Study on the sensing characteristics of Fano resonance based on a coupled streamlined resonance cavity

Abstract

Based on the theory of surface plasmon polaritons (SPPs), a metal–insulator–metal (MIM) waveguide structure consisting of a streamlined resonant cavity and a baffle is proposed. When the incident light waves enter into the waveguide structure, through the interaction between the three discrete states and the continuous state by the streamlined cavity and the baffle, three sharp asymmetric Fano resonance spectra can be formed. The transmission spectrum characteristics of the structure are simulated and analyzed by the finite element method (FEM), and the effects of structure parameters and refractive index on the transmission spectra characteristics are studied. By optimizing the structure parameters, it is found that the performance of the system can be adjusted and optimized flexibly by changing the structure parameters, the figure of merit (FOM) can reach 1.99 × 106, and the sensitivity is 2960 nm/RIU. This flexible Fano resonant-structure has several applications in micro-nano biosensor, nonlinear optics, and slow light devices.