Silicon Photonic Integrated Fano Resonator With Increased Slope Rate for Microwave Signal Processing

A tunable silicon photonic (SiP) integrated Fano resonator with an increased slope rate for microwave signal processing is proposed, fabricated, and experimentally demonstrated. A grating-based Fabry-Perot (FP) cavity-coupled micro-ring resonator (MRR) joint with a Mach-Zehnder Interferometer (MZI) is used to form the proposed Fano resonator. Since the resonant modes of the FP cavity and the MZI interfere with that of the MRR, a Fano resonator with an ultra-sharp asymmetric line shape is realized. A microheater is placed on top of the MRR to achieve thermal tuning of the Fano resonance frequency. The proposed Fano resonator is fabricated and experimentally evaluated. A high slope rate (SR) of 379.08 dB/nm and an extinction ratio (ER) of 22.97 dB are obtained. Thanks to its ultra-sharp asymmetric line shape, the applications of the proposed Fano resonator for microwave signal processing are discussed and experimentally demonstrated, including instantaneous frequency measurement with an improved resolution of +/- 0.2 GHz in a 7 GHz frequency measurement range, and optical temporal differentiation with an increased differentiation gain.