On-Chip Refractive Index Sensor With Ultra-High Sensitivity Based on Sub-Wavelength Grating Racetrack Microring Resonators and Vernier Effect

An approach to optimize the sensitivity and limit of detection on-chip refractive index sensor is proposed demonstrated based on sub-wavelength grating racetrack microring resonator Vernier effect. The waveguide can reduce structure limitation light field, which beneficial enhancing interaction between photon analyte. By optimizing parameters resonator, could be significantly improved 664 nm/RIU. Subsequently, capitalizing effect, a two cascaded microring-based designed. Owing wavelength spacings among overlapped peaks effectively amplified more than ten times, leading high performance. results demonstrate that an ultra-high 7061 nm/RIU low 1.74 × 10 ?5 RIU. With advantages detection, integrated device has important value in fields environmental monitoring biosensors.