Near-infrared plasmonic sensors based on surface plasmon resonances in two-dimensional metasurfaces of silver nanostructures

Abstract

This paper presents the results of theoretical research and numerical simulation of two-dimensional (2D) metasurfaces of silver (Ag) nanostructures that enable the surface plasmon resonances in the near-infrared regions. To clarify the mechanism of surface plasmon resonance that appears in the designed structures under electromagnetism stimuli, the theory of localised surface plasmon resonance and propagating surface plasmon resonance was presented. The finite-difference time-domain (FDTD) method was used to simulate the optical properties of 2D periodically arranged Ag nanostructures and to verify the theoretical prediction results. Calculated and simulated results for the dependence of the surface plasmon resonance and the refractive index of the surrounding medium are performed and show that the proposed structure is sensitive to the gas environment, with an average sensitivity of 1423.7 nm/RIU (refractive index unit) and the average quality factor (FOM) characterising the selectivity is 110.2 RIU^-1. The calculation and simulation results provide a general guideline for plasmonic metasurface sensing device designs that are sensitive to small changes in the surrounding environment.