Tunable Optical Add/Drop Filter for CWDM Systems Using Photonic Crystal Ring Resonator

In this paper an add/drop filter based on a two dimensional (2D) photonic crystal ring resonator (PCRR) is proposed and its performance is studied. This device is comprised of a hexagonal PCRR between two parallel waveguides formed by creating line defects in a 2D lattice structure with an array of 20 × 20 Si (Silicon) rods in air host. The lattice constant a is 636 nm and the radius of silicon (Si) rods r is 0.2 a . The size of the add/drop filter is 6 μm × 6 μm. We have achieved nearer to 100% dropping efficiency when the wavelength ( λ ) of the optical input signal is 1.55 μm. Optical signal can be made to drop at a different port by varying its wavelength or radius of Si rods. Simulation of the device is performed using a licensed RSoft FullWAVE tool based on a finite difference time domain (FDTD) simulator. The proposed structure could be used as an add/drop filter in the wavelength division multiplexing.