Variation of optical bandwidth in defected ternary photonic crystal under different polarisation conditions

Abstract

Photonic bandwidth of defected one-dimensional ternary photonic crystal is analytically calculated under both types of oblique incidences. Both P and S type polarised incidences on the structure are considered in order to compute transmittivity of the proposed Butterworth type bandpass filter, and passband spectrum is kept at 1,550 nm by suitably choosing structural parameters and defect density. Defect is kept within feasible limit, and ripple in the desired passband region is tailored by its controlled variation. Width of passband as function of defect density, angle of incidence and dimension of constituent layers is computed, and critical dimension for the sandwiched layer is predicted over which the structure will behave as equivalent binary one. For closely-spaced signal transmission, this narrow bandpass filter will work as excellent candidate to improve SNR.