SURFACE AND INTERFACE S-POLARIZED OPTICAL WAVES IN SUPERLATTICES

The existence of localized and resonant optical waves associated with the surface of a semi-infinite superlattice or ifs interface with a su bstrate is reported, considering the case of s-polarization (transvers e electric modes). These modes appear as well defined peaks of the den sity of states, either inside the minigaps or inside the bulk bands of the superlattice. The density of states, function of the frequency om ega, and the wave vector k(parallel to) (parallel to the interface), a re obtained from an analytic determination of the response function fo r a semi-infinite superlattice with or without a cap layer.