Study On Propagation Characteristics Of Surface Plasmon Polaritons Based On Hole Array

The extraordinary transmission of light has stimulated the people's interest to study the surface plasmon polaritons(SPPs).The SPPs are the electromagnetic waves that are confined near the interface of metal and media and propagate along the interface.The excitation of SPPs strongly depends on the metal material and the microstructures on the metal material.By making suitable metal microstructures,optical phenomena such as extraordinary transmission,directional transmission,and perfect absorption can be achieved.This leads SPPs to have potential applications in nanometer scale control,photovoltaic conversion and bio-sensing.This thesis mainly uses the aperture array to stimulate SPPs,and study the transmission properties of SPPs by controlling the spatial distributions of the aperture array.The research on the controllable propagation of SPPs through the nanostructure mainly includes the focusing of SPPs,the directed emission of SPPs,and the splitting beam of SPPs.In the study about the focusing of SPPs,the linearly polarized light,circularly polarized light,and radially polarized light are commonly chosen as the light source.The microstructure under the radially polarized light illumination is relatively simpler,but the accurate positioning in actual experimental research is very difficult because of the non-uniformity of the polarization.Relatively,the linearly polarized light and the circularly polarized light are easy to use.Simple nanostructures tend to have lower focusing efficiency,and complex structures are not easily manufactured.Therefore,it is practically significant to design a simple nanostructure and obtain the focusing of SPPs with high focusing efficiency,small focal spot and easy integration under the linearly polarized light illumination.The realization of SPPs focusing refers to the propagation and convergence of SPPs along the metal surface.The periodic nanopores are the frequently selected microstructures in studying the propagation of SPPs.Periodic nanoholes are usually etched on metal films such as gold and silver that can excite SPPs,and most of theformer research concentrate on the near-infrared and infrared light bands.There are less research in visible light bands.In addition,the influence of material on the excitation and propagation of SPPs and the polarization dependence of SPPs also need to be discussed in depth.Therefore,this thesis proposes the research on the transmission characteristics of SPPs based on aperture array.The study of this thesis mainly includes the following five aspects.1.The introduction of the thesis is given in Chapter 1.In the section,the research background of SPPs and the research work that the thesis will carry out are introduced.The basic characteristics of SPPs are briefly described,and on basis of the wave equation,the dispersion relation of SPPs and several characteristic lengths of SPPs are deduced.Some common methods to excite SPPs including prism coupling,grating coupling and intensely focusing beam are presented.At the end of the introduction,the optical parameters of four kinds of metals used in this thesis are given.These contents provide the theoretical foundation for the later research work.2.Chapter 2 introduces some common nanostructures that excite SPPs,including metal nanoparticles,multilayered nanostructures consisting of metal and dielectric and pore structures on the thin film.The physical mechanism for the excitation of SPPs and transmission characteristics of SPPs among these nanostructures are analyzed.The employment of different nanostructures makes it possible to focuse,refract,and reflect SPPs.The production of these nanostructures needs the surportion of the nanotechnology.This chapter also describes the production methods of nanostructures such as direct ink writing,nanolithography,electron beam etching and ion beam etching.The nano-structured samples used in this thesis are obtained according to the ion beam etching.3.Chapter 3 presents the research of surface plasmon lens based on rectangular aperture.Firstly,the problem of the existing surface plasmon lens is pointed out by analyzing the research background of the surface plasmon lens.In order to realize a surface plasmon lens with high focusing efficiency,short focal length and ultra-thin structure,the design of a linear plasmonic lenses based on a rectangular aperture array is proposed.Our proposed lens only consists of 11 rectangular apertures.The efficientfocusing for the single focus spot is realized by simply adjusting the position and rotation angle of the rectangular apertures.Then,the surface plasmon lens with double focus spots,where two focal lengths are equal or unequal,is proposed using two lines of rectangular apertures.An improved surface plasmon lens is also proposed based on the half waveband principle to improve the optical performance of the lens.Our proposed surface plasmon lens has the advantages of high focusing efficiency,simple structure,thin thickness and large numerical aperture.4.Chapter 4 studies the near-field surface self-imaging effect of periodic nanometer apertures.The use of periodic nanometer aperture array enables surface plasmon focusing and coupling.When the period of the nanometer aperture array is larger,SPPs also show a significant diffraction phenomenon.Therefore,during the transmission of SPPs along the interfaces between the metal and the dielectric,Talbot effect of the periodic holes takes on due to diffraction and interference effect of SPPs coming from different apertures.This paper analyzes the current research about the surface Tabor effect,and proposes the study of periodic surface self-imaging effect in order to realize the self imaging of the aperture array with the visible light illumination and explore the influence of the material and the incident polarization state on the surface self-imaging.The influence of the incident polarization state on the surface Talbot effect is investigated by using numerical simulations.The polarization dependence of the surface Talbot effect is analyzed by means of the dipole model theory.At last,the practical microstructure sample is manufactured and the experiment measurement verifies the theoretical and the simulated results.5.Chapter 5 is the summary of this thesis and outlook of the following work.A comprehensive summary of the research work that has been carried out during the study about the transmission characteristics of SPPs based on aperture array is conducted.In order to extend the obtained research results of this thesis,some further work or the related work to be developed are given.