Propagation effects in spectrally resolved transient four wave mixing measurements on excitons in GaAs multiple quantum wells

We perform spectrally resolved degenerate four wave mixing (DFWM) measurements by resonantly exciting 1s heavy hole excitons in 8 and View the MathML source wide GaAs multiple quantum wells (MQW) with subpicosecond laser pulses. The signal is detected in a self-diffraction mode in backward geometry. The DFWM spectra reveal a multiple peak structure, evolving into a double peak for positive delays. This may be related to the propagation effects in MQWs due to strong photon–exciton coupling. The different peaks in the DFWM spectra show a dissimilar dependence on pulse excitation intensity, delay and polarization.