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.