Tunable Microwave Photonic Filter Based on an Ultra-high-Q Mach–Zehnder Interferometer Coupled Microring Resonator

A tunable high-Q Mach-Zehnder interferometer (MZI) coupled micro-ring resonator (MRR) with a large free-spectra range (FSR) is demonstrated by introducing multimode waveguides assisted with modified Euler curve, both phase and coupling coefficient can be tuned. Utilization of the silicon micro-ring enables a microwave photonic band-pass filter with a 3-dB bandwidth tuned from 150 MHz to 2 GHz, and central frequency thermally tuned from 500 MHz to 40 GHz.