Abstract

Degenerate four-wave mixing (FWM) has proven to be a powerful technique for investigating coherent processes and excitonic dynamics in semiconductors and multiple quantum wells (MQWs). Conventional FWM techniques have provided considerable information about the spectral and temporal amplitudes of the emitted radiation, but they typically provide no information about the temporal or spectral phases. In addition, conventional techniques have been used to address the dependence of the magnitude of the FWM signal (or its spectrum) on the relative polarizations of the incident pulses, but there have been few attempts to measure the polarization state of the FWM signal itself. Recently, however, we have used direct time-resolved ellipsometric^1,2 and spectrally resolved interferometric techniques³ to characterize the polarization state of the FWM signal. In these experiments, we time resolved the polarization state of the emission for a range of input polarizations and for selected positive¹ and negative² delays. These studies¹,² established the sensitivity of polarization-sensitive techniques for studying many body and biexcitonic processes. However, to date, our experiments have been limited to investigations of the emission from the heavy hole (hh). That is, the laser was purposefully tuned slightly below the hh exci- ton to ensure that we excited as few light holes (lh) as possible and to avoid the complication of quantum beating between the lh and hh.

© 1998 Optical Society of America