A highly sensitive plasmonic refractive index sensor based on concentric triple ring resonator for cancer biomarker and chemical concentration detection

Abstract

A refractive index nanosensor with Metal–Insulator–Metal (MIM) waveguide setup, incorporating a concentric triple ring resonator (CTRR), is presented in this article. The proposed sensor identifies unknown materials by exploiting the linear interrelation between the refractive index and the corresponding shift of the resonant wavelength, aided by the Finite Element Method (FEM). Optimization of the initial structural parameters is performed one by one to increase the sensitivity of the designed sensor to the utmost. As a result, a maximum sensitivity of 3639.79 nm/RIU is obtained for gas sensing, with a FOM (Figure of Merit), FOM*, and Q-factor of 91.02, 0.26 × 106, and 99.75, respectively. Furthermore, the proposed optimized CTRR sensor displays a maximum sensitivity of 7530.49 nm/RIU for the biologically and chemically important refractive index range 1.30 to 1.40 and can also function as a plasmonic filter. Therefore, the numerous possible applications make the proposed sensor a promising contender in the field of refractive index sensing.