Collective Effects of Excitons in Multiple-Quantum-Well Bragg and Anti-Bragg Structures

Abstract

Femtosecond degenerate four-wave mixing is used to investigate collective excitonic effects in radiatively coupled semiconductor multiple-quantum-well Bragg and anti-Bragg structures. The experimental and theoretical analysis of Bragg structures shows that the light-induced coupling causes a faster signal decay for increasing quantum-well numbers. For anti-Bragg structures, the predicted splitting of the excitonic resonances is observed in the four-wave-mixing spectrum causing quantum beats in the time-integrated signal.