Wavelength Splitting in Photonic Band-Gap Structures with Multiple Defects

We explain the physical effects involved in optical coupling in periodic structures which allow for photonic band gaps. We use a simple model to do this, since this allows us to establish some general principles for the operation of such devices. Further, we investigate the choice of parameters, with respect to the band gap, which will allow the device to operate suitably, and we contrast systems with high and low index defects