Novel Design for Photonic Crystal Ring Resonators Based Optical Channel Drop Filter

Photonic crystal ring resonators (PCRRs) are traditional structures fordesigning 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 ofa square lattice of silicon rods with the refractive index nsi=3. 4 which are perforated inair with refractive index nair=1. Calculations of band structure and propagation ofelectromagnetic field through devices are done by plane wave expansion (PWE) andfinite difference time domain (FDTD) methods, respectively. The simulation shows,100% dropping efficiency and suitable quality factor at 1592. 6 nm wavelength achievedfor this filter. Also, in this paper, we investigate parameters which have an effect onresonant wavelength and transmission spectrum in this CDF, such as refractive index ofinner rods and whole of dielectric rods of the structure. The proposed structure is smallwhich is more suitable for used in the future photonic integrated circuits, wavelengthdivision multiplexing (WDM) systems and optical communication networkapplications. Also, we suggested a heterostructure wavelength demultiplexer iscomposed of four ring resonators. These ring resonators are located in four differentregions (heterostructure) which each region has specific dielectric constant.