted bianisotropy of a fabricated SRR medium by
measuring the cross polarization of a microwave beam
transmitted through the sample. We also demonstrate that the
magnetoelectric coupling that gives rise to the
bianisotropic response is suppressed by symmetrizing the SRR
composite structure and provide measurements comparing the
cross polarization of the symmetric and asymmetric
structures. © 2006 American Institute of
Physics.},
Doi = {10.1063/1.2218033},
Key = {063210058628}
}
@booklet{Smith06a,
Author = {D. R. Smith and J. Gollub and J. J. Mock and W. J. Padilla and D. Schurig},
Title = {Calculation and measurement of bianisotropy in a split ring
resonator metamaterial},
Journal = {Journal Of Applied Physics},
Volume = {100},
Number = {2},
Year = {2006},
Month = {July},
ISSN = {0021-8979},
Abstract = {A medium that exhibits artificial magnetism can be formed by
assembling an array of split ring resonators (SRRs)-planar
conducting elements that exhibit a resonant response to
electromagnetic radiation. The SRR exhibits a large magnetic
dipole moment when excited by a magnetic field directed
along its axis. However, the SRR also exhibits an electric
response that can be quite large depending on the symmetry
of the SRR and the orientation of the SRR with respect to
the electric component of the field. So, while the SRR
medium can be considered as having a predominantly magnetic
response for certain orientations with respect to the
incident wave, it is generally the case that the SRR
exhibits magnetoelectric coupling, and hence a medium of
SRRs arranged so as to break mirror symmetry about one of
the axes will exhibit bianisotropy. We present here a method
of directly calculating the magnetoelectric coupling terms
using averages over the fields computed from full-wave
finite-element based numerical simulations. We confirm the
predicted bianisotropy of a fabricated SRR medium by
measuring the cross polarization of a microwave beam
transmitted through the sample. We also demonstrate that the
magnetoelectric coupling that gives rise to the
bianisotropic response is suppressed by symmetrizing the SRR
composite structure and provide measurements comparing the
cross polarization of the symmetric and asymmetric
structures. (c) 2006 American Institute of
Physics.},
Key = {Smith06a}
}
@article{fds269686,
Author = {Pendry, JB and Smith, DR},
Title = {The quest for the superlens.},
Journal = {Scientific American},
Volume = {295},
Number = {1},
Pages = {60-67},
Year = {2006},
Month = {July},
ISSN = {0036-8733},
url = {http://dx.doi.org/10.1038/scientificamerican0706-60},
Abstract = {The superlens, made from metamaterials with bizarre,
controversial optical properties have the capacity to
produce images that include details finer than the
wavelength of light that is used. When an electromagnetic
wave travels through a material, the electrons within the
material's atoms or molecules experience a force and move in
response to it. This motion uses up some some of the wave's
energy which affects the properties of the wave and the way
in which it travels. Resonance, which is the tendency to
oscillate at a particular frequency, is the key to achieving
a negative response and is introduced artificially in a
metamaterial by building small circuits designed to mimic
the magnetic or electrical response of a material. The
demonstration of superlensing id the latest of many
predictions for negative-index materials to be realized
which is an indication of the rapid progress that has
occurred in the emerging field.},
Doi = {10.1038/scientificamerican0706-60},
Key = {fds269686}
}
@booklet{Padilla06,
Author = {Padilla, WJ and Basov, DN and Smith, DR},
Title = {Negative refractive index metamaterials},
Journal = {Materials Today},
Volume = {9},
Number = {7-8},
Pages = {28-35},
Publisher = {Elsevier BV},
Year = {2006},
Month = {July},
ISSN = {1369-7021},
url = {http://dx.doi.org/10.1016/S1369-7021(06)71573-5},
Abstract = {Engineered materials composed of designed inclusions can
exhibit exotic and unique electromagnetic properties not
inherent in the individual constituent components. These
artificially structured composites, known as metamaterials,
have the potential to fill critical voids in the
electromagnetic spectrum where material response is limited
and enable the construction of novel devices. Recently,
metamaterials that display negative refractive index - a
property not found in any known naturally occurring material
- have drawn significant scientific interest, underscoring
the remarkable potential of metamaterials to facilitate new
developments in electromagnetism. © 2006 Elsevier Ltd. All
rights reserved.},
Doi = {10.1016/S1369-7021(06)71573-5},
Key = {Padilla06}
}
@article{fds269685,
Author = {Pendry, JB and Schurig, D and Smith, DR},
Title = {Controlling electromagnetic fields.},
Journal = {Science (New York, N.Y.)},
Volume = {312},
Number = {5781},
Pages = {1780-1782},
Year = {2006},
Month = {June},
ISSN = {0036-8075},
url = {http://dx.doi.org/10.1126/science.1125907},
Abstract = {Using the freedom of design that metamaterials provide, we
show how electromagnetic fields can be redirected at will
and propose a design strategy. The conserved fields-electric
displacement field D, magnetic induction field B, and
Poynting vector B-are all displaced in a consistent manner.
A simple illustration is given of the cloaking of a
proscribed volume of space to exclude completely all
electromagnetic fields. Our work has relevance to exotic
lens design and to the cloaking of objects from
electromagnetic fields.},
Doi = {10.1126/science.1125907},
Key = {fds269685}
}
@article{fds319565,
Author = {Driscoll, T and Basov, DN and Starr, AF and Rye, PM and Nemat-Nasser, S and Schurig, D and Smith, DR},
Title = {Free-space microwave focusing by a negative-index gradient
lens},
Journal = {Applied Physics Letters},
Volume = {88},
Number = {8},
Pages = {081101-081101},
Publisher = {AIP Publishing},
Year = {2006},
Month = {March},
url = {http://dx.doi.org/10.1063/1.2174088},
Abstract = {Metamaterial structures designed to have simultaneously
negative permittivity and permeability are known as
left-handed materials. Their complexity and our
understanding of their properties have advanced rapidly to
the point where direct applications are now viable. We
present a radial gradient-index lens with an index of
refraction ranging from -2.67 (edge) to -0.97 (center).
Experimentally, we find that the lens can produce field
intensities at the focus that are greater than that of the
incident plane wave. These results are obtained at 10.3 GHz
and in excellent agreement with full-wave simulations. We
also demonstrate an advanced fabrication technique using
conventional printed circuit board technology which offers
significant design, mechanical, and cost advantages over
other microwave lens constructions. © 2006 American
Institute of Physics.},
Doi = {10.1063/1.2174088},
Key = {fds319565}
}
@booklet{Smith06b,
Author = {D. R. Smith and J. B. Pendry},
Title = {Homogenization of metamaterials by field averaging (invited
paper)},
Journal = {Journal Of The Optical Society Of America B-optical
Physics},
Volume = {23},
Number = {3},
Pages = {391 -- 403},
Year = {2006},
Month = {March},
ISSN = {0740-3224},
Abstract = {Over the past several years, metamaterials have been
introduced and rapidly been adopted as a means of achieving
unique electromagnetic material response. In metamaterials,
artificially structured-often periodically
positioned-inclusions replace the atoms and molecules of
conventional materials. The scale of these inclusions is
smaller than that of the electromagnetic wavelength of
interest, so that a homogenized description applies. We
present a homogenization technique in which macroscopic
fields are determined via averaging the local fields
obtained from a full-wave electromagnetic simulation or
analytical calculation. The field-averaging method can be
applied to homogenize any periodic structure with unit cells
having inclusions of arbitrary geometry and material. By
analyzing the dispersion diagrams and retrieved parameters
found by field averaging, we review the properties of
several basic metamaterial structures. (c) 2006 Optical
Society of America.},
Key = {Smith06b}
}
@article{fds331010,
Author = {Elsdon, M and Smith, D and Leach, M and Foti, SJ},
Title = {Experimental investigation of breast tumor imaging using
indirect microwave holography},
Journal = {Microwave and Optical Technology Letters},
Volume = {48},
Number = {3},
Pages = {480-482},
Publisher = {WILEY},
Year = {2006},
Month = {March},
url = {http://dx.doi.org/10.1002/mop.21384},
Abstract = {A novel indirect holographic technique for the early
detection of breast cancer, which offers considerable
benefits in terms of simplicity and expense, is presented
and discussed. It is shown how this approach, usually
employed at optical frequencies, can be adapted to image
breast tumors at microwave frequencies. Practical results,
using a simulated phantom, successfully demonstrate the
validity of this technique. © 2006 Wiley Periodicals,
Inc.},
Doi = {10.1002/mop.21384},
Key = {fds331010}
}
@article{8775845,
Author = {Schurig, D and Mock, JJ and Smith, DR},
Title = {Electric-field-coupled resonators for negative permittivity
metamaterials},
Journal = {Applied Physics Letters},
Volume = {88},
Number = {4},
Pages = {1-3},
Publisher = {AIP Publishing},
Year = {2006},
Month = {February},
ISSN = {0003-6951},
url = {http://dx.doi.org/10.1063/1.2166681},
Keywords = {metamaterials;permittivity;resonators;},
Abstract = {A lithographically patterned inductive-capacitive resonator
is described that has a strong electric response. This
resonator can be used to construct metamaterials with
desired positive or negative permittivity. Such materials
provide an alternative to wire media, and have the benefit
of not requiring continuous current paths between unit
cells. A planar medium composed of these resonators was
simulated, fabricated, and measured in the microwave
frequency range. © 2006 American Institute of
Physics.},
Doi = {10.1063/1.2166681},
Key = {8775845}
}
@booklet{Degiron06,
Author = {A. Degiron and D. R. Smith},
Title = {Numerical simulations of long-range plasmons},
Journal = {Optics Express},
Volume = {14},
Number = {4},
Pages = {1611 -- 1625},
Year = {2006},
Month = {February},
ISSN = {1094-4087},
Abstract = {We present simulations of plasmonic transmission lines
consisting of planar metal strips embedded in isotropic
dielectric media, with a particular emphasis on the
long-range surface plasmon polariton (SPP) modes that can be
supported in such structures. Our computational method is
based on analyzing the eigenfrequencies corresponding to the
wave equation subject to a mixture of periodic, electric and
magnetic boundary conditions. We demonstrate the accuracy of
our approach through comparisons with previously reported
simulations based on the semi-analytical method-of-lines. We
apply our method to study a variety of aspects of long-range
SPPs, including tradeoffs between mode confinement and
propagation distance, the modeling of bent waveguides and
the effect of disorder and periodicity on the long-ranging
modes. (c) 2006 Optical Society of America.},
Key = {Degiron06}
}
@article{06099724955,
Author = {Degiron, A and Smith, D},
Title = {Numerical simulations of long-range plasmons.},
Journal = {Optics express},
Volume = {14},
Number = {4},
Pages = {1611-1625},
Year = {2006},
Month = {February},
ISSN = {1094-4087},
url = {http://dx.doi.org/10.1364/oe.14.001611},
Keywords = {Plasmas;Strip metal;Dielectric materials;Computer
simulation;Boundary conditions;Computational
methods;Eigenvalues and eigenfunctions;},
Abstract = {We present simulations of plasmonic transmission lines
consisting of planar metal strips embedded in isotropic
dielectric media, with a particular emphasis on the
long-range surface plasmon polariton (SPP) modes that can be
supported in such structures. Our computational method is
based on analyzing the eigenfrequencies corresponding to the
wave equation subject to a mixture of periodic, electric and
magnetic boundary conditions. We demonstrate the accuracy of
our approach through comparisons with previously reported
simulations based on the semi-analytical method-of-lines. We
apply our method to study a variety of aspects of long-range
SPPs, including tradeoffs between mode confinement and
propagation distance, the modeling of bent waveguides and
the effect of disorder and periodicity on the long-ranging
modes.},
Doi = {10.1364/oe.14.001611},
Key = {06099724955}
}
@article{fds335136,
Author = {Smith, DR and Ingley, R and Holland, AD},
Title = {Proton irradiation of EMCCDs},
Journal = {IEEE Transactions on Electron Devices},
Volume = {53},
Number = {2},
Pages = {205-210},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2006},
Month = {February},
url = {http://dx.doi.org/10.1109/TED.2005.861730},
Abstract = {This paper describes the irradiation of 95 electron
multiplication charge coupled devices (EMCCDs) at the Paul
Scherrer Institut (PSI) in Switzerland, to investigate the
effects of proton irradiation on the operational
characteristics of CCDs featuring electron multiplication
technology for space use. This work was carried out in
support of the CCD development for the radial velocity
spectrometer (RVS) instrument of the European Space Agency's
cornerstone Gaia mission. Previous proton irradiations of
EMCCDs, have shown the technology to be radiation hard to
∼10 × the required six-year Gaia lifetime proton fluence,
with no device failures or unexpected operational changes.
The purpose of the study described in this paper was to
further investigate the statistical probability of device
failure as a result of radiation damage, the large number of
devices and high proton fluence used, making the study
equivalent to testing ∼50 complete RVS CCD focal planes to
the expected end of life proton dose. An outline of the
earlier EMCCD proton irradiations is given, followed by a
detailed description of the proton irradiation and
characterization of the 95 devices used in this latest
study. © 2006 IEEE.},
Doi = {10.1109/TED.2005.861730},
Key = {fds335136}
}
@article{fds331001,
Author = {Elsdon, M and Leach, M and Fdo, MJ and Foti, SJ and Smith,
D},
Title = {Early stage breast cancer detection using indirect microwave
holography},
Journal = {Proceedings of the 36th European Microwave Conference, EuMC
2006},
Pages = {1256-1259},
Publisher = {IEEE},
Year = {2006},
Month = {January},
ISBN = {9782960055160},
url = {http://dx.doi.org/10.1109/EUMC.2006.281223},
Abstract = {A novel microwave imaging approach for early stage breast
cancer detection is described. The proposed technique
involves the use of an Indirect Microwave Holographic
technique employing a patented synthetic reference wave.
This approach offers benefits in terms of simplicity,
expense, comfort and safety when compared to current
mammography techniques. Experimental results using a
simulated phantom are included to demonstrate the validity
of this technique. © 2006 EuMA.},
Doi = {10.1109/EUMC.2006.281223},
Key = {fds331001}
}
@booklet{Schurig06a,
Author = {D. Schurig and J. J. Mock and D. R. Smith},
Title = {Electric-field-coupled resonators for negative permittivity
metamaterials},
Journal = {Applied Physics Letters},
Volume = {88},
Number = {4},
Year = {2006},
Month = {January},
ISSN = {0003-6951},
Abstract = {A lithographically patterned inductive-capacitive resonator
is described that has a strong electric response. This
resonator can be used to construct metamaterials with
desired positive or negative permittivity. Such materials
provide an alternative to wire media, and have the benefit
of not requiring continuous current paths between unit
cells. A planar medium composed of these resonators was
simulated, fabricated, and measured in the microwave
frequency range. (c) 2006 American Institute of
Physics.},
Key = {Schurig06a}
}
@article{fds269585,
Author = {Degiron, A and Smith, DR},
Title = {Numerical simulations of plasmonic transmission
lines},
Journal = {Optics InfoBase Conference Papers},
Year = {2006},
Month = {January},
Abstract = {We present simulations of plasmonic transmission lines
consisting of metal strips embedded in dielectric media. Our
numerical method is based on calculating the eigenmodes
using a finite-element method as will be illustrated by
several examples. © 2005 Optical Society of
America.},
Key = {fds269585}
}
@article{fds269684,
Author = {Browning, VM and Tanielian, MH and Ziolkowski, RW and Engheta, N and Smith, DR},
Title = {A DoD perspective on left handed negative index materials
and potential applications},
Journal = {Materials Research Society Symposium Proceedings},
Volume = {919},
Pages = {1-11},
Year = {2006},
Month = {January},
ISSN = {0272-9172},
url = {http://dx.doi.org/10.1557/proc-0919-j01-02},
Abstract = {In the quest for ever smaller, lighter weight, and conformal
components and devices for radar and communication
applications, researchers in the RF community have
increasingly turned to artificially engineered, composite
structures (or "metamaterials") in order to exploit the
extraordinary electromagnetic response these materials
offer. One particularly promising class of metamaterials
that has recently received a great deal of attention are
"left-handed" or negative index materials. Because these
metamaterials exhibit the unique ability to bend and focus
light in ways no other conventional materials can, they hold
great potential for enabling a number of innovative lens and
antenna structures for a broad range of commercial and DoD
relevant applications. Exploring the possible implementation
of negative index materials for such applications will
require significant enhancements in the properties of
existing Negative Index Materials (NIM) (bandwidth, loss,
operational frequency, etc.), as well as improved
understanding of the physics of their electromagnetic
transport properties. For this reason the Defense Advanced
Research Project Agency (DARPA) has initiated a program that
seeks to further develop and demonstrate NIM for future DoD
missions including, but not limited to, the following: 1)
lightweight, compact lenses with improved optics; 2) sub
wavelength/high resolution imaging across the
electromagnetic spectrum; 3) novel approaches to beam
steering for radar, RF, and/or optical communications; and
4) novel approaches for integrating optics with
semiconductor electronics. A brief overview of the salient
properties of NIM will be presented as well as a general
discussion of a few of their potential applications. © 2006
Materials Research Society.},
Doi = {10.1557/proc-0919-j01-02},
Key = {fds269684}
}
@article{fds269776,
Author = {Palit, S and Driscoll, T and Ren, T and Mock, J and Cho, SY and Jokerst,
NM and Smith, D and Basov, D},
Title = {Toward artificial magnetism using terahertz split ring
resonator metamaterials},
Journal = {Conference Proceedings - Lasers and Electro-Optics Society
Annual Meeting-LEOS},
Pages = {248-249},
Publisher = {IEEE},
Year = {2006},
Month = {January},
ISSN = {1092-8081},
url = {http://dx.doi.org/10.1109/LEOS.2006.279022},
Abstract = {Split Ring Resonator arrays have been fabricated to
demonstrate magnetic resonance in the terahertz regime.
Spectroscopic transmission measurements as a function of
oblique angle enable quantitative values of the permeability
to be calculated © 2006 IEEE.},
Doi = {10.1109/LEOS.2006.279022},
Key = {fds269776}
}
@booklet{Padilla06a,
Author = {Padilla, WJ and Smith, DR and Basov, DN},
Title = {Spectroscopy of metamaterials from infrared top optical
frequencies},
Journal = {Journal of the Optical Society of America B: Optical
Physics},
Volume = {23},
Number = {3},
Pages = {404-414},
Publisher = {The Optical Society},
Year = {2006},
Month = {January},
ISSN = {0740-3224},
url = {http://dx.doi.org/10.1364/JOSAB.23.000404},
Abstract = {We review both the theoretical electromagnetic response and
the spectroscopic measurements of metamaterials. To
critically examine published results for metamaterial
structures operating in the range from terahertz to optical
frequencies, we focus on protocols allowing one to extract
the optical constants from experimental observables. We
discuss the complexity of this task when applied to
metamaterials exhibiting electric, magnetic, and
magneto-optical response. The general theory of the
electromagnetic response of such systems is presented and
methods are described. Finally, we briefly overview possible
solutions for implementing metamaterials with tunable
resonant behavior. © 2006 Optical Society of
America.},
Doi = {10.1364/JOSAB.23.000404},
Key = {Padilla06a}
}
@article{06169829702,
Author = {Smith, DR and Pendry, JB},
Title = {Homogenization of metamaterials by field averaging (invited
paper)},
Journal = {Journal of the Optical Society of America B: Optical
Physics},
Volume = {23},
Number = {3},
Pages = {391-403},
Publisher = {The Optical Society},
Year = {2006},
Month = {January},
ISSN = {0740-3224},
url = {http://dx.doi.org/10.1364/JOSAB.23.000391},
Keywords = {Optical properties;Electromagnetic waves;Dispersion
(waves);Computer simulation;},
Abstract = {Over the past several years, metamaterials have been
introduced and rapidly been adopted as a means of achieving
unique electromagnetic material response. In metamaterials,
artificially structured - often periodically positioned -
inclusions replace the atoms and molecules of conventional
materials. The scale of these inclusions is smaller than
that of the electromagnetic wavelength of interest, so that
a homogenized description applies. We present a
homogenization technique in which macroscopic fields are
determined via averaging the local fields obtained from a
full-wave electromagnetic simulation or analytical
calculation. The field-averaging method can be applied to
homogenize any periodic structure with unit cells having
inclusions of arbitrary geometry and material. By analyzing
the dispersion diagrams and retrieved parameters found by
field averaging, we review the properties of several basic
metamaterial structures. © 2006 Optical Society of
America.},
Doi = {10.1364/JOSAB.23.000391},
Key = {06169829702}
}
@article{063910137125,
Author = {Justice, Bryan J. and Mock, Jack J. and Guo, Liheng and Degiron, Aloyse and Schurig, David and Smith, David
R.},
Title = {Spatial mapping of the internal and external electromagnetic
fields of negative index metamaterials},
Journal = {Optics Express},
Volume = {14},
Number = {19},
Pages = {8694 - 8705},
Year = {2006},
url = {http://dx.doi.org/10.1364/OE.14.008694},
Keywords = {Conformal mapping;Spatial variables control;Microwaves;Natural
frequencies;Microwave antennas;Waveguides;Electric
fields;Electric field effects;Microstructure;},
Abstract = {We perform an experimental study of the phase and amplitude
of microwaves interacting with and scattered by
two-dimensional negative index metamaterials. The
measurements are performed in a parallel plate waveguide
apparatus at X-band frequencies (8-12 GHz), thus
constraining the electromagnetic fields to two dimensions. A
detection antenna is fixed to one of the plates, while a
second plate with a fixed source antenna or waveguide is
translated relative to the first plate. The detection
antenna is inserted into, but not protruding below, the
stationary plate so that fields internal to the metamaterial
samples can be mapped. From the measured mappings of the
electric field, the interplay between the microstructure of
the metamaterial lattice and the macroscopic averaged
response is revealed. For example, the mapped phase fronts
within a metamaterial having a negative refractive index are
consistent with a macroscopic phase - in accordance with the
effective medium predictions - which travels in a direction
opposite to the direction of propagation. The field maps are
in excellent agreement with finite element numerical
simulations performed assuming homogeneous metamaterial
structures. © 2006 Optical Society of
America.},
Key = {063910137125}
}
@article{fds331011,
Author = {Elsdon, M and Smith, D and Leach, M and Foti, S},
Title = {Microwave imaging of concealed metal objects using a novel
indirect holographic method},
Journal = {Microwave and Optical Technology Letters},
Volume = {47},
Number = {6},
Pages = {536-537},
Publisher = {WILEY},
Year = {2005},
Month = {December},
url = {http://dx.doi.org/10.1002/mop.21222},
Abstract = {A novel, inexpensive technique for the detection of
concealed metal objects is presented and discussed. It is
shown that an indirect holographic method, usually employed
at optical frequencies, can he adapted to image objects at
microwave frequencies. The practical results successfully
demonstrate that this technique can be used to determine the
location and shape of the concealed object. © 2005 Wiley Pe
riodicals, Inc.},
Doi = {10.1002/mop.21222},
Key = {fds331011}
}
@article{8482582,
Author = {Gollub, JN and Smith, DR and Vier, DC and Perram, T and Mock,
JJ},
Title = {Experimental characterization of magnetic surface plasmons
on metamaterials with negative permeability},
Journal = {Physical Review B - Condensed Matter and Materials
Physics},
Volume = {71},
Number = {19},
Pages = {195402 - 1},
Publisher = {American Physical Society (APS)},
Year = {2005},
Month = {December},
ISSN = {1098-0121},
url = {http://dx.doi.org/10.1103/PhysRevB.71.195402},
Keywords = {attenuated total reflection;finite element analysis;magnetic
permeability;metamaterials;permittivity;surface
plasmons;},
Abstract = {We study the surface plasmons (SPs) that exist at the
interface between air and a metamaterial constructed of
split ring resonators (SRRs). The SRR metamaterial possesses
a frequency band in the microwave regime (12.5-14 GHz) over
which the permeability is negative. We apply an attenuated
total reflection technique in the Otto configuration in
which a beam of microwaves is reflected from a higher
dielectric (polycarbonate) prism to excite and probe the
surface plasmons. The resulting evanescent microwave fields
on the transmission side of the prism couple to SPs on the
metamaterial and are indicated by a dip in the reflected
power. The experimental data are compared with analytic
solutions in which the metamaterial slab is approximated as
an infinite half space, for which the frequency-dependent
permeability (and permittivity) is derived from
finite-element simulations on an SRR structure with the same
parameters as those measured. © 2005 The American Physical
Society.},
Doi = {10.1103/PhysRevB.71.195402},
Key = {8482582}
}
@article{fds335137,
Author = {Short, A and Hopkinson, G and Laborie, A and Pouny, P and Vetel, C and Eaton, T and Steward, R and Holland, A and Hutchinson, I and Smith, D and De Bruijne and J and Garé, P and Perryman, M and Sarri, G and Zayer,
I},
Title = {Gaia astrometric CCDs and focal plane},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {5902},
Pages = {1-14},
Publisher = {SPIE},
Year = {2005},
Month = {December},
url = {http://dx.doi.org/10.1117/12.616999},
Abstract = {ESA's Gaia astrometry mission is due for launch in 2011. The
astrometric instrument focal plane will have an area of up
to 0.5m2 and will contain more than 100 CCDs. These will be
operated in Time Delay and Integration mode in order to
track and observe sources whilst the telescopes continuously
scan the sky. Gaia's target for astrometric precision of a
few millionths of an arc second, places extreme demands on
focal plane thermo-mechanical stability and electronics
performance. The CCDs themselves are large area, back
illuminated, full-frame, four phase devices. They require
maximum efficiency for observing the majority of (faint)
objects, yet must simultaneously be able to handle very
bright objects that will regularly cross the field of view.
Achieving the final astrometric precision will also require
excellent noise performance and MTF. In addition to
demanding excellent performance from each CCD, they will
need to be produced in large numbers which raises production
and yield issues. When analyzing Gaia data it will be
essential to understand and calibrate CCD behaviour
correctly, including the expected performance degradation
due to radiation damage. This is being addressed through
comprehensive testing and the development of CCD
models.},
Doi = {10.1117/12.616999},
Key = {fds335137}
}
@article{fds335138,
Author = {Holland, AD and Castelli, C and Hutchinson, I and Smith, DR and Calafell, J and Pool, P and Burt, D and Ambrosi, R and French,
M},
Title = {MOS CCDs for the Wide Field Imager on the XEUS
Spacecraft},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {5898},
Pages = {1-12},
Publisher = {SPIE},
Year = {2005},
Month = {December},
url = {http://dx.doi.org/10.1117/12.639708},
Abstract = {In recent years the XEUS mission concept has evolved and has
been the subject of several industrial studies. The mission
concept has now matured to the point that it could be
proposed for a Phase A study and subsequent flight
programme. The key feature of XEUS will be its X-ray optic
with collecting area ∼30-100x that of XMM. The mission is
envisaged at an orbit around the L2 point in space, and is
formed from two spacecraft; one for the mirrors, and the
other for the focal plane detectors. With a focal length of
50m, the plate scale of the optic is 6.5x that of XMM, which
using existing focal plane technology will reduce the
effective field of view to a few arc minutes. Cryogenic
instrumentation, with detector sizes of a few mm can only be
used for narrow field studies of target objects, and a wide
field instrument is under consideration using a DEPFET pixel
array to image out to a diameter of 5 arcminutes, requiring
an array of dimension 70mm. It is envisaged to extend this
field of view possibly out to 15 arcminutes through the use
of an outer detection ring comprised of MOS
CCDs.},
Doi = {10.1117/12.639708},
Key = {fds335138}
}
@article{fds335139,
Author = {Pool, PJ and Morris, DG and Burt, DJ and Bell, RT and Holland, AD and Smith, DR},
Title = {Application of electron multiplying CCD technology in space
instrumentation},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {5902},
Pages = {1-6},
Publisher = {SPIE},
Year = {2005},
Month = {December},
url = {http://dx.doi.org/10.1117/12.621627},
Abstract = {Electron multiplying CCD (EMCCD) technology has found
important initial applications in low light surveillance and
photon starved scientific instrumentation. This paper
discusses the attributes of the EMCCD which make it useful
for certain space instruments, particularly those which are
photon starved, and explores likely risks from the radiation
expected in such instruments.},
Doi = {10.1117/12.621627},
Key = {fds335139}
}
@article{fds331012,
Author = {Smith, D and Leach, M and Elsdon, M and Fernando, MJ and Foti,
SJ},
Title = {Imaging of dielectric objects from phase patterns
reconstructed using indirect holographic intensity
patterns},
Journal = {ICEAA 2005 - 9th International Conference on
Electromagnetics in Advanced Applications and EESC 2005 -
11th European Electromagnetic Structures
Conference},
Pages = {401-404},
Year = {2005},
Month = {December},
ISBN = {9788882020934},
Abstract = {This work provides a discussion of a technique developed at
Northumbria University that enables full 3D object images to
be recorded in a 2D intensity pattern, by utilizing the
holographic principle originally developed as an optical
technique.},
Key = {fds331012}
}
@article{fds331013,
Author = {Smith, D and Leach, M and Elsdon, M and Foti, SJ},
Title = {Imaging dielectric objects from scalar intensity patterns by
means of indirect holography},
Journal = {IEEE Antennas and Propagation Society, AP-S International
Symposium (Digest)},
Volume = {1 A},
Pages = {177-180},
Publisher = {IEEE},
Year = {2005},
Month = {December},
ISBN = {9780780388833},
url = {http://dx.doi.org/10.1109/APS.2005.1551275},
Abstract = {An indirect microwave holographic technique for the
reconstruction of complex scattered fields and the imaging
of objects from a single holographic intensity pattern is
described. The holographic intensity pattern is constructed
by combining the signal scattered from the dielectric object
with a synthesised reference signal. This dispenses with the
need for expensive phase measuring equipment. Reconstructed
magnitude and phase patterns of the original object have
been determined using an adaptation of optical techniques.
This work describes how dielectric objects of low contrast
to the background when viewed using reconstructed magnitude
patterns can be imaged from reconstructed phase patterns ©
2005 IEEE.},
Doi = {10.1109/APS.2005.1551275},
Key = {fds331013}
}
@article{fds269678,
Author = {Martin, MC and Zhao, H and Liddle, A and Anderson, EH and Padilla, WJ and Schurig, D and Smith, DR},
Title = {Fabrication and optical measurements of nanoscale
meta-materials: Terahertz and beyond},
Journal = {The Joint 30th International Conference on Infrared and
Millimeter Waves and 13th International Conference on
Terahertz Electronics, 2005. IRMMW-THz 2005},
Volume = {1},
Pages = {34-35},
Year = {2005},
Month = {December},
Key = {fds269678}
}
@article{fds269679,
Author = {Smith, DR and Schurig, D},
Title = {New optics using negative refraction},
Journal = {2005 OSA Topical Meeting on Information Photonics, IP
2005},
Year = {2005},
Month = {December},
Abstract = {We summarize the benefits that negative index materials
(NIMs), realizable in artificially constructed
metamaterials, can have on both geometrical and wave optics.
NIMs may lead to novel or improved future optical devices.
© Optical Society of America.},
Key = {fds269679}
}
@booklet{Greegor05,
Author = {Greegor, RB and Parazzoli, CG and Nielsen, JA and Thompson, MA and Tanielian, MH and Smith, DR},
Title = {Simulation and testing of a graded negative index of
refraction lens},
Journal = {Applied Physics Letters},
Volume = {87},
Number = {9},
Year = {2005},
Month = {August},
ISSN = {0003-6951},
url = {http://dx.doi.org/10.1063/1.2037202},
Abstract = {A gradient index (GRIN) lens using a negative index of
refraction material (NIM) has been designed and tested. The
GRIN lens was fabricated using a NIM slab with a variable
index of refraction perpendicular to the propagation
direction. Ray tracing calculations based on the isotropic
Eikonal equation determined the index of refraction gradient
required for a given focal length. An electromagnetic code
was then used to design the required ring and wire unit
cells. Finally, the index of refraction was approximated
using ten discrete steps in an effective medium simulation
for the GRIN lens that agreed with the experimental
measurements. © 2005 American Institute of
Physics.},
Doi = {10.1063/1.2037202},
Key = {Greegor05}
}
@article{8601580,
Author = {Schurig, D and Smith, DR},
Title = {Sub-diffraction imaging with compensating
bilayers},
Journal = {New Journal of Physics},
Volume = {7},
Number = {1},
Pages = {162-162},
Publisher = {IOP Publishing},
Year = {2005},
Month = {August},
ISSN = {1367-2630},
url = {http://dx.doi.org/10.1088/1367-2630/7/1/162},
Keywords = {lenses;metamaterials;optical focusing;refractive
index;},
Abstract = {We derive a general expression for the material properties
of a compensating bilayer, which is a pair of material
layers which transfer the field distribution from one side
of the bilayer to the other with resolution limited only by
the deviation of the material properties from specified
values. One of the layers can be free space, a special case
of which is the perfect lens, but the layers need not have
equal thickness. Compensating a thick layer of free space
with a thin layer creates a focusing device with increased
working distance, and employs an anisotropic material. It is
also possible to achieve compensation of materials with
property tensors that are neither positive nor negative
definite. In this case, we refer to such media as
indefinite, and we analyse, in detail, bilayers of these
media which support coupling of internal propagating waves
to incident waves of any transverse wave vector. In this
case, we find that the enhanced spatial resolution provided
by large transverse wave vectors is far less sensitive to
loss than that of the perfect lens. © IOP Publishing Ltd
and Deutsche Physikalische Gesellschaft.},
Doi = {10.1088/1367-2630/7/1/162},
Key = {8601580}
}
@article{fds269576,
Author = {Schurig, D and Smith, DR},
Title = {Negative Index Lenses},
Pages = {213-248},
Publisher = {JOHN WILEY & SONS INC},
Year = {2005},
Month = {August},
url = {http://dx.doi.org/10.1002/0471744751.ch5},
Doi = {10.1002/0471744751.ch5},
Key = {fds269576}
}
@booklet{Schurig05,
Author = {D. Schurig and D. R. Smith},
Title = {Sub-diffraction imaging with compensating
bilayers},
Journal = {New Journal Of Physics},
Volume = {7},
Year = {2005},
Month = {August},
ISSN = {1367-2630},
Abstract = {We derive a general expression for the material properties
of a compensating bilayer, which is a pair of material
layers which transfer the field distribution from one side
of the bilayer to the other with resolution limited only by
the deviation of the material properties from specified
values. One of the layers can be free space, a special case
of which is the perfect lens, but the layers need not have
equal thickness. Compensating a thick layer of free space
with a thin layer creates a focusing device with increased
working distance, and employs an anisotropic material. It is
also possible to achieve compensation of materials with
property tensors that are neither positive nor negative
definite. In this case, we refer to such media as
indefinite, and we analyse, in detail, bilayers of these
media which support coupling of internal propagating waves
to incident waves of any transverse wave vector. In this
case, we find that the enhanced spatial resolution provided
by large transverse wave vectors is far less sensitive to
loss than that of the perfect lens.},
Key = {Schurig05}
}
@article{fds269676,
Author = {Padilla, WJ and Yen, TJ and Fang, N and Vier, DC and Smith, DR and Pendry,
JB and Zhang, X and Basov, DN},
Title = {Infrared spectroscopy and ellipsometry of magnetic
metamaterials},
Journal = {Progress in Biomedical Optics and Imaging - Proceedings of
SPIE},
Volume = {5732},
Pages = {460-469},
Publisher = {SPIE},
Year = {2005},
Month = {July},
ISSN = {1605-7422},
url = {http://dx.doi.org/10.1117/12.581787},
Abstract = {We present S and P polarized measurements of artificial
bianisotropic magnetic metamaterials with resonant behavior
at infrared frequencies. These metamaterials consist of an
array of micron sized (∼40μm) copper rings fabricated
upon a quartz substrate. Simulation of the reflectance is
obtained through a combination of electromagnetic eigenmode
simulation and Jones matrix analysis, and we find excellent
agreement with the experimental data. It is shown that
although the artificial magnetic materials do indeed exhibit
a magnetic response, care must be taken to avoid an
undesirable electric dipole resonance, due to lack of
reflection symmetry in one orientation. The effects of
bianisotropy on negative index are detailed and shown to be
beneficial for certain configurations of the material
parameters.},
Doi = {10.1117/12.581787},
Key = {fds269676}
}
@article{fds335141,
Author = {Smith, DR and Holland, AD},
Title = {Proton irradiation of e2v technologies L3Vision
devices},
Journal = {Nuclear Instruments and Methods in Physics Research, Section
A: Accelerators, Spectrometers, Detectors and Associated
Equipment},
Volume = {546},
Number = {3},
Pages = {544-552},
Publisher = {Elsevier BV},
Year = {2005},
Month = {July},
url = {http://dx.doi.org/10.1016/j.nima.2005.02.035},
Abstract = {This paper describes the proton irradiation and subsequent
analysis of 8 e2v technologies CCD65 L3Vision devices with
the intention of assessing the suitability of L3Vision
technology to applications in space. In particular the use
of L3Vision charge coupled devices (CCDs) on the Radial
Velocity Spectrometer (RVS) instrument of the planned
European Space Agency GAIA mission is discussed. The
operational properties of the devices were characterised
before irradiation with protons to a 10 MeV equivalent
fluence of 2.5×109protonscm-2. The devices were then
characterised again before undergoing a second proton
irradiation which increased the total 10 MeV equivalent
proton fluence received by each device to
2.1×1010protonscm-2. All 8 devices functioned as expected
after each irradiation, with no catastrophic failures
occurring even after the second irradiation which increased
the total proton fluence to approximately 10 times the
expected 6 year RVS fluence. © 2005 Elsevier B.V. All
rights reserved.},
Doi = {10.1016/j.nima.2005.02.035},
Key = {fds335141}
}
@booklet{Koschny05,
Author = {Koschny, T and Markoš, P and Economou, EN and Smith, DR and Vier, DC and Soukoulis, CM},
Title = {Impact of inherent periodic structure on effective medium
description of left-handed and related metamaterials},
Journal = {Physical Review B - Condensed Matter and Materials
Physics},
Volume = {71},
Number = {24},
Publisher = {American Physical Society (APS)},
Year = {2005},
Month = {June},
ISSN = {1098-0121},
url = {http://dx.doi.org/10.1103/PhysRevB.71.245105},
Abstract = {We study the frequency dependence of the effective
electromagnetic parameters of left-handed and related
metamaterials of the split ring resonator and wire type. We
show that the reduced translational symmetry (periodic
structure) inherent to these metamaterials influences their
effective electromagnetic response. To anticipate this
periodicity, we formulate a periodic effective medium model
which enables us to distinguish the resonant behavior of
electromagnetic parameters from effects of the periodicity
of the structure. We use this model for the analysis of
numerical data for the transmission and reflection of
periodic arrays of split ring resonators, thin metallic
wires, cut wires, as well as the left-handed structures. The
present method enables us to identify the origin of the
previously observed resonance-antiresonance coupling as well
as the occurrence of negative imaginary parts in the
effective permittivities and permeabilities of those
materials. Our analysis shows that the periodicity of the
structure can be neglected only for the wavelength of the
electromagnetic wave larger than 30 space periods of the
investigated structure. © 2005 The American Physical
Society.},
Doi = {10.1103/PhysRevB.71.245105},
Key = {Koschny05}
}
@booklet{Gollub05,
Author = {J. N. Gollub and D. R. Smith and D. C. Vier and T. Perram and J. J. Mock},
Title = {Experimental characterization of magnetic surface plasmons
on metamaterials with negative permeability},
Journal = {Physical Review B},
Volume = {71},
Number = {19},
Year = {2005},
Month = {May},
ISSN = {1098-0121},
Abstract = {We study the surface plasmons (SPs) that exist at the
interface between air and a metamaterial constructed of
split ring resonators (SRRs). The SRR metamaterial possesses
a frequency band in the microwave regime (12.5-14 GHz) over
which the permeability is negative. We apply an attenuated
total reflection technique in the Otto configuration in
which a beam of microwaves is reflected from a higher
dielectric (polycarbonate) prism to excite and probe the
surface plasmons. The resulting evanescent microwave fields
on the transmission side of the prism couple to SPs on the
metamaterial and are indicated by a dip in the reflected
power. The experimental data are compared with analytic
solutions in which the metamaterial slab is approximated as
an infinite half space, for which the frequency-dependent
permeability (and permittivity) is derived from
finite-element simulations on an SRR structure with the same
parameters as those measured.},
Key = {Gollub05}
}
@article{fds269680,
Author = {Smith, DR},
Title = {Applied physics. How to build a superlens.},
Journal = {Science (New York, N.Y.)},
Volume = {308},
Number = {5721},
Pages = {502-503},
Year = {2005},
Month = {April},
url = {http://www.ncbi.nlm.nih.gov/pubmed/15845838},
Doi = {10.1126/science.1110900},
Key = {fds269680}
}
@booklet{Depine05,
Author = {Depine, RA and Lakhtakia, A and Smith, DR},
Title = {Enhanced diffraction by a rectangular grating made of a
negative phase-velocity (or negative index)
material},
Journal = {Physics Letters, Section A: General, Atomic and Solid State
Physics},
Volume = {337},
Number = {1-2},
Pages = {155-160},
Publisher = {Elsevier BV},
Year = {2005},
Month = {March},
ISSN = {0375-9601},
url = {http://dx.doi.org/10.1016/j.physleta.2005.01.028},
Abstract = {The diffraction of electromagnetic plane waves by a
rectangular grating formed by discrete steps in the
interface of a homogeneous, isotropic, linear, negative
phase-velocity (negative index) material with free space is
studied using the semi-analytic C method. When a nonspecular
diffracted order is of the propagating type, coupling to
that order is significantly larger for a negative index
material than for a conventional material. The computed
coupling strengths reported here are in agreement with
recent experiments, and illustrate the role of evanescent
fields localized at the grating interface in producing this
enhanced coupling. © 2005 Published by Elsevier
B.V.},
Doi = {10.1016/j.physleta.2005.01.028},
Key = {Depine05}
}
@booklet{Smith05a,
Author = {D. R. Smith and D. C. Vier and T. Koschny and C. M.
Soukoulis},
Title = {Electromagnetic parameter retrieval from inhomogeneous
metamaterials},
Journal = {Physical Review E},
Volume = {71},
Number = {3},
Year = {2005},
Month = {March},
ISSN = {1063-651X},
Abstract = {We discuss the validity of standard retrieval methods that
assign bulk electromagnetic properties, such as the electric
permittivity epsilon and the magnetic permeability mu, from
calculations of the scattering (S) parameters for
finite-thickness samples. S-parameter retrieval methods have
recently become the principal means of characterizing
artificially structured metamaterials, which, by nature, are
inherently inhomogeneous. While the unit cell of a
metamaterial can be made considerably smaller than the free
space wavelength, there remains a significant variation of
the phase across the unit cell at operational frequencies in
nearly all metamaterial structures reported to date. In this
respect, metamaterials do not rigorously satisfy an
effective medium limit and are closer conceptually to
photonic crystals. Nevertheless, we show here that a
modification of the standard S-parameter retrieval procedure
yields physically reasonable values for the retrieved
electromagnetic parameters, even when there is significant
inhomogeneity within the unit cell of the structure. We thus
distinguish a metamaterial regime, as opposed to the
effective medium or photonic crystal regimes, in which a
refractive index can be rigorously established but where the
wave impedance can only be approximately defined. We present
numerical simulations on typical metamaterial structures to
illustrate the modified retrieval algorithm and the impact
on the retrieved material parameters. We find that no
changes to the standard retrieval procedures are necessary
when the inhomogeneous unit cell is symmetric along the
propagation axis; however, when the unit cell does not
possess this symmetry, a modified procedure-in which a
periodic structure is assumed-is required to obtain
meaningful electromagnetic material parameters.},
Key = {Smith05a}
}
@booklet{Smith05,
Author = {D. R. Smith and J. J. Mock and A. F. Starr and D.
Schurig},
Title = {Gradient index metamaterials},
Journal = {Physical Review E},
Volume = {71},
Number = {3},
Year = {2005},
Month = {March},
ISSN = {1063-651X},
Abstract = {Metamaterials-artificially structured materials with
tailored electromagnetic response-can be designed to have
properties difficult or impossible to achieve with
traditional materials fabrication methods. Here we present a
structured metamaterial, based on conducting split ring
resonators (SRRs), which has an effective index of
refraction with a constant spatial gradient. We
experimentally confirm the gradient by measuring the
deflection of a microwave beam by a planar slab of the
composite metamaterial over a range of microwave
frequencies. The gradient index metamaterial may prove an
advantageous alternative approach to the development of
gradient index lenses and similar optics, especially at
higher frequencies. In particular, the gradient index
metamaterial we propose may be suited for terahertz
applications, where the magnetic resonant response of SRRs
has recently been demonstrated.},
Key = {Smith05}
}
@article{8388993,
Author = {Smith, DR and Mock, JJ and Starr, AF and Schurig,
D},
Title = {Gradient index metamaterials.},
Journal = {Physical review. E, Statistical, nonlinear, and soft matter
physics},
Volume = {71},
Number = {3 Pt 2B},
Pages = {036609},
Year = {2005},
Month = {March},
ISSN = {1539-3755},
url = {http://dx.doi.org/10.1103/PhysRevE.71.036609},
Keywords = {metamaterials;microwave photonics;optical
materials;refractive index;},
Abstract = {Metamaterials--artificially structured materials with
tailored electromagnetic response--can be designed to have
properties difficult or impossible to achieve with
traditional materials fabrication methods. Here we present a
structured metamaterial, based on conducting split ring
resonators (SRRs), which has an effective index of
refraction with a constant spatial gradient. We
experimentally confirm the gradient by measuring the
deflection of a microwave beam by a planar slab of the
composite metamaterial over a range of microwave
frequencies. The gradient index metamaterial may prove an
advantageous alternative approach to the development of
gradient index lenses and similar optics, especially at
higher frequencies. In particular, the gradient index
metamaterial we propose may be suited for terahertz
applications, where the magnetic resonant response of SRRs
has recently been demonstrated.},
Doi = {10.1103/physreve.71.036609},
Key = {8388993}
}
@article{8420161,
Author = {Smith, DR and Vier, DC and Koschny, T and Soukoulis,
CM},
Title = {Electromagnetic parameter retrieval from inhomogeneous
metamaterials.},
Journal = {Physical review. E, Statistical, nonlinear, and soft matter
physics},
Volume = {71},
Number = {3 Pt 2B},
Pages = {036617},
Year = {2005},
Month = {March},
ISSN = {1539-3755},
url = {http://dx.doi.org/10.1103/PhysRevE.71.036617},
Keywords = {metamaterials;optical materials;periodic
structures;S-parameters;},
Abstract = {We discuss the validity of standard retrieval methods that
assign bulk electromagnetic properties, such as the electric
permittivity epsilon and the magnetic permeability mu, from
calculations of the scattering (S) parameters for
finite-thickness samples. S-parameter retrieval methods have
recently become the principal means of characterizing
artificially structured metamaterials, which, by nature, are
inherently inhomogeneous. While the unit cell of a
metamaterial can be made considerably smaller than the free
space wavelength, there remains a significant variation of
the phase across the unit cell at operational frequencies in
nearly all metamaterial structures reported to date. In this
respect, metamaterials do not rigorously satisfy an
effective medium limit and are closer conceptually to
photonic crystals. Nevertheless, we show here that a
modification of the standard S-parameter retrieval procedure
yields physically reasonable values for the retrieved
electromagnetic parameters, even when there is significant
inhomogeneity within the unit cell of the structure. We thus
distinguish a metamaterial regime, as opposed to the
effective medium or photonic crystal regimes, in which a
refractive index can be rigorously established but where the
wave impedance can only be approximately defined. We present
numerical simulations on typical metamaterial structures to
illustrate the modified retrieval algorithm and the impact
on the retrieved material parameters. We find that no
changes to the standard retrieval procedures are necessary
when the inhomogeneous unit cell is symmetric along the
propagation axis; however, when the unit cell does not
possess this symmetry, a modified procedure--in which a
periodic structure is assumed--is required to obtain
meaningful electromagnetic material parameters.},
Doi = {10.1103/physreve.71.036617},
Key = {8420161}
}
@article{fds335142,
Author = {Ambrosi, MR and Smith, DR and Abbey, AF and Hutchinson, IB and Kendziorra, E and Short, A and Holland, A and Turner, MJL and Wells,
A},
Title = {Erratum: The impact of low energy proton damage on the
operational characteristics of EPIC-MOS CCDs (Nuclear
Instruments and Methods in Physics Research B (2003) 207
(175-185) DOI:10.1016/S0168-583X(03)008832.2)},
Journal = {Nuclear Instruments and Methods in Physics Research, Section
B: Beam Interactions with Materials and Atoms},
Volume = {229},
Number = {1},
Pages = {159},
Publisher = {Elsevier BV},
Year = {2005},
Month = {February},
url = {http://dx.doi.org/10.1016/j.nimb.2004.11.027},
Doi = {10.1016/j.nimb.2004.11.027},
Key = {fds335142}
}
@article{fds335132,
Author = {Feder, R and Mazzucato, E and Munsat, T and Park, H and Smith, DR and Ellis, R and Labik, G and Priniski, C},
Title = {Mechanical design of the NSTX high-k scattering
diagnostic},
Journal = {Proceedings - Symposium on Fusion Engineering},
Publisher = {IEEE},
Year = {2005},
Month = {January},
ISBN = {9781424401505},
url = {http://dx.doi.org/10.1109/FUSION.2005.252971},
Abstract = {The NSTX High-k Scattering Diagnostic measures small-scale
density fluctuations by the heterodyne detection of waves
scattered from a millimeter wave probe beam at 280 GHz and
λ=1. 07 mm. To enable this measurement, major alterations
were made to the NSTX vacuum vessel and Neutral Beam armor.
Close collaboration between the PPPL physics and engineering
staff resulted in a flexible system with steerable launch
and detection optics that can position the scattering volume
either near the magnetic axis (p ≈ . T) or near the edge
(p ≈ . 8). ISO feet of carefully aligned corrugated
waveguide was installed for injection of the probe beam and
collection of the scattered signal in to the detection
electronics. © IEEE.},
Doi = {10.1109/FUSION.2005.252971},
Key = {fds335132}
}
@article{fds269584,
Author = {Smith, DR and Schurig, D},
Title = {New optics using negative refraction},
Journal = {Optics InfoBase Conference Papers},
Year = {2005},
Month = {January},
Abstract = {We summarize the benefits that negative index materials
(NIMs), realizable in artificially constructed
metamaterials, can have on both geometrical and wave optics.
NIMs may lead to novel or improved future optical devices.
© Optical Society of America.},
Key = {fds269584}
}
@article{fds269681,
Author = {Smith, D},
Title = {Superlens breaks optical barrier},
Journal = {Physics World},
Volume = {18},
Number = {8},
Pages = {23-24},
Publisher = {IOP Publishing},
Year = {2005},
Month = {January},
url = {http://dx.doi.org/10.1088/2058-7058/18/8/30},
Abstract = {A lens developed by physicists that can image nano-scale
objects using visible light is discussed. It is found that
diffraction restricts the resolution of microscopes and
other optical devices to the wavelength of light used. The
new superlens can produce a much sharper image than a
conventional lens because it is bale to focus the near field
components of the transmitted light. The lenses could be
used to image structures with a resolution as high as
one-quarter the wavelength of the incident light.
Superlensing may find applications in industries such as
optical lithography or optical storage and will enable
manufacturers to fabricate devices on smaller
scales.},
Doi = {10.1088/2058-7058/18/8/30},
Key = {fds269681}
}
@article{fds335140,
Author = {Ambrosi, RM and Holland, AD and Smith, DR and Hutchinson, IB and Denby,
M},
Title = {The effect of the prompt particle environment at L2 on
optical CCDs for astronomy and astrophysics},
Journal = {Planetary and Space Science},
Volume = {53},
Number = {14-15},
Pages = {1449-1465},
Publisher = {Elsevier BV},
Year = {2005},
Month = {January},
url = {http://dx.doi.org/10.1016/j.pss.2005.10.004},
Abstract = {The increasing number of probes carrying large focal planes
consisting of many charge-coupled devices (CCDs), planned to
be sent to the L2 Lagrangian point, 1.5 million kilometres
from Earth in the next 15 years, implies that a detailed
study of the effects of the prompt particle environment at
L2 on CCDs is required. The focus of this study will be on
CCDs for optical astronomy, astrometry and photometric
applications. This study will be of particular interest to
GAIA the European Space Agency's (ESA) cornerstone optical
astronomy mission to further explore and map sections of our
galaxy in greater detail. The results will also have
implications for future X-ray astronomy missions like the
X-ray Evolving Universe Spectroscopy Mission (XEUS). Both
the above missions will require large area focal planes
incorporating many CCD detectors. The sources of the
instrument background are both solar and galactic and if a
probe is launched around the peak in the next solar cycle
(2010), the possible false detection rate or the amount of
data that could be lost during a mission must be determined.
This paper presents measured data for a spacecraft in a
geostationary orbit, specifically Geosynchronous Operational
Environmental Satellites (GOES) data, and makes predictions
of the flux and energy of the particle environment at L2.
The solar and galactic cosmic ray background was determined
by using the Cosmic Ray Effects on Micro-Electronics or
CREME96 code. A comparison was then made between the GOES
data and the output from the CREME96 code in order to make
predictions about the L2 environment. © 2005 Elsevier Ltd.
All rights reserved.},
Doi = {10.1016/j.pss.2005.10.004},
Key = {fds335140}
}
@article{fds335143,
Author = {Lim, T and Swinyard, B and Aramburu, A and Bock, J and Ferlet, M and Griffin, D and Griffin, M and Margrave, P and King, K and Leeks, S and Naylor, D and Ronayette, S and Sawyer, E and Schulz, B and Sidher, S and Spencer, L and Smith, D and Woodcraft, A},
Title = {First results from Herschel-SPIRE performance
tests},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {5487},
Number = {PART 1},
Pages = {460-468},
Publisher = {SPIE},
Year = {2004},
Month = {December},
url = {http://dx.doi.org/10.1117/12.551684},
Abstract = {The Spectral and Photometric Imaging REceiver (SPIRE) is one
of the three scientific instruments on the European Space
Agency's Herschel mission. At the start of 2004 the
Cryogenic Qualification Model (CQM) of SPIRE was tested with
the aim of verifying the instrument system design and
evaluating key performance parameters. We present a
description of the test facility, an overview of the
instrument tests carried out on the CQM, and the first
results from the analysis of the test data. Instrument
optical efficiency and detector noise levels are close to
the values expected from unit-level tests, and the SPIRE
instrument system works well, with no degradation in
performance from stray light, electromagnetic interference
or microphonically induced noise. Some anomalies and
imperfections in the instrument performance, test set-up,
and test procedures have been identified and will be
addressed in the next test campaign.},
Doi = {10.1117/12.551684},
Key = {fds335143}
}
@article{fds269826,
Author = {Starr, AF and Nemat-Nasser, S and Smith, DR and Plaisted,
TA},
Title = {Integrated sensing networks in composite
materials},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {5391},
Pages = {197-201},
Publisher = {SPIE},
Year = {2004},
Month = {December},
ISSN = {0277-786X},
url = {http://dx.doi.org/10.1117/12.540209},
Abstract = {Increasingly, the demand to monitor structures in service is
driving technology in new directions. Advances in many areas
including novel sensor technologies afford new opportunities
in structural health monitoring. We present efforts to
develop structural composite materials which include
networks of embedded sensors with decision-making
capabilities that extend the functionality of the composite
materials to be information-aware. The next generation of
structural systems will include the capability to acquire,
process, and if necessary respond to structural or other
types of information. This work brings together many
important developments over the last few years in several
areas: developments in composites and the emergence of
multifunctional composites, the emergence of a broad range
of new sensors, smaller and lower power microelectronics
with increased and multiple integrated functionality, and
the emergence of algorithms that extract important
structural health information from large data sets. This
work seeks to leverage these individual advances by solving
the challenges needed to integrate these into an
information-aware composite structure. We present details of
efforts to integrate and entrap connectorized
microelectronic components within fiber/conductor braided
bundles to minimize their impact as composite crack
initiation centers. The bundles include conductors to
transmit electric signals for power and communications. They
are suitable for inclusion in woven composite fabrics or
directly in the composite lay-up. The low-power electronic
devices can operate on a multi-drop and point-to-point
networks. Future directions include implementing in-network
local processing, adding a greater range of sensors, and
developing the composite processing techniques that allow
sensor network integration.},
Doi = {10.1117/12.540209},
Key = {fds269826}
}
@article{fds335144,
Author = {Smith, DR and Holland, AD and Hutchinson, I and Abbey, AF and Pool, P and Burt, D and Morris, D},
Title = {Low noise charge injection in the CCD22},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {5501},
Pages = {189-196},
Publisher = {SPIE},
Year = {2004},
Month = {December},
url = {http://dx.doi.org/10.1117/12.551393},
Abstract = {The inclusion of a charge injection structure on a charge
coupled device (CCD) allows for the mitigation of charge
transfer loss which can be caused by radiation induced
charge trapping defects. Any traps present in the pixels of
the CCD are filled by the injected charge as it is swept
through the device and consequently, the charge transfer
efficiency is improved in subsequently acquired images. To
date, a number of different types of CCD have been
manufactured featuring a variety of charge injection
techniques. The e2v Technologies CCD22, used in the EPIC MOS
focal plane instruments of XMM-Newton, is one such device
and is the subject of this paper. A detailed understanding
of charge injection operation and the use of charge
injection to mitigate charge transfer losses resulting from
radiation damage to CCDs will benefit a number of space
projects planned for the future, including the ESA GAIA and
X-ray Evolving Universe Spectrometry (XEUS) missions. The
charge injection structure and mode of operation of the
CCD22 are presented, followed by a detailed analysis of the
uniformity and repeatability of the charge injection
amplitude across the columns of the device. The effects of
proton irradiation on the charge injection characteristics
are also presented, in particular the effect of radiation
induced bright pixels on the injected charge
level.},
Doi = {10.1117/12.551393},
Key = {fds335144}
}
@article{fds331014,
Author = {Ooi, SF and Gao, S and Sambell, A and Smith, D and Butterworth,
P},
Title = {High efficiency class-F Power Amplifier design},
Journal = {IEEE High Frequency Postgraduate Student
Colloquium},
Pages = {113-118},
Year = {2004},
Month = {December},
Abstract = {In this paper, a high efficiency, low voltage, class-F Power
Amplifier (PA) is described. The effect of different output
harmonic terminations on the Power-Added Efficiency (PAE) of
the PA has also been analysed. A medium power PHEMT PA
operating at 900MHz is designed and measured. A peak PAE of
71.4% with 22dBm output power (Pout) and 14dB power gain
(Gp) is achieved at a very low drain voltage (Vds) of 3V. A
PAE above 60% has been achieved over a bandwidth of 13%. ©
2004 IEEE.},
Key = {fds331014}
}
@article{fds331015,
Author = {Smith, D and Leach, M and Elsdon, M and Foti, SJ},
Title = {Imaging concealed objects from scalar microwave
holograms},
Journal = {2004 RF and Microwave Conference, RFM 2004 -
Proceedings},
Pages = {99-102},
Year = {2004},
Month = {December},
ISBN = {9780780386716},
Abstract = {A new technique for the imaging of concealed objects using
indirect holographic imaging principles is outlined. A brief
examination of the underlying theory followed by a
description of the novel experimental system that has been
developed to overcome some of the previous issues regarding
this technique, is presented along with some initial results
obtained from the imaging of passive objects concealed by
material and plastic. © 2004 IEEE.},
Key = {fds331015}
}
@booklet{Schurig04,
Author = {Schurig, D and Smith, DR},
Title = {Negative index lens aberrations.},
Journal = {Physical review. E, Statistical, nonlinear, and soft matter
physics},
Volume = {70},
Number = {6 Pt 2},
Pages = {065601},
Year = {2004},
Month = {December},
ISSN = {1539-3755},
url = {http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000226299200005&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=47d3190e77e5a3a53558812f597b0b92},
Abstract = {We examine the Seidel aberrations of thin spherical lenses
composed of media with refractive index not restricted to be
positive. We find that consideration of this expanded
parameter space allows for the reduction or elimination of
more aberrations than is possible with only positive index
media. In particular, we find that spherical lenses
possessing real aplanatic focal points are possible only
with a negative index. We perform ray tracing, using a
custom code that relies only on Maxwell's equations and
conservation of energy, that confirms the results of the
aberration calculations.},
Doi = {10.1103/physreve.70.065601},
Key = {Schurig04}
}
@article{fds331016,
Author = {Ooi, SF and Gao, S and Sambell, A and Smith, D and Butterworth,
P},
Title = {A high efficiency class-f power amplifier design
technique},
Journal = {Microwave Journal},
Volume = {47},
Number = {11},
Pages = {110-122},
Year = {2004},
Month = {November},
Abstract = {In this article, a medium power pseudomorphic HEMT device is
used in the design of a high efficiency class-F power
amplifier (PA) operating at 900 MHz. The purpose of this
article is to describe the design procedure of a class-F PA
with a very low drain bias voltage (V ds). The realized PA
achieves a peak power-added efficiency (PAE) of 71.4 percent
with a 22 dBm output power (P out) and a 14 dB power gain (G
p) (2.3 dB compression) at V ds=3 V and 8 dBm input power (P
in). A PAE of above 60 percent is attained over a frequency
range of 850 to 970 MHz (13 percent BW).},
Key = {fds331016}
}
@article{fds269677,
Author = {Depine, RA and Lakhtakia, A and Efros, AL and Koschny, T and Markoš, P and Smith, DR and Soukoulis, CM},
Title = {Comment I on "Resonant and antiresonant frequency dependence
of the effective parameters of metamaterials"},
Journal = {Physical Review E - Statistical, Nonlinear, and Soft Matter
Physics},
Volume = {70},
Number = {4 2},
Pages = {048601-1-048603-1},
Publisher = {American Physical Society (APS)},
Year = {2004},
Month = {October},
ISSN = {1539-3755},
url = {http://dx.doi.org/10.1103/PhysRevE.70.048601},
Doi = {10.1103/PhysRevE.70.048601},
Key = {fds269677}
}
@article{04478465820,
Author = {Smith, DR and Rye, PM and Mock, JJ and Vier, DC and Starr,
AF},
Title = {Enhanced diffraction from a grating on the surface of a
negative-index metamaterial},
Journal = {Physical Review Letters},
Volume = {93},
Number = {13},
Pages = {137405-1-137405-4},
Publisher = {American Physical Society (APS)},
Year = {2004},
Month = {September},
url = {http://dx.doi.org/10.1103/PhysRevLett.93.137405},
Keywords = {Surface treatment;Refractive index;Optical
devices;Magnetoelectric effects;Refraction;Microwaves;Magnetic
permeability;Permittivity;Functions;Boundary
conditions;Mathematical models;Computer simulation;},
Abstract = {The stepping of the refraction interface, due to the finite
unit cell size was showed by numerical simulation and by
measurements on negative-index metamaterial wedge samples.
The surface stepping on the metamaterial sample constitutes
a grating, which could be expected to generate a diffracted
beam in addition to the zeroth order refracted beam. The
results confirms theoretical predictions of enhanced
diffraction for negative index grating surfaces. It was
found that a surface stepping added to a positive index
wedge produces a single refracted beam identical to that of
the smooth wedge.},
Doi = {10.1103/PhysRevLett.93.137405},
Key = {04478465820}
}
@article{04388358163,
Author = {Smith, DR and Vier, DC},
Title = {Design of metamaterials with negative refractive
index},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {5359},
Pages = {52-63},
Publisher = {SPIE},
Address = {San Jose, CA, United States},
Year = {2004},
Month = {September},
ISSN = {0277-786X},
url = {http://dx.doi.org/10.1117/12.518133},
Keywords = {Refractive index;Electromagnetism;Refraction;Electrodynamics;Light
propagation;Magnetic permeability;Wave equations;Computer
simulation;},
Abstract = {Due to the recent experimental validations of left-handed
metamaterials, negative refractive index has now become
recognized as a new parameter space for the electromagnetic
response of materials. Because materials with negative index
behave quite differently than materials with positive index,
many familiar electromagnetic phenomena must be
reconsidered. Having established now the scientific basis of
negative index, the effort of the community is turning
toward the practical realization of both the predicted
scientific phenomena and associated applications. In both of
these pursuits, the ability to design, characterize and
fabricate negative index materials is critical; we can
consider the current status of negative refraction in some
sense a materials issue, as our ability to demonstrate the
predicted phenomena is linked to the quality of
metamaterials we can produce. In this paper we consider
several issues associated with the design and simulation of
negative index metamaterials.},
Doi = {10.1117/12.518133},
Key = {04388358163}
}
@article{fds335145,
Author = {Smith, DR and Holland, AD and Hutchinson, IB},
Title = {Random telegraph signals in charge coupled
devices},
Journal = {Nuclear Instruments and Methods in Physics Research, Section
A: Accelerators, Spectrometers, Detectors and Associated
Equipment},
Volume = {530},
Number = {3},
Pages = {521-535},
Publisher = {Elsevier BV},
Year = {2004},
Month = {September},
url = {http://dx.doi.org/10.1016/j.nima.2004.03.210},
Abstract = {An investigation of fluctuating pixels resulting from proton
irradiation of an E2V Technologies CCD47-20 device is
presented. The device structure, experimental set up and
irradiation methodology are described, followed by a
detailed analysis of radiation induced random telegraph
signals, RTS. The characteristics of the observed flickering
pixels are discussed in detail and the proposed models
explaining the mechanism behind the phenomena are viewed in
light of the collected data. © 2004 Elsevier B.V. All
rights reserved.},
Doi = {10.1016/j.nima.2004.03.210},
Key = {fds335145}
}
@article{fds269833,
Author = {Hall, LJ and March-Russell, J and Okui, T and Smith,
DR},
Title = {Towards a theory of flavor from orbifold
GUTs},
Journal = {Journal of High Energy Physics},
Volume = {8},
Number = {9},
Pages = {587-607},
Year = {2004},
Month = {September},
url = {http://dx.doi.org/10.1088/1126-6708/2004/09/026},
Abstract = {We show that the recently constructed 5-dimensional
supersymmetric S 1 /(Z2 × Z′2) orbifold GUT models allow
an appealing explanation of the observed hierarchical
structure of the quark and lepton masses and mixing angles.
Flavor hierarchies arise from the geometrical suppression of
some couplings when fields propagate in different numbers of
dimensions, or on different fixed branes. Restrictions
arising from locality in the extra dimension allow
interesting texture zeroes to be easily generated. In
addition the detailed nature of the SU(5)-breaking orbifold
projections lead to simple theories where b - τ unification
is maintained but similar disfavored SU(5) relations for the
lighter generations are naturally avoided. We find that
simple 5d models based on S1 /(Z2 × Z′2) are strikingly
successful in explaining many features of the masses and
mixing angles of the 2nd and 3rd generation. Successful
three generation models of flavor including neutrinos are
constructed by generalizing the S1 /(Z2 × Z′2) model to
six dimensions. Large angle neutrino mixing is elegantly
accommodated. Novel features of these models include a
simple mu = 0 configuration leading to a solution of the
strong CP problem. © SISSA/ISAS 2004.},
Doi = {10.1088/1126-6708/2004/09/026},
Key = {fds269833}
}
@article{fds269830,
Author = {Smith, DR and Pendry, JB and Wiltshire, MCK},
Title = {Metamaterials and negative refractive index},
Journal = {Science},
Volume = {305},
Number = {5685},
Pages = {788-792},
Publisher = {American Association for the Advancement of Science
(AAAS)},
Year = {2004},
Month = {August},
url = {http://dx.doi.org/10.1126/science.1096796},
Abstract = {Recently, artificially constructed metamaterials have become
of considerable interest, because these materials can
exhibit electromagnetic characteristics unlike those of any
conventional materials. Artificial magnetism and negative
refractive index are two specific types of behavior that
have been demonstrated over the past few years, illustrating
the new physics and new applications possible when we expand
our view as to what constitutes a material. In this review,
we describe recent advances in metamaterials research and
discuss the potential that these materials may hold for
realizing new and seemingly exotic electromagnetic
phenomena.},
Doi = {10.1126/science.1096796},
Key = {fds269830}
}
@article{fds269831,
Author = {Lin, H and Mock, J and Smith, D and Gao, T and Sailor,
MJ},
Title = {Surface-enhanced Raman scattering from silver-plated porous
silicon},
Journal = {Journal of Physical Chemistry B},
Volume = {108},
Number = {31},
Pages = {11654-11659},
Publisher = {American Chemical Society (ACS)},
Year = {2004},
Month = {August},
ISSN = {1520-6106},
url = {http://dx.doi.org/10.1021/jp049008b},
Abstract = {Silver micro- and nanocrystallites are prepared on porous Si
substrates by immersion plating, and their activity toward
SERS (surface-enhanced Raman scattering) is assessed.
Scanning electron microscopy reveals a rough silver film
containing randomly spaced dendritic structures. SERS
spectra of Rhodamine 6G (R6G) and adenine are obtained using
an 18-mW, 488-nm laser. The SERS signal from these analytes
is dramatically improved by pretreatment of the
silver-plated porous Si samples (Ag-PS) with a 1 mM mineral
acid solution. Detection of R6G and adenine from 1 nM
solutions is demonstrated, corresponding to (at most) 9 ×
10 5 molecules in the experimental configuration used in the
current study. Ag-PS samples that have been stored in air
for 10 days still display high sensitivity. The presence of
chloride either in the analyte solution or in the
pretreatment solution is found to dramatically reduce the
limit of detection for R6G.},
Doi = {10.1021/jp049008b},
Key = {fds269831}
}
@article{fds335146,
Author = {Holland, AD and Perryman, M and Vetel, C and Steward, R and Hutchinson,
IB and Ambrosi, RM and Smith, DR and Bowring, S and Burt, D and Eaton, T and Morris, D and Pool, P and Davancens, R and Laborie, A and Pouny, P and Safa, F and Zayer, I and Short, A},
Title = {Development of the CCDs for ESA's GAIA cornerstone
mission},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {5167},
Pages = {38-49},
Publisher = {SPIE},
Year = {2004},
Month = {May},
url = {http://dx.doi.org/10.1117/12.515401},
Abstract = {The ESA cornerstone mission GAIA will perform astrometric
and photometric measurements on one billion objects, and is
due for launch in 2010 into L2 orbit. The key astrometric
focal plane will comprise over 180 large area CCDs with a
focal surface of about 0.5m2. The 45×60mm2 CCDs for the
focal plane will include technical features new to CCDs.
This paper will discuss the characteristics of these
devices, including the measures to improve the radiation
hardness of the technology.},
Doi = {10.1117/12.515401},
Key = {fds335146}
}
@article{fds335147,
Author = {Holland, AD and Cropper, M and Katz, D and Hutchinson, IB and Ambrosi,
RM and Stevenson, T and Smith, DR and Walton, D and Burt, D and Pool, P and Morris, D and Paulsen, T},
Title = {CCDs for the Radial Velocity Spectrometer on
GAIA},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {5251},
Pages = {253-260},
Publisher = {SPIE},
Year = {2004},
Month = {May},
url = {http://dx.doi.org/10.1117/12.517151},
Abstract = {The ESA cornerstone mission GAIA will perform astrometric,
photometric and spectroscopic measurements and is due for
launch in 2010 into L2 orbit. The astrometric telescope
system will catalogue the position of over 109 objects down
to 20th magnitude and perform broadband photometry. The
spectroscopic telescope will provide narrow-band photometry
and feed a Radial Velocity Spectrometer which will
accurately determine the radial velocities of objects down
to 17-18 magnitude. This paper discusses the characteristics
of the detectors envisaged for the focal plane of the RVS
instrument.},
Doi = {10.1117/12.517151},
Key = {fds335147}
}
@article{04198155680,
Author = {Starr, AF and Rye, PM and Mock, JJ and Smith, DR},
Title = {Angle resolved microwave spectrometer for metamaterial
studies},
Journal = {Review of Scientific Instruments},
Volume = {75},
Number = {4},
Pages = {820-825},
Year = {2004},
Month = {April},
url = {http://dx.doi.org/10.1063/1.1669119},
Keywords = {Electromagnetic wave scattering;Electromagnetic wave
polarization;Optimization;Scanning;Refraction;},
Abstract = {The angle resolved microwave spectrometer (ARMS) provides
highly reproductible automated data acquisition of microwave
refraction from positive and negative refracting samples.
The flexibility of the instrument allows many types of
metamaterial experiments to be carried out efficiently. The
two-dimensional character of the measurement allows for easy
and cost-effective sample preparation.},
Doi = {10.1063/1.1669119},
Key = {04198155680}
}
@article{fds335148,
Author = {Holland, AD and Hutchinson, IB and Smith, DR and Pool,
P},
Title = {Proton damage in the E2V swept charge device},
Journal = {Nuclear Instruments and Methods in Physics Research, Section
A: Accelerators, Spectrometers, Detectors and Associated
Equipment},
Volume = {521},
Number = {2-3},
Pages = {393-398},
Publisher = {Elsevier BV},
Year = {2004},
Month = {April},
url = {http://dx.doi.org/10.1016/j.nima.2003.11.041},
Abstract = {The swept charge device has been developed using CCD
technology to perform photon counting X-ray spectroscopy in
the 0.5-10keV band as an alternative to silicon PIN and
drift diode detectors. The key benefits of the detector are
large area, combined with reduced electrical interconnects,
with X-ray performance obtained using modest cooling to
around -20°C. Here we test the technology for its
suitability for space use where solar protons degrade the
CTI of the detector leading to a degradation in its
resolution as a spectrometer. We report on the irradiation
experiments conducted and discuss changes in leakage current
and energy resolution in the detector. © 2003 Elsevier B.V.
All rights reserved.},
Doi = {10.1016/j.nima.2003.11.041},
Key = {fds335148}
}
@article{04208158307,
Author = {Smith, DR and Schurig, D and Mock, JJ and Kolinko, P and Rye,
P},
Title = {Partial focusing of radiation by a slab of indefinite
media},
Journal = {Applied Physics Letters},
Volume = {84},
Number = {13},
Pages = {2244-2246},
Year = {2004},
Month = {March},
ISSN = {0003-6951},
url = {http://dx.doi.org/10.1063/1.1690471},
Keywords = {Anisotropy;Permittivity;Magnetic permeability;Electromagnetic
waves;Refractive index;Geometrical optics;Electromagnetic
wave propagation;Electromagnetic wave scattering;Optical
resonators;Boundary conditions;Computer simulation;},
Abstract = {The indefinite medium slab for which the permeability
component along the z-axis of propagation was negative,
while other permeability and permittivity tensors were
positive was discussed. It was observed from simulations and
transmission experiments on the SRR lattice that the
component of the permeability perpendicular to the SRR axes
was -1 near 11.3 GHz. It was found that the permittivity of
the indefinite media was isotropic and equal to unity and
the principal elements of the permeability tensors were also
unity. It was also observed that the results of substantial
field enhancement was consistent with ray tracing and
numerical simulations which indicated that indefinite
material had the potential for lens structures.},
Doi = {10.1063/1.1690471},
Key = {04208158307}
}
@article{fds269827,
Author = {Yen, TJ and Padilla, WJ and Fang, N and Vier, DC and Smith, DR and Pendry,
JB and Basov, DN and Zhang, X},
Title = {Terahertz magnetic response from artificial
materials.},
Journal = {Science (New York, N.Y.)},
Volume = {303},
Number = {5663},
Pages = {1494-1496},
Year = {2004},
Month = {March},
url = {http://dx.doi.org/10.1126/science.1094025},
Abstract = {We show that magnetic response at terahertz frequencies can
be achieved in a planar structure composed of nonmagnetic
conductive resonant elements. The effect is realized over a
large bandwidth and can be tuned throughout the terahertz
frequency regime by scaling the dimensions of the structure.
We suggest that artificial magnetic structures, or hybrid
structures that combine natural and artificial magnetic
materials, can play a key role in terahertz
devices.},
Doi = {10.1126/science.1094025},
Key = {fds269827}
}
@article{fds331018,
Author = {Gao, S and Sambell, A and Korolkiewicz, T and Smith,
D},
Title = {Erratum: A broadband microstrip antenna: SGMEP antenna
(Microwave Opt Technol Lett (2003) 39, (175-178))},
Journal = {Microwave and Optical Technology Letters},
Volume = {40},
Number = {4},
Pages = {347},
Year = {2004},
Month = {February},
url = {http://dx.doi.org/10.1002/mop.11376},
Doi = {10.1002/mop.11376},
Key = {fds331018}
}
@article{fds331017,
Author = {Smith, D and Leach, M and Kellner, A},
Title = {Indirect holographic imaging of antennas using an
electronically synthesised "slow-wave"},
Journal = {IEEE Antennas and Propagation Society, AP-S International
Symposium (Digest)},
Volume = {1},
Pages = {703-706},
Year = {2004},
Month = {January},
url = {http://dx.doi.org/10.1109/aps.2004.1329767},
Abstract = {The use of indirect holographic techniques, where radiation
characteristics and antenna aperture fields can be obtained
from simple intensity measurements made in the near field,
has traditionally been restricted to the measurement of
large antennas with small angular spread. The following work
describes how this limitation can be overcome by
synthesising a reference wave with wave vector in excess of
the free space wave vector. This enables the radiation
characteristics and complex aperture fields of much smaller
antennas to be determined. Results are included to show how
this technique can be applied to a standard gain pyramidal
horn antenna.},
Doi = {10.1109/aps.2004.1329767},
Key = {fds331017}
}
@article{fds269575,
Author = {Gregoire, T and Smith, DR and Wacker, JG},
Title = {What precision electroweak physics says about the [Formula
Presented] little Higgs model},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {69},
Number = {11},
Publisher = {American Physical Society (APS)},
Year = {2004},
Month = {January},
ISSN = {1550-7998},
url = {http://dx.doi.org/10.1103/PhysRevD.69.115008},
Abstract = {We study precision electroweak constraints on the close
cousin of the littlest Higgs model, the [Formula Presented]
model. We identify a near-oblique limit in which the heavy
[Formula Presented] and [Formula Presented] decouple from
the light fermions, and then calculate oblique corrections,
including one-loop contributions from the extended top
sector and the two Higgs doublets. We find regions of
parameter space that give acceptably small precision
electroweak corrections and only mild fine-tuning in the
Higgs potential, and also find that the mass of the lightest
Higgs boson is relatively unconstrained by precision
electroweak data. The fermions from the extended top sector
can be as light as [Formula Presented] and the [Formula
Presented] can be as light as [Formula Presented] We include
an independent breaking scale for the [Formula Presented]
which can still have a mass as low as a few hundred GeV. ©
2004 The American Physical Society.},
Doi = {10.1103/PhysRevD.69.115008},
Key = {fds269575}
}
@article{fds269825,
Author = {Caloz, C and Lee, CJ and Smith, DR and Pendry, JB and Itoh,
T},
Title = {Existence and properties of microwave surface plasmons at
the interface between a right-handed and a left-handed
media},
Journal = {IEEE Antennas and Propagation Society, AP-S International
Symposium (Digest)},
Volume = {3},
Pages = {3151-3154},
Year = {2004},
Month = {January},
ISSN = {1522-3965},
url = {http://dx.doi.org/10.1109/aps.2004.1332047},
Abstract = {Surface plasmons (SPs) are interface waves very similar to
Zenneck waves but existing only at optical frequencies where
metals exhibit a negative permittivity. The availability of
novel structured metamaterials with tailorable
positive/negative constitutive parameters allows the
generation of SPs in the microwave range, which may lead to
novel components and antennas applications. This paper
describes SPs existing at the interface between a
right-bunded (RH) and a left-handed (LH) materials. The
dispersion relation is established, the properties of these
SPs are discussed, a transmission line (TL) LC
implementation of the RH/LH interface is proposed, and the
phenomena are demonstrated by full-wave simulation in an
effective medium approach.},
Doi = {10.1109/aps.2004.1332047},
Key = {fds269825}
}
@article{fds269828,
Author = {Marqués, R and Smith, DR},
Title = {Comment on “Electrodynamics of Metallic Photonic Crystals
and the Problem of Left-Handed Materials},
Journal = {Physical Review Letters},
Volume = {92},
Number = {5},
Pages = {1},
Year = {2004},
Month = {January},
url = {http://dx.doi.org/10.1103/PhysRevLett.92.059401},
Doi = {10.1103/PhysRevLett.92.059401},
Key = {fds269828}
}
@article{fds269829,
Author = {Pendry, JB and Smith, DR},
Title = {Reversing light with negative refraction},
Journal = {Physics Today},
Volume = {57},
Number = {6},
Pages = {37-43},
Publisher = {AIP Publishing},
Year = {2004},
Month = {January},
ISSN = {0031-9228},
url = {http://dx.doi.org/10.1063/1.1784272},
Abstract = {The phenomenon of negative refraction is studied. This new
field has generated great enthusiasm but also controversy,
yet even the controversies have had the positive effect that
key concepts have been critically scrutinized in the past 18
months. Many groups are already moving forward with
applications. Many researchers are joining this fascinating
field: 2003 saw more than 200 papers published on negative
refraction.},
Doi = {10.1063/1.1784272},
Key = {fds269829}
}
@article{fds269832,
Author = {Starr, AF and Rye, PM and Smith, DR and Nemat-Nasser,
S},
Title = {Fabrication and characterization of a negative-refractive-index
composite metamaterial},
Journal = {Physical Review B - Condensed Matter and Materials
Physics},
Volume = {70},
Number = {11},
Pages = {113102-1-113102-4},
Publisher = {American Physical Society (APS)},
Year = {2004},
Month = {January},
url = {http://dx.doi.org/10.1103/PhysRevB.70.113102},
Abstract = {We have designed, produced, and experimentally characterized
2.7 mm thick composite panels having negative refractive
index between 8.4 and 9.2 GHz. The composite metamaterial is
fabricated using conventional commercial multilayer
circuit-board lithography; three-dimensional physical (as
opposed to electromagnetic) structure is introduced by the
use of vias to form sections of the scattering elements in
the direction perpendicular to the circuit board surfaces.
From scattering parameter measurements, we show that the
complex permittivity, permeability, index, and impedance of
the composite can be unambiguously determined. The
measurements enable the quantitative determination of the
negative index band and associated losses. The extracted
material parameters are shown to be in excellent agreement
with simulation results.},
Doi = {10.1103/PhysRevB.70.113102},
Key = {fds269832}
}
@article{04328303467,
Author = {Smith, DR},
Title = {Beating the diffraction limit},
Journal = {Physics World},
Volume = {17},
Number = {5},
Pages = {23-24},
Publisher = {IOP Publishing},
Year = {2004},
Month = {January},
url = {http://dx.doi.org/10.1088/2058-7058/17/5/31},
Keywords = {Light refraction;Refractive index;Lenses;Image
reconstruction;Diffraction;Light propagation;},
Abstract = {The subject of negative-index phenomena is drawing
significant interest among researchers due to the emergence
of a new class of artificially structured materials called
metamaterials. Such materials can be engineered so that they
have a much wider range of electromagnetic responses.
Results reported to date demonstrate the negative refraction
at microwave frequencies. Furthermore, recent experiments
and theoretical work indicate that photonic crystals allow
these effects to be demonstrated at visible
wavelengths.},
Doi = {10.1088/2058-7058/17/5/31},
Key = {04328303467}
}
@article{04158106248,
Author = {Smith, DR and Rye, P and Vier, DC and Starr, AF and Mock, JJ and Perram,
T},
Title = {Design and Measurement of Anisotropic Metamaterials that
Exhibit Negative Refraction},
Journal = {IEICE Transactions on Electronics},
Volume = {E87-C},
Number = {3},
Pages = {359-370},
Year = {2004},
Month = {January},
Keywords = {Anisotropy;Refractive index;Electromagnetic
waves;Semiconductor lasers;Crystals;Electromagnetic wave
propagation;Optical waveguides;Permittivity;Damping;Scattering;Electromagnetic
wave reflection;Computer simulation;},
Abstract = {Artificial electromagnetic structures have significantly
broadened the range of wave propagation phenomena available.
In particular, it has been shown that metamaterials can be
constructed for which the index-of-refraction is negative
over a finite band of frequencies. In this paper, we present
the design, fabrication and characterization of a
metamaterial that exhibits negative refraction. The
metamaterial design we explore is an Isotropic in the plane
of propagation. Based on our analysis and supporting
simulations and measurements, we demonstrate that for the
geometry considered, the anisotropic metamaterial has the
identical negative refraction properties as would an
isotropic negative index metamaterial.},
Key = {04158106248}
}
@article{04518729664,
Author = {Smith, DR and Kolinko, P and Schurig, D},
Title = {Negative refraction in indefinite media},
Journal = {Journal of the Optical Society of America B: Optical
Physics},
Volume = {21},
Number = {5},
Pages = {1032-1043},
Publisher = {The Optical Society},
Year = {2004},
Month = {January},
ISSN = {0740-3224},
url = {http://dx.doi.org/10.1364/JOSAB.21.001032},
Keywords = {Refractive index;Permittivity;Mechanical permeability;Light
refraction;Light reflection;Anisotropy;Interfaces
(materials);Vacuum applications;Electromagnetic
dispersion;Finite element method;Computer
simulation;},
Abstract = {Initial experiments on wedge samples composed of isotropic
metamaterials with simultaneously negative permittivity and
permeability have indicated that electromagnetic radiation
can be negatively refracted. In more recently reported
experiments [Phys. Rev. Lett. 90, 1074011 (2003)],
indefinite metamaterial samples, for which the permittivity
and permeability tensors are negative along only certain of
the principal axes of the metamaterial, have also been used
to demonstrate negative refraction. We present here a
detailed analysis of the refraction and reflection behavior
of electromagnetic waves at an interface between an
indefinite medium and vacuum. We conclude that certain
classes of indefinite media have identical refractive
properties as isotropic negative index materials. However,
there are limits to this correspondence, and other
complicating phenomena may occur when indefinite media are
substituted for isotropic negative index materials. We
illustrate the results of our analysis with
finite-element-based numerical simulations on planar slabs
and wedges of negative index and indefinite media. © 2004
Optical Society of America.},
Doi = {10.1364/JOSAB.21.001032},
Key = {04518729664}
}
@article{fds330366,
Author = {Koschny, T and Markoš, P and Smith, DR and Soukoulis,
CM},
Title = {Reply to Comments on “Resonant and antiresonant frequency
dependence of the effective parameters of
metamaterials”},
Journal = {Physical Review E - Statistical Physics, Plasmas, Fluids,
and Related Interdisciplinary Topics},
Volume = {70},
Number = {4},
Pages = {1},
Publisher = {American Physical Society (APS)},
Year = {2004},
Month = {January},
url = {http://dx.doi.org/10.1103/PhysRevE.70.048603},
Abstract = {We argue, in agreement with our previous work, that
periodicity of the metamaterial is responsible for
antiresonant behavior of the effective permittivity as well
as for the negative sign of the imaginary part of an
effective permittivity or permeability. This agrees with the
Comment of Efros. © 2004 The American Physical
Society.},
Doi = {10.1103/PhysRevE.70.048603},
Key = {fds330366}
}
@article{fds331019,
Author = {Smith, D and Leach, M},
Title = {3D imaging of antenna fields and metal objects using a new
indirect holographic method},
Journal = {ICEAA 2003 - International Conference on Electromagnetics in
Advanced Applications},
Pages = {711-714},
Year = {2003},
Month = {December},
ISBN = {9788882020095},
Abstract = {This work describes a new technique for producing indirect
holographic intensity patterns from which antenna far field
radiation patterns can be obtained and images of antenna
fields can be reconstructed. It also describes how this
technique can be extended to the 3D imaging of passive metal
objects.},
Key = {fds331019}
}
@article{fds269672,
Author = {Mock, JJ and Smith, DR and Barbic, M and Oldenburg, SJ and Schultz, DA and Schultz, S},
Title = {Spectroscopic studies of individual plasmon resonant
nanoparticles},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {5221},
Pages = {66-75},
Publisher = {SPIE},
Year = {2003},
Month = {December},
url = {http://dx.doi.org/10.1117/12.506523},
Abstract = {We present a detailed description of the apparatus and
techniques that we have utilized in our experimental study
of individual plasmon resonant nanoparticles, along with a
brief description of some major results. The apparatus
consists of a spectroscopic system combined with a modified
darkfield microscope, which enables the user to sequentially
select individual resonant nanostructures in the microscopic
field of view for spectroscopic study. Plasmon resonant
nanostructures scatter light elastically, and typically have
very large scattering cross-sections at their resonant
optical wavelengths. In general, spectra can be obtained
with acquisition times between. 1 to 30 seconds, and color
images can be captured using consumer digital color cameras.
Spheres, tetrahedrons, and pentagonal platelets were
fabricated using colloidal chemistry techniques. To produce
highly anisotropic structures such as nanorods and
"barbells", templates were used. Many of these
nanostructures have been individually spectroscopically
characterized, and their spectra correlated with their shape
and size as determined by transmission electron microscope
(TEM). The unique shape, size, composition, and dielectric
surroundings of the individual plasmon resonant
nanostructures determine their plasmon resonant behavior. We
will show how the composition of the substrate on which the
particles are immobilized and the dielectric of the
surrounding medium have a significant effect on the plasmon
resonance of the individual particles.},
Doi = {10.1117/12.506523},
Key = {fds269672}
}
@article{fds269673,
Author = {Su, KH and Wei, QH and Zhang, X and Mock, JJ and Smith, DR and Schultz,
S},
Title = {Optical Properties of Coupled Nano Gold Particles},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {5221},
Pages = {108-115},
Publisher = {SPIE},
Year = {2003},
Month = {December},
ISSN = {0277-786X},
url = {http://dx.doi.org/10.1117/12.506371},
Abstract = {Nano gold particles interact strongly with visible light to
excite the collaborative oscillation of conductive electrons
within nano particles resulting in a surface plasmon
resonance which makes them useful for various applications
including bio-labeling. In this paper, we study the effect
of particle sizes with particle plasmon resonant wavelength
and the coupling between pair of elliptical metallic disks
and ellipsoid particles by simulations and experiments. The
red-shift resonant peak wavelength of coupled particles to
that of single particle is due to particle plasmons
near-field coupling. The shift decays is approximately
exponentially with increasing particle spacing, and reaches
zero when the gap between the two particles exceeds about
2.5 times the particle short axis length. It is also found
that the exponential decay of peak shift with particle gap
is size independent but shape dependent.},
Doi = {10.1117/12.506371},
Key = {fds269673}
}
@article{fds269824,
Author = {Koschny, T and Markoš, P and Smith, DR and Soukoulis,
CM},
Title = {Resonant and antiresonant frequency dependence of the
effective parameters of metamaterials},
Journal = {Physical Review E - Statistical, Nonlinear, and Soft Matter
Physics},
Volume = {68},
Number = {6 2},
Pages = {656021-656024},
Year = {2003},
Month = {December},
ISSN = {1063-651X},
url = {http://dx.doi.org/10.1103/PhysRevE.68.065602},
Abstract = {The numerical analysis of the electromagnetic response of
two metamaterials which include an array of split ring
resonators (SRR) and an array of thin metallic cut wires was
presented. It was found that the effective parameters of
these systems exhibit resonant and antiresonant behavior
similar to that found in the double-negative metamaterials.
The antiresonant behavior of the thin wires was due to the
refractive index possessing finite spatial periodicity. The
results show that the observed seemingly unphysical behavior
of effective material parameters is an intrinsic property of
composites.},
Doi = {10.1103/PhysRevE.68.065602},
Key = {fds269824}
}
@article{fds331020,
Author = {Gao, S and Sambell, A and Korolkiewicz, T and Smith,
D},
Title = {A broadband microstrip antenna: SGMFP antenna},
Journal = {Microwave and Optical Technology Letters},
Volume = {39},
Number = {3},
Pages = {175-178},
Publisher = {WILEY},
Year = {2003},
Month = {November},
url = {http://dx.doi.org/10.1002/mop.11161},
Abstract = {A novel structure of broadband microstrip antennas, termed
the SGMFP antenna, is proposed. It is consisted of a slot in
the ground plane, a microstrip feedline supported on a
substrate, a foam layer, and a patch. It can achieve broad
bandwidth and high polarisation purity. By using a single
patch, two design examples are provided, which achieves a
bandwidth (S11 < - 10 dB) of 23.7% and 20.3%,
respectively.},
Doi = {10.1002/mop.11161},
Key = {fds331020}
}
@article{fds335150,
Author = {Smith, DR and Holland, AD and Robbins, MS},
Title = {The effect of protons on E2V Technologies L3Vision
CCDs},
Journal = {Nuclear Instruments and Methods in Physics Research, Section
A: Accelerators, Spectrometers, Detectors and Associated
Equipment},
Volume = {513},
Number = {1-2 SPEC. ISS.},
Pages = {296-299},
Publisher = {Elsevier BV},
Year = {2003},
Month = {November},
url = {http://dx.doi.org/10.1016/j.nima.2003.08.051},
Abstract = {The effect of different 10 MeV equivalent proton fluences on
the performance of E2V Technologies (formerly Marconi
applied technologies, formerly EEV) L3Vision Charge Coupled
Devices (CCDs) was investigated. The first experimental
radiation damage results of the L3Vision device are
presented, with emphasis given to the analysis of damage to
the gain register of the device. Changes in dark current and
generation of bright pixels in the CCD image, store, readout
register and gain register as a result of proton irradiation
are reported and viewed in light of the potential use of the
device in space-based applications. © 2003 Elsevier B.V.
All rights reserved.},
Doi = {10.1016/j.nima.2003.08.051},
Key = {fds335150}
}
@article{fds331021,
Author = {Smith, D and Leach, M and Sambell, AJ},
Title = {Microwave indirect holographic imaging using an adaptation
of optical techniques},
Journal = {IEEE Microwave and Wireless Components Letters},
Volume = {13},
Number = {9},
Pages = {379-381},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2003},
Month = {September},
url = {http://dx.doi.org/10.1109/LMWC.2003.817134},
Abstract = {Indirect holography provides a quick and inexpensive
three-dimensional (3-D) imaging technique at optical
frequencies which has not been directly adapted to microwave
imaging. This letter describes a technique whereby a
radiated offset reference plane wave can be electronically
synthesized allowing this technique to be used at microwave
frequencies. In this letter, this technique has been applied
to the problem of determining antenna radiation patterns and
reconstructing complex near fields. Early experimental
results compare favorably with results taken using
traditional methods.},
Doi = {10.1109/LMWC.2003.817134},
Key = {fds331021}
}
@article{fds269823,
Author = {Su, KH and Wei, QH and Zhang, X and Mock, JJ and Smith, DR and Schultz,
S},
Title = {Interparticle coupling effects on plasmon resonances of
nanogold particles},
Journal = {Nano Letters},
Volume = {3},
Number = {8},
Pages = {1087-1090},
Publisher = {American Chemical Society (ACS)},
Year = {2003},
Month = {August},
url = {http://dx.doi.org/10.1021/nl034197f},
Abstract = {The collaborative oscillation of conductive electrons in
metal nanoparticles results in a surface plasmon resonance
that makes them useful for various applications including
biolabeling. We investigate the coupling between pairs of
elliptical metal particles by simulations and experiments.
The results demonstrate that the resonant wavelength peak of
two interacting particles is red-shifted from that of a
single particle because of near-field coupling. It is also
found that the shift decays approximately exponentially with
increasing particle spacing and become negligible when the
gap between the two particles exceeds about 2.5 times the
particle short-axis length.},
Doi = {10.1021/nl034197f},
Key = {fds269823}
}
@article{fds269822,
Author = {Wu, D and Fang, N and Sun, C and Zhang, X and Padilla, WJ and Basov, DN and Smith, DR and Schultz, S},
Title = {Terahertz plasmonic high pass filter},
Journal = {Applied Physics Letters},
Volume = {83},
Number = {1},
Pages = {201-203},
Publisher = {AIP Publishing},
Year = {2003},
Month = {July},
url = {http://dx.doi.org/10.1063/1.1591083},
Abstract = {Terahertz plasmonic high pass filter was studied. The sharp
change of reflection and transmission of electromagnetic
waves at plasma frequency made the structure a high pass
filter. Fourier transform infrared spectroscopy was used to
characterize the reflection response, and a plasma frequency
at 0.7 THz was observed.},
Doi = {10.1063/1.1591083},
Key = {fds269822}
}
@article{fds335151,
Author = {Ambrosi, RM and Smith, DR and Abbey, AF and Hutchinson, IB and Kendziorra, E and Short, A and Holland, A and Turner, MJL and Wells,
A},
Title = {The impact of low energy proton damage on the operational
characteristics of EPIC-MOS CCDs},
Journal = {Nuclear Instruments and Methods in Physics Research, Section
B: Beam Interactions with Materials and Atoms},
Volume = {207},
Number = {2},
Pages = {175-185},
Publisher = {Elsevier BV},
Year = {2003},
Month = {June},
url = {http://dx.doi.org/10.1016/S0168-583X(03)00832-2},
Abstract = {The University of Tübingen 3.5 MeV Van de Graaff
accelerator facility was used to investigate the effect of
low-energy protons on the performance of the European Photon
Imaging Camera, metal-oxide-semiconductor, charge-coupled
devices (CCDs). Two CCDs were irradiated in different parts
of their detecting areas using different proton spectra and
dose rates. Iron-55 was the calibration source in all cases
and was used to measure any increases in charge transfer
inefficiency (CTI) and spectral resolution of the CCDs.
Additional changes in the CCD bright pixel table and changes
in the low X-ray energy response of the device were
examined. The Monte Carlo code Stopping Range of Ions in
Matter was used to model the effect of a 10 MeV equivalent
fluence of protons interacting with the CCD. Since the
non-ionising energy loss function could not be applied
effectively at such low proton energies. From the 10 MeV
values, the expected CTI degradation could be calculated and
then compared to the measured CTI changes. © 2003 Elsevier
Science B.V. All rights reserved.},
Doi = {10.1016/S0168-583X(03)00832-2},
Key = {fds335151}
}
@article{7583055,
Author = {Schurig, D and Smith, DR},
Title = {Spatial filtering using media with indefinite permittivity
and permeability tensors},
Journal = {Applied Physics Letters},
Volume = {82},
Number = {14},
Pages = {2215-2217},
Year = {2003},
Month = {April},
url = {http://dx.doi.org/10.1063/1.1562344},
Keywords = {band-pass filters;high-pass filters;low-pass
filters;magnetic permeability;permittivity;spatial
filters;},
Abstract = {The construction of bandpass spatial, low pass and high pass
filters was discussed. Bilayers of media with indefinite
permittivity and permeability tensors were used for the
construction. The filters formed had sharp adjustable
roll-offs and could operate both below and above free space
cutoff to select beam angles or spatial variation components
from an image or source.},
Doi = {10.1063/1.1562344},
Key = {7583055}
}
@article{fds335152,
Author = {Smith, DR and Ambrosi, RM and Holland, AD and Hutchinson, IE and Wells,
A},
Title = {The prompt particle background and micrometeoroid
environment at L2 and its implications for
Eddington},
Journal = {European Space Agency, (Special Publication) ESA
SP},
Number = {538},
Pages = {417-420},
Year = {2003},
Month = {April},
Abstract = {The Eddington spacecraft will orbit the Sun at the L2 point
during its 5 year asteroseismology and planet finding
mission. The successful detection of objects of interest and
the amount and accuracy of the data that is recorded will
depend on the prompt particle background interacting with
the detectors in the focal plane of the instrument. The
sources of the particle background are both solar and
galactic. Eddington will be operational during the next
period of solar maximum and therefore consideration of the
particle environment is important in deducing the shielding
requirement for the Eddington CCD detectors and the impact
the environment will have on the collected science. This
paper presents measured spacecraft data and predictions of
the flux and energy of the particle environment at L2. An
understanding of the micrometeoroid environment at L2 is
also critical to the Eddington mission. The impact of
micrometeoroids on the Eddington focal plane has the
potential of causing catastrophic failure of one or several
detectors resulting in a large reduction in the data
obtained. A review of the dust particle background and the
stability of dust accumulated around the L2 point is also
presented and is the subject of further study.},
Key = {fds335152}
}
@article{7694827,
Author = {Mock, JJ and Smith, DR and Schultz, S},
Title = {Local refractive index dependence of plasmon resonance
spectra from individual nanoparticles},
Journal = {Nano Letters},
Volume = {3},
Number = {4},
Pages = {485-491},
Publisher = {American Chemical Society (ACS)},
Year = {2003},
Month = {April},
ISSN = {1530-6984},
url = {http://dx.doi.org/10.1021/nl0340475},
Keywords = {nanoparticles;optical microscopy;red shift;refractive
index;silver;surface plasmon resonance;},
Abstract = {We present an experimental optical darkfield microscope
study of the dependence of the plasmon resonance spectrum of
individual silver nanoparticles on the local index of
refraction. We systematically characterize the position of
the resonance peaks associated with the same set of
individual silver nanoparticles embedded sequentially in
index oils with increasing refractive index. This technique
effectively allows the local refractive index to be stepped
in increments of 0.04. As the local index is increased, the
spectrum from each of the nanoparticles generally undergoes
a very regular and reproducible red shift; however, we find
that the amount of red shift per index increase varies
depending on the shape of the nanoparticle and the mode of
excitation. In particular, we find that the spectral peak
that occurs in triangular nanoparticles exhibits a
noticeably larger red shift than that associated with the
dipole mode corresponding to spherical nanoparticles. Our
results are consistent with experiments performed on
ensembles of similar nanoparticles and suggest that
individual nanoparticles may be utilized in biosensing
applications where currently ensembles are being
investigated.},
Doi = {10.1021/nl0340475},
Key = {7694827}
}
@article{03157430058,
Author = {Smith, DR and Schurig, D and Rosenbluth, M and Schultz, S and Ramakrishna, SA and Pendry, JB},
Title = {Limitations on subdiffraction imaging with a negative
refractive index slab},
Journal = {Applied Physics Letters},
Volume = {82},
Number = {10},
Pages = {1506-1508},
Year = {2003},
Month = {March},
url = {http://dx.doi.org/10.1063/1.1554779},
Keywords = {Imaging techniques;Refractive index;Electromagnetic wave
diffraction;Optical materials;Surface plasmon
resonance;Electromagnetic wave propagation;Fourier
optics;Finite difference method;Computational
geometry;Computer simulation;},
Abstract = {Limitations on subdiffraction imaging with a negative
refractive index slab was studied. The planar geometry
allowed a straight forward analysis to be implemented. The
fields from an arbitray electromagnetic source were expanded
in a Fourier series over homogeneous and inhomogeneous plane
waves. The sensitivity of subwavelength focus to the slab
material properties, periodicity and its connection to slab
surface plasmon modes were studied. It was concluded that
significant subwavelength resollution was achievable with a
single negative index slab, only over a restrictive range of
parameters.},
Doi = {10.1063/1.1554779},
Key = {03157430058}
}
@article{fds269541,
Author = {Starr, A and Nemat-Nasser, S and Smith, DR and Plaisted,
TA},
Title = {Integrated sensing in structural composites},
Journal = {Structural Health Monitoring 2003: From Diagnostics and
Prognostics to Structural Health Management - Proceedings of
the 4th International Workshop on Structural Health
Monitoring, IWSHM 2003},
Pages = {879-886},
Year = {2003},
Month = {January},
ISBN = {9781932078206},
Abstract = {Increasing demand for monitoring of in-service structures is
driving technology in new directions. Advances in many
related technologies, including novel sensor design and
implementation, have created new opportunities in structural
health monitoring. We present efforts to develop structural
composite materials that employ networks of embedded
transducers to extend the functionality of the composite
beyond that of load bearing. The capability to acquire,
process, and if necessary respond to structural or other
types of information represents the next generation of
structural systems. Sensorized composite materials bring
together many disparate yet fundamentally important
developments that have occurred over the last few years in
several areas: developments in composites and the emergence
of multifunctional composites, the emergence of a broad
range of new sensors, smaller and lower power
microelectronics with increased and multiple integrated
functionality, and the emergence of device level single-wire
long haul communications protocols. Information-aware
composite structures are now feasible due to the recent
advances in these fields, although the integration of these
technologies remains a challenge. In this work, we summarize
our efforts to integrate and embed connectorized
microelectronic components within fiber/conductor braided
bundles to minimize their impact as composite crack
initiation centers. The resulting bundles have mm size
diameters, and are suitable for inclusion in woven composite
fabrics or directly in the composite lay-up. The low-power
electronic devices operate on a multi-drop network with a
single wire providing power and communications. A
computer-network interface is provided by multiple channel
external electronic driver circuitries. Future directions
include implementing in-network local processing, a greater
range of sensors, adding in-situ power generation, and
optimizing the composite processing techniques.},
Key = {fds269541}
}
@article{fds269542,
Author = {Su, KH and Wei, QH and Zhang, X and Mock, JJ and Smith, DR and Schultz,
S},
Title = {Surface plasmon coupling between two nano Au
particles},
Journal = {Proceedings of the IEEE Conference on Nanotechnology},
Volume = {1},
Pages = {279-282},
Publisher = {IEEE},
Year = {2003},
Month = {January},
ISBN = {0780379764},
ISSN = {1944-9399},
url = {http://dx.doi.org/10.1109/NANO.2003.1231772},
Abstract = {Nano metal particles which interact strongly with visible
light make themselves useful for molecular detection and
biosensing. To facilitate the useful application for these
nano particles, it is important to design and fabricate the
particles at a desired frequency. In this paper, we present
our experimental and computer simulation studies on the
plasmon resonance of single nano Au particles and nano Au
particle pairs in close proximity. The results show that the
resonant wavelength peak of two particle plasmons is
red-shifted in comparison to that of a single particle and
the shift decays approximately exponentially with particle
spacing, and drops to zero when the gap between two
particles exceeds about 2.5 times the particle short axis
length. It is also found that the decay function of the
resonant wavelength shift is size-independent.},
Doi = {10.1109/NANO.2003.1231772},
Key = {fds269542}
}
@article{fds331022,
Author = {Smith, D and Leach, M},
Title = {3D imaging of antenna fields from electronically synthesised
scalar intensity patterns},
Journal = {2003 Asia-Pacific Conference on Applied Electromagnetics,
APACE 2003 - Proceedings},
Pages = {50-53},
Publisher = {IEEE},
Year = {2003},
Month = {January},
ISBN = {9780780381292},
url = {http://dx.doi.org/10.1109/APACE.2003.1234466},
Abstract = {This work describes a new technique for the determination of
antenna far field radiation patterns and the imaging of
antenna fields from holographic intensity patterns. These
intensity patterns are obtained by combining the sampled
antenna near field with an electronically synthesised offset
reference plane wave. The resultant intensity pattern can be
recorded in a fast and inexpensive manner. This work also
indicates that true 3D images can be reconstructed from the
measured 2D intensity patterns.},
Doi = {10.1109/APACE.2003.1234466},
Key = {fds331022}
}
@article{fds331023,
Author = {Smith, D and Leach, M and Dlay, SS and Woo, WL},
Title = {A novel technique for the determination of the radiation
patterns of medium gain antennas from scalar intensity
measurements},
Journal = {ISAPE 2003 - 2003 6th International Symposium on Antennas,
Propagation and EM Theory, Proceedings},
Pages = {373-376},
Publisher = {IEEE},
Year = {2003},
Month = {January},
ISBN = {9780780378315},
url = {http://dx.doi.org/10.1109/ISAPE.2003.1276705},
Abstract = {Holographic techniques have proved useful -for the
determination of antenna radiation patterns and imaging
antenna fields. Traditionally this has been achieved mainly
by the direct measurement of complex near fields of the
antenna over a measurement plane located close to the
antenna under test.[l] This is a slow and expensive process
requiring equipment capable of determining both amplitude
and phase of the sampled antenna near field. An alternative
approach has been to use an indirect technique, as often
employed at optical frequencies, and record the scalar
intensity pattern produced by the interference of the
antenna near field and a radiated phase coherent reference
wave [2], A limitation of this technique is the requirement
that the antenna must have a radiation pattern of small
angular extent, restricting this method to the measurement
of high gain antennas. This work describes the further
development of a recently reported technique whereby an
intensity pattern is formed using an electronically derived
reference signal. [3] A significant advantage of this
technique is that it allows an unlimited phase difference to
be applied to adjacent samples. This overcomes the practical
limitation imposed using a radiated reference signal and
enables the radiation patterns of medium gain antennas to be
determined.},
Doi = {10.1109/ISAPE.2003.1276705},
Key = {fds331023}
}
@article{fds269645,
Author = {Smith, D and Weiner, N},
Title = {Inelastic dark matter at DAMA, CDMS and future
experiments},
Journal = {Nuclear Physics B - Proceedings Supplements},
Volume = {124},
Pages = {197-200},
Publisher = {Elsevier BV},
Year = {2003},
Month = {January},
url = {http://dx.doi.org/10.1016/S0920-5632(03)02105-4},
Abstract = {The DAMA annual modulation signature, interpreted as
evidence for a spin-independent WIMP coupling, seems in
conflict with null results from CDMS. However, in models of
"inelastic dark matter", the experiments are compatible.
Inelastic dark matter can arise in supersymmetric theories
as the real component of a sneutrino mixed with a singlet
scalar. In contrast with ordinary sneutrino dark matter,
such particles can satisfy all experimental constraints
while giving the appropriate relic abundance. We discuss the
modifications to the signal seen at DAMA, in particular
noting the strong suppression of low energy events in both
modulated and unmodulated components. We discuss future
experiments, with emphasis on distinguishing inelastic dark
matter from ordinary dark matter, and stressing the
significance of experiments with heavy target nuclei, such
as xenon and tungsten.},
Doi = {10.1016/S0920-5632(03)02105-4},
Key = {fds269645}
}
@article{fds269671,
Author = {Wu, D and Fang, N and Sun, C and Zhang, X and Padilla, WJ and Basov, DN and Smith, DR and Schultz, S},
Title = {Artificial plasmonic metamaterial fabricated by
micro-stereolithography},
Journal = {American Society of Mechanical Engineers,
Micro-Electromechanical Systems Division Publication
(MEMS)},
Volume = {5},
Pages = {89-91},
Year = {2003},
Month = {January},
url = {http://dx.doi.org/10.1115/imece2003-41569},
Abstract = {Micro-structured materials, which contain engineered
sub-wavelength components, can be designed to have positive
or negative ε and μ at desired frequency. In this paper,
we demonstrate a high pass Terahertz (THz) filter which
utilizes the lowered plasma frequency of thin metal wire
structures. This high pass filter may have applications in
the THz imaging systems. The filter is formed by
two-dimensional cubic lattice of thin metal wires. The
diameter of the wire is 30 μm, the lattice constant is 120
μm, and the length of the wire is 1mm. Micro-stereolithography
technique is applied to fabricate this high aspect ratio
cylinders. The reflection property of the filter is
characterized by Fourier transform infrared (FTIR)
spectroscopy, and a plasma frequency at 0.7 THz is observed,
which agrees with the approximate theory.},
Doi = {10.1115/imece2003-41569},
Key = {fds269671}
}
@article{fds269674,
Author = {Pendry, JB and Smith, DR},
Title = {Comment on “Wave Refraction in Negative-Index Media:
Always Positive and Very Inhomogeneous},
Journal = {Physical Review Letters},
Volume = {90},
Number = {2},
Pages = {029703/1-029704/1},
Year = {2003},
Month = {January},
url = {http://dx.doi.org/10.1103/PhysRevLett.90.029703},
Abstract = {A Comment on the Letter by P.M. Valanju, R.M. Walser,
andA.P. Valanju, Phys. Rev. Lett. 88, 187401 (2002). The
authors of the Letter offer a Reply. © 2003 The American
Physical Society.},
Doi = {10.1103/PhysRevLett.90.029703},
Key = {fds269674}
}
@article{fds269819,
Author = {Goldberger, WD and Nomura, Y and Smith, DR},
Title = {Warped supersymmetric grand unification},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {67},
Number = {7},
Publisher = {American Physical Society (APS)},
Year = {2003},
Month = {January},
ISSN = {0556-2821},
url = {http://dx.doi.org/10.1103/PhysRevD.67.075021},
Abstract = {We construct a realistic theory of grand unification in
[Formula Presented] truncated by branes, in which the
unified gauge symmetry is broken by boundary conditions and
the electroweak scale is generated by the AdS warp factor.
We show that the theory preserves the successful gauge
coupling unification of the 4D MSSM at the
leading-logarithmic level. Kaluza-Klein (KK) towers,
including those of the XY gauge and colored Higgs
multiplets, appear at the TeV scale, while the extra
dimension provides natural mechanisms for doublet-triplet
splitting and proton decay suppression. In one possible
scenario supersymmetry is strongly broken on the TeV brane,
in which case the lightest [Formula Presented] gauginos are
approximately Dirac and the mass of the lightest XY gaugino
is pushed well below that of the lowest gauge boson KK mode,
improving the prospects for its production at the CERN LHC.
The bulk Lagrangian possesses a symmetry that we call GUT
parity. If GUT parity is exact, the lightest GUT particle,
most likely an XY gaugino, is stable. Once produced in a
collider, the XY gaugino hadronizes to form mesons, some of
which will be charged and visible as highly ionizing tracks.
The lightest supersymmetric particle is the gravitino of
mass [Formula Presented] which is also stable if R parity is
conserved. © 2003 The American Physical
Society.},
Doi = {10.1103/PhysRevD.67.075021},
Key = {fds269819}
}
@article{fds269821,
Author = {Nomura, Y and Smith, DR},
Title = {Spectrum of TeV particles in warped supersymmetric grand
unification},
Journal = {Physical Review D},
Volume = {68},
Number = {7},
Publisher = {American Physical Society (APS)},
Year = {2003},
Month = {January},
ISSN = {0556-2821},
url = {http://dx.doi.org/10.1103/PhysRevD.68.075003},
Abstract = {In warped supersymmetric grand unification, XY gauge
particles appear near the TeV scale along with Kaluza-Klein
towers of the standard model gauge fields. In spite of this
exotic low-energy physics, the successful gauge coupling
unification prediction of the minimal supersymmetric
standard model (MSSM) is preserved and proton decay is
naturally suppressed. In this paper we study in detail the
low-lying mass spectrum of superparticles and grand unified
particles in this theory, taking supersymmetry breaking to
be localized to the TeV brane. The masses of the MSSM
particles, Kaluza-Klein modes, and XY states are all
determined by two parameters, one that fixes the strength of
the supersymmetry breaking and the other that sets the scale
of the infrared brane. A particularly interesting result is
that for relatively strong supersymmetry breaking, the XY
gauginos and the lowest Kaluza-Klein excitations of the MSSM
gauginos may both lie within reach of the CERN Large Hadron
Collider, providing the possibility that the underlying
unified gauge symmetry and the enhanced N=2 supersymmetry of
the theory will both be revealed. © 2003 The American
Physical Society.},
Doi = {10.1103/PhysRevD.68.075003},
Key = {fds269821}
}
@article{04278253472,
Author = {Kolinko, P and Smith, DR},
Title = {Numerical study of electromagnetic waves interacting with
negative index materials},
Journal = {Optics Express},
Volume = {11},
Number = {7},
Pages = {640-648},
Publisher = {The Optical Society},
Year = {2003},
Month = {January},
ISSN = {1094-4087},
url = {http://dx.doi.org/10.1364/OE.11.000640},
Keywords = {Light scattering;Permittivity;Prisms;Refractive
index;Parameter estimation;Waveguides;Polarization;Lighting;Maxwell
equations;Approximation theory;Computational
methods;Computer simulation;},
Abstract = {We study numerically the electromagnetic scattering
properties of structures with negative indices of
refraction. To perform this analysis, we utilize a
commercial finite-element based electromagnetic solver
(HFSS, Ansoft), in which a negative index material can be
formed from mesh elements whose permittivity and
permeability are both negative. In particular, we
investigate the expected transmission characteristics of a
finite beam incident on negative index prisms and lenses. We
also confirm numerically the predicted superlens effect of
an image formed by a planar slab with index n=-1, using two
subwavelength (λ/20) slits as objects. © 2003 Optical
Society of America.},
Doi = {10.1364/OE.11.000640},
Key = {04278253472}
}
@article{7580297,
Author = {Smith, DR and Schurig, D},
Title = {Electromagnetic Wave Propagation in Media with Indefinite
Permittivity and Permeability Tensors},
Journal = {Physical Review Letters},
Volume = {90},
Number = {7},
Pages = {4},
Publisher = {American Physical Society (APS)},
Year = {2003},
Month = {January},
url = {http://dx.doi.org/10.1103/PhysRevLett.90.077405},
Keywords = {anisotropic media;electromagnetic wave propagation;electromagnetic
wave reflection;focusing;inhomogeneous media;refractive
index;},
Abstract = {We study the behavior of wave propagation in materials for
which not all of the principal elements of the permeability
and permittivity tensors have the same sign. We find that a
wide variety of effects can be realized in such media,
including negative refraction, near-field focusing, and high
impedance surface reflection. In particular, a bilayer of
these materials can transfer a field distribution from one
side to the other, including near fields, without requiring
internal exponentially growing waves. © 2003 The American
Physical Society.},
Doi = {10.1103/PhysRevLett.90.077405},
Key = {7580297}
}
@article{03227488267,
Author = {Smith, DR},
Title = {The reality of negative refraction},
Journal = {Physics World},
Volume = {16},
Number = {5},
Pages = {23-24},
Publisher = {IOP Publishing},
Year = {2003},
Month = {January},
url = {http://dx.doi.org/10.1088/2058-7058/16/5/29},
Keywords = {Microwaves;Interfaces (materials);Refractive
index;Diffraction;Polytetrafluoroethylenes;},
Abstract = {Recent experiments that demonstrated the negative refraction
of light were presented. The refraction at the interface
between a positive-index material and a negative index
material teared the wave apart, leaving no single negatively
refracted wave. The researchers used a positive-index Teflon
wedge as a control sample, which caused the path of a
microwave beam to exit the sample at a positive
angle.},
Doi = {10.1088/2058-7058/16/5/29},
Key = {03227488267}
}
@article{fds335149,
Author = {Koschny, T and Markoš, P and Smith, DR and Soukoulis,
CM},
Title = {Resonant and antiresonant frequency dependence of the
effective parameters of metamaterials},
Journal = {Physical Review E - Statistical Physics, Plasmas, Fluids,
and Related Interdisciplinary Topics},
Volume = {68},
Number = {6},
Publisher = {American Physical Society (APS)},
Year = {2003},
Month = {January},
url = {http://dx.doi.org/10.1103/PhysRevE.68.065602},
Abstract = {We present a numerical study of the electromagnetic response
of the metamaterial elements that are used to construct
materials with negative refractive index. For an array of
split ring resonators (SRR) we find that the resonant
behavior of the effective magnetic permeability is
accompanied by an antiresonant behavior of the effective
permittivity. In addition, the imaginary parts of the
effective permittivity and permeability are opposite in
sign. We also observe an identical resonant versus
antiresonant frequency dependence of the effective materials
parameters for a periodic array of thin metallic wires with
cuts placed periodically along the length of the wire, with
roles of the permittivity and permeability reversed from the
SRR case. We show in a simple manner that the finite unit
cell size is responsible for the antiresonant behavior. ©
2003 The American Physical Society.},
Doi = {10.1103/PhysRevE.68.065602},
Key = {fds335149}
}
@article{fds345913,
Author = {Smith, DR},
Title = {‘Voyager’: An educational card game},
Journal = {Physics Education},
Volume = {38},
Number = {1},
Pages = {47-51},
Year = {2003},
Month = {January},
url = {http://dx.doi.org/10.1088/0031-9120/38/1/308},
Abstract = {�‘Voyager’ is an educational card game involving
scientific satellites, developed for use in schools with
children aged 9 to 13 years. The idea of the game is to
improve pupils’ knowledge about the large number of
scientific satellites there are in space in a fun way, while
also practising numeracy skills. Several copies of the game
were produced using funding obtained from the Particle
Physics and Astronomy Research Council (PPARC) as a Public
Understanding of Science (PUS) award. These initial
‘trial’ versions of the game were taken to three
different schools where feedback obtained from both pupils
and staff was used to produce a final copy of the game that
can be distributed to other schools along with a set of
companion notes to form the basis of a science lesson. This
article reports the findings of the school trials and
indicates possible future developments of other scientific
card games that could be beneficial to the classroom. ©
2003 IOP Publishing Ltd.},
Doi = {10.1088/0031-9120/38/1/308},
Key = {fds345913}
}
@article{fds335153,
Author = {Abbey, AF and Ambrosi, RM and Smith, DR and Kendziorra, E and Hutchinson, I and Short, A and Bennie, P and Holland, A and Clauss, T and Kuster, M and Rochow, W and Brandt, M and Turner, MJL and Wells,
A},
Title = {The effect of low energy protons on the operational
characteristics of EPIC-MOS CCDs},
Journal = {Proceedings of the European Conference on Radiation and its
Effects on Components and Systems, RADECS},
Volume = {1},
Number = {2},
Pages = {201-208},
Year = {2002},
Month = {December},
Abstract = {The University of Tubingen 3.5 MeV Van de Graaf accelerator
facility was used to investigate the effect of low energy
protons on the performance of the European Photon Imaging
Camera (EPIC), metal-oxide semiconductor (MOS), charge
coupled devices (CCDs). Two CCDs were irradiated in
different parts of their detecting areas using different
proton spectra and dose rates. Iron-55 was the calibration
source in all cases and was used to measure any increases in
charge transfer inefficiency (CTI) and resolution of the
CCDs as a result of proton damage. Additional changes in the
CCD bright pixel table and changes in the low X-ray energy
response of the device were examined. The Monte Carlo code
SR1M was used to model the effect of a 10 MeV equivalent
fluence of protons interacting with the CCD. Since the
non-ionising energy loss (NIEL) function could not be
applied effectively at such low proton energies. From the 10
MeV values, the expected CTI degradation could be calculated
and then compared to the measured CTI changes.},
Key = {fds335153}
}
@article{fds335154,
Author = {Smith, DR and Holland, AD and Robbins, MS and Ambrosi, RM and Hutchinson, IB},
Title = {Proton induced leakage current in CCDs},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {4851},
Number = {2},
Pages = {842-848},
Publisher = {SPIE},
Year = {2002},
Month = {December},
url = {http://dx.doi.org/10.1117/12.461331},
Abstract = {The effect of different proton fluences on the performance
of two E2V Technologies (formerly Marconi Applied
Technologies, formerly EEV) CCD47-20 devices was
investigated with particular emphasis given to the analysis
of 'Random telegraph signal' (RTS) generation, bright pixel
generation and induced changes in base dark current level.
The results show that bright pixel frequency increases as
the mean energy of the proton beam is increased, and that
the base dark current level after irradiation scales with
the level of ionisation damage. For the RTS study, 500
pixels on one device were monitored over a twelve hour
period. This data set revealed a number of distinct types of
pixel charge level fluctuation and a system of
classification has been devised. Previously published RTS
data is discussed and reviewed in light of the new
data.},
Doi = {10.1117/12.461331},
Key = {fds335154}
}
@article{fds269644,
Author = {Hall, L and Nomura, Y and Okui, T and Smith, D},
Title = {SO(10) unified theories in six dimensions},
Journal = {Physical Review D},
Volume = {65},
Number = {3},
Publisher = {American Physical Society (APS)},
Year = {2002},
Month = {December},
ISSN = {0556-2821},
url = {http://dx.doi.org/10.1103/PhysRevD.65.035008},
Abstract = {We construct supersymmetric models of SO(10) unification in
which the gauge symmetry is broken by orbifold
compactification. We find that using boundary conditions to
break the gauge symmetry down to SU(3) C⊗ SU(2) L ⊗U(1)
Y⊗U(1) X without leaving unwanted massless states requires
at least two extra dimensions, motivating us to work with 6D
orbifolds. SO(10) is broken by two operations, each of which
induces gauge breaking to either the Georgi-Glashow,
Pati-Salam, or flipped SU(5)⊗U(1) subgroups; assigning
different unbroken subgroups to the two operations leaves
only the-standard model gauge group and U(1) X unbroken. The
models we build employ extra-dimensional mechanisms for
naturally realizing doublet-triplet splitting, suppressing
proton decay, and avoiding unwanted grand-unified fermion
mass relations. We find some tension between being free of
anomalies of the 6D bulk, accommodating a simple mechanism
for generating right-handed neutrino masses, and preserving
the precise prediction of the weak mixing angle. © 2002 The
American Physical Society.},
Doi = {10.1103/PhysRevD.65.035008},
Key = {fds269644}
}
@article{fds269817,
Author = {Oldenburg, SJ and Mock, JJ and Glass, J and Asenjo, A and Genick, C and Smith, DR and Schultz, DA and Schultz, S},
Title = {Metal nanoparticles for biodetection},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {4810},
Pages = {36-41},
Publisher = {SPIE},
Year = {2002},
Month = {December},
url = {http://dx.doi.org/10.1117/12.450805},
Abstract = {The large scattering cross section of plasmon resonant gold
and silver nanoparticles functionalized with the appropriate
ligand allows for sensitive and specific detection of
nucleic acids and proteins. By varying the size, shape, and
material morphology populations with a specific peak plasmon
resonance can be prepared. By varying the order and length
of plasmon resonant bar segment in a composite nanowire one
can obtain a large number of particle populations. Distinct
populations can be used for labels for multiplexing or as a
platform for biological assays. An larger number of color
populations can be obtained with composite nanowires that
are fabricated with various lengths of silver, gold, or
nickel segments. The order and length of the different
plasmon resonance rod segments can be used to uniquely
identify a rod population allowing for a large degree of
multiplexing within a single sample.},
Doi = {10.1117/12.450805},
Key = {fds269817}
}
@article{fds269670,
Author = {Smith, DR and Schurig, D and Pendry, JB},
Title = {Negative refraction of modulated electromagnetic
waves},
Journal = {Applied Physics Letters},
Volume = {81},
Number = {15},
Pages = {2713-2715},
Publisher = {AIP Publishing},
Year = {2002},
Month = {October},
ISSN = {0003-6951},
url = {http://dx.doi.org/10.1063/1.1512828},
Abstract = {We show that a modulated Gaussian beam undergoes negative
refraction at the interface between a positive and negative
refractive index material. While the refraction of the beam
is clearly negative, the modulation interference fronts are
not normal to the group velocity, and thus exhibit a
sideways motion relative to the beam - an effect due to the
inherent frequency dispersion associated with the negative
index medium. In particular, the interference fronts appear
to bend in a manner suggesting positive refraction, such
that for a plane wave, the true direction of the energy flow
associated with the refracted beam is not obvious. © 2002
American Institute of Physics. © 2002 American Institute of
Physics.},
Doi = {10.1063/1.1512828},
Key = {fds269670}
}
@article{fds269820,
Author = {Hall, L and Nomura, Y and Smith, D},
Title = {Gauge-higgs unification in higher dimensions},
Journal = {Nuclear Physics B},
Volume = {639},
Number = {1-2},
Pages = {307-330},
Publisher = {Elsevier BV},
Year = {2002},
Month = {September},
ISSN = {0550-3213},
url = {http://dx.doi.org/10.1016/S0550-3213(02)00539-4},
Abstract = {The electroweak Higgs doublets are identified as components
of a vector multiplet in a higher-dimensional supersymmetric
field theory. We construct a minimal model in 6D where the
electroweak SU (2) ⊗ U (1) gauge group is extended to
SU(3), and unified 6D models with the unified SU(5) gauge
symmetry extended to SU(6). In these realistic theories the
extended gauge group is broken by orbifold boundary
conditions, leaving Higgs doublet zero modes which have
Yukawa couplings to quarks and leptons on the orbifold fixed
points. In one SU(6) model the weak mixing angle receives
power law corrections, while in another the fixed point
structure forbids such corrections. A 5D model is also
constructed in which the Higgs doublet contains the fifth
component of the gauge field. In this case Yukawa couplings
are introduced as nonlocal operators involving the Wilson
line of this gauge field. © 2002 Elsevier Science B.V. All
rights reserved.},
Doi = {10.1016/S0550-3213(02)00539-4},
Key = {fds269820}
}
@article{fds269669,
Author = {Ramakrishna, SA and Pendry, JB and Schurig, D and Smith, DR and Schultz,
S},
Title = {The asymmetric lossy near-perfect lens},
Journal = {Journal of Modern Optics},
Volume = {49},
Number = {10},
Pages = {1747-1762},
Publisher = {Informa UK Limited},
Year = {2002},
Month = {August},
ISSN = {0950-0340},
url = {http://dx.doi.org/10.1080/09500340110120950},
Abstract = {We extend the ideas of the perfect lens recently proposed
[J.B. Pendry, Phys. Rev. Lett. 85, 3966 (2000)] to an
alternative structure. We show that a slab of a medium with
negative refractive index bounded by media of different
positive refractive index also amplifies evanescent waves
and can act as a near-perfect lens. We examine the role of
the surface states in the amplification of the evanescent
waves. The image resolution obtained by this asymmetric lens
is more robust against the effects of absorption in the
lens. In particular, we study the case of a slab of silver,
which has a negative dielectric constant, with air on one
side and other media such as glass or GaAs on the other side
as an 'asymmetric' lossy near-perfect lens for p-polarized
waves. It is found that retardation has an adverse effect on
the imaging due to the positive magnetic permeability of
silver, but we conclude that subwavelength image resolution
is possible in spite of it.},
Doi = {10.1080/09500340110120950},
Key = {fds269669}
}
@article{fds331024,
Author = {Smith, D and Leach, M and Sambell, A},
Title = {An indirect holographic method for determining antenna
radiation patterns and imaging antenna fields},
Journal = {IEEE Antennas and Propagation Society, AP-S International
Symposium (Digest)},
Volume = {3},
Pages = {706-709},
Year = {2002},
Month = {August},
Abstract = {This work describes a new technique for the determination of
antenna radiation patterns and the imaging of antenna
aperture fields. It uses an indirect holographic method to
record simple intensity patterns formed by a combination of
antenna near field signal and an offset reference signal and
is similar to methods employed at optical frequencies. This
is as an alternative to the traditional direct holographic
method of measuring complex amplitude and phase values. It
outlines how previous practical difficulties, which have
prevented this method being usefully employed at microwave
frequencies, can be overcome by the synthesis of an offset
reference plane wave. It describes how far field antenna
radiation patterns can be obtained from knowledge of the
resultant intensity pattern and how the information
contained within this pattern can be further processed to
provide images of the antenna aperture fields. It includes
the results of mathematical simulations which strongly
support the ideas outlined. Currently an experimental system
is being assembled to provide practical measurements. It is
envisaged that preliminary experimental results will be
available shortly.},
Key = {fds331024}
}
@article{7571878,
Author = {Barbic, M and Mock, JJ and Smith, DR and Schultz,
S},
Title = {Single crystal silver nanowires prepared by the metal
amplification method},
Journal = {Journal of Applied Physics},
Volume = {91},
Number = {11},
Pages = {9341-9345},
Year = {2002},
Month = {June},
ISSN = {0021-8979},
url = {http://dx.doi.org/10.1063/1.1476071},
Keywords = {electroless deposition;electron diffraction
crystallography;membranes;nanostructured
materials;nanotechnology;optical microscopy;polymer
films;porous materials;silver;transmission electron
microscopy;},
Abstract = {We present a method of fabricating single crystal silver
nanowires based on the electroless deposition of silver into
the pores of the polycarbonate membranes by the metal
amplification process. A gold film on one side of the
nanoporous membrane is used as the initiation layer for the
silver crystal growth, while the pores of the membrane are
used for guiding the growth of the silver crystal into a
cylindrical nanostructure. Optical microscopy and
spectroscopy of individual nanowires, transmission electron
microscopy (TEM), and TEM diffraction crystallography were
used to characterize the silver nanostructures. The metal
amplification technique presents an electroless, simple, and
inexpensive solution to the challenge of fabricating silver
nanowires for electronic, optical, and biological
applications. © 2002 American Institute of
Physics.},
Doi = {10.1063/1.1476071},
Key = {7571878}
}
@article{7442974,
Author = {Mock, JJ and Oldenburg, SJ and Smith, DR and Schultz, DA and Schultz,
S},
Title = {Composite Plasmon Resonant Nanowires},
Journal = {Nano Letters},
Volume = {2},
Number = {5},
Pages = {465-469},
Publisher = {American Chemical Society (ACS)},
Year = {2002},
Month = {May},
url = {http://dx.doi.org/10.1021/nl0255247},
Keywords = {electroless deposition;electroplating;filled
polymers;gold;light scattering;nanostructured
materials;nickel;optical microscopy;silver;surface plasmon
resonance;},
Abstract = {We present an experimental study of the polarization-dependent
scattering of light from homogeneous and multisegment
silver, gold, and nickel nanowires. The metallic nanowires
are prepared within a polycarbonate membrane template by a
combination of electroplating (gold and nickel) and
electroless (silver) growth processes. The size range of the
nanowire segments is such that surface plasmon resonances
are supported, dominating the optical spectra. We
characterize the light scattering properties of individual
composite nanowires using an optical microscope configured
for single particle spectroscopy. Because of the scattering
efficiency associated with the plasmon resonance, very
narrow (∼30 nm diameter) nanowires can be readily observed
under white-light illumination, with the spectral
characteristics of each subsection easily distinguishable.
Because of their compactness, these simply prepared
multiisegment plasmon resonant nanowires are capable of
hosting a large number of segment sequences over a
comparatively small spatial range, suggesting their possible
application as unique nanolabels in biological
assays.},
Doi = {10.1021/nl0255247},
Key = {7442974}
}
@article{fds335155,
Author = {Ambrosi, RM and Short, ADT and Abbey, AF and Wells, AA and Smith,
DR},
Title = {The effect of proton damage on the X-ray spectral response
of MOS CCDs for the Swift X-ray telescope},
Journal = {Nuclear Instruments and Methods in Physics Research, Section
A: Accelerators, Spectrometers, Detectors and Associated
Equipment},
Volume = {482},
Number = {3},
Pages = {644-652},
Publisher = {Elsevier BV},
Year = {2002},
Month = {April},
url = {http://dx.doi.org/10.1016/S0168-9002(01)01734-X},
Abstract = {The effect of non-ionising energy loss of protons in
charge-coupled devices is to displace silicon atoms and any
dopant materials present from their lattice positions to
form lattice defects which in turn can trap electrons (IEEE
Trans. Nucl. Sci. NS-40 (1993) 1628). A CCD operating as a
photon counter for X-ray spectroscopy relies on the
efficient transfer of charge from one region to another. The
number of defects produced will reduce the charge transfer
efficiency and hence degrade the spectral resolution of the
energy distribution of interest (Jet-X Project Document:
JET-X(94) UL-230 WP2220 (1994)). The Swift X-ray telescope
will be equipped with a single EPIC MOS CCD22 as developed
for the XMM project SPIE 3445 (1998) 13. It is the aim of
this study to determine the effect of the radiation
environment on the performance of the CCD and its impact on
the scientific objective of the X-ray telescope, to probe
the X-ray afterglow of gamma-ray bursts. © 2002 Elsevier
Science B.V. All rights reserved.},
Doi = {10.1016/S0168-9002(01)01734-X},
Key = {fds335155}
}
@article{02206947052,
Author = {Mock, JJ and Barbic, M and Smith, DR and Schultz, DA and Schultz,
S},
Title = {Shape effects in plasmon resonance of individual colloidal
silver nanoparticles},
Journal = {Journal of Chemical Physics},
Volume = {116},
Number = {15},
Pages = {6755-6759},
Publisher = {AIP Publishing},
Year = {2002},
Month = {April},
url = {http://dx.doi.org/10.1063/1.1462610},
Keywords = {Silver;Colloids;Particle size analysis;Surface plasmon
resonance;Heat treatment;Spectrum analysis;Transmission
electron microscopy;},
Abstract = {The effect of shape of individual silver colloidal
nanoparticle on surface plasmon resonance was investigated
by an optical detection technique combined with high
resolution transmission electron microscopy (TEM). The
geometrical shape of nanoparticle had a major role in
determining plasmon resonance, while the spectrum redshifted
with increasing particle size. Heat treatment was found to
be capable of modifying particle shape, resulting in a
change in its plasmon resonant properties.},
Doi = {10.1063/1.1462610},
Key = {02206947052}
}
@article{fds300150,
Author = {Wu, D and Fang, N and Sun, C and Zhang, X and Padilla, W and Basov, D and Smith, D},
Title = {Fabrication and characterization of THz plasmonic
filter},
Journal = {Proceedings of the IEEE Conference on Nanotechnology},
Volume = {2002-January},
Pages = {229-231},
Year = {2002},
Month = {January},
ISBN = {0780375386},
ISSN = {1944-9399},
url = {http://dx.doi.org/10.1109/NANO.2002.1032234},
Abstract = {Terahertz imaging systems have applications for explosives
detection, aircraft guidance and landing in zero-visibility
weather condition, as well as terrestrial and astronomical
remote sensing. These critical applications need a variety
of optical elements in the THz frequency, which has yet to
be explored. In this paper, we demonstrate a high pass THz
filter which utilizes the lowered plasma frequency of thin
metal wire structures. The microstereolithography technique
is applied to fabricate the 2D lattice of thin metal
cylinders. The reflection property of the filter is
characterized by FTIR, and the plasma frequency is
determined at 0.7 THz, which agrees with the approximate
theory.},
Doi = {10.1109/NANO.2002.1032234},
Key = {fds300150}
}
@article{fds269648,
Author = {Skiba, W and Smith, D},
Title = {Localized fermions and anomaly inflow via
deconstruction},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {65},
Number = {9},
Pages = {7},
Year = {2002},
Month = {January},
ISSN = {0556-2821},
url = {http://dx.doi.org/10.1103/PhysRevD.65.095002},
Abstract = {We study fermion localization in gauge theory space. We
consider four-dimensional product gauge groups in which
light chiral fermions transform under different gauge
factors of the product group. This construction provides a
suppression of higher dimensional operators. For example, it
can be used to suppress dangerous proton decay operators.
The anomalies associated with the light chiral fermions are
compensated by Wess-Zumino terms, which in the continuum
limit reproduce the five-dimensional Chern-Simons term. ©
2002 The American Physical Society.},
Doi = {10.1103/PhysRevD.65.095002},
Key = {fds269648}
}
@article{fds269668,
Author = {Smith, DR and Schultz, S and Markoš, P and Soukoulis,
CM},
Title = {Determination of effective permittivity and permeability of
metamaterials from reflection and transmission
coefficients},
Journal = {Physical Review B - Condensed Matter and Materials
Physics},
Volume = {65},
Number = {19},
Pages = {1-5},
Year = {2002},
Month = {January},
ISSN = {0163-1829},
url = {http://dx.doi.org/10.1103/PhysRevB.65.195104},
Abstract = {We analyze the reflection and transmission coefficients
calculated from transfer matrix simulations on finite
lengths of electromagnetic metamaterials, to determine the
effective permittivity (ε) and permeability (µ). We
perform this analysis on structures composed of periodic
arrangements of wires, split ring resonators (SRRs), and
both wires and SRRs. We find the recovered
frequency-dependent ε and µ are entirely consistent with
analytic expressions predicted by effective medium
arguments. Of particular relevance are that a wire medium
exhibits a frequency region in which the real part of ε is
negative, and SRRs produce a frequency region in which the
real part of µ is negative. In the combination structure,
at frequencies where both the recovered real parts of ε and
µ are simultaneously negative, the real part of the index
of refraction is also found to be unambiguously negative. ©
2002 The American Physical Society.},
Doi = {10.1103/PhysRevB.65.195104},
Key = {fds269668}
}
@article{fds269818,
Author = {Low, I and Smith, D},
Title = {Little Higgs bosons from an antisymmetric
condensate},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {66},
Number = {7},
Publisher = {American Physical Society (APS)},
Year = {2002},
Month = {January},
ISSN = {0556-2821},
url = {http://dx.doi.org/10.1103/PhysRevD.66.072001},
Abstract = {We construct an (Formula presented) non-linear sigma model
in which the Higgs bosons arise as pseudo Goldstone bosons.
There are two Higgs doublets whose masses have no one-loop
quadratic sensitivity to the cutoff of the effective theory,
which can be at around 10 TeV. The Higgs potential is
generated by gauge and Yukawa interactions, and is
distinctly different from that of the minimal supersymmetric
standard model. At the TeV scale, the new bosonic degrees of
freedom are a single neutral complex scalar and a second
copy of (Formula presented) gauge bosons. Additional
vector-like pairs of colored fermions are also present. ©
2002 The American Physical Society.},
Doi = {10.1103/PhysRevD.66.072001},
Key = {fds269818}
}
@article{fds269816,
Author = {Kottmann, J and Martin, OJ and Smith, DR and Schultz,
S},
Title = {Plasmon resonances of silver nanowires with a nonregular
cross section},
Journal = {Physical Review B - Condensed Matter and Materials
Physics},
Volume = {64},
Number = {23},
Pages = {2354021-23540210},
Year = {2001},
Month = {December},
ISSN = {0163-1829},
url = {http://dx.doi.org/10.1103/physrevb.64.235402},
Abstract = {We investigate numerically the spectrum of plasmon
resonances for metallic nanowires with a nonregular Z, cross
section, in the 20-50 nm range. We first consider the
resonance spectra corresponding to nanowires whose cross
sections form different simplexes. The number of resonances
strongly increases when the section symmetry decreases: A
cylindrical wire exhibits one resonance, whereas we observe
more than five distinct resonances for a triangular
particle. The spectral range covered by these different
resonances becomes very large, giving to the particle-
specific distinct colors. At the resonance, dramatic field
enhancement is observed at the vicinity of nonregular
particles, where the field amplitude can reach several
hundred times that of the illumination field. This
near-field enhancement corresponds to surface-enhanced Raman
scattering (SERS) enhancement locally in excess of 1012. The
distance dependence of this enhancement is investigated and
we show that it depends on the plasmon resonance excited in
the particle, i.e., on the illumination wavelength. The
average Raman enhancement for molecules distributed on the
entire particle surface is also computed and discussed in
the context of experiments in which large numbers of
molecules are used.},
Doi = {10.1103/physrevb.64.235402},
Key = {fds269816}
}
@article{fds331025,
Author = {Arkani-Hamed, N and Hall, L and Murayama, H and Smith, D and Weiner,
N},
Title = {Small neutrino masses from supersymmetry
breaking},
Journal = {Physical Review D},
Volume = {64},
Number = {11},
Pages = {15},
Publisher = {American Physical Society (APS)},
Year = {2001},
Month = {December},
url = {http://dx.doi.org/10.1103/PhysRevD.64.115011},
Abstract = {An alternative to the conventional seesaw mechanism is
proposed to explain the origin of small neutrino masses in
supersymmetric theories. The masses and couplings of the
right-handed neutrino field are suppressed by supersymmetry
breaking, in a way similar to the suppression of the Higgs
doublet mass μ. New mechanisms for light Majorana and Dirac
neutrinos arise, depending on the degree of suppression.
Superpartner phenomenology is greatly altered by the
presence of weak scale right-handed sneutrinos, which may
have a coupling to a Higgs boson and a left-handed
sneutrino. The sneutrino spectrum and couplings are quite
unlike the conventional case - the lightest sneutrino can be
the dark matter and predictions are given for event rates at
upcoming halo dark matter direct detection experiments.
Higgs boson decays and search strategies are changed.
Copious Higgs boson production at hadron colliders can
result from cascade decays of squarks and gluinos. ©2001
The American Physical Society.},
Doi = {10.1103/PhysRevD.64.115011},
Key = {fds331025}
}
@article{fds269814,
Author = {Weiland, T and Schuhmann, R and Greegor, RB and Parazzoli, CG and Vetter, AM and Smith, DR and Vier, DC and Schultz,
S},
Title = {Ab initio numerical simulation of left-handed metamaterials:
Comparison of calculations and experiments},
Journal = {Journal of Applied Physics},
Volume = {90},
Number = {10},
Pages = {5419-5424},
Publisher = {AIP Publishing},
Year = {2001},
Month = {November},
url = {http://dx.doi.org/10.1063/1.1410881},
Abstract = {Using numerical simulation techniques, the transmission and
reflection coefficients, or S parameters, for left-handed
metamaterials are calculated. Metamaterials consist of a
lattice of conducting, nonmagnetic elements that can be
described by an effective magnetic permeability μeff and an
effective electrical permittivity εeff, both of which can
exhibit values not found in naturally occurring materials.
Because the electromagnetic fields in conducting
metamaterials can be localized to regions much smaller than
the incident wavelength, it can be difficult to perform
accurate numerical simulations. The metamaterials simulated
here, for example, are based on arrays of split ring
resonators (SRRs), which produce enhanced and highly
localized electric fields within the gaps of the elements in
response to applied time dependent fields. To obtain greater
numerical accuracy we utilize the newly developed
commercially available code MICROWAVE STUDIO, which is based
on the finite integration technique with the perfect
boundary approximation. The simulation results are in
agreement with published experimental results for the
frequencies and bandwidths of the propagation and stop bands
associated with the various structures. We further analyze
the properties of an individual SRR, and find the dependence
of the resonant frequency on the SRR radius, ring thickness,
inner/outer radial gap, azimuthal gap, electrical
permittivity, and magnetic permeability of the components'
materials. Comparison with previously published analytical
estimates shows only approximate agreement with the
simulation results. © 2001 American Institute of
Physics.},
Doi = {10.1063/1.1410881},
Key = {fds269814}
}
@article{fds269643,
Author = {Nomura, Y and Smith, D and Weiner, N},
Title = {GUT breaking on the brane},
Journal = {Nuclear Physics B},
Volume = {613},
Number = {1-2},
Pages = {147-166},
Publisher = {Elsevier BV},
Year = {2001},
Month = {October},
url = {http://dx.doi.org/10.1016/S0550-3213(01)00388-1},
Abstract = {We present a five-dimensional supersymmetric SU(5) theory in
which the gauge symmetry is broken maximally (i.e., at the
5D Planck scale M*) on the same 4D brane where chiral matter
is localized. Masses of the lightest Kaluza-Klein modes for
the colored Higgs and X and Y gauge fields are determined by
the compactification scale of the fifth dimension, MC~1015
GeV, rather than by M*. These fields' wave functions are
repelled from the GUT-breaking brane, so that proton decay
rates are suppressed below experimental limits. Above the
compactification scale, the differences between the standard
model gauge couplings evolve logarithmically, so that
ordinary logarithmic gauge coupling unification is
preserved. The maximal breaking of the grand unified group
can also lead to other effects, such as O(1) deviations from
SU(5) predictions of Yukawa couplings, even in models
utilizing the Froggatt-Nielsen mechanism.},
Doi = {10.1016/S0550-3213(01)00388-1},
Key = {fds269643}
}
@article{fds269642,
Author = {Arkani-Hamed, N and Hall, L and Nomura, Y and Smith, D and Weiner,
N},
Title = {Finite radiative electroweak symmetry breaking from the
bulk},
Journal = {Nuclear Physics B},
Volume = {605},
Number = {1-3},
Pages = {81-115},
Publisher = {Elsevier BV},
Year = {2001},
Month = {July},
url = {http://dx.doi.org/10.1016/S0550-3213(01)00203-6},
Abstract = {A new physical origin for electroweak symmetry breaking is
proposed, involving compact spatial dimensions of scale
1/R≈1 TeV. The higher-dimensional theory is
supersymmetric, and hence requires the top-quark Yukawa
coupling to be localized on some "Yukawa brane" in the bulk.
The short distance divergence in the Higgs-boson mass is
regulated because supersymmetry is unbroken in the vicinity
of this Yukawa brane. A finite, negative Higgs mass-squared
is generated radiatively by the top-quark supermultiplet
propagating a distance of order R from the Yukawa brane to
probe supersymmetry breaking. The physics of electroweak
symmetry breaking is therefore closely related to this top
propagation across the bulk, and is dominated by the mass
scale 1/R, with exponential insensitivity to higher energy
scales. The masses of the superpartners and the Kaluza-Klein
resonances are also set by the mass scale 1/R, which is
naturally larger than the W boson mass by a loop factor.
Explicit models are constructed which are highly constrained
and predictive. The finite radiative correction to the Higgs
mass is computed, and the Higgs sector briefly explored. The
superpartner and Kaluza-Klein resonance spectra are
calculated, and the problem of flavor violation from squark
and slepton exchange is solved. Important collider
signatures include highly ionizing charged tracks from
stable top squarks, and events with two Higgs bosons and
missing transverse energy. © 2001 Elsevier Science
B.V.},
Doi = {10.1016/S0550-3213(01)00203-6},
Key = {fds269642}
}
@article{fds269811,
Author = {Kottmann, JP and Martin, OJF and Smith, DR and Schultz,
S},
Title = {Dramatic localized electromagnetic enhancement in plasmon
resonant nanowires},
Journal = {Chemical Physics Letters},
Volume = {341},
Number = {1-2},
Pages = {1-6},
Publisher = {Elsevier BV},
Year = {2001},
Month = {June},
url = {http://dx.doi.org/10.1016/S0009-2614(01)00171-3},
Abstract = {We investigate numerically the plasmon resonances of 10-50
nm nanowires with a non-elliptical section. Such wires have
a much more complex behavior than elliptical wires and their
resonances span a larger frequency range. The field
distribution at the surface of these wires exhibits a
dramatic enhancement, up to several hundred times the
incident field amplitude. These strongly localized fields
can provide an important mechanism for surface enhanced
Raman scattering (SERS). © 2001 Elsevier Science
B.V.},
Doi = {10.1016/S0009-2614(01)00171-3},
Key = {fds269811}
}
@article{fds335156,
Author = {Lipschultz, B and Pappas, DA and Labombard, B and Rice, JE and Smith, D and Wukitch, SJ},
Title = {A study of molybdenum influxes and transport in alcator
C-Mod},
Journal = {Nuclear Fusion},
Volume = {41},
Number = {5},
Pages = {585-596},
Publisher = {IOP Publishing},
Year = {2001},
Month = {May},
url = {http://dx.doi.org/10.1088/0029-5515/41/5/311},
Abstract = {A characterization is presented of Mo sources ΓMo, core Mo
content NMo and their dependences on the Alcator C-Mod
operational regimes. The primary impurity source locations
are the divertor, the inner wall and the ICRF antenna
limiters. Boronization is used to coat the first wall
surfaces with a thin layer of B, which greatly reduces the
Mo sources for a period of time, eroding away with an e
folding period of 15-50 discharges. The penetration of Mo
into the core plasma under different conditions is analysed
using the concept of penetration factor, PF = NMo/ΓMo (s).
In general, the inner wall Mo source is large (∼1018 s-1),
but is found to be relatively uncorrelated with the core Mo
content in diverted plasmas. The outer divertor source is of
a similar order to that of the inner wail and has a
penetration factor in the range 10-5-2 ∼ 10-3 s depending
on density and confinement mode. The antenna limiter Mo
sources are typically smaller, but with higher penetration
factors of 10-3-2 × 10-2 s. The behaviour of the antenna
limiter sources is consistent with physical sputtering due
to the influence of RF sheath rectification. The
measurements of the plasma potential on feld lines connected
to the antenna are very high when the antennas are
energized, often reaching hundreds of volts.},
Doi = {10.1088/0029-5515/41/5/311},
Key = {fds335156}
}
@article{fds269810,
Author = {Kottmann, JP and Martin, OJ and Smith, DR and Schultz,
S},
Title = {Non-regularly shaped plasmon resonant nanoparticle as
localized light source for near-field microscopy.},
Journal = {Journal of microscopy},
Volume = {202},
Number = {Pt 1},
Pages = {60-65},
Year = {2001},
Month = {April},
ISSN = {0022-2720},
url = {http://dx.doi.org/10.1046/j.1365-2818.2001.00866.x},
Abstract = {We study numerically two-dimensional nanoparticles with a
non-regular shape and demonstrate that these particles can
support many more plasmon resonances than a particle with a
regular shape (e.g. an ellipse). The electric field
distributions associated with these different resonances are
investigated in detail in the context of near-field
microscopy. Depending on the particle shape, extremely
strong and localized near-fields, with intensity larger than
105 that of the illumination wave, can be generated. We also
discuss the spectral dependence of these near-fields and
show that different spatial distributions are observed,
depending which plasmon resonance is excited in the
particle.},
Doi = {10.1046/j.1365-2818.2001.00866.x},
Key = {fds269810}
}
@article{01216510625,
Author = {Shelby, RA and Smith, DR and Schultz, S},
Title = {Experimental verification of a negative index of
refraction.},
Journal = {Science (New York, N.Y.)},
Volume = {292},
Number = {5514},
Pages = {77-79},
Year = {2001},
Month = {April},
url = {http://dx.doi.org/10.1126/science.1058847},
Keywords = {Microwaves;Arrays;Prisms;Electromagnetic wave
scattering;},
Abstract = {We present experimental scattering data at microwave
frequencies on a structured metamaterial that exhibits a
frequency band where the effective index of refraction (n)
is negative. The material consists of a two-dimensional
array of repeated unit cells of copper strips and split ring
resonators on interlocking strips of standard circuit board
material. By measuring the scattering angle of the
transmitted beam through a prism fabricated from this
material, we determine the effective n, appropriate to
Snell's law. These experiments directly confirm the
predictions of Maxwell's equations that n is given by the
negative square root of epsilon.mu for the frequencies where
both the permittivity (epsilon) and the permeability (mu)
are negative. Configurations of geometrical optical designs
are now possible that could not be realized by positive
index materials.},
Doi = {10.1126/science.1058847},
Key = {01216510625}
}
@article{04057982916,
Author = {Shelby, RA and Smith, DR and Nemat-Nasser, SC and Schultz,
S},
Title = {Microwave transmission through a two-dimensional, isotropic,
left-handed metamaterial},
Journal = {Applied Physics Letters},
Volume = {78},
Number = {4},
Pages = {489-491},
Publisher = {AIP Publishing},
Year = {2001},
Month = {January},
url = {http://dx.doi.org/10.1063/1.1343489},
Abstract = {We present experimental data, numerical simulations, and
analytical transfer-matrix calculations for a
two-dimensionally isotropic, left-handed metamaterial (LHM)
at X-band microwave frequencies. A LHM is one that has a
frequency band with simultaneously negative εeff(ω) and
μeff(ω), thereby having real values of index of refraction
and wave vectors, and exhibiting extended wave propagation
over that band. Our physical demonstration of a
two-dimensional isotropic LHM will now permit experiments to
verify some of the explicit predictions of reversed
electromagnetic-wave properties including negative index of
refraction as analyzed by Veselago [Usp. Fiz. Nauk 92, 517
(1964), Sov. Phys. Usp. 10, 509 (1968)]. © 2001 American
Institute of Physics.},
Doi = {10.1063/1.1343489},
Key = {04057982916}
}
@article{fds269640,
Author = {Arkani-Hamed, M and Hall, L and Smith, D and Weiner,
N},
Title = {Exponentially small supersymmetry breaking from extra
dimensions},
Journal = {Physical Review D},
Volume = {63},
Number = {5},
Pages = {5},
Publisher = {American Physical Society (APS)},
Year = {2001},
Month = {January},
ISSN = {0556-2821},
url = {http://dx.doi.org/10.1103/PhysRevD.63.056003},
Abstract = {The supersymmetric "shining" of free massive chiral
superficiels in extra dimensions from a distant source brane
can trigger exponentially small supersymmetry breaking on
our brane of order e~27rR, where R is the radius of the
extra dimensions. This supersymmetry breaking can be
transmitted to the superpartners in a number of ways, for
instance by gravity or via the standard model gauge
interactions. The radius R can easily be stabilized at a
size 0(10) larger that the fundamental scale. The models are
extremely simple, relying only on free, classical bulk
dynamics to solve the hierarchy problem. ©2001 The American
Physical Society.},
Doi = {10.1103/PhysRevD.63.056003},
Key = {fds269640}
}
@article{fds269641,
Author = {Smith, D},
Title = {Inelastic dark matter},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {64},
Number = {4},
Pages = {11},
Publisher = {American Physical Society (APS)},
Year = {2001},
Month = {January},
ISSN = {0556-2821},
url = {http://dx.doi.org/10.1103/PhysRevD.64.043502},
Abstract = {Many observations suggest that much of the matter of the
universe is nonbaryonic. Recently, the DAMA NaI dark matter
direct detection experiment reported an annual modulation in
their event rate consistent with a WIMP relic. However, the
Cryogenic Dark Matter Search (CDMS) Ge experiment excludes
most of the region preferred by DAMA. We demonstrate that if
the dark matter can only scatter by making a transition to a
slightly heavier state (Formula presented) the experiments
are no longer in conflict. Moreover, differences in the
energy spectrum of nuclear recoil events could distinguish
such a scenario from the standard WIMP scenario. Finally, we
discuss the sneutrino as a candidate for inelastic dark
matter in supersymmetric theories. © 2001 The American
Physical Society.},
Doi = {10.1103/PhysRevD.64.043502},
Key = {fds269641}
}
@article{fds335157,
Author = {Lipschultz, B and Pappas, DA and LaBombard, B and Rice, JE and Smith, D and Wukitch, S},
Title = {Molybdenum sources and transport in Alcator
C-Mod},
Journal = {Journal of Nuclear Materials},
Volume = {290},
Number = {293},
Pages = {286-290},
Publisher = {Elsevier BV},
Year = {2001},
Month = {January},
url = {http://dx.doi.org/10.1016/S0022-3115(00)00436-0},
Abstract = {We present a characterization of molybdenum sources, ΓMo,
core Mo content, NMo, and their dependencies on Alcator
C-Mod operational regimes. This includes sources from the
divertor, the inner wall and the ICRF antenna limiters. We
also present information characterizing the penetration of
these impurities into the core plasma under different
conditions based on penetration factors, PF = NMo/ΓMo (s).
In general, the inner wall Mo source is large (approximately
1018 s-1) but is found to be relatively uncorrelated with
the core Mo level in diverted plasmas. The outer divertor
source is of similar order to that from the inner wall and
has a penetration factor in the range 10-5-2×10-3 s
depending on density and confinement mode. The antenna
limiter Mo sources are typically smaller, but with higher
penetration factors - 10-3-2×10-2 s. The behavior of the
antenna limiter sources is consistent with physical
sputtering due to the influence of RF sheath
rectification.},
Doi = {10.1016/S0022-3115(00)00436-0},
Key = {fds335157}
}
@article{fds269812,
Author = {Aubert, B and Boutigny, D and Gaillard, JM and Hicheur, A and Karyotakis, Y and Lees, JP and Robbe, P and Tisserand, V and Palano, A and Chen, GP and al, E},
Title = {Measurement of the decays B → φK and B →
φK},
Journal = {Physical Review Letters},
Volume = {87},
Number = {15},
Pages = {151801/1-151801/7},
Year = {2001},
ISSN = {0031-9007},
Abstract = {An attempt was made to observe B decays to φK +, φK 0, φK
*+, and φK *0 with significances, including systematic
uncertainties, of greater than four standard deviations. It
was found that the decay B + → φπ + has both
Cabibbo-Kobayashi-Maskawa and color suppression relative to
φK +.},
Key = {fds269812}
}
@article{fds269813,
Author = {Aubert, B and Boutigny, D and Gaillard, JM and Hicheur, A and Karyotakis, Y and Lees, JP and Robbe, P and Tisserand, V and Palano, A and Chen, GP and al, E},
Title = {Measurement of branching fractions and search for
CP-violating charge asymmetries in charmless two-body B
decays into pions and kaons},
Journal = {Physical Review Letters},
Volume = {87},
Number = {15},
Pages = {151802/1-151802/7},
Year = {2001},
ISSN = {0031-9007},
Abstract = {Branching ratios were measured for the rate charmless decays
B 0→π +π -, B 0→K +π -, B +→K +π 0, B +→K 0π +,
and B 0→π +π 0, and B +→K̃ 0K +. No evidence was
found for direct CP violation in the observed decays. 90%
confidence level intervals were set.},
Key = {fds269813}
}
@article{fds269815,
Author = {Aubert, B and Boutigny, D and Gaillard, JM and Hicheur, A and Karyotakis, Y and Lees, JP and Robbe, P and Tisserand, V and Palano, A and Chen, GP and al, E},
Title = {Measurements of the branching fractions of exclusive
charmless B meson decays with η′ or ω
mesons},
Journal = {Physical Review Letters},
Volume = {87},
Number = {22},
Pages = {221802/2-221802/7},
Year = {2001},
ISSN = {0031-9007},
Abstract = {An overview is given on the results of searches for B decays
to the charmless two-body final states B +→wπ +, B +→wK
+, B +→η'π +, B +→η'K +, B 0→wK 0, B 0→wπ 0, and
B 0→η,'K 0. The results are based on data taken in the
1999-2000 run. The data were collected with the BABAR
detector at the PEP-II asymmetric e +e - collider located at
the Stanford Linear Accelerator Center.},
Key = {fds269815}
}
@article{fds269809,
Author = {Kottmann, JP and Martin, OJF and Smith, DR and Schultz,
S},
Title = {Field polarization and polarization charge distributions in
plasmon resonant nanoparticles},
Journal = {New Journal of Physics},
Volume = {2},
Pages = {27-27},
Publisher = {IOP Publishing},
Year = {2000},
Month = {November},
url = {http://dx.doi.org/10.1088/1367-2630/2/1/327},
Abstract = {We study the plasmon resonances for small two-dimensional
silver particles (nanowires) with elliptical or triangular
shapes in the 20 nm size range. While the elliptical
particle has only two resonances, a well known fact, we
demonstrate that the triangular particle displays a much
more complex behaviour with several resonances over a broad
wavelength range. Using animations of the field amplitude
and field polarization, we investigate the properties of
these different resonances. The field distribution
associated with each plasmon resonance can be related to the
polarization charges on the surface of the particles.
Implications for the design of plasmon resonant structures
with specific properties, for example, for nano-optics or
surface enhanced Raman scattering are discussed.},
Doi = {10.1088/1367-2630/2/1/327},
Key = {fds269809}
}
@article{6740385,
Author = {Smith, DR and Kroll, N},
Title = {Negative refractive index in left-handed
materials},
Journal = {Physical Review Letters},
Volume = {85},
Number = {14},
Pages = {2933-2936},
Publisher = {American Physical Society (APS)},
Year = {2000},
Month = {October},
ISSN = {0031-9007},
url = {http://dx.doi.org/10.1103/PhysRevLett.85.2933},
Keywords = {electromagnetic wave propagation;permittivity;refractive
index;},
Abstract = {The presence of negative refractive index in steady-state
problems was explored. It was observed that this index leads
to unusual and unexplored phenomena in wave propagation. A
formalism was derived that can be applied to time dependent
currents and pulses in 'left handed' (LH) media, or
combinations of LH and 'right-hand' RH media.},
Doi = {10.1103/PhysRevLett.85.2933},
Key = {6740385}
}
@article{04057969601,
Author = {Smith, DR and Vier, DC and Kroll, N and Schultz, S},
Title = {Direct calculation of permeability and permittivity for a
left-handed metamaterial},
Journal = {Applied Physics Letters},
Volume = {77},
Number = {14},
Pages = {2246-2248},
Publisher = {AIP Publishing},
Year = {2000},
Month = {October},
url = {http://dx.doi.org/10.1063/1.1314884},
Abstract = {Recently, an electromagnetic metamaterial was fabricated and
demonstrated to exhibit a "left-handed" (LH) propagation
band at microwave frequencies. A LH metamaterial is one
characterized by material constants - the permeability and
permittivity - which are simultaneously negative, a
situation never observed in naturally occurring materials or
composites. While the presence of the propagation band was
shown to be an inherent demonstration of left handedness,
actual numerical values for the material constants were not
obtained. In the present work, using appropriate averages to
define the macroscopic fields, we extract quantitative
values for the effective permeability and permittivity from
finite-difference simulations using three different
approaches. © 2000 American Institute of
Physics.},
Doi = {10.1063/1.1314884},
Key = {04057969601}
}
@article{04057957932,
Author = {Smith, DR and Padilla, WJ and Vier, DC and Nemat-Nasser, SC and Schultz,
S},
Title = {Composite medium with simultaneously negative permeability
and permittivity},
Journal = {Physical review letters},
Volume = {84},
Number = {18},
Pages = {4184-4187},
Year = {2000},
Month = {May},
url = {http://dx.doi.org/10.1103/PhysRevLett.84.4184},
Abstract = {We demonstrate a composite medium, based on a periodic array
of interspaced conducting nonmagnetic split ring resonators
and continuous wires, that exhibits a frequency region in
the microwave regime with simultaneously negative values of
effective permeability &mgr;(eff)(omega) and permittivity
varepsilon(eff)(omega). This structure forms a "left-handed"
medium, for which it has been predicted that such phenomena
as the Doppler effect, Cherenkov radiation, and even Snell's
law are inverted. It is now possible through microwave
experiments to test for these effects using this new
metamaterial.},
Doi = {10.1103/physrevlett.84.4184},
Key = {04057957932}
}
@article{fds269667,
Author = {Schultz, S and Smith, DR and Mock, JJ and Schultz,
DA},
Title = {Single-target molecule detection with nonbleaching
multicolor optical immunolabels.},
Journal = {Proceedings of the National Academy of Sciences of the
United States of America},
Volume = {97},
Number = {3},
Pages = {996-1001},
Year = {2000},
Month = {February},
ISSN = {0027-8424},
url = {http://dx.doi.org/10.1073/pnas.97.3.996},
Abstract = {We introduce and demonstrate the use of colloidal silver
plasmon-resonant particles (PRPs) as optical reporters in
typical biological assays. PRPs are ultrabright, nanosized
optical scatterers, which scatter light elastically and can
be prepared with a scattering peak at any color in the
visible spectrum. PRPs are readily observed individually
with a microscope configured for dark-field microscopy, with
white-light illumination of typical power. Here we
illustrate the use of PRPs, surface coated with standard
ligands, as target-specific labels in an in situ
hybridization and an immunocytology assay. We propose that
PRPs can replace or complement established labels, such as
those based on radioactivity, fluorescence,
chemiluminescence, or enzymatic/colorimetric detection that
are used routinely in biochemistry, cell biology, and
medical diagnostic applications. Moreover, because PRP
labels are nonbleaching and bright enough to be rapidly
identified and counted, an ultrasensitive assay format based
on single-target molecule detection is now practical. We
also present the results of a model sandwich immunoassay for
goat anti-biotin antibody, in which the number of PRP labels
counted in an image constitutes the measured
signal.},
Doi = {10.1073/pnas.97.3.996},
Key = {fds269667}
}
@article{6899993,
Author = {Smith, DR and Padilla, W and Vier, DC and Nemat-Nasser, SC and Schultz,
S},
Title = {Negative permeability from split ring resonator
arrays},
Journal = {Conference on Lasers and Electro-Optics Europe - Technical
Digest},
Pages = {49},
Address = {Nice, France},
Year = {2000},
Month = {January},
url = {http://dx.doi.org/10.1109/CLEOE.2000.909747},
Keywords = {arrays;dispersion relations;electrodynamics;magnetic
permeability;Maxwell equations;resonators;},
Abstract = {A single split ring resonator (SRR) was fabricated
lithographically and its accompanying resonance curve is
shown to determine if periodic arrays of SRRs can have a
resonantly enhanced effective permeability displaying
frequency regions with large positive or negative values.
The SRR medium now offers the possibility of engineering
materials to respond to time varying magnetic fields as well
as time varying electric fields. Combining such composite
media with standard materials offers the potential to yield
novel and advantageous electromagnetic devices.},
Key = {6899993}
}
@article{fds269666,
Author = {Kottmann, JP and Martin, OJF and Smith, DR and Schultz,
S},
Title = {Spectral response of plasmon resonant nanoparticles with a
non-regular shape},
Journal = {Optics Express},
Volume = {6},
Number = {11},
Pages = {213-219},
Publisher = {The Optical Society},
Year = {2000},
Month = {January},
ISSN = {1094-4087},
url = {http://dx.doi.org/10.1364/OE.6.000213},
Abstract = {We study the plasmon resonances of 10-100(nm)
two-dimensional metal particles with a non-regular shape.
Movies illustrate the spectral response of such particles in
the optical range. Contrary to particles with a simple shape
(cylinder, ellipse) non-regular particles exhibit many
distinct resonances over a large spectral range. At
resonance frequencies, extremely large enhancements of the
electromagnetic fields occur near the surface of the
particle, with amplitudes several hundred-fold that of the
incident field. Implications of these strong and localized
fields for nano-optics and surface enhanced Raman scattering
(SERS) are also discussed. © 2000 Optical Society of
America.},
Doi = {10.1364/OE.6.000213},
Key = {fds269666}
}
@article{fds331026,
Author = {Arkani-Hamed, N and Hall, L and Smith, D and Weiner,
N},
Title = {Solving the hierarchy problem with exponentially large
dimensions},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {62},
Number = {10},
Pages = {7},
Publisher = {American Physical Society (APS)},
Year = {2000},
Month = {January},
url = {http://dx.doi.org/10.1103/PhysRevD.62.105002},
Abstract = {In theories with (sets of) two large extra dimensions and
supersymmetry in the bulk, the presence of
non-supersymmetric brane defects naturally induces a
logarithmic potential for the volume of the transverse
dimensions. Since the logarithm of the volume rather than
the volume itself is the natural variable, parameters of
O(10) in the potential can generate an exponentially large
size for the extra dimensions. This provides a true solution
to the hierarchy problem, on the same footing as technicolor
or dynamical supersymmetry breaking. The area moduli have a
Compton wavelength of about a millimeter and mediate Yukawa
interactions with gravitational strength. We present a
simple explicit example of this idea which generates two
exponentially large dimensions. In this model, the area
modulus mass is in the millimeter range even for six
dimensional Planck scales as high as 100 TeV. © 2000 The
American Physical Society.},
Doi = {10.1103/PhysRevD.62.105002},
Key = {fds331026}
}
@article{6416238,
Author = {Kroll, N and Schultz, S and Smith, DR and Vier, DC},
Title = {Photonic Band Gap accelerator cavity design at 90
GHz},
Journal = {Proceedings of the IEEE Particle Accelerator
Conference},
Volume = {2},
Pages = {830-832},
Address = {New York, NY, USA},
Year = {1999},
Month = {December},
url = {http://dx.doi.org/10.1109/PAC.1999.795370},
Keywords = {accelerator cavities;},
Abstract = {In previous work we have proposed utilizing Photonic Band
Gap (PBG) structures as a new class of high-energy,
high-intensity accelerator cavities. We have completed
extensive MAFIA numerical calculations of multicell PBG
structures, with each cell consisting of a square array of
metal cylinders terminated by conducting sheets and
surrounded by microwave absorber on the periphery. We find
that our PBG structure has good higher order mode
suppression, superior pumping properties, and potential
fabricational advantages when compared to conventional
cavity designs. These advantages scale favorably with
increasing frequency, leading us to propose use of a PBG
accelerator structure at W-band (91.392 GHz).},
Key = {6416238}
}
@article{99114907465,
Author = {Smith, DR and Vier, DC and Padilla, W and Nemat-Nasser, SC and Schultz,
S},
Title = {Loop-wire medium for investigating plasmons at microwave
frequencies},
Journal = {Applied Physics Letters},
Volume = {75},
Number = {10},
Pages = {1425-1427},
Year = {1999},
Month = {September},
url = {http://dx.doi.org/10.1063/1.124714},
Keywords = {Microwaves;Permittivity;Plasmas;Computer
simulation;},
Abstract = {A localized surface plasmon resonance is demonstrated at
microwave frequencies. The plasmon structure is based on the
assumption that the effective dielectric constant of the
loop wire is due to the self-inductance of the constituent
wire. The plasmon structure reveals subwavelength surface
plasmon resonances below the bulk plasma
frequency.},
Doi = {10.1063/1.124714},
Key = {99114907465}
}
@article{fds269664,
Author = {Schultz, S and Mock, J and Smith, DR and Schultz,
DA},
Title = {Nanoparticle based biological assays},
Journal = {Journal of Clinical Ligand Assay},
Volume = {22},
Number = {2},
Pages = {214-216},
Year = {1999},
Month = {June},
ISSN = {1081-1672},
Abstract = {An introduction to the utilization of plasmon resonant
particles as optical labels for diverse biological
applications is presented. Plasmon resonant particles
(PRP(TM)) (Seashell Technology LLC, La Jolla, CA) are sub-
micron (40-100 nanometer), ultra-bright, nonbleaching,
multicolor, light scattering objects that can be attached to
standard biomolecules. The basic concepts and use of PRP in
various biological applications such as immunoassays and
histology, including in-situ hybridization, and tissue
labeling are discussed. We suggest that this new label will
replace and/or complement the traditional labels presently
used that are based on radioactivity, fluorescence, or
chemiluminescence. Since the detection of each individual
label is readily performed, the measured signal is a simple
count of all of the detected labels. Thus, the ultimate
sensitivity of the assay is set by both the degree of label
binding to the individual 'target' molecular entity, and the
corresponding number of labels that bind
nondiscriminately.},
Key = {fds269664}
}
@article{fds269638,
Author = {Hall, LJ and Smith, D},
Title = {Leading order textures for lepton mass matrices},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {59},
Number = {11},
Pages = {1-9},
Year = {1999},
Month = {May},
url = {http://dx.doi.org/10.1103/PhysRevD.59.113013},
Abstract = {In theories with three light neutrinos, certain simplicity
assumptions allow the construction of a complete list of
leading order lepton mass matrices. These matrices are
consistent with (Formula presented) and (Formula presented)
as suggested by measurements of atmospheric and solar
neutrino fluxes. The list contains twelve generic cases: two
have three degenerate neutrinos, eight have two neutrinos
forming a Dirac state, and in only two cases is one neutrino
much heavier than the other two. For each of these twelve
generic cases the possible forms for the perturbations which
yield (Formula presented) are given. Ten special textures
are also found. © 1999 The American Physical
Society.},
Doi = {10.1103/PhysRevD.59.113013},
Key = {fds269638}
}
@article{fds269663,
Author = {Martin, OJF and Girard, C and Smith, DR and Schultz,
S},
Title = {Generalized Field Propagator for Arbitrary Finite-Size
Photonic Band Gap Structures},
Journal = {Physical Review Letters},
Volume = {82},
Number = {2},
Pages = {315-318},
Publisher = {American Physical Society (APS)},
Year = {1999},
Month = {January},
url = {http://dx.doi.org/10.1103/physrevlett.82.315},
Abstract = {We investigate the properties of photonic hand gap
structures of finite size and arbitrary geometry using the
density of states deduced from scattering calculations. We
first demonstrate this procedure on a finite 2D array of
cylinders and then study at optical frequencies a system
formed by a finite array of finite height cylinders
positioned on a substrate and illuminated with an evanescent
field.},
Doi = {10.1103/physrevlett.82.315},
Key = {fds269663}
}
@article{fds269639,
Author = {Hall, LJ and Smith, D},
Title = {Cosmological constraints on theories with large extra
dimensions},
Journal = {Physical Review D - Particles, Fields, Gravitation and
Cosmology},
Volume = {60},
Number = {8},
Pages = {1-5},
Publisher = {American Physical Society (APS)},
Year = {1999},
Month = {January},
url = {http://dx.doi.org/10.1103/PhysRevD.60.085008},
Abstract = {In theories with large extra dimensions, constraints from
cosmology lead to nontrivial lower bounds on the
gravitational scale M, corresponding to upper bounds on the
radii of the compact extra dimensions. These constraints are
especially relevant to the case of two extra dimensions,
since only if M is 10 TeV or less do deviations from the
standard gravitational force law become evident at distances
accessible to planned submillimeter gravity experiments. By
examining the graviton decay contribution to the cosmic
diffuse gamma radiation, we derive, for the case of two
extra dimensions, a conservative bound (Formula presented)
corresponding to (Formula presented) well beyond the reach
of these experiments. We also consider the constraint coming
from graviton overclosure of the universe and derive an
independent bound (Formula presented) or (Formula presented)
© 1999 The American Physical Society.},
Doi = {10.1103/PhysRevD.60.085008},
Key = {fds269639}
}
@article{fds335158,
Author = {Smith, DR and D'Angelo, JP and Lee, K and Sturmfels,
R},
Title = {Actuator-based vibration control using position
feedback},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {3668},
Number = {II},
Pages = {1010-1016},
Year = {1999},
Month = {January},
Abstract = {A control strategy based on the relative position of the
armature and body, and an actuator which has the necessary
features to take advantage of this approach, is developed.
This strategy provides a modular approach to vibration
isolation because it acts independently of the dynamics of
any attached structures. While the system is unable to match
the peak performance of adaptive multiple-input
multiple-output controllers, it provides significant
broadband isolation with a simple, local controller. This
control can be implemented within the actuator, providing
more sophisticated controllers with an actuator that has
less force transmission than conventional devices. This
offers the potential of additional gains in isolation
performance.},
Key = {fds335158}
}
@article{fds269637,
Author = {Barbieri, R and Hall, LJ and Smith, D and Weiner, NJ and Strumia,
A},
Title = {Oscillations of solar and atmospheric neutrinos},
Journal = {Journal of High Energy Physics},
Volume = {2},
Number = {12},
Pages = {XVII-30},
Year = {1998},
Month = {January},
ISSN = {1029-8479},
url = {http://dx.doi.org/10.1088/1126-6708/1998/12/017},
Abstract = {Motivated by recent results from SuperKamiokande, we study
both solar and atmospheric neutrino fluxes in the context of
oscillations of the three known neutrinos. We aim at a
global view which identifies the various possibilities,
rather than attempting the most accurate determination of
the parameters of each scenario. For solar neutrinos we
emphasise the importance of performing a general analysis,
independent of any particular solar model and we consider
the possibility that any one of the techniques - chlorine,
gallium or water Cerenkov - has a large unknown systematic
error, so that its results should be discarded. The
atmospheric neutrino anomaly is studied by paying special
attention to the ratios of upward and downward going ve and
vμ fluxes. Both anomalies can be described in a minimal
scheme where the respective oscillation frequencies are
widely separated or in non-minimal schemes with two
comparable oscillation frequencies. We discuss explicit
forms of neutrino mass matrices in which both atmospheric
and solar neutrino fluxes are explained. In the minimal
scheme we identify only two 'zeroth order' textures that can
result from unbroken symmetries. Finally we discuss
experimental strategies for the determination of the various
oscillation parameters.},
Doi = {10.1088/1126-6708/1998/12/017},
Key = {fds269637}
}
@article{fds331027,
Author = {Keen, KM and Smith, D and Lee, BS},
Title = {Improved form of backfire bifilar helix conical beam
antenna},
Journal = {Microwave and Optical Technology Letters},
Volume = {14},
Number = {5},
Pages = {278-280},
Publisher = {WILEY},
Year = {1997},
Month = {April},
url = {http://dx.doi.org/10.1002/(SICI)1098-2760(19970405)14:5<278::AID-MOP7>3.0.CO;2},
Abstract = {The nonresonant-length backfire bifilar helix is often used
as a vehicle satcom antenna, as it has a circularly
polarized conical beam with azimuthal symmetry. Some antenna
configurations, however, exhibit poor back-lobe levels. It
is shown that radiation patterns can be significantly
improved by correct termination of the helix. © 1997 John
Wiley & Sons, Inc.},
Doi = {10.1002/(SICI)1098-2760(19970405)14:5<278::AID-MOP7>3.0.CO;2},
Key = {fds331027}
}
@article{fds331028,
Author = {Smith, D},
Title = {Low cost tyre monitoring system using electronic article
surveillance techniques},
Journal = {IEE Colloquium (Digest)},
Number = {46},
Year = {1997},
Month = {January},
Abstract = {A low cost method for tire monitoring is designed using a
passive LC circuit tag is used for contactless sensing.
Circuit response to bursts of radio frequency pulses is made
to vary with changes in tire pressure. Separate transmit and
receive antennas are employed with a distance of about 100
mm. between the antennas and the LC circuit. A good clean
signal is obtained with a significant reduction of signal
level for a small variation of resonant frequency. The
principles used in the system has the ability to detect
changes in circuit performance which make it suitable for
incorporation into a tire sidewall or tire
valve.},
Key = {fds331028}
}
@article{fds269660,
Author = {Smith, DR},
Title = {Thermal conductivity of fibrous glass board by guarded hot
plates and heat flow meters: An international
round-robin},
Journal = {International Journal of Thermophysics},
Volume = {18},
Number = {6},
Pages = {1557-1573},
Publisher = {Springer Nature},
Year = {1997},
Month = {January},
url = {http://dx.doi.org/10.1007/BF02575351},
Abstract = {In the early 1980s, an international round-robin was held in
which the apparent thermal conductivity of specimens of
fibrous glass insulation board was measured by users of
guarded hot plates (GHPs) and heat-flow meters (HFMs). The
round-robin was performed over a period of several years by
laboratories in Europe, North America, Australia, and the
Far East. Participants in this round-robin were organized
into 12 "loops," 8 for participants with GHPs and 4 for
those with HFMs. Each loop included laboratories located in
the same region of the world and sharing the same set of
specimens. In an attempt to obtain insight into the accuracy
of the measurements, participants were also asked to measure
the thermal conductivity of a layer of air. The data
submitted in this round-robin are exhibited and analyzed.
The overall agreement of individual measurements with a
least-squares fitted curve, as measured by one standard
deviation σ, was σ = 2.4% for GHPs and σ = 2.7% for HFMs.
Suggestions are made for conducting future round-robins of
this type. © 1997 Plenum Publishing Corporation.},
Doi = {10.1007/BF02575351},
Key = {fds269660}
}
@article{fds269661,
Author = {Slifka, AJ and Smith, DR},
Title = {Thermal expansion of an E-glass/vinyl ester composite from 4
to 293 K},
Journal = {International Journal of Thermophysics},
Volume = {18},
Number = {5},
Pages = {1249-1256},
Publisher = {Springer Nature},
Year = {1997},
Month = {January},
url = {http://dx.doi.org/10.1007/BF02575259},
Abstract = {We have measured the thermal expansion of the three
principal orthogonal directions of an E-glass/vinyl ester
structural composite from liquid helium temperature, 4.2 K,
to room temperature, 293 K. The linear thermal expansion at
4.2 K ranged from -0.23 to -0.71%, referenced to zero
expansion at 293 K. We fitted the linear thermal expansion
data from 4.2 to 293 K with a cubic polynomial for each of
the three principal orthogonal directions.},
Doi = {10.1007/BF02575259},
Key = {fds269661}
}
@article{5788007,
Author = {Li, D. and Kroll, N. and Smith, D.R. and Schultz,
S.},
Title = {Wake-field studies on Photonic Band Gap accelerator
cavities},
Journal = {AIP Conf. Proc. (USA)},
Number = {398},
Pages = {528 - 37},
Address = {Lake Tahoe, CA, USA},
Year = {1997},
Keywords = {accelerator cavities;photonic band gap;Q-factor;wakefield
accelerators;},
Abstract = {We have studied the wake-field of several metal Photonic
Band Gap (PBG) cavities which consist of either a square or
a hexagonal array of metal cylinders, bounded on top and
bottom by conducting or superconducting sheets, surrounded
by placing microwave absorber at the periphery or by
replacing outer rows of metal cylinders with lossy
dielectric ones, or by metallic walls. A removed cylinder
from the center of the array constitutes a site defect where
a localized electromagnetic mode can occur. While both
monopole and dipole wake-fields have been studied, we
confine our attention here mainly to the dipole case. The
dipole wake-field is produced by modes in the propagation
bands which tend to fill the entire cavity more or less
uniformly and are thus easy to damp selectively. MAFIA time
domain simulation of the transverse wake-field has been
compared with that of a cylindrical pill-box comparison
cavity. Even without damping the wake-field of the metal PBG
cavity is substantially smaller than that of the pill-box
cavity and may be further reduced by increasing the size of
the lattice. By introducing lossy material at the periphery
we have been able to produce Q factors for the dipole modes
in the 40 to 120 range without significantly degrading the
accelerating mode},
Key = {5788007}
}
@article{5730769,
Author = {Smith, D.R.},
Title = {A simplified module interface style for synthesis
education},
Journal = {Proceedings. 1997 IEEE International Conference on
Microelectronic Systems Education, MSE'97. `Doing More with
Less in a Rapidly Changing Environment' (Cat.
No.97TB100127)},
Pages = {73 - 4},
Address = {Arlington, VA, USA},
Year = {1997},
url = {http://dx.doi.org/10.1109/MSE.1997.612553},
Keywords = {application specific integrated circuits;built-in self
test;circuit CAD;computer aided instruction;computer science
education;educational courses;electronic engineering
education;field programmable gate arrays;integrated circuit
design;integrated memory circuits;logic CAD;random-access
storage;},
Abstract = {In the synthesis course at Stony Brook we have made it
possible for students to complete the tasks of
specification, simulation, synthesis, FPGA fitting, low
level verification, both on homework sets and on a
non-trivial project, all within one semester. We do it by
using a set of standard components and a consistent and
standardized interface throughout: for the library
components, for the designs themselves, and for the
testbenches. It is possible to get designs working quickly
because the control is implicit and the synthesis scripts
are standardised, even though the projects covered a range
from radix 4 multiplication and division, memory
interleaver, a synchrotron controller, and parts for a 3
dimensional graphics engine. The paper summarizes the method
and illustrates it on a design for a RAM built-in
self-test},
Key = {5730769}
}
@article{5788006,
Author = {Smith, D.R. and Derun Li and Vier, D.C. and Kroll, N. and Schultz, S.},
Title = {Recent progress on Photonic Band Gap accelerator
cavities},
Journal = {AIP Conf. Proc. (USA)},
Number = {398},
Pages = {518 - 27},
Address = {Lake Tahoe, CA, USA},
Year = {1997},
Keywords = {accelerator cavities;photonic band gap;},
Abstract = {We report on the current status of our program to apply
Photonic Band Gap (PBG) concepts to produce novel
high-energy, high-intensity accelerator cavities. The PBG
design on which we have concentrated our inital efforts
consists of a square array of metal cylinders, terminated by
conducting or superconducting sheets, and surrounded by
microwave absorber on the periphery of the structure. A
removed cylinder from the center of the array constitutes a
site defect where a localized electromagnetic mode can
occur. In previous work, we have proposed that this
structure could be utilized as an accelerator cavity, with
advantageous properties over conventional cavity designs. In
the present work, we present further studies, including
MAFIA-based numerical calculations and experimental
measurements, demonstrating the feasibility of using the
proposed structure in a real accelerator
application},
Key = {5788006}
}
@article{fds269658,
Author = {Shtrikman, S and Smith, DR},
Title = {Analytic and quasi-analytic formulae for MR
heads},
Journal = {IEEE Transactions on Magnetics},
Volume = {32},
Number = {1},
Pages = {43-48},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {1996},
Month = {December},
ISSN = {0018-9464},
url = {http://dx.doi.org/10.1109/20.477548},
Abstract = {We present analytic procedures for calculating the
magnetostatic and response functions of magnetoresistive
(MR) recording heads. To apply these methods we make several
simplifying approximations, which have been found to be
valid for typical recording head geometries. In particular,
we show how to calculate the bias magnetization
distribution, ideal transition pulse shape, and frequency
response for the unshielded MR (UMR) head. To do this, we
summarize a method based on conformal mapping and
reciprocity, and present a simpler direct method which
produces identical results. We extend this alternate method
to find analytic expressions for the saturated bias
magnetization. © 1996 IEEE.},
Doi = {10.1109/20.477548},
Key = {fds269658}
}
@article{fds269659,
Author = {Shtrikman, S and Smith, DR},
Title = {Analytical formulas for the unshielded magnetoresistive
head},
Journal = {IEEE Transactions on Magnetics},
Volume = {32},
Number = {3 PART 2},
Pages = {1987-1994},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {1996},
Month = {December},
ISSN = {0018-9464},
url = {http://dx.doi.org/10.1109/20.492899},
Abstract = {The magnetostatic and frequency response characteristics of
the unshielded magnetoresistive (UMR) head have been
previously calculated by means of a numerical simulation
which ultilized the principle of reciprocity to reduce the
computational task of solving the relevant micromagnetic
equations. The results of the simulation were found to be in
excellent agreement with measurements made on actual UMR
heads [N. Smith and D. Wachenschwanz, IEEE Trans. Magn.,
MAG-23, p. 2494 (1987)]. In the present paper, we analyze an
idealized UMR head, following in spirit the procedure
outlined in the previous work; however, we formulate the
problem by introducing simplifying approximations which
retain the essential physics, deriving simple equations
describing the bias magnetization distribution, and the
frequency response. The equations obtained in this way are
analytic and simple, yet in agreement with the micromagnetic
simulation and experimental measurements. Furthermore, the
analytic formulas provide a source of insight which may be
of use in the design or optimization of UMR recording heads.
© 1996 IEEE.},
Doi = {10.1109/20.492899},
Key = {fds269659}
}
@article{fds331029,
Author = {Geen, D and Smith, D},
Title = {Compact anechoic chamber and antenna measurement system for
microwave teaching and research applications},
Journal = {Microwave and Optical Technology Letters},
Volume = {12},
Number = {3},
Pages = {150-154},
Publisher = {WILEY},
Year = {1996},
Month = {June},
url = {http://dx.doi.org/10.1002/(SICI)1098-2760(19960620)12:3<150::AID-MOP8>3.0.CO;2},
Abstract = {The design of a small, low-cost anechoic chamber well suited
to the teaching of antenna theory and measurement techniques
is described. The chamber design allows for dismantling,
relocation, and reassembly when required. Its performance in
the range 18-30 GHz has been found to be good. The
incorporation of the chamber into an automated antenna
pattern measurement system for education and research
purposes is also described. © 1996 John Wiley & Sons,
Inc.},
Doi = {10.1002/(SICI)1098-2760(19960620)12:3<150::AID-MOP8>3.0.CO;2},
Key = {fds331029}
}
@article{96023036050,
Author = {Suzuki, T and Yu, PKL and Smith, DR and Schultz, S},
Title = {Experimental and theoretical study of dipole emission in the
two-dimensional photonic band structure of the square
lattice with dielectric cylinders},
Journal = {Journal of Applied Physics},
Volume = {79},
Number = {2},
Pages = {582-594},
Year = {1996},
Month = {January},
url = {http://dx.doi.org/10.1063/1.360800},
Keywords = {Electromagnetic waves;Crystal lattices;Dielectric
materials;Green's function;Integration;Microwaves;Frequencies;Electric
fields;Emission spectroscopy;Eigenvalues and
eigenfunctions;Interpolation;Antennas;},
Abstract = {Dipole radiation in a two-dimensional periodic dielectric
structure is studied both theoretically and experimentally
in this article. For the two-dimensional square lattice
structure with dielectric cylinders, the emission power of
an electric dipole in the photonic band structure is
computed numerically by a combination of the plane wave
method, the dyadic Green's function, the Poynting theorem,
and the triangular integration method. The theoretical
results are compared with experimental measurements in a
microwave frequency region. The computed radiation spectra
in the photonic band structure show good agreement with the
experimentally measured results. © 1996 American Institute
of Physics.},
Doi = {10.1063/1.360800},
Key = {96023036050}
}
@article{fds331030,
Author = {Geen, D and Smith, D},
Title = {Performance of a novel dual-band horn antenna @
20/30GHz},
Journal = {1996 26th European Microwave Conference, EuMC
1996},
Volume = {2},
Pages = {795-798},
Publisher = {IEEE},
Year = {1996},
Month = {January},
url = {http://dx.doi.org/10.1109/EUMA.1996.337697},
Abstract = {The design for a narrow angle feed horn radiating low levels
of cross polarisation in two widely separated frequency
bands is presented. The horn uses corrugations to control
the cross polarisation in the lower frequency band and a
synthesised aperture distribution controlled by a TM 11 mode
transducer in the input waveguide to reduce cross
polarisation in the upper frequency band. Provisional
theoretical radiation patterns and VSWR characteristics are
included to indicate antenna performance. © 1996
IEEE.},
Doi = {10.1109/EUMA.1996.337697},
Key = {fds331030}
}
@article{fds331031,
Author = {Geen, D and Smith, D},
Title = {Wide flare-angle horn antenna with means for radiating low
levels of crosspolarisation in two widely separated
frequency bands},
Journal = {IEEE Antennas and Propagation Society, AP-S International
Symposium (Digest)},
Volume = {3},
Pages = {2026-2029},
Year = {1996},
Month = {January},
Abstract = {Preliminary results for a horn antenna with good crosspolar
performance in two discrete frequency bands in addition to
desirable VSWR characteristics are presented. The horn
combines two different design concepts. It uses corrugations
to control the crosspolarisation in the lower frequency band
when the corrugation depth is approximately λ/4, and in the
upper frequency band when the corrugation depth tends
towards λ/2, crosspolarisation is reduced by controlling
the aperture distribution with the addition of the necessary
magnitude and phase of TM11 mode controlled by a mode
transducer in the input waveguide.},
Key = {fds331031}
}
@article{fds269657,
Author = {Suzuki, T and Yu, PKL and Smith, DR and Schultz, S},
Title = {New type of waveguide structures with photonic band
structures},
Journal = {IEEE MTT-S International Microwave Symposium
Digest},
Volume = {2},
Pages = {911-914},
Year = {1996},
Month = {January},
Abstract = {We study a new type of waveguide structures -
two-dimensional photonic crystals sandwiched between two
metal conductors. In the structures, not only the
electromagnetic propagation, but also the radiation spectra
can be controlled. Radiation from microwave dipole antennas
can be completely suppressed in band gaps and enormously
enhanced at specific pass bands frequencies.},
Key = {fds269657}
}
@article{5392654,
Author = {Smith, D.R.},
Title = {Hardware synthesis from encapsulated Verilog
modules},
Journal = {Proceedings. International Conference on
Application-Specific Systems, Architectures and Processors
1996 (Cat. No.96TB100068)},
Pages = {284 - 92},
Address = {Chicago, IL, USA},
Year = {1996},
url = {http://dx.doi.org/10.1109/ASAP.1996.542823},
Keywords = {computational complexity;hardware description
languages;inference mechanisms;logic design;},
Abstract = {This paper discusses experience with synthesis from a
Verilog writing style using encapsulated modules. The method
is shown to be capable of significant advantages in
reduction of code complexity, re-use of submodules, and
automatic inference of control. In order to pass synthesis
and low level simulation, care must be taken in the
translation of the encapsulated modules through an
intermediate style accessible to industry synthesizers. If
the encapsulated modules are edge activated then the control
points need to be staggered in time through the clock cycle
as control is passed down through the hierarchy. Examples
are given of a such an intermediate style which is
acceptable to synthesis and low level simulation. A
conclusion discusses other implications of adapting the
objective style to hardware design},
Key = {5392654}
}
@article{fds269574,
Author = {Hayward, TD and Dowell, DH and Vetter, AM and Lancaster, C and Milliman,
L and Smith, D and Adamski, J and Parazzoli, C},
Title = {High duty factor electron linac for FEL},
Journal = {Proceedings of the IEEE Particle Accelerator
Conference},
Volume = {1},
Pages = {248-250},
Year = {1995},
Month = {December},
Abstract = {An 18-MeV, 433-MHz linac capable of operating at 25% RF duty
factor (DF) is being commissioned for FEL applications.
Comprising a two-cell RF photocathode injector followed by
four new multicell cavities, the linac is an extension of
the photoinjector which previously delivered 5 nC at 27 MHz
micropulse repetition frequency, and 25% DF. The system is
constructed using equipment from the Ground Based Laser and
the Average Power Laser Experiment (APLE). The linac can
serve as the driver for an infrared FEL or as the
preaccelerator for a higher energy linac driving a visible
FEL.},
Key = {fds269574}
}
@article{fds269656,
Author = {Goplen, B and Ludeking, L and Smith, D and Warren,
G},
Title = {User-configurable MAGIC for electromagnetic PIC
calculations},
Journal = {Computer Physics Communications},
Volume = {87},
Number = {1-2},
Pages = {54-86},
Publisher = {Elsevier BV},
Year = {1995},
Month = {May},
ISSN = {0010-4655},
url = {http://dx.doi.org/10.1016/0010-4655(95)00010-D},
Abstract = {MAGIC is a user-configurable code that solves Maxwell's
equations together with Lorentz particle motion. A variety
of 2D, finite-difference electromagnetic algorithms and 3D
particle-in-cell algorithms may be combined in
problem-specific ways to provide fast, accurate,
steady-state and transient calculations for many research
and design needs. Default configurations provide good speed
and accuracy for most applications, and a library of
templates offers optimized algorithm configurations for
specific devices. A programmable processor named POSTER
provides advanced post-analysis of the field and particle
solutions. Coordinate systems, boundary conditions,
geometry, and materials are specified by the user, and grid
generation can be manual, user-assisted, or fully automatic.
MAGIC has a fully 3D counterpart called SOS. Programs exist
to connect these analysis tools to parametric and CAD input
from an integrated design environment. ©
1995.},
Doi = {10.1016/0010-4655(95)00010-D},
Key = {fds269656}
}
@article{fds331032,
Author = {Geen, D and Smith, D},
Title = {Design, construction and performance of a small, low cost
anechoic measuring system for research applications},
Journal = {IEEE Antennas and Propagation Society, AP-S International
Symposium (Digest)},
Volume = {4},
Pages = {1738-1741},
Year = {1995},
Month = {January},
Abstract = {A low cost anechoic measuring system has been designed,
constructed and evaluated. It consists of a small anechoic
chamber, designed specifically for measurements of high
performance feed horns within the range 18-30GHz, and a
simple antenna positioner. The chamber features hinged sides
to ease relocation and improve access and is characterised
by a simple and low cost design in addition to a
reflectivity level better than -52dB. The antenna positioner
is under the control of a PC which interfaces with a network
analyser to achieve a fully automated magnitude and phase
pattern measuring system.},
Key = {fds331032}
}
@article{fds332088,
Author = {Geen, D and Smith, D},
Title = {Enhanced teaching of antenna theory and measurement
techniques using a low cost anechoic measuring
system},
Journal = {1995 25th European Microwave Conference},
Volume = {2},
Pages = {942-944},
Publisher = {IEEE},
Year = {1995},
Month = {January},
ISBN = {9780000000002},
url = {http://dx.doi.org/10.1109/EUMA.1995.337100},
Abstract = {A low cost anechoic chamber and simple antenna positioner
have been constructed. They have been incorporated into a
fully automated antenna pattern measuring system which takes
advantage of the department's existing network analyser as
both the source and receiver to obtain accurate results and
simplify data collection. The chamber has been designed as
part of a research project investigating horn antennas
within the range 18-30GHz and as such is characterised by a
reflectivity level better than ¿52dB [1]. However, the
improved physical and visual access to the chamber as a
result of it's design, and the system's ease of use brought
about by the convenience of the network analyser make it a
useful tool with which to enhance the teaching of both
antenna theory and antenna measurement techniques.},
Doi = {10.1109/EUMA.1995.337100},
Key = {fds332088}
}
@article{5212036,
Author = {Smith, D.R. and Morris, S.C.},
Title = {VHDL-based methodology for modelling computer communication
systems},
Journal = {1995 Canadian Conference on Electrical and Computer
Engineering (Cat. No.95TH8103)},
Volume = {vol.2},
Pages = {627 - 31},
Address = {Montreal, Que., Canada},
Year = {1995},
url = {http://dx.doi.org/10.1109/CCECE.1995.526282},
Keywords = {CAD;computer networks;digital simulation;hardware
description languages;telecommunication computing;},
Abstract = {Currently the design and development process employs
different modelling and design techniques at each level of
system abstraction. This makes the process inefficient and
costly. VHDL, however, has the potential to unify this
process. VHDL's widespread use in the design, development
and synthesis of ASICs is an indication of its success. It
has already lead to revolutionary changes in the way
traditional systems design is performed. Today new ASIC
design starts with a VHDL description of the circuit and
then the ASIC is synthesized from this description. The next
step in VHDL's evolutionary use is in the modelling of
systems at higher levels of abstraction. The specification
and design of an entire large scale system is possible. This
paper presents a VHDL-based methodology for modelling
computer communication systems, called VCCS, to demonstrate
VHDL's ability to design and model systems at a high level
of abstraction. The methodology, design strategy and primary
characteristics of the VHDL implementation are
explained},
Key = {5212036}
}
@article{5081597,
Author = {Smith, DR and Schildknecht, RR},
Title = {A circuit-switched shared-memory multiprocessor},
Journal = {Int. J. Mini Microcomput. (USA)},
Volume = {17},
Number = {3},
Pages = {108-118},
Year = {1995},
Keywords = {circuit switching;CMOS integrated circuits;delays;hypercube
networks;message passing;performance evaluation;shared
memory systems;virtual machines;},
Abstract = {A circuit-switched shared-memory multiprocessor based on the
2D spanning bus hypercube is described. This design
eliminates most of the processing overhead attributed to
message passing systems. Circuit switching allows the sender
to transfer directly into the receiver's address space by
establishing a dedicated transmission path between the two
nodes. Thus, data sets for cascaded calculations (using
separate processors) can be prepared directly in the
following processor's address space. A system was designed
as an extension to a VME-based multiprocessor. This work
investigates the potential efficiency of a circuit-switched
topology using a simulation model. A simulation model for
the implementation was developed using the NETWORK II.5
simulation system. The simulation results are used to
specify the performance requirements of a switching element
for a hypercube-connected multiprocessor. Next, the design
and the operation of the interconnection mechanism are
detailed. The design was implemented and tested in 3 μm
CMOS technology using the suite of Mentor Graphics tools to
establish the connection and communication delay parameters
for the system architecture. Using the derived VLSI switch
parameters, the performance of the 2D spanning bus hypercube
is compared against that of two message-passing
architectures based on the binary hypercube and the spanning
bus hypercube. In both cases, the circuit-switched
shared-memory design significantly reduced the processing
overhead and the delay times involved in data
transfers},
Key = {5081597}
}
@article{4983835,
Author = {Hudson, R and Chikhani, AY and Ferland, G and Smith, DR and Salama,
MMA},
Title = {Modelling the interaction of multiple small harmonic current
sources in an isolated power distribution
system},
Journal = {Can. J. Electr. Comput. Eng. (Canada)},
Volume = {20},
Number = {2},
Pages = {85-90},
Year = {1995},
Keywords = {digital simulation;distribution networks;harmonic
distortion;load (electric);naval engineering computing;power
system analysis computing;power system harmonics;ships;software
packages;},
Abstract = {Given the growing number of interactive nonlinear loads in
power distribution systems, some techniques to monitor the
spread of harmonics through the power system need to be
developed. This paper examines the nature of harmonics in a
naval power distribution system and develops a harmonic
model using the CYMHARMO package to monitor current sources
and the interaction that can occur in the Canadian Patrol
Frigate (CPF) power distribution system. The results
indicate that a significant level of harmonics can exist in
the CPF system due to 43 identified harmonic current
sources. The presence of any capacitive loads will only
serve to increase the level of distortion if resonance
occurs. With shipboard testing to confirm equipment loading
and identify capacitive elements, the model will be a useful
tool for naval engineers to examine and modify the CPF
system},
Key = {4983835}
}
@article{4759795,
Author = {Smith, DR and Schultz, S and Kroll, N and Sigalas, M and Ho, KM and Soukoulis, CM},
Title = {Experimental and theoretical results for a two-dimensional
metal photonic band-gap cavity},
Journal = {Applied Physics Letters},
Volume = {65},
Number = {5},
Pages = {645-647},
Publisher = {AIP Publishing},
Year = {1994},
Month = {December},
ISSN = {0003-6951},
url = {http://dx.doi.org/10.1063/1.112258},
Keywords = {defect electron energy states;energy gap;localised electron
states;optical constants;},
Abstract = {We demonstrate, by both microwave experiments and numerical
simulation, that a two-dimensional lattice of metal
cylinders can form a complete photonic band-gap (PBG)
structure. The band structure exhibits a single broad PBG
extending from zero frequency to a threshold frequency,
above which all modes may propagate in some direction. A
single cylinder removed from the lattice produces a defect
mode localized about the defect site, with an energy density
attenuation rate of 30 dB per lattice constant. The
frequency dependence of the transmission through a finite
thickness of this structure is also calculated in good
agreement with the measurements. We suggest that the defect
mode resonant cavity when formed by appropriate low loss
metals may be advantageous for use in PBG high energy
accelerator structures that we are evaluating.},
Doi = {10.1063/1.112258},
Key = {4759795}
}
@article{fds335159,
Author = {Smith, DR and Fonck, RJ and McKee, GR and Schoenbeck, N and Uzun-Kaymak,
I and Winz, G and Feder, F and Feder, R and Labik, G and Stratton,
BC},
Title = {Overview of the beam emission spectroscopy diagnostic system
on the National Spherical Torus Experiment},
Journal = {IEEE Transactions on Magnetics},
Volume = {30},
Number = {4},
Pages = {2665-2668},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {1994},
Month = {January},
url = {http://dx.doi.org/10.1109/20.305828},
Abstract = {A beam emission spectroscopy (BES) system has been installed
on the National Spherical Torus Experiment (NSTX) to study
ion gyroscale ?uctuations. The BES system measures
Dαemission from a deuterium neutral heating beam. The
system includes two optical views centered at r/a ≈0.45
and 0.85 and aligned to magnetic ?eld pitch angles at the
neutral beam. f/1.5 collection optics produce 2-3 cm spot
sizes at the neutral beam. The initial channel layout
includes radial arrays, poloidal arrays, and two-dimensional
grids. Radial arrays provide coverage from r/a≈0.1 to
beyond the last-closed flux surface. Photodetectors and
digital filters provide high-sensitivity, low-noise
measurements at frequencies of up to 1 MHz. The BES system
will be a valuable tool for investigating ion gyroscale
turbulence and Alfv'n/energetic particle modes on NSTX. ©
1994 IEEE},
Doi = {10.1109/20.305828},
Key = {fds335159}
}
@article{4651529,
Author = {Smith, DR and Schultz, S and McCall, SL and Platzmann,
PM},
Title = {Defect studies in a two-dimensional periodic photonic
lattice},
Journal = {J. Mod. Opt. (UK)},
Volume = {41},
Number = {2},
Pages = {395-404},
Publisher = {Informa UK Limited},
Year = {1994},
url = {http://dx.doi.org/10.1080/09500349414550401},
Keywords = {energy gap;microwave spectra of inorganic
solids;},
Abstract = {Structures arranged so as to exhibit a complete photonic
bandgap (PGB) have been proposed for a variety of
technological applications. McCall et al. have reported an
experimental and numerical investigation of microwave
propagation in a two-dimensional array consisting of
low-loss high-dielectric-constant cylinders. This system was
shown to have a complete PBG, as well as a defect mode. Here
we present an experimental investigation of the properties
of a variety of defect modes, created by altering a region
in the otherwise periodic lattice of dielectric cylinders.
These alterations include removing one or more cylinders
from the lattice in a variety of spatial separations and
orientations, and also a procedure whereby the defect mode
frequency may be tuned by slightly perturbing those
cylinders closest to the defect region. The implication of
these results for supercell numerical simulations and
potential technical applications are discussed},
Doi = {10.1080/09500349414550401},
Key = {4651529}
}
@article{94041257776,
Author = {Schultz, S and Smith, DR and Kroll, N},
Title = {Photonic band gap resonators for high energy
accelerators},
Journal = {Proceedings of the IEEE Particle Accelerator
Conference},
Volume = {4},
Pages = {2559-2563},
Address = {Washington, DC, USA},
Year = {1993},
Month = {December},
url = {http://dx.doi.org/10.1109/PAC.1993.309387},
Keywords = {Particle accelerators;Microwave devices;Mathematical
models;Energy gap;Model structures;Cryogenics;Dielectric
properties;Electromagnetic waves;},
Abstract = {We have proposed that a new type of microwave resonator,
based on Photonic Band Gap (PBG) structures, may be
particularly useful for high energy accelerators. We provide
an explanation of the PBG concept and present data which
illustrate some of the special properties associated with
such structures. Further evaluation of the utility of PBG
resonators requires laboratory testing of model structures
at cryogenic temperatures, and at high fields. We provide a
brief discussion of our test program, which is currently in
progress.},
Key = {94041257776}
}
@article{94031223333,
Author = {Smith, DR and Dalichaouch, R and Kroll, N and Schultz, S and Mc Call,
SL and Platzman, PM},
Title = {Photonic band structure and defects in one and two
dimensions},
Journal = {Journal of the Optical Society of America B: Optical
Physics},
Volume = {10},
Number = {2},
Pages = {314-321},
Publisher = {The Optical Society},
Year = {1993},
Month = {January},
url = {http://dx.doi.org/10.1364/JOSAB.10.000314},
Keywords = {Energy gap;Band structure;Electromagnetic wave
propagation;Quantum theory;},
Abstract = {We present an experimental and numerical study of
electromagnetic wave propagation in one-dimensional (D) and
two-dimensional (2D) systems composed of periodic arrays of
dielectric scatterers. We demonstrate that there are regions
of frequency for which the waves are exponentially
attenuated for all propagation directions. These regions
correspond to band gaps in the calculated band structure,
and such systems are termed photonic band-gap (PBG)
structures. Removal of a single scatterer from a PBG
structure produces a highly localized defect mode, for which
the energy density decays exponentially away from the defect
origin. Energy-density measurements of defect modes are
presented. The experiments were conducted at 6-20 GHz, but
we suggest that they may be scaled to infrared frequencies.
Analytic and numerical solutions for the band structure and
the defect states in D structures are derived. Applications
of 2D PBG structures are briefly discussed. © 1993 Optical
Society of America.},
Doi = {10.1364/JOSAB.10.000314},
Key = {94031223333}
}
@article{fds343758,
Author = {Smith, D and Livingstone, B and Jefferson, RL},
Title = {Effects of load impedance os the dimensions and beamwidth of
a dual feed nearly square patch antenna for circular
polarisations},
Journal = {IEEE Antennas and Propagation Society, AP-S International
Symposium (Digest)},
Volume = {1992-June},
Pages = {1427-1430},
Year = {1992},
Month = {January},
ISBN = {0780307305},
url = {http://dx.doi.org/10.1109/APS.1992.221625},
Doi = {10.1109/APS.1992.221625},
Key = {fds343758}
}
@article{fds269655,
Author = {Smith, N and Smith, DR and Shtrikman, S},
Title = {Analysis Of A Dual Magnetoresistive Head},
Journal = {IEEE Transactions on Magnetics},
Volume = {28},
Number = {5},
Pages = {2295-2297},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {1992},
Month = {January},
url = {http://dx.doi.org/10.1109/20.179473},
Abstract = {A recently proposed dual magnetoresistive (DMR) reproduce
head, consisting of two identical, adjacent MR stripes
separated by a nonmagnetic spacer and connected electrically
in parallel, was shown to have potential in very high
density magnetic recording applications. The present work
considers the micromagnetics of this device, and derives
approximate analytical expressions for the expected signal
output as a function of linear recording density. The
results are found to be in good agreement with numerical
computations based on reciprocity. Comparison with
analytical results for other MR head configurations is
discussed. © 1992 IEEE},
Doi = {10.1109/20.179473},
Key = {fds269655}
}
@article{fds331033,
Author = {Jefferson, RL and Smith, D},
Title = {Dual circular polarised microstrip antenna design for a
passive microwave transponder},
Journal = {IEE Conference Publication},
Number = {333 pt 1},
Pages = {141-143},
Year = {1991},
Month = {January},
ISBN = {0852965087},
Abstract = {This work has extended the use of a simple cavity model to
the case of a dual feed nearly square antenna for circular
polarisation. The addition of the second feed is found to
alter the conditions required for the generation of circular
polarisation and requires a change in antenna dimensions to
compensate. Preliminary experimental work has supported the
results obtained from the model.},
Key = {fds331033}
}
@article{fds269653,
Author = {McCall, SL and Platzman, PM and Dalichaouch, R and Smith, D and Schultz,
S},
Title = {Microwave propagation in two-dimensional dielectric
lattices},
Journal = {Physical Review Letters},
Volume = {67},
Number = {15},
Pages = {2017-2020},
Publisher = {American Physical Society (APS)},
Year = {1991},
Month = {January},
url = {http://dx.doi.org/10.1103/PhysRevLett.67.2017},
Abstract = {We have calculated and measured the properties of X-band
microwaves propagating in a 2D array of low-loss
high-dielectric-constant cylinders. Transmission bands and
photonic band gaps are conclusively identified in excellent
agreement with the theoretical predictions. Detailed data on
the properties of isolated defect states are also presented.
We conclude that studies of this model scattering system
allow the quantitative evaluation and testing of ideas
regarding wave propagation and localization in strongly
scattering media. © 1991 The American Physical
Society.},
Doi = {10.1103/PhysRevLett.67.2017},
Key = {fds269653}
}
@article{4682078,
Author = {Smith, D.R. and Schildknecht, R.R.},
Title = {Design of an intelligent switch for a shared memory
two-dimensional spanning bus hypercube multiprocessor},
Journal = {Proceedings of the Fourth ISMM/IASTED International
Conference Parallel and Distributed Computing and Systems -
II},
Pages = {25 - 7},
Address = {Washington, DC, USA},
Year = {1991},
Keywords = {CMOS integrated circuits;delays;digital simulation;hypercube
networks;message passing;shared memory systems;},
Abstract = {Multiprocessor architectures can be used to increase the
amount of work that can be performed and to divide the
software effort into manageable tasks units. The two major
methods of inter-processor communication in these
multiprocessors make use of message passing using a
communications sub-system or the preparation of data buffers
in processor shared memory. A message passing system
requires a certain amount of processing overhead which
subtracts from the total processing resource. A circuit
switched, shared memory multiprocessor based on the
two-dimensional spanning bus hypercube is described. This
design eliminates most of the processing overhead attributed
to message passing systems. Circuit switching allows the
sender to transfer directly into the receivers' address
space by establishing a dedicated transmission path between
the two nodes. Thus, data sets for cascaded calculations
(using separate processors) can be prepared directly in the
following processors' address space. This work details the
design and the operation of the interconnection mechanism.
The paper describes the global and local addressing schemes
that were devised to allow a VME bus-based multiprocessor to
operate as a shared memory multiprocessor configured as a
two-dimensional spanning bus hypercube. An intelligent
switch has been designed to permit multiple connections
within the spanning bus hypercube. A simulation model for
the implementation was developed using the NETWORK II.5
simulation system. The design was implemented and tested in
3 μm CMOS using the suite of Mentor Graphics tools to
establish the connection and communication delay parameters
for the system architecture},
Key = {4682078}
}
@article{fds331034,
Author = {Smith, D and Jefferson, RL},
Title = {Dual polarized microstrip antenna design for a polarization
shift keying microwave transponder},
Journal = {Conference Proceedings - European Microwave
Conference},
Number = {19},
Pages = {149-154},
Year = {1989},
Month = {December},
ISBN = {0946821763},
Abstract = {This work describes a novel method of data transmission by
means of polarization shift keying. It analyzes the system
performance in terms of S/N ratio and defines the required
antenna cross polarization performance to achieve an
acceptable S/N ratio. A theoretical analysis of antenna
cross polarization performance is provided. This analysis
predicts a dependence of cross polarization upon antenna
substrate and angle of observation which is supported by
experimental evidence. This work has also enabled accurate
design criteria to be successfully applied to the
fabrication of a dual feed circular disc antenna for
polarization shift keying at 2.45GHz.},
Key = {fds331034}
}
@article{fds344698,
Author = {BURTON, RM and FORSYTH, JD and OBEL, B},
Title = {ORGANIZATIONAL RESPONSES TO THE NEW BUSINESS CONDITIONS - AN
EMPIRICAL PERSPECTIVE - PREFACE},
Journal = {TECHNOVATION},
Volume = {8},
Number = {1-3},
Pages = {R7-R7},
Year = {1988},
url = {http://dx.doi.org/10.1016/0166-4972(88)90049-1},
Doi = {10.1016/0166-4972(88)90049-1},
Key = {fds344698}
}
@article{fds343759,
Author = {Smith, DR and Stair, AT and Steed, AJ and Burt, DA},
Title = {Cryogenic infrared radiance instrumentation for shuttle
(Cirris)},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {265},
Pages = {310-315},
Year = {1981},
Month = {April},
url = {http://dx.doi.org/10.1117/12.959879},
Abstract = {In recent years, the Air Force Geophysics Laboratory has
flown several rocketborne experiments with cryogenic
interferometers to measure natural and induced infrared
atmospheric emissions. AFGL is currently developing two
separate shuttle payloads based on advanced versions of
these rocket sensors mated to cryogenic high off-axis
rejection telescopes. CIRRIS will have a spectral resolution
capability of better than 1 cm-1 over the 4 - 25 μm region,
and will be dedicated to measurements of infrared emissions
from the earthlimb at altitudes from 30 - 300 km. CIRRIS
data is expected to provide an assessment of the effects of
the atmosphere on current and planned AF space systems and a
comprehensive data base for atmospheric modelling.
Additional CIRRIS objectives are to measure and assess the
effects of shuttle contamination on other planned shuttle
experiments and to obtain data on a large number of
atmospheric trace species. Specifics of the CIRRIS
instrument, measurement plan and capabilities are presented.
© 1981 SPIE.},
Doi = {10.1117/12.959879},
Key = {fds343759}
}
@article{1458990,
Author = {Bhatt, D. and Smith, D.R.},
Title = {Communications in a hierarchical multicomputer},
Journal = {COMPCON 79 Proceedings. Using Microprocessors, Extending Our
Reach},
Pages = {374 - 9},
Address = {Washington, DC, USA},
Year = {1979},
Keywords = {computer architecture;multiprocessing systems;},
Abstract = {Describes the design of the hardware and the basic functions
of the operating system for a tree organized multicomputer
now being constructed in the Computer Science department at
Stony Brook. The processors have separate local memories and
are interconnected by communication links specialized for
the transfers of short control type messages and large
blocks of data. Also discussed is the influence of previous
simulation studies and the operating system considerations
on the design of the hardware and interprocessor
communication protocols},
Key = {1458990}
}
@article{1121896,
Author = {Harris, J.A. and Smith, D.R.},
Title = {Hierarchical multiprocessor organizations},
Journal = {4th Annual Symposium on Computer Architecture},
Pages = {41 - 8},
Address = {Silver Spring, MD, USA},
Year = {1977},
url = {http://dx.doi.org/10.1145/800255.810651},
Keywords = {computer architecture;multiprocessing systems;},
Abstract = {The primary advantages of `multi-microprocessor
architectures' are their potential for improvements in cost,
reliability, and possibly speed over conventional large
computers. However, the realization of these advantages
requires improvements in the techniques necessary to
translate problems into parallel algorithms for
multi-microprocessors, and in the architectures of the
multi-microprocessors themselves. This paper describes an
architecture currently being investigated at SUNY-Stony
Brook. It discusses various strategies of design, the
structure of the proposed system, and some classes of
problems for which the architecture is suited},
Key = {1121896}
}