Abstract

Degenerate four-wave mixing (FWM) has been shown to be a powerful tool for studying coherent transient processes in semiconductors, and recent studies^1,2 indicate that the polarization-selection rales can be very useful in discriminating among various proposed models for these processes, particularly in delineating the roles of excitation-induced dephasing (EID), the local- field correction (LFC), and biexcitons. Here, we describe the measurement of all four Stokes parameters that completely characterize the polarization state and degree of polarization of the FWM signal in GaAs/AlGaAs multiple-quantum-well samples under a variety of experimental conditions. The ellipticity, the azimuthal angle of the ellipse, and the degree of polarization vary dramatically with experimental conditions and the sample type. Nevertheless, we show that all of the observed tendencies agree qualitatively with models that include EID and LFC phenomenologically. Homogeneous or inhomogeneously broadened two or three-level models are invoked as appropriate for the experimental conditions and sample type.

© 1995 Optical Society of America