Publication # 030

We report the realisation of optically bistable switching and memory elements, and the transphasor (an all-optical transistor) in simple one element noninear Fabry-Perot interferometers made from the semiconductor InSb. These devices, which operate at 5 K and 77 K with mW powers from a cw CO laser between 5 and 6 um rely on a strongly intensity-dependent refractive index discovered near the bandgap region of InSb and explained by bandgap resonant saturation. Switching speeds are shown to be , 500 ns in these first devices and operation to much shorter timescales is predicted. Operation at room temperature and in other semiconductors at other wavelengths remains a powwibility and such devices offer considerable potential for all-optical switching in integrated optics and laser pulse control.