Sensing characteristics of feedback waveguide slot grating microring resonators

To enhance the quality factor and sensitivity of refractive index sensors, a feedback waveguide slot grating micro-ring resonator was proposed. An air-hole grating structure was introduced based on the slot micro-ring, utilizing the reflection of the grating to achieve the electromagnetic-like induced transparency effect at different wavelengths. The high slope characteristics of the EIT-like effect enabled a higher quality factor and sensitivity. The transmission principle of the structure was analyzed using the transmission matrix method, and the transmission spectrum and mode field distribution were simulated using the finite-difference time-domain (FDTD) method, and the device structure parameters were adjusted for optimization. Simulation results show that the proposed structure achieves an EIT-like effect with a quality factor of 59 267.5. In the analysis of refractive index sensing characteristics, the structure exhibits a sensitivity of 408.57 nm/RIU and a detection limit of 6.23×10^-5 RIU. Therefore, the proposed structure achieved both a high quality factor and refractive index sensitivity, demonstrating excellent sensing performance for applications in environmental monitoring, biomedical fields, and other areas with broad market potential.