Ultracompact channel filters based on race-track photonic crystal ring resonators

Abstract

We proposed a new channel drop filter (CDF) based on race-track photonic crystal ring resonator (PCRR) composed of square-lattice cylindrical silicon rods in air. Two representative scenarios, parallel and perpendicular, related to the direction of race track and bus channel waveguide, are comparably studied by using 2D finite-difference time-domain technique. A good set of parameters with adequate modal spacing can be determined by adjusting the amount and size of scatterers. By optimizing the relationship among surrounding periods, race-track ring size and coupling strength, more than 150 spectral quality factor and 93.9% dropped efficiency can be achieved at 1370-nm channel for one single race-track PCRR. These findings enhance and enrich the PCRRs as an alternative to current micro-ring resonators for ultra-compact WDM components and high density photonic integration.