Multilevel infrared coupling of excitons in quantum-well semiconductors

We study the effects of multilevel mixing of the 1s and 2s states of the E1-HH1 and E2-HH1 excitons in the emission spectra of an undoped quantum well. This is done by investigating the E1-HH1 exciton emission spectra in the presence of an intense CO/sub 2/ laser near resonance with the transition between El and E2. Our results show that, depending on the frequency of the CO/sub 2/ laser, these spectra are quenched peculiarly. We explain these phenomena based on the frequency dependence of the mixing configurations of the exciton states and infrared enhancement of the nonradiative decay rates of E1-HH1 excitons. We also study the effect of the nonparabolicity of the hole subband (HH1) in the infrared mixing of the E1-HH1 and E2-HH1 excitons.