Design and Simulation of an Optical Channel Drop Filter Based on Two Dimensional Photonic Crystal Single Ring Race Track Resonator

Abstract

Here, we propose an optical channel drop filter based on single ring two dimensional photonic crystals all circular race track resonator. The
structure is made of a square lattice of silicon rods with the refractive index n1=3.46 which are perforated in air (with refractive index n2=1).
The widest photonic band gap obtains for the filling ratio of r/a = 0.17. Two linear defect W1 waveguides are instantly coupled to the ring.
With the appropriate coupling distance between the ring and waveguide, our channel drop filter is formed. Filter’s dropping efficiency for the
operational window which is in the C-band of optical telecommunications, is 100% complete for 12-fold resonant mode which is degenerated.
Also the quality factor of this mode is 386. Normalized frequencies corresponding to this resonant mode are a/λ = 0.368 and a/λ = 0.362. Full
Width Half Maximum bandwidth of the filter at the output transmission spectrum - from 1.535~1.565μm - is 30nm. Our proposed structure is
very small and the overall dimension is 12μm×12μm. Resonant modes of the all circular ring resonator and their corresponding degenerate
poles are calculated using the PWE method; and the filter’s transmission spectrum wavelengths are calculated using 2D-FDTD numerical
method.