Reconfigurable RF Filter Based on Cascaded Microring Resonators

To meet the requirement of radio frequency signal processing tasks among various frequency bands, here we have demonstrated a reconfigurable microwave photonic bandpass filter by flipping the optical notch spectrum of a cascaded microring resonator (MRR) filter pool chip through phase modulation. We experimentally characterize the cascaded MRR filter pool chip on the Si3N4 platform and evaluate the system performance of the established microwave photonic filter (MPF). In the demonstrated microwave photonic filter system, the center frequency can be tuned within 5.8--18.2 GHz and the bandwidth can be tuned within 2.1--3.5 GHz. In particular, the MPF system features a response with a shape factor of ∼2.2. With the advantages of reconfigurability and good shape factor, the demonstrated reconfigurable RF bandpass filter shows a potential application in future software-defined RF frontends.