Diffraction effects in guided photonic band gap structure

The concept of the photonic band gap (FBC) structures stems from ideas of Y ablonovitch. The idea is to design components so that they affect the prope rties of photons, in much the same way that ordinary semiconductor crystals affect the properties of electrons. In fact, the PEG structures forbid pro pagation of photons For a particular range of energy. They can be used to r ealise optical filters with large stop band and sharp transmission resonanc e. In the guided PEG structures, the existence of diffractive effects in th e vertical dimension could limit the quality factor of such filters. In thi s paper, we have investigated the origin of diffraction losses in one-dimen sional guided PGB structures using 2D and 3D numerical tools. We propose an analytical approach based on Bragg diffraction relation to explain these l osses phenomenon. From this approach, the influence of some design paramete rs on the electromagnetic behaviour and the spectral response of PEG resona tors will be explained.