Optical switches and heterojunction bipolar transistors in InP for monolithic integration

We report optical switching devices and heterojunction bipolar transistors (HBTs) in the InGaAsP/InP material system which are designed to be fully compatible with monolithic integration. One early application envisaged for these integrated structures is an optical switch whose external interfaces employ standard logic levels (e.g. ECL), instead of the higher drive voltages (10-20V) of the electro-optic devices themselves. In the longer term, we envisage optical switching components which are capable of performing self-routing functions based on information contained within the data stream. The heterojunction bipolar transistor is an excellent driver for the optical switch, since very high gain and transition frequency can be achieved.