Linear time-resolved reflection on the heavy-hole exciton transition of high-quality multiple GaAs quantumwell 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.

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Resonance Rayleigh scattering by periodic semiconductor multiple quantum-well structures is studied experimentally and theoretically. Polaritonic effects are found to dominate disorder in the secondary emission dynamics. The coexistence of several radiant polaritonic modes with different radiative decay times leads to polarization beating between modes, strongly influences the rise times, and determines the fast decay times of the resonance Rayleigh scattered signals.

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