Optical bistability in semiconductors

Detailed results are presented on optical bistability (OB) and two-beam optical transistor (transphasor) action in simple, one-element Fabry-Perot devices, with the semiconductor InSb using a CW CO laser near the bandgap region, and OB for semiconductors in general is discussed. OB and multistability are seen in transmission and reflection at 5 K. At 77 K, cm²/W [corresponding to an effective ESU] is measured and OB is observed at ∼8 mW. Transphasor action at 5 K is presented and the influence of degenerate four-wave mixing is discussed. The basic physics of the microscopic mechanism for n2(bandgap-resonant saturation) is summarized and a simplified, generalized model is derived. This model and arguments on cavity optimization are used to predict order of magnitude limits to switching power, energy, and speed, both in InSb and other semiconductors, even in the absence of excitonic enhancement.