ASYMMETRIC QUANTUM-WELL OPTICS FROM A MEAN-FIELD POLARITON THEORY

We cosider the elementary excitations in quantum wells of arbitrary sh ape, as they result from the coupling between excitons and electromagn etic radiation. The exciton states are obtained from a two-band model [1]. The solutions of Maxwell equations with the appropriate exciton d ependent nonlocal susceptibility are obtained by using a mean field ap proach [2] based on the fact that the radiation wavelength lambda is m uch larger than the well width L. Application to asymmetric wells give s the polariton dispersion modes and the radiative linewidths for all possible well shapes. The splitting of the Z-mode and the values of th e radiative lifetimes strongly depend on the well width L and its asym metry. The reflectivity and absorption are computed and are shown to g ive strong evidence of polariton modes.