ARMY LAB COMMAND WATERTOWN MA MATERIAL TECHNOLOGY LAB
This report describes progress in measuring and modeling the nonlinear optical properties of and picosecond carrier dynamics in bulk ternary alloys and multiple quantum wells MQWs. Studies of the bulk alloy AlxGa1-xAs have been produced the first experimental isolation of the electron exchange energy in a dense electron-hole plasma, and the observation of enhanced band-gap renormalization as a consequence of alloy disorder, stimulated emission from the indirect gap for x-values as large as 0.52, and large optical nonlinearities from band filling, band-gap renormalization, and screening of the excitonic continuum states. The latter appear promising for room temperature absorptive and dispersive optical bistability. An exact theory of the influence of an intense radiation field on the excitonic energy levels of a MQW has been developed and has led to the prediction of two-wave mixing gain. Keywords Nonlinear optics Ultrafast phenomena Multiple quantum wells Band gap renormalization Alloy disorder Optical bistability.