cw and femtosecond optical nonlinearities of type-II quantum wells

Abstract

Femtosecond time-resolved and quasi-cw measurements of optical nonlinearities of type-II GaAs/AlAs quantum wells are reported. A pronounced blueshift of the heavy-hole exciton is observed, which develops on a 100-ps time scale after resonant interband excitation. The experimental observations are analyzed using many-body theory, explaining exciton blueshift and dynamical evolution in terms of electron-hole Coulomb enhancement, hole-phase-space filling, and hole-plasma cooling.