A High-Performance Microwave Photonic Phase Shifter Based on Cascaded Silicon Nitride Microrings

A microwave photonic phase shifter based on four cascaded tunable silicon nitride microring resonators is proposed. The phase shifts and RF power variations of the microwave photonic phase shifter were investigated theoretically and experimentally. Good overall performances with full phase tuning range of 400°, low RF power variations of ± 1.5 dB with a broad bandwidth of 11 GHz, fiber to fiber insertion loss about 5.2 dB were achieved. The maximum frequency can be extended to about 40 GHz, which is limited by the MRR's free spectra range.