Frontiers in Optics
Many-particle theory of all-optical polarization switching in semiconductor quantum wells
I. Rumyantsev, N. H. Kwong, Rolf H. Binder, Eric J. Gansen, Arthur L. Smirl
Abstract
Semiconductor quantum wells exhibit numerous nonlinear optical effects that are potentially useful in electro-optical or all-optical devices. In general, the underlying physical mechanisms are complex many-particle processes and can be viewed as interesting research subjects in their own right. One example of such a device is the all-optical polarization switch that has been demonstrated [1]. In that device, conventional (i.e. non-strained) GaAs quantum wells are used in conjunction with two polarizers to switch the throughput of a weak probe pulse with a strong pump pulse. The switching is due to an effective polarization rotation of the probe light by the pump light. The basic idea underlying this effective polarization rotation can be based on a simplified picture of two spin-degenerate heavy-hole exciton transitions. A linearly polarized probe pulse, which consists of right ("+") and left ("-") circularly polarized components, would not undergo polarization rotation, because it couples to both transitions in the same way. If, however, a circularly polarized pump beam modifies, for example, the transition frequency of the "+" transition, the absorption of the "+" component of the probe light differs from that of the "-" component. This leads to an effective polarization rotation.