novel design for photonic crystal ring resonators based optical channel drop filter

Photonic crystal ring resonators (pcrrs) are traditional structures for designing optical channel drop filters. in this paper, photonic crystal channel drop filter (cdfs) with a new configuration of ring resonator is presented. the structure is made of a square lattice of silicon rods with the refractive index nsi=3. 4 which are perforated in air with refractive index nair=1. calculations of band structure and propagation of electromagnetic field through devices are done by plane wave expansion (pwe) and finite difference time domain (fdtd) methods, respectively. the simulation shows, 100% dropping efficiency and suitable quality factor at 1592. 6 nm wavelength achieved for this filter. also, in this paper, we investigate parameters which have an effect on resonant wavelength and transmission spectrum in this cdf, such as refractive index of inner rods and whole of dielectric rods of the structure. the proposed structure is small which is more suitable for used in the future photonic integrated circuits, wavelength division multiplexing (wdm) systems and optical communication network applications. also, we suggested a heterostructure wavelength demultiplexer is composed of four ring resonators. these ring resonators are located in four different regions (heterostructure) which each region has specific dielectric constant.