GREENS-FUNCTION THEORY FOR ROW AND PERIODIC DEFECT ARRAYS IN PHOTONICBAND STRUCTURES

The defect modes associated with a row or a periodic array of defects in a two-dimensional photonic band structure are studied using exact G reen's-function methods. Specifically, we consider the above-described defect problems created in a pure photonic band-structure system that models an experimental system recently investigated by McCall et al. This is a square lattice array of cylindrical rods formed of linear di electric material with epsilon=9 surrounded by vacuum and of filling f raction f=0.4488. In one study a row of rods is replaced in the photon ic band structure by a row of impurity rods that may be of either line ar or nonlinear dielectric material, and conditions are determined for the existence of impurity modes, associated with the impurity array, in the photonic band gap. The electric fields of the impurity modes ar e computed for impurity modes in the gaps. In a second study, a two-di mensionally periodic array of defects is introduced into the photonic band structure such that the periodicity of the defect array may or ma y not coincide with the periodicity of the original photonic band stru cture. The defect rods are treated in the cases for which the impuriti es are formed from both linear and nonlinear dielectric materials, and the conditions necessary for defect modes to exist in the photonic ba nd gaps are determined.