TRANSMITTANCE AND BRAGG REFLECTIVITY OF 2-DIMENSIONAL PHOTONIC LATTICES

A general method based on the plane-wave expansion for calculating the transmittance and the Bragg reflectivity of two-dimensional photonic lattices is presented. According to this method, the transmission and the Bragg reflection spectra of a triangular and a square lattice of c ircular rods were numerically calculated for two independent polarizat ions. In addition to the opaque frequency ranges accompanied by the ph otonic band gaps, the existence of an uncoupled mode which cannot be e xcited by an external plane wave, a large amount of energy transfer to the Bragg waves, and pronounced interference structures were found. T hese three properties are not accounted for by the band calculation an d the theoretical investigation which fully allows for the boundary co ndition at the surface of a specimen is necessary for proper understan ding of experimental observations.