Bandwidth-tunable optical filter based on microring resonator and MZI with Fano resonance

A bandwidth-tunable optical filter is fabricated by combining Mach–Zehnder interferometer (MZI) and microring resonator. Both bandwidth red-shift and blue-shift are observed in the experiment. The bandwidth can be tuned from 0.46 to 3.09 nm by controlling two phase shifters. The device also shows an extinction ratio higher than 25 dB. Potential applications are integrated optical signal processing such as reconfigurable filtering and channel selecting in wavelength division multiplexer.