Reconfigurable silicon filter with continuous bandwidth tunability

We present the design and the fabrication of compact tunable silicon-on-insulator bandpass filters based on the integration of a Mach–Zehnder interferometer with ring resonators and activated via thermo-optic phase shifters. The proposed architecture provides wide filter bandwidth tunability from 10% to 90% of the free spectral range preserving the filter off-band rejection. Possible applications are channel subset selection in wavelength division multiplexing optical systems, adaptive filtering to signal bandwidth, and reconfigurable filters for gridless networking.