Spectrum And Devices Of Cylinder Structures Coated With Ag At Nanometer Scale

In this paper,we present a new scheme of dielectric nano cylindrical grating.The finite element method is used to study the characteristics of reflection spectrum,transmission spectrum and absorption spectrum.A silver nano dielectric cylindrical grating is proposed on the basis of this research,the scheme of using the finite element method of surface plasmon polaritons(SPPs)characteristics and structure parameters of grating reflection spectrum,transmission spectrum and absorption spectrum.In the first chapter,the propagation characteristics of surface plasmon polaritons,the research progress and the development of subwavelength gratings are introduced.In the second chapter,the dispersion and excitation conditions of the surface plasmon polaritons are introduced,and the propagation characteristics and resonance frequencies of the SPPs induced by the interface between a semi infinite medium and a semi infinite metal are derived.It is found that the propagation length of SPPs is related to the refractive index of the medium.In the third chapter,the spectral properties of cylindrical dielectric gratings are studied.This paper discusses the influence of the cylinder radius and the grating period on the wavelength of the reflection peak and the reflection peak.It is found that the wavelength of the reflection peak increases with the increase of the radius of the cylinder.At the same time,when the cylinder radius remains constant,the wavelength of the reflection peak increases with the increase of the grating period.In the fourth chapter,the absorption properties of silver plated cylindrical dielectric subwavelength gratings are studied.The influence of the structure parameters on the absorption wavelength and the absorption peak position is discussed.It is found that the maximum absorption peak is 59.5%,and the maximum absorption can be obtained only when the appropriate structural parameters are obtained.The absorption characteristics of the subwavelength cylindrical dielectric gratings coated with silver are more important than that of the subwavelength cylindrical dielectric gratings.This is due to the formation of surface plasmon polaritons on the silver plated cylindrical grating structure,and there are two modes:the coupling mode between the two silver cylinders and the standing wave pattern in the cylinder coated with sliver.When the incident wavelength is 640 nm,the maximum resonance absorption rate is found to be about 59.5%,and the intensity of the coupling between the standing wave mode in the silver plated cylinder and the coupling mode between the two silver plated cylinders is almost equal.The study found that in the cylindrical nano dielectric grating,for certain wavelengths,produces high reflectivity,can even have reached high reflectivity of more than 99.9%,which can be used to design optical devices ultra high reflectivity mirrors or filters.The absorption peak position and absorption value of the sub wavelength grating with silver plated cylindrical medium are changed with the change of structural parameters.Under the given structural parameters,the absorption peak position changes with the change of refractive index of the external medium.The results can be used to design a new dielectric refractive index detector.Therefore,the research results have some reference value for the practical application of subwavelength grating devices.