Optical control of microwave HBT oscillators.

Abstract

Fiber optics have the potential to impact future radar and communication systems through the distribution of microwave signals to the individual antenna elements and through the processing of microwave signals using the large delay time-bandwidth product of fibers. Their light weight and small volume advantages make them very attractive for signal distribution. Optical control of microwaves, switching, injection locking, phase and frequency shifting of microwave signals by optical control, can benefit immensely from fiber optics. In phased array antenna systems, where a large number of signals need to be distributed, the advantage is obvious. A new Multi-Quantum-Well Heterojunction Bipolar Transistor (HBT) device which can generate a negative differential output resistance under certain optical illumination conditions has been fabricated and tested. A transparent emitter ohmic contact technology has been developed for easy light access into the transistor. Direct optical injection locking has been demonstrated at 5.7 GHz using these devices. A new HBT fabrication process with very high energy oxygen implant isolation has been developed which yielded an f$\sb{\rm MAX}$ = 90 GHz. Optical receivers employing monolithically integrated Metal-Semiconductor-Metal (MSM) detectors and HBT's have been designed, fabricated and tested.