Comparartive analysis of quadruple optical ring resonator based filter using SOI waveguides

Optical filters using ring resonators made of silicon on insulator (SOI) based waveguides are enabling technology in the ever expanding field of optical communications. In this work series coupled four rings of two different radii have been used to expand the free spectral range (FSR) on the basis of Vernier principle with two SOI waveguides of different refractive indices (1.7 and 2.5). The quadruple ring resonator architecture with five directional optical couplers has been considered in this work and analyzed using delay line signal processing technique coupled with Mason´s gain formula. Our main aim behind the work had been to enhance the FSR for similar architectures and compare it for various models under different conditions which would lend consistency to the application. Finesse, Group Delay and Dispersion like important characteristics of such integrated optic devices have been determined.