Novel single quantum well optoelectronic devices based on exciton bleaching

Novel planar high-speed optoelectronic devices offering advantages for optoelectronic integration are proposed. Exciton-resonant light propagates along a single-mode rib waveguide containing a single quantum well (SQW), the only absorbing medium in the waveguide. The two-dimensional (2D) excitonic optical absorption is controlled by the bleaching effect induced by free carriers, whose electrical conduction simultaneously makes possible optical detection and high-speed transistor action. Three such optical modulating devices are: 1) a gate-controlled single quantum well field-effect transistor (FET) optical modulator (FETOM), 2) an optically-readable memory element, and 3) an optically-switched charge storage device. The FETOM, in which the free-carrier density in the SQW is controlled by the gate voltage, offers high speed (22 ps), small size (125 μm), and unique potential for optoelectronic integration.