Design of tunable filter by Kerr effect used in optical communications

The discovery of photonic Band-gap (PBG) materials and their use in controlling light propagation is a new and exciting development. An optical design of a wavelength-selective tunable filter permitting to select a channel of 1 nm of spectral width among 40 channels situated between 1550 nm and 1590 nm is considered in this paper. Guided modes in a two dimensional dielectric photonic crystal (PC) waveguides are studied by the transfer matrix method (TMM) and Galerkin method. A cavity (localized defect) between two waveguides in the PC structure is introduced. Among several wavelengths circulating into the first guide, the resonance wavelength with the defect can be extracted by coupling effect, and then is injected into the second guide. The tuning effect is obtained by Kerr effect applied in the cavity.