Design and optimization of photonic crystal ring resonator based optical add-drop filter

In this paper, an add-drop filter is designed based on a two-dimensional photonic crystal ring resonator. The square lattice of Photonic crystal structure comprises of silicon rods with a refractive index of 3.464 suspended in the air. Initially, a ring resonator is designed and analyzed without the scattering rods. Further, the scattering rods are inserted to enhance the spectral selectivity and the dropping efficiency. To shift the dropping wavelength to a higher wavelength and to enhance the quality factor, the inner rods of the ring resonator are changed to GaAs with a refractive index of 3.382, and the radius of the center rod is optimized to 179 nm. Finally, the add-drop filter is optimized at a wavelength of 1522 nm with high spectral selectivity, high dropping efficiency, and good quality factor.