| Surface Plasmons（SPs）are the collective forced movement of constrained electrons outside the atomic nucleus under the influence of an incident magnetic field,usually at the interface between the dielectric and the metal.The two important forms of SPs are Surface Plasmon Polaritons（SPPs）and Localized Surface Plasmon（LSP）.SPPs refer to SPs in propagation mode,which usually occur at the interface between a flat metal and a dielectric material.LSP refers to local mode SPs,which usually occur under the influence of external field and single metal nanoparticles.When the energies of SPPs and LSP are similar,the transmission of metal nanohole structure can be enhanced.The more complex the metal nanostructures are,the more transmission characteristics can be seen in the transmission spectrum and electric field distribution under the irradiation of light.In this paper,the theory and application of light-enhanced transmission of two metal structures are studied using COMSOL Multiphysics software.The main content of this article is divided into the following two aspects:（1）First,a novel metallic Y-shaped hole array is conceived in this paper,and its light-enhanced transmission phenomenon in the subwavelength field and its application to refractive index sensors are studied.The research results show that this Y-shaped metal nanohole structure can provide extremely strong electric field and super transmittance in the range of 0.6?m to 1.2?m,and the electric field distribution at the corner is particularly obvious.Structural parameters such as the deflection angle,width,thickness,period,and refractive index all have effects on the transmission characteristics,and the influence of the deflection angle on the transmission characteristics is particularly significant.When the deflection angle increases,the transmission coefficient will increase significantly.The transmittance at a wavelength of 0.67?m increases from 0.558 to 0.628 and and the transmittance 0.289 at a wavelength of 1.08?m increases to 0.840 at 1.17?m.The influence of medium refractive index on the transmission characteristics are studied by increasing the refractive index in steps of 0.04 RIU from 1 to 1.2.The sensitivity of the refractive index sensing in the two modes are 900 nm/RIU and 350 nm/RIU.According to the definition of detection resolution,the detection resolutions of the two modes are2.22?10-4RIU and5.71?10-4RIU respectively.Such light-enhanced transmission characteristics and high sensitivity characteristics are beneficial for designing nano-refractive index sensors and bandpass filters with high sensitivity and have certain reference value for the application of biosensors.（2）A diamond-shaped periodic silver film array is also designed in this paper to achieve non-resonant enhanced transmission.The positional relationship of the rhombic holes of the unit size is divided into three states:intersection,tangent and separation.When light irradiates the diamond-shaped hole structure,the distance between adjacent diamond-shaped holes S is increased from-9 nm to 9 nm and undergoes the states of intersection,tangent and separation sequentially.The corresponding transmission coefficient decreases and the electric field distribution changes from the strong excitation electric field at the tip of the rhombic hole to the electric field mainly distributed at the edge and surrounding of the rhombic hole,which show that the transmission coefficient at the intersection is much higher than the transmission coefficient at the time of separation.The research results show that the diamond-shaped periodic silver film array can achieve broadband transmission in the 5?m-20?m wavelength range and the four structural parameters of the distance between adjacent diamond-shaped holes S,width L,lateral period P and longitudinal period H are strongly related to the light transmission characteristics.This structure is of great significance for the design of devices that realize broadband transmission. |
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