ELECTRO-OPTICAL DEVICE

An electro-optical device includes a vertical cavity surface emitting laser a heterojunction light emitting device and heterojunction phototransistor on a semiconductor substrate. Layers of the heterojunction phototransistor and the heterojunction light-emitting device are electrically and optically coupled so there is regenerative optical and electrical feedback between them. Layers of the heterojunction light-emitting devices are proton implanted to control the feedback. Plural such devices are electrically and optically coupled together to perform logic functions, such as EXCLUSIVE OR, in response to optical signals.