Interaction-induced effects in the nonlinear coherent response of quantum-well excitons

Interaction-induced processes are studied using the third-order nonlinear p olarization created in polarization-dependent four-wave-mixing experiments (FWM) on a ZnSe single quantum well. We discuss their influence by a compar ison of the experimental FWM with calculations based on extended optical Bl och equations including local-field effects, excitation-induced dephasing, and biexciton formation. The investigations show that, for copolarized inpu t fields, excitation-induced dephasing is the dominant FWM mechanism, follo wed by the conventional density-grating FWM process, biexcitonic contributi ons, and local-field effects. For cross-linear polarized input fields the e xcitation-induced dephasing mechanism is canceled so that the conventional density-grating FWM process and biexcitonic contributions are dominating. [ S0163-1829(99)05428-4].