| Surface Plasmon Polaritons(SPPs)are a special type of electromagnetic wave.They usually exist between metals and dielectrics and are generated by the interaction of free electrons on the metal surface with photons.They are transverse evanescent waves with an electromagnetic field distribution that decays exponentially in the direction perpendicular to the metal surface.Surface plasmons have the characteristics of breaking the diffraction limit and enhancing the local field,which can realize optical information transmission and processing at the nanoscale.Due to its unique optical properties,it has been widely used in fields such as biomedicine,information detection,super-resolution imaging,and signal storage.This paper starts from the theory of SPPs,introduces its development process and derives its dispersion relationship by formula;secondly,it analyzes the electromagnetic scattering mechanism of a concentric circular periodic structure composed of metal nanocomposite columns,and discusses its near-field and far-field optical properties respectively;then,it designs an optical sensor based on surface plasmon resonance and proposes an optimization scheme for the sensor;finally,it studies the transmission characteristics of electromagnetic waves in an array structure composed of composite columns composed of anisotropic materials and metals.The main research contents are as follows:(1)A composite structure model composed of 7 identical metal-coated nanocylinders is designed.Each metal-coated nanocylinder is composed of silver and silica.This composite structure is based on the theory of surface plasmon resonance and is very sensitive to changes in the refractive index of the surrounding environment.It can detect the concentration of the measured medium within a certain frequency band.Through the analysis of the electromagnetic scattering characteristics of this structural model,we obtained its surface plasmon excitation frequency and resonance mode.The influence of physical parameters(metal coating thickness,nanocolumn spacing)on its resonance effect was numerically analyzed,and an improved scheme was proposed by doping gain/loss materials in silica dielectric columns to improve the sensitivity of this composite structure to changes in environmental refractive index.By measuring different concentrations of sodium chloride solution,the sensor application of this structure was verified and tested.As a surface plasmon resonance optical sensor,this composite structure has a sensitivity that can reach =3205.139)8)/,and has advantages such as high corrosion resistance,strong anti-interference ability,and real-time detection.(2)An array structure model composed of four composite dielectric cylinders as the smallest unit is designed.Each composite dielectric cylinder is composed of anisotropic magneto-optic material yttrium iron garnet(YIG)and silver metal.Under the influence of magneto-optic effects,different static magnetic field application methods will affect the excitation frequency of surface plasmons in array structures.Therefore,by changing the way and position of applying static magnetic fields in array structures or adjusting the frequency of excitation sources,both can achieve control over electromagnetic wave transmission paths.According to electromagnetic scattering theory,numerical analysis was performed on how different static magnetic field application methods affect the optical properties of unit structures.And based on this array structure model,design ideas for functional optical devices such as optical isolators,optical beam splitters,optical storage devices,channel selectors were proposed.Finally,through simulation verification,the effectiveness of the design scheme was verified. |
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