Excitonic polarization grating in semiconductors induced by short light pulses

A scattering-state approach is proposed to study the propagation of extremely short optical pulses through a semiconductor. The formalism is applied to the propagation of exciton–polaritons in semiconductor films: Our simulated experiments predict the formation of an exciton-induced polarization grating when the light pulse is resonant with the excitonic transition, and suggest physical conditions for its experimental detection. Moreover, our analysis of the polariton transport in thick semiconductor layers reveals a decrease of the average polariton group velocity as a function of time, which we ascribe to a re-emission–re-absorption of light by excitons