Optical flip-flop and astable nultivibrator functions by vertical and direct integration of heterojunction phototransistors and laser diodes

A optoelectronic integrated device in which six heterojunction phototransistors and two laser diodes are vertically and directly integrated is developed to achieve new functions important for optical signal processing and optical computing. It is demonstrated that the device has a bistable flip-flop function, in which the output portion is switched alternately by the corresponding optical input. The function is extended to a tristable flip-flop, which is especially important for multistable logic, by using multiple HPTS and their internal optical and/or electrical couplings. Moreover, an astable multivibrator function or a self-oscillating function, is successfully demonstrated by applying the interconnecting technique to the bistable flip-flop function.