Crosstalk suppression bandwidth optimisation of a vertically coupled ring resonator add/drop filter

In this study, a vertical coupled single ring resonator add/drop filter is simulated and the effect of different design parameters on the crosstalk suppression bandwidth is numerically investigated. Crosstalk suppression is defined as the difference between drop port and through port spectral responses. In a vertically coupled ring resonator, coupling efficiency between the evanescent tails of modes on the bus and bent waveguides is controlled by vertical separation and lateral deviation between waveguides. Designing a small size (single ring) add/drop filter that provides an increased crosstalk suppression bandwidth (to drop 10 Gbps non-return to zero signals) is proposed. As the analytical calculations cannot produce an accurate prediction of the design parameters, a simulation-driven design optimisation procedure is used to determine the values of the design parameters that produce a 21 GHz crosstalk suppression bandwidth.