Generation and manipulation of the Fano resonance with high refractive index sensitivity based on the square split ring dimer

The Optical properties of the Square Split Ring dimer (SSRD) nanostructure is studied by the finite element method (FEM). Fano resonance can be excited in the visible and near-infrared bands by changing geometrical parameters of the SSRD or the arrangement of two square split rings (SSR). The production mechanism of Fano resonance is illustrated by using the plasmon hybridization theory (PHT). At the meantime, a pair of reverse current circulation is formed in the SSRD nanostructures and the maximum magnetic field enhancement reaches 45.69. In addition, calculation results show that the maximum refractive index sensitivities and the figure of merit (FOM) of SSRD systems reached 2043 nm/RIU and 57.9, respectively. Based on these features of the SSRD system, it may have potential application in sensor devices and surface-enhanced Raman scattering (SERS).