Intensity dependence of superradiant emission from radiatively coupled excitons in multiple-quantum-well Bragg structures

Linear time-resolved reflection on the heavy-hole exciton transition of high-quality multiple GaAs quantum-well Bragg samples reveals enhanced radiative emission and accelerated decay of the coherent optical polarization due to radiative interwell coupling. It is shown that this superradiant mode gradually vanishes with increasing excitation intensity. Microscopic calculations attribute this decoupling to the carrier-carrier Coulomb interaction in the individual quantum wells leading to excitation-induced dephasing. The intricate density dependence is discussed comparing computed results for the excitation-dependent decay in single quantum wells and multiple-quantum-well Bragg structures.