Phase shifted photonic crystal based filter with flat-top response

Abstract

In this paper, design of a phase shifted 1D photonic crystal filter with nearly squared flat top spectral characteristics is reported. Estimated phase shifts are incorporated into the structure through proper extension in dielectric layers of specific unit cells. Performance of the flat top filter is analyzed using transfer matrix method. The flat top pass band characteristics of such filter is tailored to support shifts of signal wavelength in an allotted channel within its tolerance limit, which is specified as 14 nm by ITU-T Recommendation G.694.2 in case of a coarse wavelength division multiplexing (CWDM) system.