Polarization-Dependent Picosecond Excitonic Nonlinearities and the Complexitiesof Disorder

摘要

Time-resolved emission of the hhl exciton transient four-wave-mixing response inmultiple quantum wells shows the unexpected result that the signal emission is either a photon echo or a free polarization decay, depending on the relative polarization of the excitation beams. The energy and temperature dependences of the dephasing rates and the transport and saturation characteristics show that the two excitations are significantly different. Explanations for the disappearance of the echo, which arises due to the presence of disorder, and the origin of the prompt signal are considered.