Study About The Design Of Transmission Metasurface Functional Elements And The Light Wavefront Control

Classical optical effects such as refraction,diffraction and polarization usually require the use of traditional optical elements such as lenses,wave plates and polarizers to complete the accumulation of the phase,polarization and amplitude of the light field on the optical transmission path.In order to achieve the purpose of light field control,traditional optical components are usually relatively large.Obviously,large-size traditional optical components cannot meet the needs of modern optics for the miniaturization and integration of components.Ultra-thin and compact metasurface optical components have the advantage of being easier to integrate than traditional optical components.The metasurface can cause a sudden phase change at the interface,which makes it possible to manipulate the phase,amplitude,and polarization of the transmitted or reflected light on the interface.This also opens the door for the design and manufacture of new planar optical components.Therefore,metasurface optics The research of components has attracted widespread attention.Metasurface has the advantages of ultra-thin and compact structure,powerful light manipulation ability and high degree of freedom,and has broad application prospects in electromagnetic stealth,super-resolution imaging,optical micro-manipulation,optical processing,etc.For this reason,the design of metasurface functional elements has become a research hotspot in the field of nanophotonics.The design of various micro-optical elements based on metasurfaces has important scientific significance and application value to promote the wide application of metasurfaces.This thesis is based on the optical transmission metasurface,a variety of metasurface micro-optical elements are designed based on metasurface phase modulation,and the realization of the metasurface effective control of the wavefront of the light field is studied.The innovative work of this thesis includes the following three aspects: one is to put forward the theory to guide the design of metasurface plasmon vortex generator,the other is to design a metasurface array illuminator based on Fresnel holography,and the third is to design a metasurface vortex structured light generator based on holographic metasurface.The transmissive metasurface micro-optical element designed in this paper has the advantages of compact structure,convenient production,simple use,flexible and controllable functions,and has an important impact on the expansion of the design and application of the metasurface optical element.The specific content of the paper is arranged as follows.The first chapter is the introduction part of the thesis.The introduction introduces the research background and current situation of metasurfaces and the work to be carried out in this thesis.Since the design of metasurface optical components mainly relies on the phase modulation of the optical field by the metasurface,this chapter first introduces various optical metasurfaces according to the different phase control methods.The design and optical performance of optical functional elements constructed from metasurface including metalens,metasurface vortex light generator and metasurface hologram are analyzed.The excellent performance of metasurface micro-optical elements fully illustrate the physical significance of designing and researching metasurface micro-optical elements.The second chapter introduces the unified theory of plasmonic vortex generator based on nanoholes design proposed.In view of the wide application of surface plasmon vortices in super-resolution imaging and optical micro-manipulation,in order to provide theoretical guidance for the design of metasurface plasmonic vortex generators,this chapter uses the radiation model of dipoles on the propagation of surface plasmons.Theoretical analysis was carried out.The analytical expressions of the transmission field of the anisotropic unit under linearly polarized light and circularly polarized light were given,and a unified theory for the design of surface plasmon vortex generators was formed.Various examples of surface plasmon vortex generators verify the validity of the proposed theory.This theory can also be extended to the design of reflective plasmon vortex generators,so this work has laid a solid foundation for the generation and application of high-efficiency plasmon vortices.Chapter 3 introduces the metasurface array illuminators designed based on the Fresnel holographic principle,and regulates the spatial distribution of the light field to form a controllable array spot output.In view of the practical applications of array illuminator optical power distribution,optical calculation,optical interconnection and optical communication,in order to obtain high-precision array spot,this chapter designs a metasurface array illuminator based on a holographic metasurface.The information of the metasurface holography comes from the Fresnel hologram after the target light pattern is binarized.The phase adjustment of the metasurface to the light field comes from the geometric phase shift introduced by the rotating rectangular nanohole.Through a reasonable spatial layout,the metasurface structure of the array illuminator is constructed,and a micron-scale array spot is formed under circularly polarized light illumination.The metasurface array illuminator we proposed has the advantages of ultra-thin thickness,compact structure,high resolution and easy production,which provides an important basis for the application of integrated array illuminators.Chapter 4 introduces a kind of vortex structured light generator based on a holographic metasurface,which can achieve complex spiral phase wavefront and polarization controllable output.Similar to the optical field amplitude and phase distribution of Laguerre-Gaussian beams,the vortex structure optical field is also composed of multiple concentric rings,and the phase in each region increases linearly by an integer multiple of 2π in the angular direction.The difference is that the integers of the phase increase of 2π in each region can be the same or different.The essence introduces the distribution characteristics of this vortex structured light,the metasurface structure designed based on Fresnel holography technology and the various vortex structured lights produced.The vortex structured light has a specific amplitude and phase distribution,which puts forward high requirements on the design of optical metasurfaces,but the simulation and experimental results strongly verify the good optical performance of the structured light generator we designed.This vortex structured light generator provides a powerful tool for designing structured light fields,and can be used for optical micro-manipulation and particle screening.Chapter 5 gives the summary of this thesis.This chapter summarizes the main content and innovations of the paper,points out the deficiencies in the paper,explains the unsurpassed difficulties,and also elaborates the next work plan.