Optical response of linear and nonlinear photonic superlattices near the first photonic band gap

We have studied how the photonic band structure effects govern the macroscopic optical properties of 1D superlattices. In the linear regime, an analogue of the Borrmann effect has been found; the polariton spectrum of a QW superlattice has been studied in various geometries and shown to depend strongly on the disposition of the QWs in the primitive cell. A new numerical approach has been developed to cope with any kind of nonlinear 1D photonic crystal. Several striking effects have been found both in one-and in two-beam configurations; depending on frequencies, the system can behave as a limiter or show bistability; it can also present a new spatial periodicity, due to a coherent superposition of Bloch waves.