Intraband Crosstalk Properties of Add–Drop Filters Based on Active Microring Resonators

The dynamic operation of add-drop filters based on active microring cavities is numerically investigated for the first time to our knowledge, with high bit-rate return-to-zero (RZ) input signals at both the input and the add port. The use of an active ring cavity allows the complete loss compensation, which has been suggested in order to eliminate the intraband crosstalk between the incoming signals. Strong degradation of the dropped and added signals is observed due to the imperfect spectral response of the through and drop ports. A double-stage topology that addresses the inefficiencies of the single add-drop ring is proposed and the successful operation of 40-Gb/s RZ signals is numerically demonstrated.