Analysis and Design of Refractive Index Sensor Based on Waveguide Coupling

This paper presents a new refractive index sensor based on the Fano resonance in optical phenomena. The sensor has two main parts: a metal-insulator-metal (MIM) as the base waveguide and a V -shaped ring resonant cavity with a convex outer ring (VRROR) as the coupling structure. The sensing characteristics of the structure are rationalized by applying the finite element method, and the specific effects of the various parameters in the structure on the sensitivity(S) and superiority of the VRROR are analyzed. The final sensitivity of the VRROR type sensor reaches 2960 nm/RIU, and the figure of merit (FOM) under the corresponding system reaches 51.3.