Investigation of a Novel PCRR based Channel Selective Filter for 3rd Optical Comminucation Window

Ring resonators are fascinating elements for wavelength division multiplexing (WDM) and photonics integrated circuits (PICs). Photonic crystal based ring resonators (PCRR) are considered as new type of linear defects which their size is determined by the desired resonant wavelength. In this paper, we propose a channel drop filter based on two-dimensional all circular PCRR. The structure is made of a square lattice of silicon rods with the refractive index n1=3.464 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 in TM polarization. Two linear defect W1 waveguides are instantly clung 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 deca-pole degenerated resonant mode. Normalized frequencies corresponding to this degenerate mode are, a/? = 0.3684 and a/? = 0.3645. Full Width Half Maximum bandwidth of the filter at the output transmission spectrum - from 1.541~1.564?m - is 23nm. Our proposed structure is very small and the overall dimension is 9?m×9?m. 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.