Optical response in multi-quantum wells under Bragg conditions

A microscopic description of matter polarization and electromagnetic field is used to study the linear optical response of N quantum wells under Bragg condition at the resonant wavelength. In this system the radiative interaction among induced polarizations plays an essential role and the inclusion of this effect leads to a correct description of the size and internal structure dependence of the optical response. The spectral evolution of reflectivity and absorbance with increasing N from the super-radiance regime to the 1D photonic crystal limit (N ? ?) is shown. Polaritonic dispersion curves are calculated for the infinite system and compared with the photonic dispersion curves due to the background dielectric function modulation. A decomposition of the polaritonic matrix of interaction is proposed in order to separate different contributions in the optical response and to achieve a comparison with the response of a cluster of non-interacting units.