TRANSIENT DEGENERATE 4-WAVE-MIXING ON EXCITONS IN GAAS QUANTUM-WELLS

The polarization dependence of time-integrated and time-resolved degen erate four-wave mixing on the 2D exciton transition in GaAs quantum we lls demonstrates that heavy and light hole excitons cannot be describe d in the framework of the two noninteracting three-level systems with opposite circular polarization selection rules. Extensions of the mode l taking into account many-body Coulomb interactions, implying local f ield effects, excitation induced dephasing, the formation of biexciton s, and disorder-induced coupling of excitonic states result in a very good agreement between experimental data and theoretical predictions.