Design Of Sub Wavelength Filter Based On Surface Plasmon

Surface plasmon is a special form of electromagnetic wave which appears on the interface between metal and dielectric.It is a plane wave propagating along the interface between two materials.Its most important characteristic is that it can break the diffraction limit of light and limit the energy of electromagnetic wave to nanometer size.This characteristic can greatly promote the development of miniaturization of optical components.Optical components have many advantages that can not be compared with electronic components.It can be predicted that surface plasmon technology will be widely used in production and life in the near future.Optical components will gradually replace traditional electronic components.All-optical network for communication will be built,and communication speed and quality will be greatly improved.At the same time,surface plasmons are also widely used in biomedicine,superconducting materials,optical enhancement and other fields.The main contents of this paper are as follows.Firstly,the principle and design of sub-wavelength filter based on surface plasmon are discussed.The theoretical knowledge involved in surface plasmon technology is introduced,the theoretical derivation of diffraction limit,the dispersion relationship of metals,the Drude model of metal dispersion model widely used in simulation calculation and the method of exciting surface plasmon in practice are deduced.Surface plasmons can not be generated automatically,and they need to meet certain matching conditions before they can be activated.In this paper,several common excitation modes are described in terms of principle and practical operation.The numerical methods commonly used for surface plasmon calculations are introduced.Finite element method(FEM)and finite difference time domain(FDTD)are the two most common numerical algorithms.We will introduce the two algorithms in detail in theory and compare their advantages and disadvantages,characteristics and scope of application.Then,we study the common surface plasmon filter structures,which are the basis of designing filters,such as tooth,rectangular resonator,ring resonator and so on.The filter structure is analyzed from two aspects of theoretical derivation and simulation,and the quantitative influence of different parameters adjustment on the filtering effect is obtained.Finally,according to the conclusions of the study,a novel ring-notched resonator filter structure is proposed.The model is analyzed and studied by using the simulation software COMSOL Multyphysics.According to the transmission spectrum and other results,it is known that the model has good band-pass filtering effect and has important application value in the development of surface plasmon filter.At the end of the article,the whole research process is summarized,and the future development direction is predicted based on the research results already obtained.The deficiencies in the research are found and the deficiencies are improved.