Polariton propagation in weak-confinement quantum wells

Exciton-polariton propagation in a quantum well, under center-of-mass quantization, is computed by a variational self-consistent microscopic theory. The Wannier exciton envelope functions basis set is given by the simple analytical model of D'Andrea and Del Sole [Phys. Rev. B 41, 1413 (1990)], based on pure states of the center-of-mass wave vector, free from fitting parameters and "ad hoc" (the so-called additional boundary conditions-ABCs) assumptions. In the present paper, the former analytical model is implemented in order to reproduce the center-of-mass quantization in a large range of quantum well thicknesses (5aB?L??). The role of the dynamical transition layer at the well/barrier interfaces is discussed at variance of the classical Pekar's dead layer and ABCs. The Wannier exciton eigenstates are computed and compared with various theoretical models with different degrees of accuracy. Exciton-polariton transmission spectra in large quantum wells (L?aB) are computed and compared with experimental results of Schneider et al. [Phys. Rev. B 63, 045202 (2001)] in high-quality GaAs samples. The sound agreement between theory and experiment allows to unambiguously assign the exciton-polariton dips of the transmission spectrum to the pure states of the Wannier exciton center-of-mass quantization.