High-density excitation effects of excitons in ZnSe quantum wells by spectrally resolved four-wave mixing

We performed two-beam spectrally resolved four-wave mixing (SR-FWM) experim ents around the exciton resonance in the reflection geometry in ZnSe multip le quantum wells (MQWs) to investigate the high-density excitation effects of biexcitons as well as excitons. This experiment is performed in the exci ton-density region where chi((3))-process is no longer a good approximation . The exciton-density dependence of the FWM spectra reveals that the excito n energy shows a blue-shift but the biexciton energy is almost unchanged. T he exciton-density dependence of the homogeneous line width shows that the dephasing process is governed by the scattering with incoherent excitons. B iexcitons are affected by incoherent excitons less than excitons. (C) 2000 Elsevier Science B.V. All rights reserved.