Abstract

Much interest has been emerging in optical signal processing and optical computing. In these fields, various functional devices are greatly demanded. A vertical and direct integration of a light-receiving device and a light-emitting device is an attractive method to achieve these functional devices [1–5]. The integrated device exhibits not only the simple combined characteristics of constituent devices but also the more elevated characteristics due to their internal optical couplings. For example, the integrated device composed of four heterojunction phototransistors (HPTs) and one laser diode (LD) offers the functions of light-controlled optical bistability, light-controlled optical thresholding, and optical tristability [6].

© 1993 Optical Society of America