Flexible Filtering Element on SOI With Wide Bandwidth Tunability and Full FSR tuning

We demonstrate a silicon-on-insulator flexible filtering element, relying on two serially coupled micro-ring resonators equipped with three thermo-optically tuned Mach–Zehnder interferometers, acting as variable optical couplers. A single electrode configuration is adopted, enabling the low-complexity thermo-optical control of the filtering element for bandwidth and wavelength tunability. The module's performance has been studied in detail via simulation analysis, and the obtained results were verified through experimental evaluation. Wide bandwidth tunability from 9 GHz to 103 GHz is achieved with a power efficiency of 0.284 mW/GHz, while full free spectral range wavelength tuning is achieved with an efficiency of 0.297 mW/GHz. Module's insertion loss lays below 3 dB.