Room Temperature Optical Nonlinearities in GaAs Multiple Quantum Wells

Progress towards practical all-optical switching and signal processing devices depends crucially on finding suitable nonlinear materials. Consequently, various workers have explored so-called 'dynamic' nonlinear optical effects in semiconductors(1) in which the optical properties change as a result of real excitation of the material. Semiconductors are particularly attractive for fabrication as small devices. Unfortunately, while some of these effects should persist to room temperature, one of the most attractive, saturation of free exciton resonances(2) is basically limited to low temperatures in conventional semiconductors because of thermal broadening.