DYNAMICS OF THE AMPLITUDE, PHASE AND POLARIZATION STATE OF COHERENT EMISSION FROM QUANTUM-WELLS

A dual-channel version of spectral interferometry is used to completel y characterize the extremely weak ultrashort coherent four wave mixing (FWM) emission from multiple quantum wells (MQWs) bg time resolving t he polarization state, as well as the scalar amplitude and phase. The amplitudes and the phases of the x and y components of the coherent FW M emission are found to exhibit systematic (but distinct) variations w ith excitation fluence, time delay between the two incident pulses, de tuning of the laser wavelength from the heavy hole (hh) exciton, and t he orientation of the input polarizations. From these. a self consiste nt picture of the temporal dynamics of the amplitude, phase and polari zation state is obtained that delineates the roles of many body effect s, such as local field corrections, excitation-induced dephasing and b iexcitons, in determining the excitonic dynamics.