Femtosecond coherent spectroscopy of bulk ZnSe and ZnCdSe/ZnSe quantum wells

Femtosecond two beam, self-diffraction experiments are performed in ZnSe and ZnCdSe/ZnSe quantum wells. Degenerate wave mixing signals from the third to the thirteenth order are easily visible to the naked eye, implying that nonlinear effects in this system may already be in the nonperturbative regime. Spectrally resolved data indicate that the nonlinearities originate entirely from the excitonic resonance. In addition, the existence of four-wave mixing signals in bulk ZnSe at negative time delay suggests that exciton-exciton interaction plays an important role. Exciton-phonon interaction rates are deduced as a function of temperature in ZnSe and ZnCdSe/ZnSe quantum wells.