Plasmonic Refractive Index Sensor Including Two Waveguides, Rings and Two Cavities with Teeth Connected on Fano Resonances

Abstract

A plasmonic refractive index sensor based on a metal-insulator-metal (MIM) waveguide coupled with rings and two cavities and interconnected teeth is proposed and investigated numerically. Transfer (T), sensitivity (S) and Figure of Merit (FOM) were calculated and analysed via Finite Difference Time Domain method (FDTD). The simulation results show the generation of double Fano resonances in the system that the resonance line-shapes and the resonance wavelength can be adjusted by changing the geometry of the device. By optimizing the structure in the initial configuration, the maximum sensitivity of 2832 nm / RIU and FOM of 15.1 is achieved. Then we change the structure parameters and the number of resonators. In this case, the maximum sensitivity and FOM are 2083nm / RIU and 18.9 respectively. Therefore two detection points can be used for the refractive index sensor. Such a plasmonic sensor with simple and optimal framework could be suitable and practical for sensing systems and integrated optical circuits.