ABSTRACT

The close form of Eq. (10.11) indicates that a ring resonator in this particular case is very similar with Fabry-Pérot cavity concept, which has an input and output mirror with a field reflectivity, (1 − k), and a fully reflecting mirror. k is the coupling coefficient, and x = exp(−aL/2) represents a roundtrip loss coefficient, f0 = kLn0 and fNL = kLn2|Ein|2 are the linear and nonlinear phase shifts, k = 2p/l is the wave propagation number in a vacuum. L and a are the waveguide length and linear absorption coefficient, respectively. In this chapter, the iterative method is introduced to obtain the resonant results and similarly, when the output field is connected and input into the other ring resonators. In order to retrieve the required signals, we propose to use the add/drop device with the appropriate parameters. This is given in the following details in the optical circuits of ring resonator add/drop filters for the through port and drop port given by Eqs (10.12) and (10.13), respectively [27].