A Generalized Analytical Approach for Designing of One Dimensional Photonic Crystal Based Optical Filter With Flat-Top Response

One dimensional photonic crystal based optical band pass filter has been analyzed using coupled mode approach in order to achieve a desired filter response in terms of full width at half maximum. The power transmittance through successive primitive cells of the crystal has been rationalized by considering weak coupling between the forward and specularly reflected waves within the crystal, which is modeled as distributed feedback structure. The time constants, associated with the optical resonator and responsible for a weakly coupled eigen mode to exist, have been estimated. These time constants would actually be used to determine the number of primitive cells, on either side of a defect, required to build up a desired mode. The collateral observations provide necessary conditions of resonance.