Tunable Filter based on hexagonal shape photonic crystal ring resonator using Core/Shell rods defect

This paper investigates an ultra-compact channel drop filter based on a photonic crystal ring resonator (PCRR) suitable for optical communication systems. The investigated filter is composed of two linear waveguides attached by a hexagonal-shaped resonator. We study the effect of various parameters of the suggested design on the output frequency. Finite Difference Time Domain (FDTD) method was chosen for simulation to demonstrate the functionality of the designed structure. The numerical simulation results show that by changing the radius of coupling and inner rods we can tune our filter. Also we can obtain various output frequencies by changing the refractive index of the rods of the system. Dropping efficiency and quality factor are 100% and 1327 respectively. The total size of the considered device is about 97 $\mu$m2, that is good for integrated optical circuits (PICs).