9623248 Heiman The aim of this proposal is to investigate a new optoelectronic effect based on Faraday rotation in quantum well structures. Preliminary work has demonstrated that an applied voltage can be used to control the degree of Faraday rotation. This effect is novel in the sense that the degree of rotation is controlled by an electric field as opposed to a magnetic field. This could lead to electronic control of light switches and wide bandwidth optical modulators. Optoelectronic devices based on the Faraday-Stark effect would require only a low switching voltage (~ volt) and a small dc magnetic field (< l tesla) supplied by a permanent magnet. Some unique features for optical modulators include: * high-bandwidth light modulation, >10^10 Hz; * very low transmission in the off-state, < 10^-5; and > 40 dB modulation depth; * compatibility with microlithography and waveguides. Initial experiments on the Faraday-Stark effect were performed on a GaAs quantum well sample grown at UC Santa Barbara (group of A.C. Gossard). Although this structure was not optimized for the Faraday-Stark effect, improved structures are being grown in the Electrical Engineering Department at MIT (group of C. Fonstad). Of particular importance for room temperature devices are structures made from II-VI magnetic semiconductor structures. These will be grown in our own MBE machine, which was fabricated with funding from an NSF Engineering Research Grant and seed funding from AT&T. A variety of II-VI and III-V material structures will be investigated using magneto-optical experiments. These results will be helpful in examining the possibilities for designing devices that operate at wavelengths of interest. Our ambition is to determine the limitations and optimum conditions required for optoelectronic light switches, modulators, and electrically-controlled optical isolators. This research program will provide students with a broad education in engineering, physics, and materi als science. It also provides hands-on training in many areas including optics, magnetism, semiconductors, MBE crystal growth, microfabrication, low-dimensional science, high-speed electronics, cryogenics, and high-field magnets. Such a broad-based education is likely to impact on the future employment of both graduate and undergraduate students. In addition, an education in the field of optics is exceptionally valuable since that job market usually exceeds the number of qualified graduates. ***
