Exciton-Exciton Interaction in GaAs-GaAlAs Superlattices

Abstract

Multi-quantum well structures (MQWS) have been shown to be a very attractive material for optical devices. One of the most interesting features is their large non-linear optical response in the frequency region of the excitons This bound state of an electron in the conduction band and a hole in the valence band leads to strong absorption lines in the optical spectra of MQWS ; these lines are very sensitive to any perturbation introduced by optical means in the system, giving rise to associated large changes in the optical response (1). Further, excitons are observed even at room temperature, in contrast with the case of almost all bulk semiconductors. It is very important to characterize the exact nature of the exciton modification and its time evolution, both from a fundamental point of vue and for any application to an optical device.