Abstract:
We demonstrate an all-optical switch that operates at ultra-low-light levels and exhibits several features
necessary for use in optical switching networks. An input switching beam, wavelength lambda, with an energy
density of 10−2 photons per optical cross section sigma=lambda^2 / 2 pi changes the orientation of a two-spot pattern
generated via parametric instability in warm rubidium vapor. The instability is induced with less than 1 mW of
total pump power and generates several uWs of output light. The switch is cascadable: the device output is
capable of driving multiple inputs, and exhibits transistor-like signal-level restoration with both saturated and
intermediate response regimes. Additionally, the system requires an input power proportional to the inverse of
the response time, which suggests thermal dissipation does not necessarily limit the practicality of optical logic
devices.