T-Shape Suspended Silicon Nitride Ring Resonator for Optical Sensing Applications

A T-shape suspended silicon nitride racetrack ring resonator sitting on a silicon dioxide pedestal is experimentally demonstrated. Compared with unsuspended device, it allows an enhanced interaction with the surrounded environment while maintaining a high quality factor. The resonator consists of a directional coupler with a waveguide width of 1.3 μm and a ring structure with curve radius of 20 μm. More than 1.6 × 104 quality factor at a wavelength of 1550.4 nm can be obtained, with a moderate extinction ratio of ~9.2 dB and a free-spectral range of 5.48 nm. The measured device sensitivity is ~247 nm/RIU. The device is expected to have a wide optical sensing application prospect.