Picosecond Bistable Optical Switch Using Two-Photon Transitions.
DEPARTMENT OF THE NAVY WASHINGTON DC
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This patent discloses a bistable optical switch comprising a Fabry Perot resonator containing a nonlinear semiconductor medium with a desired band structure and whose susceptibility refractive index varies with optical energy density. The Fabry-Perot resonator is biased to a point where two stable transmission states are possible. Switching is accomplished by pumping the nonlinear material with an energy hw in the range 12 to 1 of the bandgap between the upper valence band and the conduction band of the nonlinear material, in order to stimulate a two photon valence to conduction band absorption transition at a non minimum energy and thereby make possible a one-hw photon virtual transition between the heavy hole and split-off valence bands of the nonlinear material. This virtual transition alters the susceptibility thereby switching the resonator to a different stable transmission state. Switching times on the order of picoseconds are obtained because switching time is not dependent on the carrier recombination time.
- Solid State Physics