Polarization state dynamics induced by the virtual excitation of spin-polarized carriers in semiconductor quantum wells

Abstract

By using a circularly polarized pulse that is tuned well below resonance, we create a virtual population of spin-polarized coherent excitons in a GaAs/AlGaAs multiple quantum well, and we study its effects on the polarization state of a weak signal pulse using a combination of time-resolved and spectrally resolved ellipsometric techniques. From these data the polarization state contributions to an all-optical polarization switch, which exhibits a ∼415 fs switching time and large contrast ratios, are identified and the performance of the switch is demonstrated.