Bandgap resonant optical nonlinearities in InAs and their use in optical bistability

A detailed study of bandgap resonant optical nonlinearities in n-type InAs and their use in an optical bistable device is presented. The results of measurements of both nonlinear absorption and nonlinear refraction taken with an HF laser show good agreement with a band-filling model in which the contribution from the light-hole band and the effects of large initial free carrier densities are included. Evidence of the saturation of the nonlinear refraction through the carrier-density-dependent recombination rate is presented, and it is shown that this effect together with diffraction effects accounts for the critical power for bistability observed in the reflected signal from an InAs etalon at 77 K.