2D photonic band-gap crystals: characteristics & optical properties

We investigate theoretically the optical properties of a 2D photonic band-gap crystal (square lattice of circular dielectric rods in air) through the plane-wave expansion method. We calculate the photonic band structure for both TE and TM polarizations for the 2D photonic structure. Band gaps exist only for TM polarization (E parallel to the rods). Also we study the effect of varying the dielectric constant of the rods and the rods radius-to-pitch ratio r/a on the first gap appeared in the photonic band structure for TM polarization.