Excitonic Optical Nonlinearities in Semiconductor Quantum Wells

The confinement of electron-hole pairs in ultrathin semiconductor layers produces quantum size effects that modify drastically the excitonic behavior as compared to that of the bulk parent material. In this talk we will review our experimental and theoretical investigations of the transient nonlinear optical processes observed in GaAs quantum wells. 

We will describe effects of real populations of free electron-hole pairs and excitons as well as those of virtual pairs populations excited above, at and below the fundamental gap by tunable femtosecond, picosecond and cw lasers. We will present theoretical interpretations stressing the effects of reduced dimensionality in quantum wells.