Ring Resonators: Theory and Modeling

Abstract

One of the first papers to deal about the simulation of an integrated ring resonator for a bandpass filter has been published in 1969 by E. A. Marcatili. This can be regarded as the standard configuration for an integrated ring resonator channel dropping filter. Two straight waveguides also known as the bus or the port waveguides are coupled either by directional couplers through the evanescent field or by multimode interference couplers to the ring resonator. A simpler configuration is obtained, when the second bus or port waveguide is removed. Then the filter is typically referred to as “notch” filter because of the unique filter characteristic. In the following chapter, the ring resonator simulation model is described beginning with the basic notch configuration and adding more bus waveguides and ring resonators to eventually build a multiple coupled ring resonator filter. Different types of ring resonator simulation models will be explained, so as to be able to chose from a range of models which best suit the need.