SiP Fano Resonator With Increased Slope Rate for Microwave Signal Processing

A thermally tunable Fano resonator with an increased slope rate (SR) for microwave signal processing is reported. The Fano resonator is implemented by using a grating-based Fabry–Perot (FP) cavity-coupled microring resonator (MRR) at the add-drop ports combined with a bus waveguide to form a Mach-Zehnder Interferometer (MZI). Due to the resonant mode interference between the MRR and the MZI, the MRR and the Fabry–Perot (FP) cavity, two parallel Fano resonators with asymmetric line shapes are resulted. A microheater is incorporated in the MRR to achieve thermal tunability. By tuning the direct current (DC) voltage applied to the microheater, the Fano resonance with a high SR of 379.08 dB/nm and an extinction ratio (ER) of 22.97 dB is achieved. Thanks to its ultra-sharp line shape, instantaneous frequency measurement (IFM) with improved sensitivity and resolution is experimentally demonstrated. A frequency measurement range of 7 GHz with a resolution better than ±0.2 GHz is achieved.