Publications of Martin Fischer :recent first combined listing:
%% Papers Published
@article{fds53148,
Author = {B. Gutiérrez-Medina and M. C. Fischer and M. G.
Raizen},
Title = {Observation of the quantum Zeno and anti-Zeno effects in an
unstable system},
Booktitle = {The Physics of Comm.: Proc. XXII Solvay Conf.
Phys.},
Publisher = {World Scientific},
Editor = {Antoniou},
Year = {2003},
Key = {fds53148}
}
%% Journal Articles
@article{fds232550,
Author = {Jianjun Yu, and Fischer, M and Chand, N and Kojima, K and Swaminathan,
V},
Title = {10-Gb/s transmission over 200-km conventional fiber without
dispersion compensation using the bias control
technique},
Journal = {IEEE Photonics Technology Letters},
Volume = {14},
Number = {12},
Pages = {1746-1748},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2002},
Month = {December},
url = {http://dx.doi.org/10.1109/lpt.2002.804668},
Abstract = {Transmission of 10-Gb/s nonreturn-to-zero (NRZ) signal over
200 km conventional single-mode fiber without any dispersion
compensation was discussed. A bias control technique
involving simultaneous charge of α parameter of an LiNbO3
modulator (LN-MOD) and the extinction ratio was used. It was
found that when the bias is shifted and the modulated
voltage on the LN-MOD is fixed the chirp and the ER are
changed simultaneously.},
Doi = {10.1109/lpt.2002.804668},
Key = {fds232550}
}
@article{fds232549,
Author = {Shin, DS and Wang, J and Bosch, F and Kiely, PA and Chand, N and Fischer,
M and Kojima, K and Kasper, BL and Peral, EM and Ransijn,
H},
Title = {10 Gbit∕s transmission over 50 km nonzero
dispersion-shifted fibre using 1.3 [micro sign]m directly
modulated uncooled transmitters},
Journal = {Electronics Letters},
Volume = {38},
Number = {16},
Pages = {864-864},
Publisher = {Institution of Engineering and Technology
(IET)},
Year = {2002},
ISSN = {0013-5194},
url = {http://dx.doi.org/10.1049/el:20020606},
Abstract = {A 1.3 μm uncooled transmitter with wide-open eye diagrams
at laser temperatures of 20, 50, and 85°C is presented.
Using this transmitter, it is demonstrated that 10 Gbit/s
transmission is possible over a 50 km nonzero
dispersion-shifted Lucent TrueWave-RS fibre. This result is
compared with transmission over a 55 km standard singlemode
fibre.},
Doi = {10.1049/el:20020606},
Key = {fds232549}
}
@article{fds232501,
Author = {Yu, J and Kojima, K and Chand, N and Fischer, MC and Espindola, R and Mason, TGB},
Title = {160GB/s single-channel unrepeatered transmission over 200km
of non-zero dispersion shifted fiber},
Journal = {European Conference on Optical Communication,
ECOC},
Volume = {6},
Pages = {20-21},
Year = {2001},
Month = {December},
Abstract = {Single-channel 160Gb/s unrepeated transmission over 200km of
non-zero dispersion shifted fiber (NZDSF) was reported using
distributed Raman amplification. Clock recovery and
demultiplexing were realized simultaneously by cascading a
tandem electro-absorption modulator (TEAM and another EAM.
When 160Gbit/s signal was transmitted over 175km fiber span,
the power penalty was found to be 1.8dB.},
Key = {fds232501}
}
@article{fds335295,
Author = {Villafana, T and Brown, B and Delaney, J and Fischer, M and Warren, W and Stranick, S},
Title = {3D chemical imaging of historic artworks and cultural
heritage materials},
Journal = {ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL
SOCIETY},
Volume = {251},
Pages = {1 pages},
Publisher = {AMER CHEMICAL SOC},
Year = {2016},
Month = {March},
Key = {fds335295}
}
@article{fds232543,
Author = {Spector, ZZ and Emami, K and Fischer, MC and Zhu, J and Ishii, M and Yu, J and Kadlecek, S and Driehuys, B and Panettieri, RA and Lipson, DA and Gefter, W and Shrager, J and Rizi, RR},
Title = {A small animal model of regional alveolar ventilation using
HP 3He MRI1.},
Journal = {Acad Radiol},
Volume = {11},
Number = {10},
Pages = {1171-1179},
Year = {2004},
Month = {October},
ISSN = {1076-6332},
url = {http://www.ncbi.nlm.nih.gov/pubmed/15530811},
Abstract = {RATIONALE AND OBJECTIVES: The aim of this study was to
establish a standardized procedure for the measurement of
regional fractional ventilation in a healthy rat model as a
baseline for further studies of pulmonary disorder models.
MATERIALS AND METHODS: The lungs of five healthy male
Sprague-Dawley rats were imaged using hyperpolarized
helium-3 magnetic resonance imaging. From these images,
regional fractional ventilation was calculated and maps
generated detailing the distribution of fractional
ventilation in the lung. The 1.56 mm x 1.56 mm x 4 mm
regions of interest were assigned on 5 cm x 5 cm field of
view lung maps. Histograms were also generated showing the
frequency distribution of fractional ventilation values. To
compare fractional ventilation values between animals, the
ventilation procedure was standardized to results from
individual pulmonary function tests. Each animal's
spontaneous tidal volume, respiratory rate, and inspiration
percentage (percent of total respiratory cycle in
inspiration) were used in their mechanical ventilation
settings. RESULTS: Results were similar among all five
healthy rats based on examination of ventilation
distribution maps and frequency distribution histograms.
Mean (0.13) and standard deviation (0.07) were calculated
for fractional ventilation in each animal. However, these
values were determined to be influenced by slice selection,
and therefore the maps and histograms were favored in
analysis of results. CONCLUSION: This study shows consistent
results in healthy rat lungs and will serve as a baseline
study for future measurements in emphysematous rat
lungs.},
Doi = {10.1016/j.acra.2004.08.001},
Key = {fds232543}
}
@article{fds232481,
Author = {Piletic, IR and Fischer, MC and Samineni, P and Warren,
WS},
Title = {Accessing nonlinear contrast in imaging using rapid pulse
shaping techniques},
Journal = {Optics InfoBase Conference Papers},
Year = {2008},
Month = {January},
ISBN = {9781557528612},
Abstract = {We have designed an interferometric acousto-optic pulse
shaper capable of shaping individual pulses differently from
a mode-locked laser. The design enables the measurement of
weak nonlinear optical signals at megahertz (MHz) rates for
imaging applications. © 2008 Optical Society of
America.},
Key = {fds232481}
}
@article{fds351261,
Author = {Piletic, IR and Fischer, MC and Samineni, P and Warren,
WS},
Title = {Accessing nonlinear contrast in imaging using rapid pulse
shaping techniques},
Journal = {Optics InfoBase Conference Papers},
Year = {2008},
Month = {January},
ISBN = {9781557528612},
url = {http://dx.doi.org/10.1364/fio.2008.ftuy3},
Abstract = {We have designed an interferometric acousto-optic pulse
shaper capable of shaping individual pulses differently from
a mode-locked laser. The design enables the measurement of
weak nonlinear optical signals at megahertz (MHz) rates for
imaging applications. © 2008 Optical Society of
America.},
Doi = {10.1364/fio.2008.ftuy3},
Key = {fds351261}
}
@article{fds232529,
Author = {Fischer, MC and Samineni, P and Li, B and Claytor, K and Warren,
WS},
Title = {Accessing nonlinear phase contrast in biological tissue
using femtosecond laser pulse shaping},
Journal = {Progress in Biomedical Optics and Imaging - Proceedings of
SPIE},
Volume = {8086},
Number = {8086},
Pages = {80860O},
Publisher = {SPIE},
Year = {2011},
Month = {July},
ISBN = {9780819486837},
ISSN = {1605-7422},
url = {http://dx.doi.org/10.1117/12.889668},
Abstract = {Nonlinear imaging takes advantage of the localized nature of
the interaction to achieve high spatial resolution, optical
sectioning, and deeper penetration in tissue. However,
nonlinear contrast (other than fluorescence or harmonic
generation) is generally difficult to measure because it is
overwhelmed by the large background of detected illumination
light. Especially challenging to measure is the nonlinear
refractive index - accessing this quantity would allow the
extension of widely employed phase microscopy methods to the
nonlinear regime. We have developed a technique to suppress
the background in these types of measurements by using
femtosecond pulse shaping to encode nonlinear interactions
in background-free regions of the frequency spectrum. Using
this individual pulse shaping based technique we have been
able to measure self-phase modulation (SPM) in highly
scattering environments, such as biological tissue, with
very modest power levels. Using our measurement technique we
have demonstrated strong intrinsic SPM signatures of
glutamate-induced neuronal activity in hippocampal brain
slices. We have also extended this measurement method to
cross-phase modulation, the two-color analogue to SPM. The
two-color approach dramatically improves the measurement
sensitivity by reducing undesired background and associated
noise. We will describe the nonlinear phase contrast
measurement technique and report on its application for
imaging neuronal activity. © 2011 SPIE-OSA.},
Doi = {10.1117/12.889668},
Key = {fds232529}
}
@article{fds232499,
Author = {Robles, FE and Wilson, JW and Fischer, MC and Warren,
WS},
Title = {Adapting phasor analysis for nonlinear pump-probe
microscopy},
Journal = {Progress in Biomedical Optics and Imaging - Proceedings of
SPIE},
Volume = {8589},
Publisher = {SPIE},
Year = {2013},
Month = {May},
ISBN = {9780819493583},
ISSN = {1605-7422},
url = {http://dx.doi.org/10.1117/12.2002600},
Abstract = {Phasor analysis has become a powerful tool for examining
signals in fluorescence life-time microscopy (FLIM), where
the analysis provides a fast, robust and intuitive means of
separating different fluorescent species and mixtures
thereof. In this work we adapt this analysis for pump-probe
microscopy, a method that provides molecular contrast of
pigmented samples by probing their excited state dynamic
properties. The bipolar nature of the pump-probe signals
presents important differences in the resulting phasors
compared to FLIM - here, we discuss these differences and
describe the behavior of bipolar signals in phasor analysis.
Results show that this method is indeed able to separate
multiple molecular species of interests and allows facile
assessment of pigment chemistry and its distribution in
samples. © 2013 Copyright SPIE.},
Doi = {10.1117/12.2002600},
Key = {fds232499}
}
@article{fds355544,
Author = {Jiang, J and Grass, D and Zhou, Y and Warren, WS and Fischer,
MC},
Title = {Beyond intensity modulation: new approaches to pump-probe
microscopy.},
Journal = {Optics letters},
Volume = {46},
Number = {6},
Pages = {1474-1477},
Publisher = {The Optical Society},
Year = {2021},
Month = {March},
url = {http://dx.doi.org/10.1364/ol.417905},
Abstract = {Pump-probe microscopy is an emerging nonlinear imaging
technique based on high repetition rate lasers and fast
intensity modulation. Here, we present new methods for
pump-probe microscopy that keep the beam intensity constant
and instead modulate the inter-pulse time delay or the
relative polarization. These techniques can improve image
quality for samples that have poor heat dissipation or
long-lived radiative states and can selectively address
nonlinear interactions in the sample. We experimentally
demonstrate this approach and point out the advantages over
conventional intensity modulation.},
Doi = {10.1364/ol.417905},
Key = {fds355544}
}
@article{fds328433,
Author = {Wilson, JW and Robles, FE and Deb, S and Warren, WS and Fischer,
MC},
Title = {Comparison of pump-probe and hyperspectral imaging in
unstained histology sections of pigmented
lesions},
Journal = {Biomedical Optics Express},
Volume = {8},
Number = {8},
Pages = {3882-3882},
Publisher = {The Optical Society},
Year = {2017},
Month = {August},
url = {http://dx.doi.org/10.1364/boe.8.003882},
Abstract = {Microscopic variations in melanin composition can be mapped
through linear and nonlinear optical responses. Though
instrumentation to measure linear attenuation is simple and
inexpensive, the nonlinear response provides more degrees of
freedom with which to spectroscopically resolve pigments.
The objective of this study is to assess differences in
imaging melanin contrast by comparing hyperspectral (linear)
versus pump-probe (nonlinear) microscopy of unstained
histology sections of pigmented lesions. The images and
analysis we have presented here show that pump-probe
uncovers a greater variation in pigment composition,
compared with hyperspectral microscopy, and that the two
methods yield complimentary biochemical information.},
Doi = {10.1364/boe.8.003882},
Key = {fds328433}
}
@article{fds365642,
Author = {Grass, D and Beasley, GM and Fischer, MC and Selim, MA and Zhou, Y and Warren, WS},
Title = {Contrast mechanisms in pump-probe microscopy of
melanin.},
Journal = {Opt Express},
Volume = {30},
Number = {18},
Pages = {31852-31862},
Publisher = {Optica Publishing Group},
Year = {2022},
Month = {August},
url = {http://dx.doi.org/10.1364/OE.469506},
Abstract = {Pump-probe microscopy of melanin in tumors has been proposed
to improve diagnosis of malignant melanoma, based on the
hypothesis that aggressive cancers disaggregate melanin
structure. However, measured signals of melanin are complex
superpositions of multiple nonlinear processes, which makes
interpretation challenging. Polarization control during
measurement and data fitting are used to decompose signals
of melanin into their underlying molecular mechanisms. We
then identify the molecular mechanisms that are most
susceptible to melanin disaggregation and derive
false-coloring schemes to highlight these processes in
biological tissue. We demonstrate that false-colored images
of a small set of melanoma tumors correlate with clinical
concern. More generally, our systematic approach of
decomposing pump-probe signals can be applied to a multitude
of different samples.},
Doi = {10.1364/OE.469506},
Key = {fds365642}
}
@article{fds232530,
Author = {Zhang, R and Greenberg, JA and Fischer, MC and Gauthier,
DJ},
Title = {Controllable ultrabroadband slow light in a warm rubidium
vapor},
Journal = {Journal of the Optical Society of America B: Optical
Physics},
Volume = {28},
Number = {11},
Pages = {2578-2583},
Publisher = {The Optical Society},
Year = {2011},
ISSN = {0740-3224},
url = {http://hdl.handle.net/10161/5105 Duke open
access},
Abstract = {We study ultrabroadband slow light in a warm rubidium vapor
cell. By working between the D1 and D2 transitions, we find
a several-nanometer window centered at 788:4nm in which the
group index is highly uniform and the absorption is small
(<1%). We demonstrate that we can control the group delay
by varying the temperature of the cell, and we observe a
tunable fractional delay of 18 for pulses as short as 250 fs
(6:9nm bandwidth) with a fractional broadening of only 0.65
and a power leakage of 55%. We find that a simple
theoretical model is in excellent agreement with the
experimental results. Using this model, we discuss the
impact of the pulse's spectral characteristics on the
distortion it incurs during propagation through the vapor.
© 2011 Optical Society of America.},
Doi = {10.1364/JOSAB.28.002578},
Key = {fds232530}
}
@article{fds232509,
Author = {Kadlecek, SJ and Emami, K and Fischer, MC and Ishii, M and Yu, J and Woodburn, JM and NikKhah, M and Vahdat, V and Lipson, DA and Baumgardner, JE and Rizi, RR},
Title = {Corrigendum to “Imaging physiological parameters with
hyperpolarized gas MRI” Progress in NMR Spectrosc. 47
(2005) 187},
Journal = {Progress in Nuclear Magnetic Resonance Spectroscopy},
Volume = {48},
Number = {4},
Pages = {233-235},
Publisher = {Elsevier BV},
Year = {2006},
Month = {July},
ISSN = {0079-6565},
url = {http://dx.doi.org/10.1016/j.pnmrs.2006.05.001},
Doi = {10.1016/j.pnmrs.2006.05.001},
Key = {fds232509}
}
@article{fds232518,
Author = {Samineni, P and Li, B and Wilson, JW and Warren, WS and Fischer,
MC},
Title = {Cross-phase modulation imaging},
Journal = {Optics Letters},
Volume = {37},
Number = {5},
Pages = {800-800},
Publisher = {The Optical Society},
Year = {2012},
Month = {March},
url = {http://www.ncbi.nlm.nih.gov/pubmed/22378398},
Abstract = {We demonstrate a cross-phase modulation measurement
technique based on the sensitive detection of modulation
transfer in a pump-probe setup. By modulating the amplitude
of the pump beam and spectrally analyzing the probe beam, we
achieve a rapid, background-free measurement of nonlinear
phase modulation using power levels acceptable in biological
imaging. This measurement technique would allow the
extension of widely employed phase microscopy methods to the
nonlinear regime, providing intrinsic and universal
nonlinear contrast for biological imaging.},
Doi = {10.1364/ol.37.000800},
Key = {fds232518}
}
@article{fds350106,
Author = {Samineni, P and Fischer, MC and Warren, WS},
Title = {Cross-phase modulation microscopy},
Journal = {Optics InfoBase Conference Papers},
Year = {2011},
Month = {January},
ISBN = {9781557529176},
url = {http://dx.doi.org/10.1364/ls.2011.ltua2},
Abstract = {We report our recently developed spectral re-shaping
technique for cross-phase modulation imaging, which extends
widely employed phase microscopy to the nonlinear regime. ©
2011 OSA.},
Doi = {10.1364/ls.2011.ltua2},
Key = {fds350106}
}
@article{fds232487,
Author = {Samineni, P and Fischer, MC and Warren, WS},
Title = {Cross-phase modulation microscopy},
Journal = {Optics InfoBase Conference Papers},
Year = {2011},
Month = {December},
ISBN = {9781557529176},
Abstract = {We report our recently developed spectral re-shaping
technique for cross-phase modulation imaging, which extends
widely employed phase microscopy to the nonlinear regime. ©
2011 OSA.},
Key = {fds232487}
}
@article{fds232520,
Author = {Wilson, JW and Samineni, P and Warren, WS and Fischer,
MC},
Title = {Cross-phase modulation spectral shifting: nonlinear phase
contrast in a pump-probe microscope},
Journal = {Biomedical Optics Express},
Volume = {3},
Number = {5},
Pages = {854-854},
Publisher = {The Optical Society},
Year = {2012},
Month = {May},
ISSN = {2156-7085},
url = {http://dx.doi.org/10.1364/boe.3.000854},
Abstract = {Microscopy with nonlinear phase contrast is achieved by a
simple modification to a nonlinear pump-probe microscope.
The technique measures cross-phase modulation by detecting a
pump-induced spectral shift in the probe pulse. Images with
nonlinear phase contrast are acquired both in transparent
and absorptive media. In paraffin-embedded biopsy sections,
cross-phase modulation complements the chemically-specific
pump-probe images with structural context.},
Doi = {10.1364/boe.3.000854},
Key = {fds232520}
}
@article{fds349071,
Author = {Jiang, J and Warren, WS and Fischer, MC},
Title = {Crossed-beam pump-probe microscopy},
Journal = {Optics Express},
Volume = {28},
Number = {8},
Pages = {11259-11259},
Publisher = {Optica Publishing Group},
Year = {2020},
Month = {April},
url = {http://dx.doi.org/10.1364/oe.389004},
Abstract = {<jats:p>We present a new imaging method for pump-probe
microscopy that explores non-collinear excitation. This
method (crossed-beam pump-probe microscopy, or CBPM) can
significantly improve the axial resolution when imaging
through low-NA lenses, providing an alternative way for
depth-resolved, large field-of-view imaging. We performed a
proof-of-concept demonstration, characterized CBPM’s
resolution using different imaging lenses, and measured an
enhanced axial resolution for certain types of low-NA
lenses.</jats:p>},
Doi = {10.1364/oe.389004},
Key = {fds349071}
}
@article{fds232505,
Author = {Ye, T and Wagner, W and Tian, P and Yurtsever, G and Fischer, M and Warren,
WS},
Title = {Deep tissue imaging approaches by direct capture of
two-photon absorption},
Journal = {2004 2nd IEEE International Symposium on Biomedical Imaging:
Macro to Nano},
Volume = {1},
Pages = {668-671},
Booktitle = {Proc. IEEE Int. Symp. on Biomed. Imag.},
Year = {2004},
Month = {December},
ISBN = {9780780383883},
Abstract = {Multiphoton imaging with fluorescence detection has proven
to be a powerful method for moderately deep tissue imaging
(less than 1 mm) with molecular specificity. However, many
important endogenous biomolecules do not fluoresce (NAD) or
with low efficiency (Melanin). In this paper two femtosecond
pulse shaping methods have been demonstrated to detect
two-photon absorption (TPA), instead of fluorescence, with
high sensitivity, which opens up a wide range of molecular
targets. It also facilitates longer excitation wavelengths,
which permit greater tissue penetration. Developing the
imaging system by using these new methods will be also
discussed. © 2004 IEEE.},
Key = {fds232505}
}
@article{fds232476,
Author = {Warren, WS and Ye, T and Fischer, M and Yurtsever, G and Li, C and Liu, H and Fu, D},
Title = {Deep tissue imaging with shaped femtosecond laser
pulses},
Journal = {Optics InfoBase Conference Papers},
Year = {2006},
Month = {January},
ISBN = {9781557528100},
Abstract = {Two-photon absorption and self phase modulation can be
detected deep in tissue with modest laser powers, using
shaped femtosecond pulses. This permit microscopic-resolution
images of biologically important targets. © 2006 Optical
Society of America.},
Key = {fds232476}
}
@article{fds343499,
Author = {Yang, JKW and Mrongovius, M and Fischer, MC and Boltasseva,
A},
Title = {Design, Manufacture, and Analysis of Photonic Materials for
Historical and Modern Visual Art: feature issue
introduction},
Journal = {Optical Materials Express},
Volume = {9},
Number = {5},
Pages = {2128-2128},
Publisher = {The Optical Society},
Year = {2019},
Month = {May},
url = {http://dx.doi.org/10.1364/ome.9.002128},
Abstract = {© 2019 Optical Society of America. History has seen many
significant contributions by artists in science and vice
versa, e.g. Leonardo Da Vinci's flying machines, and Isaac
Newton's color theory. More recently, with the advent of
nanofabrication techniques, lasers, and materials, photonics
research has found exciting new applications in art. The 14
papers positioned at the boundary between art and science in
this feature issue capture this breadth of topics. Creative
art-scientists/science-artists create new art using the
colorful properties of metallic nanostructures,
birefringence of liquid crystals, interference in thin
films, and coherence of lasers. A noteworthy new art form
that is gaining interest uses metals as the "canvas", lasers
and nanolithography as the "brush", and resonant
nanostructures as the "paint". We hope the reader will enjoy
the spectrum of topics here that illustrate the potential of
cutting edge photonic research for art-related applications:
from the generation of modern visual art to the preservation
and tagging of precious historical art.},
Doi = {10.1364/ome.9.002128},
Key = {fds343499}
}
@article{fds232526,
Author = {Li, B and Cheng, Y and Liu, J and Yi, C and Brown, AS and Yuan, H and Vo-Dinh,
T and Fischer, MC and Warren, WS},
Title = {Direct Optical Imaging of Graphene In Vitro by Nonlinear
Femtosecond Laser Spectral Reshaping},
Journal = {Nano Letters},
Volume = {12},
Number = {11},
Pages = {5936-5940},
Publisher = {American Chemical Society (ACS)},
Year = {2012},
Month = {November},
url = {http://www.ncbi.nlm.nih.gov/pubmed/23101475},
Abstract = {Nonlinear optical microscopy, based on femtosecond laser
spectral reshaping, characterized and imaged graphene
samples made from different methods, both on slides and in a
biological environment. This technique clearly discriminates
between graphene flakes with different numbers of layers and
reveals the distinct nonlinear optical properties of reduced
graphene oxide as compared to mechanically exfoliated or
chemical vapor deposition grown graphene. The nonlinearity
makes it applicable to scattering samples (such as tissue)
as opposed to previous methods, such as transmission. This
was demonstrated by high-resolution imaging of breast cancer
cells incubated with graphene flakes.},
Doi = {10.1021/nl303358p},
Key = {fds232526}
}
@article{fds326161,
Author = {Robles, FE and Fischer, MC and Warren, WS},
Title = {Dispersion-based stimulated Raman scattering spectroscopy,
holography, and optical coherence tomography (Conference
Presentation)},
Journal = {Multiphoton Microscopy in the Biomedical Sciences
XVI},
Volume = {9712},
Pages = {1 pages},
Publisher = {SPIE},
Editor = {Periasamy, A and So, PT and König, K},
Year = {2016},
Month = {April},
ISBN = {9781628419467},
url = {http://dx.doi.org/10.1117/12.2212875},
Doi = {10.1117/12.2212875},
Key = {fds326161}
}
@article{fds326160,
Author = {Robles, FE and Fischer, MC and Warren, WS},
Title = {Dispersion-based stimulated Raman scattering spectroscopy,
holography, and optical coherence tomography},
Journal = {Optics Express},
Volume = {24},
Number = {1},
Pages = {485-485},
Publisher = {The Optical Society},
Year = {2016},
Month = {January},
url = {http://dx.doi.org/10.1364/oe.24.000485},
Abstract = {Stimulated Raman scattering (SRS) enables fast, high
resolution imaging of chemical constituents important to
biological structures and functional processes, both in a
label-free manner and using exogenous biomarkers. While this
technology has shown remarkable potential, it is currently
limited to point scanning and can only probe a few Raman
bands at a time (most often, only one). In this work we take
a fundamentally different approach to detecting the small
nonlinear signals based on dispersion effects that accompany
the loss/gain processes in SRS. In this proof of concept, we
demonstrate that the dispersive measurements are more robust
to noise compared to amplitude-based measurements, which
then permit spectral or spatial multiplexing (potentially
both, simultaneously). Finally, we illustrate how this
method may enable different strategies for biochemical
imaging using phase microscopy and optical coherence
tomography.},
Doi = {10.1364/oe.24.000485},
Key = {fds326160}
}
@article{fds232551,
Author = {Soole, JBD and Pafchek, R and Narayanan, C and Bogert, G and Jampanaboyana, L and Chand, N and Yu, J and Fischer, M and Ling, M and Earnshaw, MP and Kojima, K and Swaminathan, V},
Title = {DWDM performance of a packaged reconfigurable optical
add-drop multiplexer subsystem supporting modular systems
growth},
Journal = {IEEE Photonics Technology Letters},
Volume = {15},
Number = {11},
Pages = {1600-1602},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2003},
Month = {November},
url = {http://dx.doi.org/10.1109/lpt.2003.818673},
Abstract = {We describe dense wavelength-division-multiplexing (DWDM)
operation of a reconfigurable optical add-drop multiplexer
subsystem module employing silica waveguide technology that
is suitable for use with both fixed-wavelength and
wavelength-selectable add-drop transceivers. We illustrate
its use in providing modular growth in high channel-count
DWDM systems.},
Doi = {10.1109/lpt.2003.818673},
Key = {fds232551}
}
@article{fds232547,
Author = {Madison, KW and Fischer, MC and Diener, RB and Niu, Q and Raizen,
MG},
Title = {Dynamical Bloch Band Suppression in an Optical
Lattice},
Journal = {Physical Review Letters},
Volume = {81},
Number = {23},
Pages = {5093-5096},
Publisher = {American Physical Society (APS)},
Year = {1998},
Month = {December},
url = {http://dx.doi.org/10.1103/physrevlett.81.5093},
Abstract = {The first observation of dynamical suppression of Bloch
bands due to an AC field is presented. The system consists
of laser-cooled atoms in an optical lattice. The neutral
sodium atoms in the lowest band of a 1D optical lattice are
trapped. The position of the potential to realize both an
intense AC field and a weak spectroscopic probe is modulated
in order to directly observed band suppressions. In the
theoretical analysis, the quasienergies and the
corresponding coupling strengths between the first and
higher bands are calculated in order to generate a
prediction for the experimental spectral distributions. This
calculation goes beyond the single-band and tight-binding
approximations, and is in good agreement with the observed
spectra.},
Doi = {10.1103/physrevlett.81.5093},
Key = {fds232547}
}
@article{fds365339,
Author = {Fischer, MC and Madison, KW and Diener, RB and Niu, Q and Raizen,
MG},
Title = {Dynamical Bloch band suppression in an optical
lattice},
Journal = {IQEC, International Quantum Electronics Conference
Proceedings},
Pages = {239-240},
Year = {1999},
Month = {January},
ISBN = {1557525714},
Abstract = {The first observation of dynamical suppression of Bloch
bands due to an AC field is presented. The system consists
of laser-cooled atoms in an optical lattice. The neutral
sodium atoms in the lowest band of a 1D optical lattice are
trapped. The position of the potential to realize both an
intense AC field and a weak spectroscopic probe is modulated
in order to directly observed band suppressions. In the
theoretical analysis, the quasienergies and the
corresponding coupling strengths between the first and
higher bands are calculated in order to generate a
prediction for the experimental spectral distributions. This
calculation goes beyond the single-band and tight-binding
approximations, and is in good agreement with the observed
spectra.},
Key = {fds365339}
}
@article{fds376587,
Author = {Fischer, MC and Madison, KW and Diener, RB and Niu, Q and Raizen,
MG},
Title = {Dynamical Bloch band suppression in an optical
lattice},
Journal = {Optics InfoBase Conference Papers},
Year = {1999},
Month = {January},
Key = {fds376587}
}
@article{fds232532,
Author = {Emami, K and Cadman, RV and Woodburn, JM and Fischer, MC and Kadlecek,
SJ and Zhu, J and Pickup, S and Guyer, RA and Law, M and Vahdat, V and Friscia, ME and Ishii, M and Yu, J and Gefter, WB and Shrager, JB and Rizi,
RR},
Title = {Early changes of lung function and structure in an elastase
model of emphysema—a hyperpolarized3He MRI
study},
Journal = {Journal of Applied Physiology},
Volume = {104},
Number = {3},
Pages = {773-786},
Publisher = {American Physiological Society},
Year = {2008},
Month = {March},
ISSN = {8750-7587},
url = {http://dx.doi.org/10.1152/japplphysiol.00482.2007},
Abstract = {<jats:p>Early changes of lung function and structure were
studied in the presence of an elastase-induced model of
emphysema in 35 Sprague-Dawley rats at mild (5 U/100 g) and
moderate (10 U/100 g) severities. Lung ventilation was
measured on a regional basis (at a planar resolution of 3.2
mm) by hyperpolarized<jats:sup>3</jats:sup>He MRI at 5 and
10 wk after model induction. Subsequent to imaging, average
alveolar diameter was measured from histological slices
taken from the centers of each lobe. Changes of mean
fractional ventilation, mean linear intercept, and
intrasubject heterogeneity of ventilation were studied
during disease progression. Mean fractional ventilation was
significantly different between healthy controls (0.23 ±
0.04) and emphysematous animals at both time points in the
10-unit group (0.06 ± 0.02 and 0.12 ± 0.05, respectively).
Changes in average alveolar diameter were not statistically
observable until the 10th wk between healthy (37 ± 10 μm)
and emphysematous rats (73 ± 25 and 95 ± 31 μm, for 5 and
10 units, respectively). Assessment of function-structure
correlation suggested that the majority of the decline in
fractional ventilation occurred in the first 5 wk, while
enlargement of alveolar diameters appeared primarily between
the 5th and 10th wk. A thresholding metric, based on the
20th percentile of fractional ventilation over the entire
lung, was utilized to detect the onset of the disease with
confidence, independent of whether the regional ventilation
measurements were normalized with respect to the delivered
tidal volume and estimated functional residual capacity of
each individual rat.</jats:p>},
Doi = {10.1152/japplphysiol.00482.2007},
Key = {fds232532}
}
@article{fds232503,
Author = {Kojima, K and Fischer, MC and Chand, N and Klotzkin, D and Kiely, PA and Sheridan-Eng, J and Xu, Y and Tohmon, G},
Title = {Effect of reflection on un-isolated spot-size-converted 1.3
μm DFB lasers for 2.5 Gbit/s transmission},
Journal = {Conference on Optical Fiber Communication, Technical Digest
Series},
Volume = {70},
Pages = {473-475},
Year = {2002},
Month = {January},
ISBN = {1557527008},
Abstract = {Spot-size-converted 1.3 μm distributed feedback laser
transmitter modules for 2.5 Gbit/s transmission, were
fabricated. The laser was mounted on a submount, and fiber
coupling was done passively. Reflection was defined as the
ratio of optical power coming back into the transmitter. The
lasers satisfied the SDH/SONET requirements for 15 km
transmission with strong reflection up to -16.5 dB at
various locations.},
Key = {fds232503}
}
@article{fds376532,
Author = {Kojima, K and Fischer, MC and Chand, N and Klotzkin, D and Kiely, PA and Sheridan-Eng, J and Xu, Y and Tohmon, G},
Title = {Effect of reflection on un-isolated spot-size-converted 1.3
µm DFB lasers for 2.5 Gbit/s transmission},
Journal = {Optics InfoBase Conference Papers},
Pages = {473-475},
Year = {2002},
Month = {January},
Abstract = {We have fabricated SSC-DFB laser transmitter modules, which
give enough output power, and can tolerate strong
reflection. They satisfy the SDH/SONET requirements for
transmission up to 15 km at 2.5 Gbit/s. Because of the
expected low packaging cost, the transmitter modules are
expected to play a big role in the metro/access
market.},
Key = {fds376532}
}
@article{fds339394,
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 = {fds339394}
}
@article{fds350888,
Author = {Li, B and Warren, WS and Fischer, MC},
Title = {Enhancing coherent anti-stokes Raman scattering background
suppression with phase cycled structured femtosecond laser
pulses},
Journal = {Optics InfoBase Conference Papers},
Year = {2010},
Month = {January},
url = {http://dx.doi.org/10.1364/fio.2010.ftuf2},
Abstract = {We demonstrate a homodyne coherent anti-Stokes Raman
scattering technique based on femtosecond laser pulse
shaping (phase-cycling). This technique utilizes a
self-generated non-resonant background as a local oscillator
to retrieve phase information of the Raman signal. © 2010
OSA/FiO/LS 2010.},
Doi = {10.1364/fio.2010.ftuf2},
Key = {fds350888}
}
@article{fds232484,
Author = {Li, B and Warren, WS and Fischer, MC},
Title = {Enhancing coherent anti-stokes Raman scattering background
suppression with phase cycled structured femtosecond laser
pulses},
Journal = {Optics InfoBase Conference Papers},
Year = {2010},
Month = {December},
Abstract = {We demonstrate a homodyne coherent anti-Stokes Raman
scattering technique based on femtosecond laser pulse
shaping (phase-cycling). This technique utilizes a
self-generated non-resonant background as a local oscillator
to retrieve phase information of the Raman signal. © 2010
OSA/FiO/LS 2010.},
Key = {fds232484}
}
@article{fds365770,
Author = {Warren, WS and Fischer, M and Wilson, J and Robles, F and Deb,
S},
Title = {Enhancing Pigmented or Transparent Tissue Imaging with Laser
Pulse Shaping},
Journal = {Optics InfoBase Conference Papers},
Year = {2015},
Month = {January},
ISBN = {9781943580033},
Abstract = {Enhanced control over femtosecond lasers (pulse shaping or
pulse train modulation) improves contrast in tissue imaging.
Pump-probe applications to melanoma diagnosis and cross
phase modulation measurement in transparent tissues will be
presented.},
Key = {fds365770}
}
@article{fds232531,
Author = {Fischer, MC and Piletica, I and Fub, D and Matthewsa, TE and Liuc, H and Saminenia, P and Lid, B and Warrene, WS},
Title = {Enhancing two-color absorption, self-phase modulation and
raman microscopy signatures in tissue with femtosecond laser
pulse shaping},
Journal = {Progress in Biomedical Optics and Imaging - Proceedings of
SPIE},
Volume = {7183},
Publisher = {SPIE},
Year = {2009},
Month = {June},
ISSN = {1605-7422},
url = {http://dx.doi.org/10.1117/12.816488},
Abstract = {Nonlinear microscopies (most commonly, two-photon
fluorescence, second harmonic generation, and coherent
anti-Stokes Raman scattering (CARS)) have had notable
successes in imaging a variety of endogenous and exogenous
targets in recent years. These methods generate light at a
color different from any of the exciting laser pulses, which
makes the signal relatively easy to detect. Our work has
focused on developing microscopy techniques using a wider
range of nonlinear signatures (two-photon absorption of
nonfluorescent species, self phase modulation) which have
some specific advantages - for example, in recent papers we
have shown that we can differentiate between different types
of melanin in pigmented lesions, image hemoglobin and its
oxygenation, and measure neuronal activity. In general,
these signatures do not generate light at a different color
and we rely on the advantages of femtosecond laser pulse
shaping methods to amplify the signals and make them visible
(for example, using heterodyne detection of the induced
signal with one of the co-propagating laser pulses). Here we
extend this work to stimulated Raman and CARS geometries. In
the simplest experiments, both colors arise from filtering a
single fs laser pulse, then modulating afterwards; in other
cases, we demonstrate that spectral reshaping can retain
high frequency resolution in Raman and CARS geometries with
femtosecond laser pulses. © 2009 SPIE.},
Doi = {10.1117/12.816488},
Key = {fds232531}
}
@article{fds232546,
Author = {Wilkinson, SR and Bharucha, CF and Fischer, MC and Madison, KW and Morrow, PR and Niu, Q and Sundaram, B and Raizen,
MG},
Title = {Experimental evidence for non-exponential decay in quantum
tunnelling},
Journal = {Nature},
Volume = {387},
Number = {6633},
Pages = {575-577},
Publisher = {Springer Science and Business Media LLC},
Year = {1997},
Month = {June},
url = {http://dx.doi.org/10.1038/42418},
Abstract = {An exponential decay law is the universal hallmark of
unstable systems and is observed in all fields of science.
This law is not, however, fully consistent with quantum
mechanics and deviations from exponential decay have been
predicted for short as well as long times. Such deviations
have not hitherto been observed experimentally. Here we
present experimental evidence for short-time deviation from
exponential decay in a quantum tunnelling experiment. Our
system consists of ultra-cold sodium atoms that are trapped
in an accelerating periodic optical potential created by a
standing wave of light. Atoms can escape the wells by
quantum tunnelling, and the number that remain can be
measured as a function of interaction time for a fixed value
of the well depth and acceleration. We observe that for
short times the survival probability is initially constant
before developing the characteristics of exponential decay.
The conceptual simplicity of the experiment enables a
detailed comparison with theoretical predictions.},
Doi = {10.1038/42418},
Key = {fds232546}
}
@article{fds232513,
Author = {Fischer, MC and Raizen, MG},
Title = {Experiments on quantum transport of ultra-cold atoms in
optical potentials},
Volume = {789},
Pages = {205-237},
Booktitle = {Time in Quantum Mechanics},
Publisher = {Springer Berlin Heidelberg},
Year = {2009},
Month = {December},
ISBN = {9783642031731},
ISSN = {0075-8450},
url = {http://dx.doi.org/10.1007/978-3-642-03174-8_8},
Abstract = {In this chapter, we describe our experiments with ultra cold
atoms in optical potentials and show how we can address
fundamental issues of time in quantum mechanics. The high
degree of experimental control and the conceptual simplicity
are the main advantages of our system. We start with an
overview of the basic interaction of atoms and light and
make the connection between atoms in optical lattices and
solid state physics. While this latter connection has
evolved into a major theme in physics over the past decade,
at the time of this work it was still new and unexplored.
After introduction of the theoretical model and the basic
equations, we introduce the experimental apparatus. We then
review our experiments to observe the Wannier-Stark ladder
in an accelerating lattice. This system was used to study
quantum tunneling where short-time non-exponential decay was
first observed for an unstable quantum system. We then
describe our experiments to observe the quantum Zeno and
anti-Zeno effects for an unstable system that is repeatedly
interrogated. We conclude this chapter with a brief outlook
into the future. © 2010 Springer-Verlag Berlin
Heidelberg.},
Doi = {10.1007/978-3-642-03174-8_8},
Key = {fds232513}
}
@article{fds232539,
Author = {Fischer, MC and Gupta, GC and Wang, LL and Kojima, K and Mizuhara, O and Swaminathan, V},
Title = {FEC performance under optical power transient
conditions},
Journal = {IEEE Photonics Technology Letters},
Volume = {15},
Number = {11},
Pages = {1654-1656},
Publisher = {Institute of Electrical and Electronics Engineers
(IEEE)},
Year = {2003},
Month = {November},
url = {http://dx.doi.org/10.1109/lpt.2003.818665},
Abstract = {We report the investigation of the performance of an
interleaved Reed-Solomon forward error correction code in
the presence of optical power transients for the first time.
These transients were generated by adding-dropping channels
in an erbium-doped fiber amplifier or Raman amplified
systems.},
Doi = {10.1109/lpt.2003.818665},
Key = {fds232539}
}
@article{fds232480,
Author = {Fischer, MC and Liu, HC and Fu, D and Semineni, P and Matthews, T and Piletic, I and Warren, WS},
Title = {Femtosecond laser pulse shaping for molecular imaging in
biological tissue},
Journal = {Optics InfoBase Conference Papers},
Year = {2008},
Month = {January},
ISBN = {9781557528612},
Abstract = {Recently developed ultrafast laser pulse shaping technology
allows highsensitivity measurements of nonlinear optical
effects in highly scattering media. We present applications
of these techniques to extract intrinsic structural,
metabolic and functional contrast in biological tissue. ©
2008 OSA.},
Key = {fds232480}
}
@article{fds350779,
Author = {Fischer, MC and Liu, HC and Fu, D and Semineni, P and Matthews, T and Piletic, I and Warren, WS},
Title = {Femtosecond laser pulse shaping for molecular imaging in
biological tissue},
Journal = {Optics InfoBase Conference Papers},
Year = {2008},
Month = {January},
ISBN = {9781557528612},
url = {http://dx.doi.org/10.1364/fio.2008.ftuy1},
Abstract = {Recently developed ultrafast laser pulse shaping technology
allows highsensitivity measurements of nonlinear optical
effects in highly scattering media. We present applications
of these techniques to extract intrinsic structural,
metabolic and functional contrast in biological tissue. ©
2008 OSA.},
Doi = {10.1364/fio.2008.ftuy1},
Key = {fds350779}
}
@article{fds351260,
Author = {Samineni, P and Perret, Z and Warren, WS and Fischer,
MC},
Title = {Femtosecond laser pulse shaping improves self-phase
modulation measurements in scattering media},
Journal = {Optics InfoBase Conference Papers},
Year = {2010},
Month = {January},
url = {http://dx.doi.org/10.1364/fio.2010.fthg2},
Abstract = {We demonstrate that our recently developed spectral
re-shaping technique improves the accuracy and precision of
self-phase modulation measurements in scattering media over
the conventional Z-scan method. © 2010 OSA/FiO/LS
2010.},
Doi = {10.1364/fio.2010.fthg2},
Key = {fds351260}
}
@article{fds232483,
Author = {Samineni, P and Perret, Z and Warren, WS and Fischer,
MC},
Title = {Femtosecond laser pulse shaping improves self-phase
modulation measurements in scattering media},
Journal = {Optics InfoBase Conference Papers},
Year = {2010},
Month = {December},
Abstract = {We demonstrate that our recently developed spectral
re-shaping technique improves the accuracy and precision of
self-phase modulation measurements in scattering media over
the conventional Z-scan method. © 2010 OSA/FiO/LS
2010.},
Key = {fds232483}
}
@article{fds232471,
Author = {Robles, FE and Fischer, MC and Warren, WS},
Title = {Femtosecond pulse shaping enables detection of optical
Kerr-effect (OKE) dynamics for molecular
imaging},
Journal = {Optics Letters},
Volume = {39},
Number = {16},
Pages = {4788-4788},
Publisher = {The Optical Society},
Year = {2014},
Month = {August},
ISSN = {0146-9592},
url = {http://dx.doi.org/10.1364/ol.39.004788},
Abstract = {We apply femtosecond pulse shaping to generate optical pulse
trains that directly access a material's nonlinear
refractive index (n2) and can thus determine time-resolved
optical Kerr-effect (OKE) dynamics. Two types of static
pulse trains are discussed: The first uses two identical
fields delayed in time, plus a pump field at a different
wavelength. Time-resolved OKE dynamics are retrieved by
monitoring the phase of the interference pattern produced by
the two identical fields in the Fourier-domain (FD) as a
function of pump-probe-time-delay (where the probe is one of
the two identical fields). The second pulse train uses three
fields with equal time delays, but with the center field
phase shifted by π/2. In this pulse scheme, changes on a
sample's nonlinear refractive index produce a new frequency
in the FD signal, which in turn yields background-free
intensity changes in the conjugate (time) domain and
provides superior signal-to-noise ratios. The demonstrated
sensitivity improvements enable, for the first time to our
knowledge, molecular imaging based on OKE
dynamics.},
Doi = {10.1364/ol.39.004788},
Key = {fds232471}
}
@article{fds350498,
Author = {Claytor, K and Li, B and Samineni, P and Warren, W and Fischer,
M},
Title = {Femtosecond pulse shaping enables nonlinear imaging in
highly scattering materials},
Journal = {Optics InfoBase Conference Papers},
Year = {2011},
Month = {January},
ISBN = {9781557529176},
url = {http://dx.doi.org/10.1364/ls.2011.lmc5},
Abstract = {Spectral re-shaping of pulses from a mode-locked femtosecond
laser allows detection of two photon absorption and self
phase modulation in highly scattering materials, which
permits nonlinear tissue imaging with this intrinsic
contrast. © 2011 OSA.},
Doi = {10.1364/ls.2011.lmc5},
Key = {fds350498}
}
@article{fds232486,
Author = {Claytor, K and Li, B and Samineni, P and Warren, W and Fischer,
M},
Title = {Femtosecond pulse shaping enables nonlinear imaging in
highly scattering materials},
Journal = {Optics InfoBase Conference Papers},
Year = {2011},
Month = {December},
ISBN = {9781557529176},
Abstract = {Spectral re-shaping of pulses from a mode-locked femtosecond
laser allows detection of two photon absorption and self
phase modulation in highly scattering materials, which
permits nonlinear tissue imaging with this intrinsic
contrast. © 2011 OSA.},
Key = {fds232486}
}
@article{fds232468,
Author = {Park, JK and Fischer, MC and Susumu, K and Therien, MJ and Warren,
WS},
Title = {Femtosecond pulse train shaping for accurate two-photon
excited fluorescence measurements},
Journal = {Laser Science, LS 2014},
Year = {2014},
Month = {January},
ISBN = {1557522863},
Abstract = {We report a simple measurement method that exploits pulse
train shaping to suppress linear contributions to the
fluorescence, and allows for extraction of the two-photon
absorption cross sections. © 2014 OSA.},
Key = {fds232468}
}
@article{fds351259,
Author = {Park, JK and Fischer, MC and Susumu, K and Therien, MJ and Warren,
WS},
Title = {Femtosecond pulse train shaping for accurate two-photon
excited fluorescence measurements},
Journal = {Optics InfoBase Conference Papers},
Year = {2014},
Month = {October},
ISBN = {1557522863},
url = {http://dx.doi.org/10.1364/ls.2014.lth4h.3},
Abstract = {We report a simple measurement method that exploits pulse
train shaping to suppress linear contributions to the
fluorescence, and allows for extraction of the two-photon
absorption cross sections. © 2014 OSA.},
Doi = {10.1364/ls.2014.lth4h.3},
Key = {fds351259}
}
@article{fds232470,
Author = {Park, JK and Fischer, MC and Susumu, K and Therien, MJ and Warren,
WS},
Title = {Femtosecond pulse train shaping improves two-photon excited
fluorescence measurements},
Journal = {Optics Letters},
Volume = {39},
Number = {19},
Pages = {5606-5606},
Publisher = {The Optical Society},
Year = {2014},
Month = {October},
ISSN = {0146-9592},
url = {http://dx.doi.org/10.1364/ol.39.005606},
Abstract = {Measurements of two-photon absorption (TPA) cross sections
are greatly confounded by even very weak linear absorption,
for example from hot bands. In this case, the experimental
power dependence of fluorescence from amplified and
mode-locked laser systems can differ drastically, even if
the peak intensity is adjusted to be the same in both cases.
A simple pulse train shaping method suppresses linear
contributions and extracts the nonlinear absorption cross
section, demonstrated here for a meso-to-meso ethyne-bridged
bis[(porphinato)zinc(II)] fluorophore (DD) at 800 nm. This
approach permits reliable TPA cross-section measurement,
even with standard modelocked lasers under conditions
identical to that used for multiphoton microscopy.},
Doi = {10.1364/ol.39.005606},
Key = {fds232470}
}
@article{fds232493,
Author = {Villafana, TE and Brown, WP and Delaney, JK and Palmer, M and Warren,
WS and Fischer, MC},
Title = {Femtosecond pump-probe microscopy generates virtual
cross-sections in historic artwork},
Journal = {Proceedings of the National Academy of Sciences},
Volume = {111},
Number = {5},
Pages = {1708-1713},
Publisher = {Proceedings of the National Academy of Sciences},
Year = {2014},
Month = {February},
ISSN = {0027-8424},
url = {http://dx.doi.org/10.1073/pnas.1317230111},
Abstract = {<jats:title>Significance</jats:title> <jats:p>We show that a
nonlinear microscopy technique (femtosecond pump-probe
microscopy) allows for nondestructive 3D imaging of
paintings with molecular and structural contrast. Until now,
studying the layering structure of a painting has generally
required the physical removal of a cross-section sample.
Pump-probe imaging has previously been shown on biological
tissue, but applications to cultural heritage are more
challenging: the variety of pigments in the artist’s
palate is enormous compared with the biological pigments
present in skin. Nonetheless, we show virtual
cross-sectioning capabilities in mockup paintings and
nondestructive imaging on an intact 14th century painting.
This work represents a comprehensive collaborative effort
between laser and biomedical imaging experts and scientists
and conservators in national museums.</jats:p>},
Doi = {10.1073/pnas.1317230111},
Key = {fds232493}
}
@article{fds232467,
Author = {Wilson, JW and Park, JK and Warren, WS and Fischer,
MC},
Title = {Flexible digital signal processing architecture for
narrowband and spread-spectrum lock-in detection in
multiphoton microscopy and time-resolved
spectroscopy},
Journal = {Review of Scientific Instruments},
Volume = {86},
Number = {3},
Pages = {033707-033707},
Publisher = {AIP Publishing},
Year = {2015},
Month = {March},
ISSN = {0034-6748},
url = {http://dx.doi.org/10.1063/1.4916261},
Abstract = {<jats:p>The lock-in amplifier is a critical component in
many different types of experiments, because of its ability
to reduce spurious or environmental noise components by
restricting detection to a single frequency and phase. One
example application is pump-probe microscopy, a multiphoton
technique that leverages excited-state dynamics for imaging
contrast. With this application in mind, we present here the
design and implementation of a high-speed lock-in amplifier
on the field-programmable gate array (FPGA) coprocessor of a
data acquisition board. The most important advantage is the
inherent ability to filter signals based on more complex
modulation patterns. As an example, we use the flexibility
of the FPGA approach to enable a novel pump-probe detection
scheme based on spread-spectrum communications
techniques.</jats:p>},
Doi = {10.1063/1.4916261},
Key = {fds232467}
}
@article{fds232504,
Author = {Fischer, MC and Dudarev, AM and Gutiérrez-Medina, B and Raizen,
MG},
Title = {FM spectroscopy in recoil-induced resonances},
Journal = {Journal of Optics B: Quantum and Semiclassical
Optics},
Volume = {3},
Number = {4},
Pages = {279-287},
Publisher = {IOP Publishing},
Year = {2001},
Month = {August},
url = {http://dx.doi.org/10.1088/1464-4266/3/4/313},
Abstract = {We report on an experimental study of recoil-induced
resonances as a method of velocimetry for cold atomic
samples. We present a refined experimental method that
greatly improves the sensitivity of the measurement over
previous experiments. Using frequency-modulation (FM)
spectroscopy techniques we achieve a sensitivity that
approaches the shot noise limit. In addition, we present a
novel approach to deriving the line shape of the observed
signal, based on the concept of quantum transport and
tunnelling in motional Bloch bands.},
Doi = {10.1088/1464-4266/3/4/313},
Key = {fds232504}
}
@article{fds323184,
Author = {Villafana, TE and Delaney, JK and Warren, WS and Fischer,
MC},
Title = {High-resolution, three-dimensional imaging of pigments and
support in paper and textiles},
Journal = {Journal of Cultural Heritage},
Volume = {20},
Pages = {583-588},
Publisher = {Elsevier BV},
Year = {2016},
Month = {July},
url = {http://dx.doi.org/10.1016/j.culher.2016.02.003},
Abstract = {Historic works on paper, illuminated (painted) or unpainted
manuscripts, and textiles are fragile and nearly impossible
to sample. Non-invasive techniques such as visible
microscopy, X-ray fluorescence, Raman, and reflectance
spectroscopy are commonly used to determine the artist
material present. Recently, nonlinear optical ultrafast
pump-probe microscopy was shown to provide non-invasive,
high-resolution mapping of pigments in historic paintings to
investigate paint stratigraphy. In this paper, we combine
our pump-probe contrast with nonlinear fluorescence and
second-harmonic generation contrasts exhibited by fibrous
supports composed of natural bio-materials (cellulose,
collagen, or lignin). Hence, our multi-modal nonlinear
microscope is able to simultaneously investigate pigments in
conjunction with their support in three dimensions with
micrometer-scale spatial resolution. Here we examine the
utility of nonlinear pump-probe microscopy by studying a
series of mock-up samples, including indigo-dyed cotton
cloth, ultramarine blue painted on various types of paper,
and papers painted with mixtures and layers of the two
pigments. In each case we find that we can combine
pump-probe pigment contrast with nonlinear optical fiber
contrast to obtain spatial information that is otherwise
unavailable to the conservator.},
Doi = {10.1016/j.culher.2016.02.003},
Key = {fds323184}
}
@article{fds232491,
Author = {Villafaña, TE and Samineni, P and Warren, WS and Fischer,
MC},
Title = {Historical pigments revealed by pump-probe
microscopy},
Journal = {Laser Science, LS 2012},
Year = {2012},
Month = {December},
ISBN = {9781557529565},
Abstract = {Nonlinear optical pump-probe microscopy is able to
sensitively extract excited state dynamics from historical
art pigments. This technique allows three-dimensional
imaging and characterization of different pigments, with far
reaching applications for conservation science. © OSA
2012.},
Key = {fds232491}
}
@article{fds232525,
Author = {Li, B and Yi, C and Brown, A and Fischer, MC and Warren,
WS},
Title = {Homodyne near-degenerate four-wave-mixing microscopy for
graphene imaging and biomedical applications},
Journal = {2012 Conference on Lasers and Electro-Optics, CLEO
2012},
Year = {2012},
Month = {December},
ISBN = {9781467318396},
Abstract = {Homodyne detection of near-degenerate four-wave-mixing with
a single laser pulse is used to imaging graphene in
biological samples. © 2012 OSA.},
Key = {fds232525}
}
@article{fds232553,
Author = {Haczku, A and Emami, K and Fischer, MC and Kadlecek, S and Ishii, M and Panettieri, RA and Rizi, RR},
Title = {Hyperpolarized 3He MRI in Asthma},
Journal = {Academic Radiology},
Volume = {12},
Number = {11},
Pages = {1362-1370},
Publisher = {Elsevier BV},
Year = {2005},
Month = {November},
ISSN = {1076-6332},
url = {http://dx.doi.org/10.1016/j.acra.2005.08.027},
Abstract = {<h4>Rationale and objectives</h4>Quantitative regional
measurement of physiological parameters of lung may improve
both early detection of asthma and its response to treatment
by elucidating the characteristics of airway obstruction.
Recent emergence of hyperpolarized helium-3 magnetic
resonance imaging as a sensitive pulmonary imaging tool has
shown great potential in capturing important structural and
functional aspects of normal and diseased lungs. The
objective of this study was to investigate regional
ventilation changes in the mouse lung following allergen
sensitization and challenge.<h4>Materials and methods</h4>A
murine model of allergic airway inflammation was created in
mice following allergen challenge using Af and IgE-mediated
asthma. The creation of model was verified using pulmonary
function test and histology. Regional fractional ventilation
was then measured in the animals using hyperpolarized 3He
MRI on a pixel-by-pixel basis with a planar resolution of
0.24 mm. The sensitized and healthy animals were then
compared statistically to assess the potential sensitivity
of this technique in detection of such pulmonary
abnormalities.<h4>Results</h4>In this work, we have
demonstrated for the first time the quantitative measurement
of regional ventilation in normal and asthmatic mice.
Results of this study show significant changes in regional
ventilation in murine model of allergic airway sensitization
compared with that in normal control animals.<h4>Conclusion</h4>Further
development of this technique can potentially serve as a
quantitative marker to investigate the physiology of
allergen-induced airway hyperresponsiveness and to assist in
disease treatment and prevention.},
Doi = {10.1016/j.acra.2005.08.027},
Key = {fds232553}
}
@article{fds232542,
Author = {Ishii, M and Fischer, MC and Emami, K and Alavi, A and Spector, ZZ and Yu,
J and Baumgardner, JE and Itkin, M and Kadlecek, SJ and Zhu, J and Bono, M and Gefter, WB and Lipson, DA and Shrager, JB and Rizi,
RR},
Title = {Hyperpolarized helium-3 MR imaging of pulmonary
function.},
Journal = {Radiol Clin North Am},
Volume = {43},
Number = {1},
Pages = {235-246},
Year = {2005},
Month = {January},
url = {http://dx.doi.org/10.1016/j.rcl.2004.09.010},
Abstract = {Recent advances in HP MR imaging contrast agents have led to
novel tests of pulmonary function. Many of these tests show
promise in the clinical arena.},
Doi = {10.1016/j.rcl.2004.09.010},
Key = {fds232542}
}
@article{fds232508,
Author = {Ye, T and Yurtsever, G and Fischer, M and Simon, JD and Warren,
WS},
Title = {Imaging melanin by two-photon absorption
microscopy},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {6089},
Pages = {60891X},
Booktitle = {Multiphoton Micr. in the Biomed. Sciences VI, Proc.
SPIE},
Publisher = {SPIE},
Year = {2006},
Month = {May},
ISBN = {9780819461315},
ISSN = {0277-786X},
url = {http://dx.doi.org/10.1117/12.646139},
Abstract = {Multiphoton excitation fluorescence microscopy has proven to
be a powerful method for non-invasive, in vivo, thick tissue
imaging with molecular specificity. However, many important
endogenous biomolecules do not fluoresce (NAD) or fluoresce
with low efficiency (Melanin). In this report femtosecond
pulse shaping methods are used to measure two-photon
absorption (TPA) directly with very high sensitivity.
Combining with the laser scanning microscope, this
Two-photon Absorption Microscopy (TPAM) retains the
penetration and localization advantages of two-photon
fluorescence microscopy and permits direct observation of
important endogenous molecular markers (melanin or
hemoglobin) which are invisible in multiphoton fluorescence
microscopy. We have demonstrated here for the first time
that TPAM can successfully and more efficiently image
melanoma cells and tissues and provide a good melanin
contrast in optical sectioning of the melanoma lesions which
are comparable to pathological histology. Combining with the
two-photon fluorescence images acquired simultaneously, the
distribution patterns of the melanocytes and their
intratissue behavior could be studied without cutting the
lesions from patients. TPAM will undoubtedly find the
applications in the clinical diagnosis and biomedical
research.},
Doi = {10.1117/12.646139},
Key = {fds232508}
}
@article{fds232541,
Author = {KADLECEK, S and EMAMI, K and FISCHER, M and ISHII, M and YU, J and WOODBURN, J and NIKKHAH, M and VAHDAT, V and LIPSON, D and BAUMGARDNER,
J},
Title = {Imaging physiological parameters with hyperpolarized gas
MRI},
Journal = {Progress in Nuclear Magnetic Resonance Spectroscopy},
Volume = {47},
Number = {3-4},
Pages = {187-212},
Publisher = {Elsevier BV},
Year = {2005},
Month = {December},
ISSN = {0079-6565},
url = {http://dx.doi.org/10.1016/j.pnmrs.2005.08.006},
Abstract = {A survey capable of producing the desired physiological
information from a series of polarized gas MR images is
discussed. Salient requirements of an ideal radiological
method for quantitative assessment of lung function are also
discussed. The benefits of polarized gas MRI are clarified
through a comparison with other existing modalities. The
optical pumping methods for the generation of
hyperpolarization and the technical aspects of gas delivery
and storage are presented. Imaging techniques such as
MR-based coronary angiography, and PET/SPECT tests have
advanced together with extremely effective therapies and
surgical procedures.},
Doi = {10.1016/j.pnmrs.2005.08.006},
Key = {fds232541}
}
@article{fds232479,
Author = {Liu, HC and Fischer, MC and Samineni, P and Escobedo-Lozoya, Y and Yasuda, R and Warren, WS},
Title = {Intrinsic nonlinear optical signatures of neuronal
activity},
Journal = {Optics InfoBase Conference Papers},
Year = {2008},
Month = {January},
ISBN = {9781557528612},
Abstract = {Using novel femtosecond laser pulse shaping techniques and a
virtually background-free detection strategy we demonstrate
strong self-phase modulation signatures of neuronal activity
in hippocampal brain slices without the use of exogenous
contrast agents. © 2008 Optical Society of
America.},
Key = {fds232479}
}
@article{fds349890,
Author = {Liu, HC and Fischer, MC and Samineni, P and Escobedo-Lozoya, Y and Yasuda, R and Warren, WS},
Title = {Intrinsic nonlinear optical signatures of neuronal
activity},
Journal = {Optics InfoBase Conference Papers},
Year = {2008},
Month = {January},
ISBN = {9781557528612},
url = {http://dx.doi.org/10.1364/fio.2008.fwd2},
Abstract = {Using novel femtosecond laser pulse shaping techniques and a
virtually background-free detection strategy we demonstrate
strong self-phase modulation signatures of neuronal activity
in hippocampal brain slices without the use of exogenous
contrast agents. © 2008 Optical Society of
America.},
Doi = {10.1364/fio.2008.fwd2},
Key = {fds349890}
}
@article{fds323185,
Author = {Fischer, MC and Wilson, JW and Robles, FE and Warren,
WS},
Title = {Invited Review Article: Pump-probe microscopy},
Journal = {Review of Scientific Instruments},
Volume = {87},
Number = {3},
Pages = {031101-031101},
Publisher = {AIP Publishing},
Year = {2016},
Month = {March},
url = {http://dx.doi.org/10.1063/1.4943211},
Abstract = {<jats:p>Multiphoton microscopy has rapidly gained popularity
in biomedical imaging and materials science because of its
ability to provide three-dimensional images at high spatial
and temporal resolution even in optically scattering
environments. Currently the majority of commercial and
home-built devices are based on two-photon fluorescence and
harmonic generation contrast. These two contrast mechanisms
are relatively easy to measure but can access only a limited
range of endogenous targets. Recent developments in fast
laser pulse generation, pulse shaping, and detection
technology have made accessible a wide range of optical
contrasts that utilize multiple pulses of different colors.
Molecular excitation with multiple pulses offers a large
number of adjustable parameters. For example, in two-pulse
pump-probe microscopy, one can vary the wavelength of each
excitation pulse, the detection wavelength, the timing
between the excitation pulses, and the detection gating
window after excitation. Such a large parameter space can
provide much greater molecular specificity than existing
single-color techniques and allow for structural and
functional imaging without the need for exogenous dyes and
labels, which might interfere with the system under study.
In this review, we provide a tutorial overview, covering
principles of pump-probe microscopy and experimental setup,
challenges associated with signal detection and data
processing, and an overview of applications.</jats:p>},
Doi = {10.1063/1.4943211},
Key = {fds323185}
}
@article{fds325218,
Author = {Robles, FE and Deb, S and Fischer, MC and Warren, WS and Selim,
MA},
Title = {Label-Free Imaging of Female Genital Tract Melanocytic
Lesions With Pump-Probe Microscopy: A Promising Diagnostic
Tool.},
Journal = {J Low Genit Tract Dis},
Volume = {21},
Number = {2},
Pages = {137-144},
Year = {2017},
Month = {April},
url = {http://dx.doi.org/10.1097/LGT.0000000000000290},
Abstract = {OBJECTIVES: Melanomas of the female genital tract present a
unique clinical challenge. Not only are these lesions in an
anatomically sensitive area, but also they tend to be
multifocal and have high recurrence rates. Furthermore,
several benign melanocytic proliferations resemble
early-stage melanoma clinically and/or histopathologically.
Thus, there is a significant need for additional tools that
can help correctly diagnose and stage these lesions. Here,
we quantitatively and nondestructively analyze the chemical
composition of melanin in excised pigmented lesions of the
female genital tract using pump-probe microscopy, a
high-resolution optical imaging technique that is sensitive
to many biochemical properties of melanin. MATERIALS AND
METHODS: Thirty-one thin (~5 μm) tissue sections previously
excised from female genital tract melanocytic lesions were
imaged with pump-probe microscopy and analyzed. RESULTS: We
find significant quantitative differences in melanin type
and structure between melanoma and nonmalignant melanocytic
proliferations. Our analysis also suggests a link between
the molecular signatures of melanins and lesion-specific
genetic mutations. Finally, significant differences are
found between metastatic and nonmetastatic melanomas. The
limitations of this work include the fact that molecular
information is restricted to melanin pigment and the sample
size is relatively small. CONCLUSIONS: Pump-probe microscopy
provides unique information regarding the biochemical
composition of genital tract melanocytic lesions, which can
be used to improve the diagnosis and staging of vulvar
melanomas.},
Doi = {10.1097/LGT.0000000000000290},
Key = {fds325218}
}
@article{fds352217,
Author = {Fischer, EP and Fischer, MC and Grass, D and Henrion, I and Warren, WS and Westman, E},
Title = {Low-cost measurement of face mask efficacy for filtering
expelled droplets during speech.},
Journal = {Sci Adv},
Volume = {6},
Number = {36},
Pages = {eabd3083},
Publisher = {American Association for the Advancement of Science
(AAAS)},
Year = {2020},
Month = {September},
url = {http://dx.doi.org/10.1126/sciadv.abd3083},
Abstract = {Mandates for mask use in public during the recent
coronavirus disease 2019 (COVID-19) pandemic, worsened by
global shortage of commercial supplies, have led to
widespread use of homemade masks and mask alternatives. It
is assumed that wearing such masks reduces the likelihood
for an infected person to spread the disease, but many of
these mask designs have not been tested in practice. We have
demonstrated a simple optical measurement method to evaluate
the efficacy of masks to reduce the transmission of
respiratory droplets during regular speech. In
proof-of-principle studies, we compared a variety of
commonly available mask types and observed that some mask
types approach the performance of standard surgical masks,
while some mask alternatives, such as neck gaiters or
bandanas, offer very little protection. Our measurement
setup is inexpensive and can be built and operated by
nonexperts, allowing for rapid evaluation of mask
performance during speech, sneezing, or coughing.},
Doi = {10.1126/sciadv.abd3083},
Key = {fds352217}
}
@article{fds365993,
Author = {Fischer, EP and Fischer, MC and Grass, D and Henrion, I and Warren, WS and Westman, E},
Title = {Low-cost measurement of facemask efficacy for filtering
expelled droplets during speech},
Year = {2020},
Month = {June},
url = {http://dx.doi.org/10.1101/2020.06.19.20132969},
Abstract = {<jats:title>Abstract</jats:title><jats:p>Mandates for mask
use in public during the recent COVID-19 pandemic, worsened
by global shortage of commercial supplies, have led to
widespread use of homemade masks and mask alternatives. It
is assumed that wearing such masks reduces the likelihood
for an infected person to spread the disease, but many of
these mask designs have not been tested in practice. We have
applied a simple optical measurement method to evaluate the
efficacy of masks to reduce the transmission of respiratory
droplets during regular speech. We compare a variety of
commonly available mask types and observe that some mask
types approach the performance of standard surgical masks,
while some mask alternatives, such as neck fleece or
bandanas, offer very little protection. Our measurement
setup is inexpensive and can be built and operated by
non-experts, allowing for rapid evaluation of mask
performance during speech, sneezing, or coughing.</jats:p>},
Doi = {10.1101/2020.06.19.20132969},
Key = {fds365993}
}
@article{fds232514,
Author = {Samineni, P and Perret, Z and Warren, WS and Fischer,
MC},
Title = {Measurements of nonlinear refractive index in scattering
media},
Journal = {Optics Express},
Volume = {18},
Number = {12},
Pages = {12727-12727},
Publisher = {Optica Publishing Group},
Year = {2010},
Month = {June},
url = {http://www.ncbi.nlm.nih.gov/pubmed/20588401},
Abstract = {We have recently developed a spectral re-shaping technique
to simultaneously measure nonlinear refractive index and
nonlinear absorption. In this technique, the information
about the nonlinearities is encoded in the frequency domain,
rather than in the spatial domain as in the conventional
Z-scan method. Here we show that frequency encoding is much
more robust with respect to scattering. We compare spectral
re-shaping and Z-scan measurements in a highly scattering
environment and show that reliable spectral re-shaping
measurements can be performed even in a regime that
precludes standard Z-scans.},
Doi = {10.1364/oe.18.012727},
Key = {fds232514}
}
@article{fds232552,
Author = {Fischer, MC and Kadlecek, S and Yu, J and Ishii, M and Emami, K and Vahdat,
V and Lipson, DA and Rizi, RR},
Title = {Measurements of Regional Alveolar Oxygen Pressure Using
Hyperpolarized 3He MRI1},
Journal = {Academic Radiology},
Volume = {12},
Number = {11},
Pages = {1430-1439},
Publisher = {Elsevier BV},
Year = {2005},
Month = {November},
ISSN = {1076-6332},
url = {http://dx.doi.org/10.1016/j.acra.2005.07.007},
Abstract = {<h4>Rationale and objectives</h4>The aim of this work is to
review hyperpolarized (HP) helium-3 (3He) magnetic resonance
imaging (MRI) methods to measure regional alveolar oxygen
partial pressure (P(A)O2) and oxygen depletion rate (R) in
the lung. We point out limitations of the methods and
suggest improvements to increase their accuracy.<h4>Materials
and methods</h4>P(A)O2 and R can be extracted from series of
HP gas images acquired during breath hold by making use of
the depolarizing effect of oxygen on HP gas. To separate
oxygen-induced depolarization from other depolarizing
effects, several techniques can be used. We review currently
used techniques and point out their advantages and
limitations.<h4>Results</h4>We show that the precision of
oxygen measurements depends on a variety of parameters and
can vary within the measurement volume. Accuracy of the
measurement also can be influenced by diffusion of oxygen
and polarized 3He and generally is different for
single-slice and multislice measurements. We present
numerical simulations, phantom data, and in vivo data for
illustration.<h4>Conclusion</h4>HP 3He MRI is a noninvasive,
nonionizing, and repeatable imaging method that allows for
quantitative analysis of lung function. The current
techniques for measuring P(A)O2 have the potential to
deliver clinically relevant functional images.},
Doi = {10.1016/j.acra.2005.07.007},
Key = {fds232552}
}
@article{fds325815,
Author = {Warren, WS and Robles, F and Fischer, M and Wilson, J and Deb, S and Ju, K and Degan, S},
Title = {Melanin-targeted nonlinear microscopy for label-free
molecular diagnosis and staging},
Journal = {Optics InfoBase Conference Papers},
Volume = {Part F19-Translational 2016},
Publisher = {OSA},
Year = {2016},
Month = {April},
ISBN = {9781943580101},
url = {http://dx.doi.org/10.1364/TRANSLATIONAL.2016.TTh3B.3},
Abstract = {Nonlinear pump-probe microscopy differentiates cutaneous,
vulvar and conjunctival melanomas from less dangerous
lesions, and can be used to assess metastatic potential.
Applications in vivo (knockout mouse models) and in human
biopsy are presented.},
Doi = {10.1364/TRANSLATIONAL.2016.TTh3B.3},
Key = {fds325815}
}
@article{fds232521,
Author = {Li, B and Claytor, KE and Yuan, H and Vo-Dinh, T and Warren, WS and Fischer, MC},
Title = {Multicontrast nonlinear optical microscopy with a compact
and rapid pulse shaper},
Journal = {Optics Letters},
Volume = {37},
Number = {13},
Pages = {2763-2763},
Publisher = {The Optical Society},
Year = {2012},
Month = {July},
url = {http://www.ncbi.nlm.nih.gov/pubmed/22743521},
Abstract = {Homodyne detection can dramatically enhance measurement
sensitivity for weak signals. In nonlinear optical
microscopy it can make accessible a range of novel,
intrinsic, contrast like nonlinear absorption and nonlinear
phase contrast. Here a compact and rapid pulse shaper is
developed, implemented, and demonstrated for homodyne
detection in nonlinear microscopy with high-repetition rate
mode-locked femtosecond lasers. With this method we generate
two-photon absorption (TPA) and self-phase modulation images
of gold nanostars in biological samples. Simultaneous
imaging of two-photon luminescence and TPA also enables us
to produce two-photon quantum yield images.},
Doi = {10.1364/ol.37.002763},
Key = {fds232521}
}
@article{fds232512,
Author = {Warren, WS and Fischer, M and Fu, D and Ye, T and Piletic, I and Matthews,
T},
Title = {New nonlinear signatures in spectroscopy and
imaging},
Journal = {Conference on Quantum Electronics and Laser Science (QELS) -
Technical Digest Series},
Pages = {JWC1},
Year = {2008},
Month = {September},
ISBN = {9781557528599},
url = {http://dx.doi.org/10.1109/QELS.2008.4552901},
Abstract = {Ultrafast laser pulse shaping makes it possible to observe
nonlinear signatures, such as self phase modulation and sum
frequency absorption, at safe laser powers for tissue.
Neuronal activation and melanoma diagnosis are two early
targets. © 2008 Optical Society of America.},
Doi = {10.1109/QELS.2008.4552901},
Key = {fds232512}
}
@article{fds232527,
Author = {Madison, KW and Fischer, MC and Niu, Q and Raizen,
MG},
Title = {Nonexponential decay in atomic tunneling},
Journal = {Technical Digest - European Quantum Electronics
Conference},
Pages = {24},
Year = {1998},
Month = {January},
Abstract = {A simple model of the band structure with a single (trapped)
band separated by a bandgap from a free particle state is
used to study short-time deviation from exponential decay in
a quantum tunneling experiment. The system consists of
ultracold sodium atoms that are trapped in an accelerating
periodic optical potential created by a standing wave of
light. Atoms can escape the wells via a quantum tunneling,
and the number that remain is measured as a function of
interaction time for a fixed value of the well depth and
acceleration.},
Key = {fds232527}
}
@article{fds232517,
Author = {Wilson, JW and Samineni, P and Fischer, MC and Warren,
WS},
Title = {Nonlinear cross-phase modulation microscopy using spectral
shifting},
Journal = {2012 Conference on Lasers and Electro-Optics, CLEO
2012},
Year = {2012},
Month = {December},
ISBN = {9781467318396},
Abstract = {Nonlinear phase contrast may be acquired by measuring
spectral shifting of an ultrafast pulse due to cross phase
modulation. This technique is used to obtain structural
details in a pigmented cell from a melanoma biopsy. © 2012
OSA.},
Key = {fds232517}
}
@article{fds350889,
Author = {Warren, WS and Piletic, I and Fischer, M and Fu, D and Samenini, P and Matthews, T},
Title = {Nonlinear microscopy without fluorescence: Seeing the needle
in the Haystack with Femtosecond pulse shaping},
Journal = {Optics InfoBase Conference Papers},
Year = {2009},
Month = {January},
ISBN = {9781557528711},
url = {http://dx.doi.org/10.1364/ntm.2009.nmc1},
Doi = {10.1364/ntm.2009.nmc1},
Key = {fds350889}
}
@article{fds232478,
Author = {Warren, WS and Piletic, I and Fischer, M and Fu, D and Samenini, P and Matthews, T},
Title = {Nonlinear microscopy without fluorescence: Seeing the needle
in the Haystack with Femtosecond pulse shaping},
Journal = {Optics InfoBase Conference Papers},
Year = {2009},
Month = {December},
ISBN = {9781557528711},
Key = {fds232478}
}
@article{fds365771,
Author = {Fischer, MC and Villafana, TE and Brown, W and Delaney, J and Warren,
WS},
Title = {Nonlinear Optical Imaging in Art Conservation and Heritage
Science},
Journal = {Optics InfoBase Conference Papers},
Year = {2015},
Month = {January},
ISBN = {9781943580033},
Abstract = {Pump-probe microscopy can extract molecular and structural
contrast with high spatial resolution even in thick,
scattering samples. We will discuss the technique’s
principle and applications for imaging historic paintings
and other cultural heritage objects.},
Key = {fds365771}
}
@article{fds232488,
Author = {Samineni, P and Fischer, MC and Liu, HC and Yasuda, R and Warren,
WS},
Title = {Nonlinear phase contrast imaging in neuronal
tissue},
Journal = {Optics InfoBase Conference Papers},
Year = {2011},
ISSN = {2162-2701},
Key = {fds232488}
}
@article{fds349889,
Author = {Samineni, P and Fischer, MC and Liu, HC and Yasuda, R and Warren,
WS},
Title = {Nonlinear phase contrast imaging in neuronal
tissue},
Journal = {Optics InfoBase Conference Papers},
Year = {2011},
Month = {January},
ISBN = {9781557529091},
url = {http://dx.doi.org/10.1364/ntm.2011.nmd3},
Abstract = {We demonstrate nonlinear phase contrast imaging in highly
scattering media using rapid femtosecond pulse shaping of
mode-locked laser pulses. We will also discuss potential
applications of this technique for intrinsic functional
neuronal imaging. © 2011 OSA: BODA/NTM/OMP/OTA.},
Doi = {10.1364/ntm.2011.nmd3},
Key = {fds349889}
}
@article{fds232536,
Author = {Warren, WS and Fischer, MC and Tong, Y},
Title = {Novel nonlinear contrast improves deep-tissue
microscopy},
Journal = {Laser Focus World},
Volume = {43},
Number = {6},
Pages = {99-103},
Publisher = {PENNWELL PUBL CO},
Year = {2007},
Month = {June},
ISSN = {1043-8092},
Abstract = {Femtosecond laser pulse and pulse-train shaping allow
detection of new nonlinear effects, with modest powers,
making new biomarkers accessible and permitting deeper
tissue imaging than conventional microscopy. The most
developed of these technique create light at a new
wavelength, which can then be separated from the exciting
laser. While the two photon fluorescence (TPF) can be
induced by continuous wave lasers, the vast majority of
studies use short laser pulses to achieve high peak power
with relatively low tissue damage from average power
dissipation. Two photon absorption (TPA) and self-phase
modulation (SPM) are the two most important
single-wavelength effect for the purpose of tissue
engineering. TPA is more effective on the intense pulses
than on the weak ones, and it thus distorts the amplitude
modulation, creating extra sidebands. Microscopic resolution
to depths of about 1mm should be achievable in most tissues
with far more physiological contrast than conventional
microscopy.},
Key = {fds232536}
}
@article{fds365773,
Author = {Madison, KW and Bharucha, CF and Fischer, MC and Wilkinson, SR and Morrow, PR and Niu, Q and Sundaram, B and Raizen,
MG},
Title = {Observation of non-exponential decay In quantum
tunnelling},
Journal = {Optics InfoBase Conference Papers},
Year = {1997},
Month = {January},
ISBN = {1557525013},
Abstract = {We report the observation of short-time deviation from
exponential decay in tunneling of ultra-cold atoms from an
accelerating periodic optical potential. We measure a'flat
survival probability followed by a transition to exponential
decay.},
Key = {fds365773}
}
@article{fds232537,
Author = {Fischer, MC and Madison, KW and Niu, Q and Raizen,
MG},
Title = {Observation of Rabi oscillations between Bloch bands in an
optical potential},
Journal = {Physical Review A},
Volume = {58},
Number = {4},
Pages = {R2648-R2651},
Publisher = {American Physical Society (APS)},
Year = {1998},
Month = {October},
url = {http://dx.doi.org/10.1103/physreva.58.r2648},
Abstract = {We report an experimental study of atomic motion in the
Bloch band of a periodic potential. Our system consists of
cold sodium atoms in a far detuned standing wave of near
resonant light. We prepare the atoms in the lowest motional
band, and then impose phase modulation in order to drive
interband transitions. We observe Rabi oscillations between
the first and second band as a function of modulation
intensity and frequency. We also observe damped oscillations
of the population as a function of modulation frequency,
which are primarily due to a spread in Rabi frequencies over
the Bloch band. © 1998 The American Physical
Society.},
Doi = {10.1103/physreva.58.r2648},
Key = {fds232537}
}
@article{fds323189,
Author = {Gutiérrez-Medina, B and Fischer, MC and Raizen,
MG},
Title = {Observation of the quantum zeno and anti-zeno effects in an
unstable system},
Journal = {Technical Digest - Summaries of Papers Presented at the
Quantum Electronics and Laser Science Conference, QELS
2001},
Pages = {QPD1.1-QPD1.2},
Publisher = {Opt. Soc. America},
Year = {2001},
Month = {January},
ISBN = {9781557526632},
url = {http://dx.doi.org/10.1109/QELS.2001.962243},
Abstract = {We study the motion of ultra-cold atoms in an accelerating
optical lattice. We find that the tunneling dynamics are
strongly affected by repeated measurement during the
non-exponential time, leading to either inhibition (zeno) or
enhancement (anti-zeno) of decay.},
Doi = {10.1109/QELS.2001.962243},
Key = {fds323189}
}
@article{fds232538,
Author = {Fischer, MC and Gutiérrez-Medina, B and Raizen,
MG},
Title = {Observation of the Quantum Zeno and Anti-Zeno Effects in an
Unstable System},
Journal = {Physical Review Letters},
Volume = {87},
Number = {4},
Pages = {040402},
Publisher = {American Physical Society (APS)},
Year = {2001},
Month = {July},
ISSN = {0031-9007},
url = {http://dx.doi.org/10.1103/physrevlett.87.040402},
Abstract = {We report the first observation of the quantum Zeno and
anti-Zeno effects in an unstable system. Cold sodium atoms
are trapped in a far-detuned standing wave of light that is
accelerated for a controlled duration. For a large
acceleration the atoms can escape the trapping potential via
tunneling. Initially the number of trapped atoms shows
strong nonexponential decay features, evolving into the
characteristic exponential decay behavior. We repeatedly
measure the number of atoms remaining trapped during the
initial period of nonexponential decay. Depending on the
frequency of measurements we observe a decay that is
suppressed or enhanced as compared to the unperturbed
system.},
Doi = {10.1103/physrevlett.87.040402},
Key = {fds232538}
}
@article{fds232548,
Author = {Madison, KW and Fischer, MC and Raizen, MG},
Title = {Observation of the Wannier-Stark fan and the fractional
ladder in an accelerating optical lattice},
Journal = {Physical Review A},
Volume = {60},
Number = {3},
Pages = {R1767-R1770},
Publisher = {American Physical Society (APS)},
Year = {1999},
Month = {September},
url = {http://dx.doi.org/10.1103/physreva.60.r1767},
Abstract = {We report an experimental study of the Wannier-Stark fan and
the fractional Wannier-Stark ladder using laser-cooled
sodium atoms in an accelerating one-dimensional standing
wave of light. We prepare the atoms in the lowest motional
band of the optical lattice and then impose a constant
acceleration. A weak oscillatory component is added to the
acceleration in order to resonantly drive interband
transitions, and the number of atoms that remain in the
lowest band is measured as a function of the probe
frequency. The spectrum is characterized by a ladder of
resonances spaced by the atomic Bloch oscillation frequency
[Formula Presented] When an additional, strong ac component
at frequency [Formula Presented] is added, a fractional
ladder is observed with a spacing related to the electric
matching ratio [Formula Presented]. © 1999 The American
Physical Society.},
Doi = {10.1103/physreva.60.r1767},
Key = {fds232548}
}
@article{fds232498,
Author = {Wilson, JW and Degan, S and Fischer, MC and Warren,
WS},
Title = {Optical clearing and multiphoton imaging of
paraffin-embedded specimens},
Journal = {Progress in Biomedical Optics and Imaging - Proceedings of
SPIE},
Volume = {8588},
Publisher = {SPIE},
Year = {2013},
Month = {June},
ISBN = {9780819493576},
ISSN = {1605-7422},
url = {http://dx.doi.org/10.1117/12.2003155},
Abstract = {New labeling, imaging, or analysis tools could provide new
retrospective insights when applied to archived,
paraffinembedded samples. Deep-tissue multiphoton microscopy
of paraffin-embedded specimens is achieved using optical
clearing with mineral oil. We tested a variety of murine
tissue specimens including skin, lung, spleen, kidney, and
heart, acquiring multiphoton autofluorescence and
second-harmonic generation, and pump-probe images This
technique introduces the capability for non-destructive
3-dimensional microscopic imaging of existing archived
pathology specimens, enabling retrospective studies. © 2013
SPIE.},
Doi = {10.1117/12.2003155},
Key = {fds232498}
}
@article{fds232523,
Author = {Wilson, JW and Degan, S and Warren, WS and Fischer,
MC},
Title = {Optical clearing of archive-compatible paraffin embedded
tissue for multiphoton microscopy},
Journal = {Biomedical Optics Express},
Volume = {3},
Number = {11},
Pages = {2752-2752},
Publisher = {The Optical Society},
Year = {2012},
Month = {November},
url = {http://www.ncbi.nlm.nih.gov/pubmed/23162713},
Abstract = {Standard histopathology techniques (including paraffin
embedding) are incompatible with thick tissue multiphoton
imaging, and standard clearing techniques on those specimens
destroy some molecular information. We demonstrate
multiphoton imaging in specimens prepared according to
standard histopathology techniques. This permits unlabeled
3-dimensional histology on archival tissue banks, which is
of great value in evaluating prognostic indicators.},
Doi = {10.1364/boe.3.002752},
Key = {fds232523}
}
@article{fds323578,
Author = {Wilson, JW and Degan, S and Warren, WS and Fischer,
MC},
Title = {Optical clearing of archive-compatible paraffin embedded
tissue for multiphoton microscopy: erratum},
Journal = {Biomedical Optics Express},
Volume = {4},
Number = {2},
Pages = {219-219},
Publisher = {The Optical Society},
Year = {2013},
Month = {February},
url = {http://dx.doi.org/10.1364/boe.4.000219},
Doi = {10.1364/boe.4.000219},
Key = {fds323578}
}
@article{fds349888,
Author = {Li, B and Claytor, K and Warren, WS and Fischer, MC},
Title = {Optimizing shape of femtosecond laser pulses for homodyne
detection of nonlinear optical signals},
Journal = {Optics InfoBase Conference Papers},
Year = {2011},
Month = {January},
ISBN = {9781557529176},
url = {http://dx.doi.org/10.1364/fio.2011.ftuq5},
Abstract = {Based on homodyne detection of weak nonlinear signals with
our spectral reshaping technique, pulse shapes are optimized
for fast nonlinear imaging using femtosecond mode-locked
lasers. © 2011 OSA.},
Doi = {10.1364/fio.2011.ftuq5},
Key = {fds349888}
}
@article{fds232490,
Author = {Li, B and Claytor, K and Warren, WS and Fischer, MC},
Title = {Optimizing shape of femtosecond laser pulses for homodyne
detection of nonlinear optical signals},
Journal = {Optics InfoBase Conference Papers},
Year = {2011},
Month = {December},
ISBN = {9781557529176},
Abstract = {Based on homodyne detection of weak nonlinear signals with
our spectral reshaping technique, pulse shapes are optimized
for fast nonlinear imaging using femtosecond mode-locked
lasers. © 2011 OSA.},
Key = {fds232490}
}
@article{fds232515,
Author = {Li, B and Warren, WS and Fischer, MC},
Title = {Phase-cycling coherent anti-Stokes Raman scattering using
shaped femtosecond laser pulses},
Journal = {Optics Express},
Volume = {18},
Number = {25},
Pages = {25825-25825},
Publisher = {The Optical Society},
Year = {2010},
Month = {December},
url = {http://www.ncbi.nlm.nih.gov/pubmed/21164927},
Abstract = {We demonstrate a homodyne coherent anti-Stokes Raman
scattering (CARS) technique based on femtosecond laser pulse
shaping. This technique utilizes fast phase cycling to
extract nonlinear Raman signatures with a self-generated
reference signal acting as a local oscillator. The local
oscillator is generated at the focus and is intrinsically
stable relative to the Raman signal even in highly
scattering samples. We can therefore retrieve phase
information from the Raman signal and can suppress the
ubiquitous non-resonant background.},
Doi = {10.1364/oe.18.025825},
Key = {fds232515}
}
@article{fds232522,
Author = {Robles, FE and Wilson, JW and Fischer, MC and Warren,
WS},
Title = {Phasor analysis for nonlinear pump-probe
microscopy},
Journal = {Optics Express},
Volume = {20},
Number = {15},
Pages = {17082-17082},
Publisher = {The Optical Society},
Year = {2012},
Month = {July},
ISSN = {1094-4087},
url = {http://dx.doi.org/10.1364/oe.20.017082},
Abstract = {Pump-probe microscopy provides molecular information by
probing transient, excited state dynamic properties of
pigmented samples. Analysis of the transient response is
typically conducted using principal component analysis or
multi-exponential fitting, however these methods are not
always practical or feasible. Here, we show an adaptation of
phasor analysis to provide an intuitive, robust, and
efficient method for analyzing and displaying pump-probe
images, thereby alleviating some of the challenges
associated with differentiating multiple pigments. A
theoretical treatment is given to understand how the complex
transient signals map onto the phasor plot. Analyses of
cutaneous and ocular pigmented tissue samples, as well as
historical pigments in art demonstrate the utility of this
approach. ©2012 Optical Society of America.},
Doi = {10.1364/oe.20.017082},
Key = {fds232522}
}
@article{fds332388,
Author = {Stanton, IN and Ayres, JA and Stecher, JT and Fischer, MC and Scharpf,
D and Scheuch, JD and Therien, MJ},
Title = {Power-Dependent Radiant Flux and Absolute Quantum Yields of
Upconversion Nanocrystals under Continuous and Pulsed
Excitation},
Journal = {The Journal of Physical Chemistry C},
Volume = {122},
Number = {1},
Pages = {252-259},
Publisher = {American Chemical Society (ACS)},
Year = {2018},
Month = {January},
url = {http://dx.doi.org/10.1021/acs.jpcc.7b11929},
Abstract = {Elucidating structure-function relationships that determine
the photophysics of nanomaterials that upconvert high-power,
near-infrared (NIR) excitation to shorter wavelength NIR,
visible, and UV emission requires both compositional
characterization and experimental designs that rigorously
define laser excitation conditions and the manner in which
emitted photons are collected. Presented herein are laser
power-dependent, total-emitted radiant flux (watts), and
absolute quantum yield measurements of homogeneous,
solution-phase 28 nm [NaYF4; Yb (15%), Er (2%)] upconversion
nanocrystals (UCNCs) determined using a multidetector
integrating sphere spectroscopy system. These studies
compare for the first time quantitative total radiant flux
and absolute quantum yield measurements of UCNCs determined
as a function of laser power density for both 970 nm
continuous-wave (CW) and 976 nm pulsed Ti-sapphire (140 fs
pulse width, 80 MHz) laser excitation. This study
illustrates that at intensities in the range 35-225 W/cm2,
the total radiant flux is higher under CW excitation by an
average factor of 1.5, and for this range of laser powers
the high peak intensities associated with femtosecond-pulsed
excitation conditions do not drive further augmentation of
the radiant flux magnitude. This study has important
ramifications for the field as it establishes the total
radiant flux as the most appropriate figure of merit
relevant for quantifying the emissive output intensity of
UCNCs. In contrast to an UCNC emission quantum yield
measurement, the total radiant flux may be determined with a
high degree of accuracy; this point is critical, as this
parameter is more closely connected to UCNC performance
metrics important for imaging, emission fingerprinting,
tracking, and energy conversion applications.},
Doi = {10.1021/acs.jpcc.7b11929},
Key = {fds332388}
}
@article{fds345861,
Author = {Yu, J and Li, Z and Liao, Y and Kolodziej, C and Kuyuldar, S and Warren,
WS and Burda, C and Fischer, MC},
Title = {Probing the Spatial Heterogeneity of Carrier Relaxation
Dynamics in CH3NH3PbI3
Perovskite Thin Films with Femtosecond Time‐Resolved
Nonlinear Optical Microscopy},
Journal = {Advanced Optical Materials},
Volume = {7},
Number = {22},
Pages = {1901185-1901185},
Publisher = {Wiley},
Year = {2019},
Month = {November},
url = {http://dx.doi.org/10.1002/adom.201901185},
Abstract = {<jats:title>Abstract</jats:title><jats:p>The spatial
heterogeneity of carrier dynamics in polycrystalline metal
halide perovskite (MHP) thin films has a strong influence on
photovoltaic device performance; however, the underlying
cause is not yet clearly understood. Here, the
sub‐micrometer scale mapping of charge carrier dynamics in
CH<jats:sub>3</jats:sub>NH<jats:sub>3</jats:sub>PbI<jats:sub>3</jats:sub>
thin films using time‐resolved nonlinear optical
microscopy, specifically transient absorption microscopy
(TAM) with sub‐picosecond (ps) and time‐resolved
photoluminescence (PL) microscopy with nanosecond temporal
resolution is reported. To study the influence of physical
morphology on charge carrier dynamics, MHP thin films having
granular‐ and fibrous structures are investigated. On both
types of films, spatial regions with short‐lived transient
gain signals (fast nonradiative relaxation within ≈1 ps)
typically show slower charge recombination via radiative
relaxation, which is attributed to the presence of
additional energy states near the band edge. In addition,
fibrous films show longer PL lifetimes. Interestingly, the
functional contrast shown in TAM images exhibits fundamental
differences from the structural contrast shown in scanning
electron microscopy images, implying that the variation of
trap density in the bulk contributes to the observed spatial
heterogeneity in carrier dynamics.</jats:p>},
Doi = {10.1002/adom.201901185},
Key = {fds345861}
}
@article{fds232519,
Author = {Samineni, P and deCruz, A and Villafaña, TE and Warren, WS and Fischer,
MC},
Title = {Pump-probe imaging of historical pigments used in
paintings},
Journal = {Optics Letters},
Volume = {37},
Number = {8},
Pages = {1310-1310},
Publisher = {The Optical Society},
Year = {2012},
Month = {April},
url = {http://www.ncbi.nlm.nih.gov/pubmed/22513669},
Abstract = {A recently developed nonlinear optical pump-probe microscopy
technique uses modulation transfer to sensitively extract
excited-state dynamics of endogenous biological pigments,
such as eumelanin and pheomelanin. In this work, we use this
method to image and characterize several inorganic and
organic pigments used in historical art. We show substantial
differences in the near-IR pump-probe signatures from
nominally similar pigments and suggest extensions to art
restoration.},
Doi = {10.1364/ol.37.001310},
Key = {fds232519}
}
@article{fds325989,
Author = {Robles, FE and Deb, S and Wilson, JW and Gainey, CS and Selim, MA and Mosca, PJ and Tyler, DS and Fischer, MC and Warren,
WS},
Title = {Pump-probe imaging of pigmented cutaneous melanoma primary
lesions gives insight into metastatic potential.},
Journal = {Biomed Opt Express},
Volume = {6},
Number = {9},
Pages = {3631-3645},
Year = {2015},
Month = {September},
url = {http://dx.doi.org/10.1364/BOE.6.003631},
Abstract = {Metastatic melanoma is associated with a poor prognosis, but
no method reliably predicts which melanomas of a given stage
will ultimately metastasize and which will not. While
sentinel lymph node biopsy (SLNB) has emerged as the most
powerful predictor of metastatic disease, the majority of
people dying from metastatic melanoma still have a negative
SLNB. Here we analyze pump-probe microscopy images of thin
biopsy slides of primary melanomas to assess their
metastatic potential. Pump-probe microscopy reveals detailed
chemical information of melanin with subcellular spatial
resolution. Quantification of the molecular signatures
without reference standards is achieved using a geometrical
representation of principal component analysis. Melanin
structure is analyzed in unison with the chemical
information by applying principles of mathematical
morphology. Results show that melanin in metastatic primary
lesions has lower chemical diversity than non-metastatic
primary lesions, and contains two distinct phenotypes that
are indicative of aggressive disease. Further, the
mathematical morphology analysis reveals melanin in
metastatic primary lesions has a distinct "dusty" quality.
Finally, a statistical analysis shows that the combination
of the chemical information with spatial structures predicts
metastatic potential with much better sensitivity than SLNB
and high specificity, suggesting pump-probe microscopy can
be an important tool to help predict the metastatic
potential of melanomas.},
Doi = {10.1364/BOE.6.003631},
Key = {fds325989}
}
@article{fds232516,
Author = {Samineni, P and De Cruz and A and Villafana, T and Fischer, MC and Warren,
WS},
Title = {Pump-probe microscopy of pigments used in historical
art},
Journal = {2012 Conference on Lasers and Electro-Optics, CLEO
2012},
Year = {2012},
Month = {December},
ISBN = {9781467318396},
Abstract = {We have developed a nonlinear microscopy technique that uses
sensitive modulation transfer to extract excited state
dynamics with high spatial resolution. Here, we use this
technique to characterize several pigments used in
historical artwork. © 2012 OSA.},
Key = {fds232516}
}
@article{fds304370,
Author = {Spector, ZZ and Emami, K and Fischer, MC and Zhu, J and Ishii, M and Vahdat, V and Yu, J and Kadlecek, S and Driehuys, B and Lipson, DA and Gefter, W and Shrager, J and Rizi, RR},
Title = {Quantitative assessment of emphysema using hyperpolarized
3He magnetic resonance imaging.},
Journal = {Magn Reson Med},
Volume = {53},
Number = {6},
Pages = {1341-1346},
Year = {2005},
Month = {June},
ISSN = {0740-3194},
url = {http://www.ncbi.nlm.nih.gov/pubmed/15906306},
Abstract = {In this experiment, Sprague-Dawley rats with
elastase-induced emphysema were imaged using hyperpolarized
(3)He MRI. Regional fractional ventilation r, the fraction
of gas replaced with a single tidal breath, was calculated
from a series of images in a wash-in study of hyperpolarized
gas. We compared the regional fractional ventilation in
these emphysematous rats to the regional fractional
ventilations we calculated from a previous baseline study in
healthy Sprague-Dawley rats. We found that there were
differences in the maps of fractional ventilation and its
associated frequency distribution between the healthy and
emphysematous rat lungs. Fractional ventilation tended to be
much lower in emphysematous rats than in normal rats. With
this information, we can use data on fractional ventilation
to regionally distinguish between healthy and emphysematous
portions of the lung. The successful implementation of such
a technique on a rat model could lead to work toward the
future implementation of this technique in human
patients.},
Doi = {10.1002/mrm.20514},
Key = {fds304370}
}
@article{fds232534,
Author = {Piletic, IR and Fischer, MC and Samineni, P and Yurtsever, G and Warren,
WS},
Title = {Rapid pulse shaping with homodyne detection for measuring
nonlinear optical signals},
Journal = {Optics Letters},
Volume = {33},
Number = {13},
Pages = {1482-1482},
Publisher = {Optica Publishing Group},
Year = {2008},
Month = {July},
ISSN = {0146-9592},
url = {http://www.ncbi.nlm.nih.gov/pubmed/18594672},
Abstract = {We have designed a common-mode interferometric acousto-optic
pulse shaper that is capable of shaping individual pulses
differently from a mode-locked laser. The design enables the
measurement of weak nonlinear optical signals such as
two-photon absorption and self-phase modulation at megahertz
rates. The experimental apparatus incorporates homodyne
detection as a means of resolving the phase of the detected
signals. The fast data acquisition rate and the ability to
perform measurements in scattering media make this
experimental apparatus amenable to imaging applications
analogous to measurements of two-photon fluorescence using a
mode-locked laser.},
Doi = {10.1364/ol.33.001482},
Key = {fds232534}
}
@article{fds323186,
Author = {Wilson, JW and Warren, WS and Fischer, MC},
Title = {Real-time digital signal processing in multiphoton and
time-resolved microscopy},
Journal = {Progress in Biomedical Optics and Imaging - Proceedings of
SPIE},
Volume = {9703},
Publisher = {SPIE},
Year = {2016},
Month = {January},
ISBN = {9781628419375},
url = {http://dx.doi.org/10.1117/12.2218102},
Abstract = {The use of multiphoton interactions in biological tissue for
imaging contrast requires highly sensitive optical
measurements. These often involve signal processing and
filtering steps between the photodetector and the data
acquisition device, such as photon counting and lock-in
amplification. These steps can be implemented as real-time
digital signal processing (DSP) elements on
field-programmable gate array (FPGA) devices, an approach
that affords much greater flexibility than commercial photon
counting or lock-in devices. We will present progress toward
developing two new FPGA-based DSP devices for multiphoton
and time-resolved microscopy applications. The first is a
high-speed multiharmonic lock-in amplifier for transient
absorption microscopy, which is being developed for
real-time analysis of the intensity-dependence of melanin,
with applications in vivo and ex vivo (noninvasive
histopathology of melanoma and pigmented lesions). The
second device is a kHz lock-in amplifier running on a low
cost ($50 - $200) development platform. It is our hope that
these FPGA-based DSP devices will enable new, high-speed,
low-cost applications in multiphoton and time-resolved
microscopy.},
Doi = {10.1117/12.2218102},
Key = {fds323186}
}
@article{fds232510,
Author = {Fischer, MC and Liu, H and Piletic, IR and Ye, T and Yasuda, R and Warren,
WS},
Title = {Self-phase modulation and two-photon absorption imaging of
cells and active neurons},
Journal = {Progress in Biomedical Optics and Imaging - Proceedings of
SPIE},
Volume = {6442},
Pages = {64421J},
Booktitle = {Multiphoton Micr. in the Biomed. Sciences VII, Proc.
SPIE},
Publisher = {SPIE},
Year = {2007},
Month = {September},
ISBN = {9780819465559},
ISSN = {1605-7422},
url = {http://dx.doi.org/10.1117/12.698693},
Abstract = {Even though multi-photon fluorescence microscopy offers
higher resolution and better penetration depth than
traditional fluorescence microscopy, its use is restricted
to the detection of molecules that fluoresce. Two-photon
absorption (TPA) imaging can provide contrast in
non-fluorescent molecules while retaining the high
resolution and sectioning capabilities of nonlinear imaging
modalities. In the long-wavelength water window, tissue TPA
is dominated by the endogenous molecules melanin and
hemoglobin with an almost complete absence of endogenous
two-photon fluorescence. A complementary nonlinear contrast
mechanism is self-phase modulation (SPM), which can provide
intrinsic signatures that can depend on local tissue
anisotropy, chemical environment, or other structural
properties. We have developed a spectral hole refilling
measurement technique for TPA and SPM measurements using
shaped ultrafast laser pulses. Here we report on a
microscopy setup to simultaneously acquire 3D,
high-resolution TPA and SPM images. We have acquired data in
mounted B16 melanoma cells with very modest laser power
levels. We will also discuss the possible application of
this measurement technique to neuronal imaging. Since SPM is
sensitive to material structure we can expect SPM properties
of neurons to change during neuronal firing. Using our
hole-refilling technique we have now demonstrated strong
novel intrinsic nonlinear signatures of neuronal activation
in a hippocampal brain slice. The observed changes in
nonlinear signal upon collective activation were up to
factors of two, unlike other intrinsic optical signal
changes on the percent level. These results show that TPA
and SPM imaging can provide important novel functional
contrast in tissue using very modest power levels suitable
for in vivo applications.},
Doi = {10.1117/12.698693},
Key = {fds232510}
}
@article{fds232535,
Author = {Fischer, MC and Liu, HC and Piletic, IR and Escobedo-Lozoya, Y and Yasuda, R and Warren, WS},
Title = {Self-phase modulation signatures of neuronal
activity},
Journal = {Optics Letters},
Volume = {33},
Number = {3},
Pages = {219-219},
Publisher = {Optica Publishing Group},
Year = {2008},
Month = {February},
ISSN = {0146-9592},
url = {http://www.ncbi.nlm.nih.gov/pubmed/18246134},
Abstract = {We use phase-sensitive detection of spectral hole refilling
to demonstrate strong novel intrinsic nonlinear signatures
of neuronal activation in hippocampal brain slices. The
ability to gain access to this fundamentally new intrinsic
contrast with modest power levels suggests a new approach to
in vivo neural imaging. We expect that we can extrapolate
our method to high spatial and temporal resolution in deep
tissue while retaining the noninvasive character.},
Doi = {10.1364/ol.33.000219},
Key = {fds232535}
}
@article{fds323188,
Author = {Wilson, JW and Anderson, M and Park, JK and Fischer, MC and Warren,
WS},
Title = {Separating higher-order nonlinearities in transient
absorption microscopy},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {9584},
Publisher = {SPIE},
Year = {2015},
Month = {January},
ISBN = {9781628417500},
url = {http://dx.doi.org/10.1117/12.2187133},
Abstract = {The transient absorption response of melanin is a promising
optically-accessible biomarker for distinguishing malignant
melanoma from benign pigmented lesions, as demonstrated by
earlier experiments on thin sections from biopsied tissue.
The technique has also been demonstrated in vivo, but the
higher optical intensity required for detecting these
signals from backscattered light introduces higher-order
nonlinearities in the transient response of melanin. These
components that are higher than linear with respect to the
pump or the probe introduce intensity-dependent changes to
the overall response that complicate data analysis. However,
our data also suggest these nonlinearities might be
advantageous to in vivo imaging, in that different types of
melanins have different nonlinear responses. Therefore,
methods to separate linear from nonlinear components in
transient absorption measurements might provide additional
information to aid in the diagnosis of melanoma. We will
discuss numerical methods for analyzing the various
nonlinear contributions to pump-probe signals, with the
ultimate objective of real time analysis using digital
signal processing techniques. To that end, we have replaced
the lock in amplifier in our pump-probe microscope with a
high-speed data acquisition board, and reprogrammed the
coprocessor field-programmable gate array (FPGA) to perform
lock-in detection. The FPGA lock-in offers better
performance than the commercial instrument, in terms of both
signal to noise ratio and speed. In addition, the
flexibility of the digital signal processing approach
enables demodulation of more complicated waveforms, such as
spread-spectrum sequences, which has the potential to
accelerate microscopy methods that rely on slow relaxation
phenomena, such as photothermal and phosphorescence lifetime
imaging.},
Doi = {10.1117/12.2187133},
Key = {fds323188}
}
@article{fds326162,
Author = {Fischer, M},
Title = {Shedding new light on old art},
Journal = {Physics World},
Volume = {26},
Number = {12},
Pages = {19-23},
Publisher = {IOP Publishing},
Year = {2013},
Month = {January},
url = {http://dx.doi.org/10.1088/2058-7058/26/12/30},
Doi = {10.1088/2058-7058/26/12/30},
Key = {fds326162}
}
@article{fds232533,
Author = {Fischer, MC and Liu, HC and Piletic, IR and Warren,
WS},
Title = {Simultaneous self-phase modulation and two-photon absorption
measurement by a spectral homodyne Z-scan
method},
Journal = {Optics Express},
Volume = {16},
Number = {6},
Pages = {4192-4192},
Publisher = {Optica Publishing Group},
Year = {2008},
Month = {March},
url = {http://www.ncbi.nlm.nih.gov/pubmed/18542515},
Abstract = {We developed a technique to simultaneously measure
self-phase modulation and two-photon absorption using shaped
femtosecond laser pulses. In the conventional Z-scan
measurement technique the amount of nonlinearity is
determined by measuring the change in shape and intensity of
a transmitted laser beam. In contrast, our method
sensitively measures nonlinearity-induced changes in the
pulse spectrum. In this work we demonstrate the technique in
nonlinear absorptive and dispersive samples, quantify the
obtained signal, and compare the measurements with
traditional Z-scans. This technique is capable of measuring
these nonlinearities in highly scattering
samples.},
Doi = {10.1364/oe.16.004192},
Key = {fds232533}
}
@article{fds232540,
Author = {Fischer, MC and Spector, ZZ and Ishii, M and Yu, J and Emami, K and Itkin,
M and Rizi, R},
Title = {Single-acquisition sequence for the measurement of oxygen
partial pressure by hyperpolarized gas MRI.},
Journal = {Magn Reson Med},
Volume = {52},
Number = {4},
Pages = {766-773},
Year = {2004},
Month = {October},
url = {http://dx.doi.org/10.1002/mrm.20239},
Abstract = {Magnetic resonance imaging (MRI) with hyperpolarized
3-helium gas (HP 3He) offers the possibility of studying
functional lung parameters such as the alveolar oxygen
concentration and oxygen depletion rate. Until now, a
double-acquisition technique has been utilized to extract
these parameters. A complicated single-acquisition technique
was previously developed to avoid the necessity of
performing two identical breathing maneuvers. The results
obtained with this technique were significantly less
accurate than the results obtained with the
double-acquisition method. In this work, a novel, easily
implemented single-acquisition sequence is presented that
provides results comparable to those obtained with the
established double-acquisition method. This method is
demonstrated in a phantom and a pig model on a 1.5 T scanner
using a 2D fast low-angle shot (FLASH) gradient-echo
sequence. Numerical simulations of the time evolution of the
oxygen concentration were performed. Simulation results are
presented to support the experimental data. Various
parameter regimes were experimentally and numerically
investigated.},
Doi = {10.1002/mrm.20239},
Key = {fds232540}
}
@article{fds339932,
Author = {Yu, J and Warren, WS and Fischer, MC},
Title = {Spectroscopic Differentiation and Microscopic Imaging of Red
Organic Pigments Using Optical Pump–Probe
Contrast},
Journal = {Analytical Chemistry},
Volume = {90},
Number = {21},
Pages = {12686-12691},
Publisher = {American Chemical Society (ACS)},
Year = {2018},
Month = {November},
url = {http://dx.doi.org/10.1021/acs.analchem.8b02949},
Abstract = {Analysis of red organic pigments in artworks (and in
forensics applications) is challenging, because conventional
nondestructive mapping techniques provide little contrast,
and most chemical analyses with high specificity require
sample removal. Here we demonstrate a new optical approach,
pump-probe microscopy, for the analysis of red organic
pigments. We investigate Carmine naccarat, Lac dye,
purpurin, alizarin, madder lake, and eosin Y and show that
their intrinsic photophysical properties produce distinctive
pump-probe spectra. We utilize this contrast for
high-resolution, three-dimensional imaging without the need
for physical sample removal. Lastly, we highlight the
potential of pump-probe microscopy as an analytical tool for
forensics of other types of organic colorants by
investigating a series of automotive paints.},
Doi = {10.1021/acs.analchem.8b02949},
Key = {fds339932}
}
@article{fds325217,
Author = {Robles, FE and Zhou, KC and Fischer, MC and Warren,
WS},
Title = {Stimulated Raman scattering spectroscopic optical coherence
tomography},
Journal = {Optica},
Volume = {4},
Number = {2},
Pages = {243-243},
Publisher = {The Optical Society},
Year = {2017},
Month = {February},
url = {http://dx.doi.org/10.1364/optica.4.000243},
Abstract = {We integrate spectroscopic optical coherence tomography
(SOCT) with stimulated Raman scattering (SRS) to enable
simultaneously multiplexed spatial and spectral imaging with
sensitivity to many endogenous biochemical species that play
an important role in biology and medicine. The combined
approach, termed SRS-SOCT, overcomes the limitations of each
individual method. Ultimately, SRS-SOCT has the potential to
achieve fast, volumetric, and highly sensitive label-free
molecular imaging. We demonstrate the approach by imaging
excised human adipose tissue and detecting the lipids' Raman
signatures in the high-wavenumber region.},
Doi = {10.1364/optica.4.000243},
Key = {fds325217}
}
@article{fds358289,
Author = {McKeown Wessler and GC and Wang, T and Sun, J-P and Liao, Y and Fischer,
MC and Blum, V and Mitzi, DB},
Title = {Structural, Optical, and Electronic Properties of Two
Quaternary Chalcogenide Semiconductors: Ag2SrSiS4
and Ag2SrGeS4.},
Journal = {Inorganic chemistry},
Volume = {60},
Number = {16},
Pages = {12206-12217},
Year = {2021},
Month = {August},
url = {http://dx.doi.org/10.1021/acs.inorgchem.1c01416},
Abstract = {Quaternary chalcogenide materials have long been a source of
semiconductors for optoelectronic applications. Recent
studies on I<sub>2</sub>-II-IV-X<sub>4</sub> (I = Ag, Cu,
Li; II = Ba, Sr, Eu, Pb; IV = Si, Ge, Sn; X = S, Se)
materials have shown particular versatility and promise
among these compounds. These semiconductors take advantage
of a diverse bonding scheme and chemical differences among
cations to target a degree of antisite defect resistance.
Within this set of compounds, the materials containing both
Ag and Sr have not been experimentally studied and leave a
gap in the full understanding of the family. Here, we have
synthesized powders and single crystals of two Ag- and
Sr-containing compounds, Ag<sub>2</sub>SrSiS<sub>4</sub> and
Ag<sub>2</sub>SrGeS<sub>4</sub>, each found to form in the
tetragonal <i>I</i>4̅2<i>m</i> structure of
Ag<sub>2</sub>BaGeS<sub>4</sub>. During the synthesis
targeting the title compounds, two additional materials,
Ag<sub>2</sub>Sr<sub>3</sub>Si<sub>2</sub>S<sub>8</sub> and
Ag<sub>2</sub>Sr<sub>3</sub>Ge<sub>2</sub>S<sub>8</sub>,
have also been identified. These cubic compounds represent
impurity phases during the synthesis of Ag<sub>2</sub>SrSiS<sub>4</sub>
and Ag<sub>2</sub>SrGeS<sub>4</sub>. We show through hybrid
density functional theory calculations that
Ag<sub>2</sub>SrSiS<sub>4</sub> and Ag<sub>2</sub>SrGeS<sub>4</sub>
have highly dispersive band-edge states and indirect band
gaps, experimentally measured as 2.08(1) and 1.73(2) eV,
respectively. Second-harmonic generation measurements on
Ag<sub>2</sub>SrSiS<sub>4</sub> and Ag<sub>2</sub>SrGeS<sub>4</sub>
powders show frequency-doubling capabilities in the
near-infrared range.},
Doi = {10.1021/acs.inorgchem.1c01416},
Key = {fds358289}
}
@article{fds325990,
Author = {Warren, WS},
Title = {Tissue imaging with shaped femtosecond laser
pulses},
Journal = {Optics InfoBase Conference Papers},
Volume = {88},
Pages = {807-+},
Booktitle = {Ultrafast Phenomena XV},
Publisher = {Springer-Verlag},
Year = {2009},
Month = {January},
ISBN = {9781557528780},
Abstract = {Rapid laser pulse shaping permit detection of novel
molecular signatures such as self- and cross-phase
modulation or nonlinear absorption. These effects are used
to discriminate between different melanins in tissue and to
monitor neuronal activation. © 2009 OSA/FiO/LS/AO/AIOM/COSI/LM/SRS
2009.},
Key = {fds325990}
}
@article{fds232475,
Author = {Fischer, MC and Ye, T and Yurtsever, G and Miller, A and Ciocca, M and Wagner, W and Warren, WS},
Title = {Two-photon absorption and self-phase modulation measurements
with shaped femtosecond laser pulses},
Journal = {2005 Conference on Lasers and Electro-Optics,
CLEO},
Volume = {2},
Pages = {968-970},
Year = {2005},
Month = {January},
ISBN = {9781557527950},
ISSN = {2162-2701},
url = {http://dx.doi.org/10.1109/cleo.2005.201992},
Abstract = {We demonstrate experimentally that phase sensitive detection
of spectral hole refilling can yield information about
self-phase modulation and two-photon absorption
coefficients. © 2005 Optical Society of
America.},
Doi = {10.1109/cleo.2005.201992},
Key = {fds232475}
}
@article{fds232545,
Author = {Fischer, MC and Ye, T and Yurtsever, G and Miller, A and Ciocca, M and Wagner, W and Warren, WS},
Title = {Two-photon absorption and self-phase modulation measurements
with shaped femtosecond laser pulses},
Journal = {Optics Letters},
Volume = {30},
Number = {12},
Pages = {1551-1551},
Publisher = {Optica Publishing Group},
Year = {2005},
Month = {June},
ISSN = {0146-9592},
url = {http://dx.doi.org/10.1364/ol.30.001551},
Abstract = {We show that phase-sensitive detection of spectral hole
refilling can yield information about self-phase modulation
and two-photon absorption coefficients. We expect that, when
applied to tissue microscopy, this technique will allow the
study of endogenous molecular markers beneath the surface,
even if those markers are nonfluorescent.},
Doi = {10.1364/ol.30.001551},
Key = {fds232545}
}
@article{fds365591,
Author = {Warren, WS and Miller, A and Wagner, W and Ye, T and Fischer, M and Yurtsever, G},
Title = {Two-photon absorption imaging and self-phase modulation
imaging with shaped laser pulses},
Journal = {Optics InfoBase Conference Papers},
Year = {2004},
Month = {January},
ISBN = {1557527733},
Abstract = {We present a new method for deep tissue imaging using
nonlinear optics. Specific tailored laser pulses permit
measurement of two-photon absorption or self-phase
modulation with modest near-IR powers (1-10 mW), giving good
penetration and molecular specificity.},
Key = {fds365591}
}
@article{fds365772,
Author = {Warren, WS and Miller, A and Wagner, W and Ye, T and Fischer, M and Yurtsever, G},
Title = {Two-photon absorption imaging with shaped femtosecond laser
pulses},
Journal = {Optics InfoBase Conference Papers},
Year = {2004},
Month = {January},
ISBN = {3540241108},
Abstract = {Femtosecond laser pulse shaping permits background-free
detection of two-photon absorption, which tends to refill
spectral holes. This opens up new spectroscopic windows for
monitoring tissue characteristics.},
Key = {fds365772}
}
@article{fds232506,
Author = {Warren, WS and Miller, A and Wagner, W and Ye, T and Fischer, M and Yurtsever, G},
Title = {Two-photon absorption imaging with shaped femtosecond laser
pulses},
Journal = {Springer Series in Chemical Physics},
Volume = {79},
Pages = {867-869},
Booktitle = {Ultrafast Phenomena XIV},
Publisher = {Springer-Verlag},
Year = {2004},
Month = {December},
ISSN = {0172-6218},
Abstract = {Femtosecond laser pulse shaping permits background-free
detection of two-photon absorption, which tends to refill
spectral holes. This opens up new spectroscopic windows for
monitoring tissue characteristics.},
Key = {fds232506}
}
@article{fds232528,
Author = {Ye, T and Fischer, M and Yurtsever, G and Warren,
WS},
Title = {Two-photon absorption microscopy of tissue},
Journal = {Optics InfoBase Conference Papers},
Volume = {2},
Pages = {1512-1514},
Booktitle = {Proc. of the Conf. on Lasers and Electro-Optics},
Year = {2005},
Month = {January},
ISBN = {9781557527707},
ISSN = {2162-2701},
Abstract = {Two-photon absorption microscopy (TPAM) has been
demonstrated to be able to image melanin with high
sensitivity. TPAM opens up a wide range of nonfluorescent
molecular targets. © 2005 Optical Society of
America.},
Key = {fds232528}
}
@article{fds323187,
Author = {Villafana, TE and Brown, W and Warren, WS and Fischer,
M},
Title = {Ultrafast pump-probe dynamics of iron oxide based earth
pigments for applications to ancient pottery
manufacture},
Journal = {Proceedings of SPIE - The International Society for Optical
Engineering},
Volume = {9527},
Publisher = {SPIE},
Year = {2015},
Month = {January},
ISBN = {9781628416879},
url = {http://dx.doi.org/10.1117/12.2184758},
Abstract = {We demonstrate that ultrafast pump-probe microscopy provides
unique dynamics for natural iron oxide and iron hydroxide
earth pigments, despite their chemical similarity. First, we
conducted a pump-probe spectroscopy study on heat-treated
hematite (the pure red iron oxide mineral) and found the
pump-probe dynamics to be temperature dependent. Second, we
investigated pottery fired under known conditions and
observed firing dependent pump-probe dynamics. Finally, we
imaged a New World potshard from the North Carolina Museum
of Art. Our results indicate that pump-probe microscopy
could be a useful tool in elucidating pottery
manufacture.},
Doi = {10.1117/12.2184758},
Key = {fds323187}
}
@article{fds340751,
Author = {Ju, K-Y and Fischer, MC and Warren, WS},
Title = {Understanding the Role of Aggregation in the Broad
Absorption Bands of Eumelanin},
Journal = {ACS Nano},
Volume = {12},
Number = {12},
Pages = {12050-12061},
Publisher = {American Chemical Society (ACS)},
Year = {2018},
Month = {December},
url = {http://dx.doi.org/10.1021/acsnano.8b04905},
Abstract = {In this work, we investigate the relationship between the
complex hierarchical assembly structure of eumelanin, its
characteristic broad absorption band, and the highly unusual
nonlinear dynamics revealed by pump-probe or transient
absorption microscopy. Melanin-like nanoparticles (MelNPs),
generated by spontaneous oxidation of dopamine, were created
with uniform but adjustable size distributions, and
kinetically controlled oxidation was probed with a wide
range of characterization methods. This lets us explore the
broad absorption bands of eumelanin models at different
assembly levels, such as small subunit fractions (single
monomeric and oligomeric units and small oligomer stacks),
stacked oligomer fractions (protomolecules), and large-scale
aggregates of protomolecules (parental particles). Both the
absorption and pump-probe dynamics are very sensitive to
these structural differences or to the size of intact
particles (a surprising result for an organic polymer). We
show that the geometric packing order of protomolecules in
long-range aggregation is key secondary interactions to
extend the absorption band of eumelanin to the low energy
spectrum and produce drastic changes in the transient
absorption spectrum.},
Doi = {10.1021/acsnano.8b04905},
Key = {fds340751}
}
@article{fds342577,
Author = {Ju, K-Y and Degan, S and Fischer, MC and Zhou, KC and Jia, X and Yu, J and Warren, WS},
Title = {Unraveling the molecular nature of melanin changes in
metastatic cancer},
Journal = {Journal of Biomedical Optics},
Volume = {24},
Number = {05},
Pages = {1-1},
Publisher = {SPIE-Intl Soc Optical Eng},
Year = {2019},
Month = {April},
url = {http://dx.doi.org/10.1117/1.jbo.24.5.051414},
Abstract = {More people die from melanoma after a stage I diagnosis than
after a stage IV diagnosis, because the tools available to
clinicians do not readily identify which early-stage cancers
will be aggressive. Near-infrared pump-probe microscopy
detects fundamental differences in melanin structure between
benign human moles and melanoma and also correlates with
metastatic potential. However, the biological mechanisms of
these changes have been difficult to quantify, as many
different mechanisms can contribute to the pump-probe
signal. We use model systems (sepia, squid, and synthetic
eumelanin), cellular uptake studies, and a range of pump and
probe wavelengths to demonstrate that the clinically
observed effects come from alterations of the aggregated
mode from "thick oligomer stacks" to "thin oligomer stacks"
(due to changes in monomer composition) and (predominantly)
deaggregation of the assembled melanin structure. This
provides the opportunity to use pump-probe microscopy for
the detection and study of melanin-associated
diseases.},
Doi = {10.1117/1.jbo.24.5.051414},
Key = {fds342577}
}
@article{fds344710,
Author = {Yu, J and Warren, WS and Fischer, MC},
Title = {Visualization of vermilion degradation using pump-probe
microscopy},
Journal = {Science Advances},
Volume = {5},
Number = {6},
Pages = {eaaw3136},
Publisher = {American Association for the Advancement of Science
(AAAS)},
Year = {2019},
Month = {June},
url = {http://dx.doi.org/10.1126/sciadv.aaw3136},
Abstract = {<jats:p>Pump-probe microscopy identifies metacinnabar and
metallic mercury as possible degradation product of
vermilion (α-HgS).</jats:p>},
Doi = {10.1126/sciadv.aaw3136},
Key = {fds344710}
}
@article{fds347623,
Author = {Yu, J and Li, Z and Kolodziej, C and Kuyuldar, S and Warren, WS and Burda,
C and Fischer, MC},
Title = {Visualizing the impact of chloride addition on the
microscopic carrier dynamics of MAPbI3 thin films using
femtosecond transient absorption microscopy},
Journal = {The Journal of Chemical Physics},
Volume = {151},
Number = {23},
Pages = {234710-234710},
Publisher = {AIP Publishing},
Year = {2019},
Month = {December},
url = {http://dx.doi.org/10.1063/1.5127875},
Abstract = {<jats:p>The spatial heterogeneity of carrier dynamics in
mixed halide perovskite CH3NH3PbI3−xClx thin films with a
range of different chloride additions is mapped using
femtosecond transient absorption microscopy (TAM). The
comparison of TAM images of fibrous and granular
polycrystalline CH3NH3PbI3−xClx films indicates that the
impact of chloride addition on the local heterogeneity of
carrier dynamics is highly dependent on the film preparation
method and the resulting morphology. In addition to signals
of pristine CH3NH3PbI3, CH3NH3PbI3−xClx films with a
fibrous structure show long-lived excited state absorption
(ESA) signals in localized, microscopic regions. The ESA
signal exhibits transient absorption with a rise time of
about 5 ps after the excitation pulse, indicating that these
distinct micrograins have preferential carrier trapping
properties. The chemical composition of these micrograins
does not differ detectably from their surroundings. In
contrast, in CH3NH3PbI3−xClx films with a granular
structure, Cl addition does not seem to affect the charge
carrier dynamics. These results provide insight into the
localized effects of halide mixing and on the resulting
photophysical properties of mixed halide perovskite
materials on the micrometer length scale.</jats:p>},
Doi = {10.1063/1.5127875},
Key = {fds347623}
}