9414450 Coleman The objectives of this proposal are to study and develop high and low power continuously tunable millimeter and submillimeter wave lasers based upon Landau levels in semiconductors that are of interest to the Army Research Laboratory. The initial study will be on bulk semiconductor materials (i.e., Ge,GaAs), excited by pulsed E field and dc B fields where E.B = 0. Numerous laser signals in the range 10-120cm-1 have been generated in pGe with E and B fields in the range 1-2 kV/cm and 0.5-2.0 tesla. Specific objectives are to understand the laser dynamics and laser cycle by employing excited state spectroscopy using the numerous signals available from molecular lasers. Laser efficiencies of 1-2% could readily yield kilowatts of pulsed power in a difficult range of the spectrum. For low power applications, Landau levels in heterostructures will be investigated. Practical sources above 100 GHz are difficult to achieve which makes it difficult to develop the millimeter-submillimeter region. The aim of this study is to contribute to this development. The submillimeter range is a transition region from microwave to optical techniques and as such offers the graduate student a broad education in field theory, quantum electronics, semiconductors, optics, spectroscopy and material properties. ***
