Integrated Quantum Well Bipolar Devices for Tunable Detection and Optical Logic Applications

The properties of exciton-based quantum well devices suitable for low-power photonic switching and logic applications and wavelength selective detection will be described. The basic device is a heterojunction bipolar transistor with MQW collector region monolithically integrated with a p-i(MQW)-n modulator, realized by single-step epitaxy. The integrated controller-modulator device, by virtue of its unique photocurrent-voltage characteristics, exhibits integrating-thresholding properties. These properties have been exploited to demonstrate cascadability, fan-out, optoelectronic amplification, special logic functions, programmable optical/electronic memory capabilities, and wavelength selective detection with GaAs/AlGaAs heterostructure devices.