Highly sensitive refractive index sensing based on SOI subwavelength grating microring resonators

In recent years silicon-based optoelectronic chips have great advantages in biochemical sensing due to their unique advantages. In this paper, the dispersion mechanism of a racetrack microring resonator based on a subwavelength grating waveguide is theoretically investigated, and the relationship between the electric field distributions of different parts and their parameters is studied. A highly sensitive silicon-based subwavelength grating microring resonator sensor is designed and fabricated by two-step etching photolithography process. The structure improves the sensitivity of the sensor compared with the conventional microring sensor. The resonance principle of this structure is not limited by the free spectral range due to focusing on the envelope peaks instead of individual resonance peaks. This is one of the highest refractive index sensing sensitivities reported for a microring resonator with a sensing sensitivity of 860.3 nm/RIU.