Research On Narrow Band Absorption And Its Refractive Index Sensing Characteristics Based On Surface Plasmon Metasurface

Surface plasmon(SP)is the interaction between free electrons on the metal surface and incident photons at the same frequency.The most typical characteristic of surface plasmon is to break the diffraction limit of light.With the research of surface plasmon,the refractive index sensor of the narrow band absorption based on surface plasmon metasurface structure has attracted attention.The finite element method(FEM)is used to design the metasurface structure in this paper,and the absorption characteristics and the refractive index sensing characteristics are studied and analyzed.The main research contents of this paper are as follows:1.Designed a metal-dielectric-metal(MIM)elliptical disk composite metamaterial structure in the visible band.The structure is composed of the top elliptical disk cell array,silicon dioxide dielectric layer and gold substrate.The finite element method is used to analyze the single elliptical disk structure and the I-shaped elliptical disk array structure.The effects of structural parameters and external refractive index on absorption and sensitivity were studied,and the mechanism of resonance absorption peak was studied by electric field analysis.The research results show that the sensitivity of the "I"-shaped elliptical disk absorber structure is higher than that of a single elliptical disk absorber structure,and the FOM of the I-shaped absorber is twice that of a single elliptical disk absorber.2.Designed a MIM double trapezoidal structure in the infrared band.The structure is composed of a top-layer double trapezoidal cell array,a silicon dioxide dielectric layer and a gold substrate.The effects of structural parameters and external refractive index on absorption and sensitivity were studied,and the mechanism of resonance absorption peak was studied by electric field analysis.In addition,a double trapezoidal derivative structure was designed,and the refractive index sensing characteristics of the structure were analyzed.The research results show that the sensitivity of both structures is very high,but the full width at half maximum is yet to be further optimized.3.Designed a MIM cross-shaped absorber structure which is polarization-independent in the infrared band.The structure consists of a top cross-shaped cell array,a silicon dioxide dielectric layer,and a gold substrate.The effects of structural parameters and external refractive index on absorption and sensitivity were studied,and the mechanism of resonance absorption peak was studied by electric field analysis.The research results show that the maximum sensitivity of the cross-shaped absorber structure is 1125 nm/RIU,FWHM is 10 nm and FOM is 112.The structure of the above-mentioned narrow-band absorption metastructure sensor is simple,which may provides some reference for the surface plasmon matasurface structure in optical stealth and refractive index sensors.