Optical tristable device by vertical and direct integration of heterojunction phototransistors and laser diodes

A light-controlled optical tristable device with an optical gain is actualized. The device has a configuration of vertical and direct integration of two heterojunction phototransistors (HPTs) on a laser diode (LD) along the cavity direction. An external optical input causes a bistable operation in one HPT+LD part. With the optical connection between two HPTs through the LD stripe, a bistable operation also occurs in the other HPT+LD part. The light-controlled optical tristability is achieved with the combination of the bistable operation in each HPT+LD part.<
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