Modulation of Exciton Absorption in GaAs Quantum Wells by Below Bandgap Photoexcitation

We present the first measurements of the effects of below bandgap photoexcitation on exciton absorption in quantum wells. This forms the basis of a new technique for spectroscopy of the bandtail in quantum wells. The nature of the absorption in the transparent region and its effect on the exciton directly impact on many quantum well based devices.