Optimization of Photonic crystal waveguide based optical filter

In the emerging field of signal processing and optical communication technologies, photonic integrated circuits based on Photonic Crystals are being immensely favoured. Photonic crystals possess the property of inhibiting certain frequencies of light due to the presence of a photonic band gap. This property leads to successful filtering of desired wavelengths of light. In this work, we demonstrated a novel design of an optical filter (frequency splitting device) with three waveguides based on a two dimensional (2D) photonic crystal hexagonal lattice structure of dielectric rods in air. The transmittance rate of the desired wavelengths of light through each of the waveguides has been increased and the leakage rate of unwanted wavelengths of light has been decreased to the most optimal level by introducing defect rods in the perfectly periodic crystal, whose parameters have been chosen using the band gap map of the photonic crystal. Optimum number of defect rods to be placed at the entrance of each of the three filters and the main waveguide has been proposed based on the results of the calculations of the finite difference time domain (FDTD).