ANALYSIS OF AN ELECTROOPTICAL SWITCHING DEVICE DUE TO INTRINSIC PHOTOCONDUCTIVITY

We analyse an electro-optical device consisting of a stack of undoped alternating layers of narrow- and wide-gap materials (e.g. GaAs/AlGaAs ) together with a series resistor under constant voltage bias. The dev ice depends crucially on the photoconductivity of the narrow-gap layer s with a width of the order of a carrier mean free path. The Franz-Kel dysh effect, the charge separation of photoexcited carriers in a stati c field, and the ballistic part of the current are responsible for the resulting very large electro-optical nonlinearity. In a Fabry-Perot c avity a room temperature electro-optical bistability is obtained at li ght intensities smaller than 10 mW cm-2.