Research Of The Design Of Metal Composite Nanostructures Based On SPs

At the interface between the medium and the metal,a surface evanescent wave mode of electromagnetic field is formed,which is called Surface plasmons(SPs),and it's formed by the interaction between photons and free electrons at the contact interface.It can be divided into two modes: Surface plasmon polaritons(SPPs)and Localized surface plasmons(LSPs).In the former mode,the electromagnetic wave propagates along the interface between the medium and the metal.The latter mode of electromagnetic wave is localized on metal nanoparticles and surface microstructures.After a lot of research,researchers found that metal nanostructures can excite SPs,to effectively couple the light radiation energy of its own space,and form a highly limited surface model.A very large local field is formed on the metal surface.This extremely strong local field will produce many novel physical phenomena such as optical enhanced transmission and so on.Because SPs is highly sensitive to metal microstructures and external factors,researchers can study such factors as structure shape,material,size and dielectric environment.Thus,the optical properties of metal meter nanostructures are manipulated.With the development of nanofabrication technology,many new metal nanostructures and nano-photonic devices have been designed and fabricated.Biochemistry detection and many other fields have been widely used.In 1998,Ebbesen,a French scientist,observed and explained the propagation of light through sub-porosities,and proposed that the anomalous light transmission phenomenon(Extraordinary optical transmission,EOT),has made a great contribution to the study of surface cytoplasmic gene photonics.The researchers found that metal nanostructures have the characteristics of enhancing the transmission of light,so they are beneficial to the realization of novel optoelectronic devices,such as filters,transparent conductors,optical couplers and sensors.Nowadays,due to the rapid development of electronic industry,electronic devices are required to be more miniaturized and integrated.However,when the device reaches a very small size,electronic devices will face a limit problem.Compared with the traditional electronic devices,the miniaturized optoelectronic devices have higher transmission bandwidth,higher speed and lower loss,so they have become a new research field of all-optical integration in the world.Due to the influence of diffraction limit,the size of photonic devices is limited to the order of micron,so we need to explore and develop new carriers to achieve the goal of all-optical integration and achieve nanoscale size.Due to the excitation of SPs,metal nanostructures can couple the light radiation energy of free space to the spatial range of nanoscale near their surface,and form a highly localized electromagnetic field,which can break through the limitation of optical diffraction.Therefore,it can provide reliable means for optical control of nano-scale.Based on the surface isotherm,several metal nanostructures,ring square,Chinese "back" and "diamond" metal column structures have been designed,and the parameters of metal structures have been scanned and optimized.The physical mechanism of abnormal transmission phenomenon,field intensity distribution of electric field and transmission spectrum are analyzed and studied.As follows:(1)The introduction of the research background,that is,the development history,types and related physical characteristics of SPs: dispersion relation,excitation mode,propagation mode and application;(2)Finite Difference Time-Domain method(FDTD);(3)Design and Research of Diamond Metal Nanostructures.In this chapter,a new micro-nano structure of sub-wavelength metal column array is designed.The substrate is glass substrate.The upper surface of the structure is a square block structure of the same size.Gold or silver,arranged regularly and ordered to form a diamond-like structure,has a very high transmittance under incident light waves,can reach 99%,and has a sufficiently large half peak full width,up to about 940nm;(4)In this chapter,a kind of ring metal nanostructure is designed.The structure is composed of inner square ring and outer square ring,X and Y directions are periodic,Z is the negative direction of incident light source.The phenomenon of multiple peaks appears in the transmission spectrum under this structure,which has a certain theoretical significance for the study of optical filters;(5)On the basis of periodic pore structure,a new type of rectangular cavity structure is designed in this chapter,which is compared with the previous research.The transmittance and the transmission bandwidth of the structure have been improved.Finally,the structure has been changed again,connecting the small rectangular holes around the structure to form a structure like the Chinese character "return",which also has a great influence on the transmission spectrum;(6)Summary and prospect.The results of this paper will be helpful for us to further understand the optical abnormal transmission phenomenon and provide some guidance for the theoretical study of photonic devices.