Optical waveguide ring based notch filter for microwave photonic signal processing

An optical waveguide ring based notch filter was designed and fabricated with polymer PSQ-Ls for microwave photonic signal processing. The waveguide ring consists of a Mach-Zehnder interferometer (MZI) as the tunable coupler and two micro-heaters as the thermal-optic phase shifters. The coupling states, over-, critical- and under-coupling, were obtained with the phase shifter on the arm of MZI and the maximum notch depth of about 18dB was achieved. The filtering frequency can also be tuned with the phase shifter on the ring waveguide. The notch filtering function to obtain single sideband RF signal was demonstrated experimentally with the polymer waveguide ring.