Abstract

The interband optical selection rules for multiple quantum well (MQW) semiconductors allow the creation of populations of spin-polarized excitons and free carriers by using circularly polarized light at a wavelength resonant with the heavy-hole transition. Previous pump-probe studies of n = 1 heavy-hole exciton saturation in room temperature GaAs/ AlGaAs MQWs using circular polarizations have quantified the relative contributions of phase-space filling (PSF), screening, and broadening,^1,2 while electron spin gratings have allowed the measurement of in-well electron mobilities.³ In this work we extend the use of circular polarizations to nondegenerate studies of GaAs/AlGaAs MQWs employing a dual wavelength, self-mode-locked Ti:sapphire laser to examine (a) the PSF contribution when primping at the light-hole exciton feature, (b) induced circular dichroism in n = 2 excitons, and (c) interband relaxation times.

© 1998 Optical Society of America