Over Coupled Ring Resonator Based Add/Drop Filters

The performance of add/drop filters based on over-coupled ring resonators is analysed and simulated. Over coupling improves the performance of the filters by providing a wider bandwidth over which high crosstalk suppression is achieved. Inter-band and intra-band crosstalk associated with Wavelength Division Multiplexing (WDM) in optical filters are examined as a function of coupling coefficients. The simulation results show that, in over coupled double ring resonators, the crosstalk suppression bandwidth is increased in comparison with that of critically-coupled ring resonators. Increased bandwidth will allow such filters to be used for higher data rate signls, and moreover, for different modulation techniques (such as return to zero RZ and non-return to zero NRZ).