Design and Optimization of a Hybrid Plasmonic Sensor Based on Microring Resonators for Refractive Index Sensing

Hybrid plasmonic structures offer a promising platform for highly sensitive and compact optical sensing applications. In this paper, we propose and optimize a simple but powerful hybrid plasmonic refractive index sensor that combines a silicon microring resonator with gold plasmonic structures to achieve high quality factor and low loss. Light coupling into the ring resonator is obtained through a dielectric waveguide via evanescent field coupling. Numerical simulations of the proposed structure are performed using finite element method (FEM) implemented in COMSOL Multiphysics (wave optics module). Through numerical simulations, the structural parameters of the sensor are systematically optimized to obtain the optimal performance. The optimized design achieves a relatively high sensitivity of 36 nm/RIU, with an ultra-high quality factor (Q) of 5.626 × 10³ and an excellent figure of merit (FoM) of 131. The high Q factor of the proposed sensor indicates a better limit of detection (LOD) and improved signal-to-noise ratio (SNR), making it suitable for high-precision applications. We believe this hybrid sensor demonstrates significant potential for applications in industrial and biomedical sensing due to its simple geometry, high precision, and efficient operation.