Au-SiO2-Si hybrid plasmonic waveguide micro-ring resonator sensor

Abstract

A refractive index sensor based on straight silicon waveguide and a hybrid plasmonic micro-ring resonator of radius 1 µm is presented. The hybrid waveguide is made up of a Metal-Insulator-Silicon structure, where the electric field is significantly enhanced in the thin insulator layer. The micro-ring design is optimized where silicon micro-ring waveguide width and a total height of the structure is 400 nm and 220 nm, respectively. The transmission spectrum and electric field distribution of this sensor structure are simulated using Finite Element Method (FEM). Despite the small size of hybrid micro-ring resonator and sensing medium, the sensitivity is relatively high as compared to conventional dielectric micro-ring resonator sensors. The resonance shift of Δλ = 27 nm is obtained for Δn = 0.15 and yields the best sensitivity of 180 nm/RIU in the near infrared range.