Effect of doping on defect modes of 2D photonic band gap crystals

Abstract

Here we report numerical simulation results obtained by performing photonic band structure calculations for a 2D periodic array of dielectric cylinders, having square symmetry with a lattice constant of 600nm. We have performed electromagnetic calculations using finite element method by employing COMSOL Multiphysics software. The band structure of the infinite crystal is calculated using plane wave method using MIT Photonic Band gap Package software. The calculated reflectance spectra showed three photonic bands spanning over visible and Infra-red regions a for refractive index contrast of 2.98. In order to study the property of a resonator, a point defect is introduced by replacing the dielectric cylinder with an air-cylinder. A sharp dip within the band gap of the reflectance spectra is observed and is attributed to the localized mode associated with the defect. Q-factor associated with the localized mode is calculated. The effect of refractive index of the defect on the localized mode frequency have been investigated and results are reported here.