Thermally Tunable Filters Based on Third-Order Microring Resonators for WDM Applications

We design and fabricate a thermally tunable third-order microring resonator filter based on silicon nanowire waveguides. Box-like response with low intraband ripple (~0.65 dB) and high out-of-band rejection over 40 dB is demonstrated. The insertion loss at the center of the passband is less than 0.9 dB. The filter response is successfully tuned by one free spectral range through thermo-optic effect with a tuning efficiency of 48.4 mW/nm. The dynamic tuning measurement shows the 10%-90% rise and 90%-10% fall time of the filter are 12.63 and 6.31 μs, respectively.