Pixels consisting of a single vertical-cavity laser thyristor and a double vertical-cavity phototransistor

Bidirectionally cascadable optical pixels that consist of a single-vertical-cavity surface-emitting laser (VCSEL) thyristor and a double-vertical-cavity phototransistor are proposed. Despite almost identical layer structures, each device characteristic can be independently optimized by introducing a lambda /2-spacer layer into the phototransistor section. A lasing threshold of 0.8 mA and a slope efficiency of 0.25 W/A are obtained for the laser thyristor, and a flat-topped photocurrent spectrum over 30 A and a photocurrent gain of 70 A/W are obtained for the phototransistor at the resonant wavelength. This work demonstrates the possibility of monolithic integration using thermal desorption and a regrowth technique and the suitability of these devices for massively parallel optical interconnections.>