Abstract

Time-resolved four-wave mixing (TRFWM) has been extensively used to study the influence of Coulomb interactions on the free- induction decay of excitons in semiconductor quantum-well systems (see, e.g., Refs. 1—4). We show that the ratio between the Coulomb-mediated and the pure phase-space occupation signal can be changed by more than an order of magnitude by changing the external field. The two signal contributions to the diffracted signal can be separated by variation of the excitation density, and they show completely different behaviors as a function of the applied bias.

© 1995 Optical Society of America