Investigations Of The Response Behaviors Of Quasiperiodic Dendritic Cluster Metasurfaces And Ball-thorn Shaped Metamaterials

Metamaterials,an artificially structured material composed of sub-wavelength structure units,have attracted tremendous attention in the fields of physics,materials science and engineering in the past few decades.Many fantastic electromagnetic phenomena and functions can be realized by using metamaterials.By controlling the design of the sub-wavelength structure unit,the electromagnetic properties of the metamaterial can be adjusted;through changing the size of the structure unit,the working frequency band of the metamaterial can be adjusted to achieve different purposes.Most of the early metamaterials worked in the microwave frequency band.With the development of micro-nano processing technology,the working band of metamaterials has been expanded to infrared and visible light bands by reducing the size of structure units.Due to its simpler preparation process,lower loss and other characteristics,a 2D metamaterial—metasurface has developed rapidly in recent years.Considering the practical application requirements,visible light metamaterials are an area that must be developed.In order to obtain metamaterials that can operate in the visible light band,it is necessary to prepare the structure with nano-scale periodicity and feature sizes that are much smaller than the wavelength.In the case of existing lithography technologies,the realization of visible metamaterials is still difficult.Nowadays,a small amount of visible metamaterials have been prepared with the development of nanopreparation technology and the emergence of new structural designs.However,the complexity,high cost of etching technology,and the anisotropy and high loss of existing metamaterials still hinder the rapid development and application of visible metamaterials.In terms of these problems,we propose a quasi-periodic dendritic cluster metasurface that is easy to prepare and can produce similar optical response behavior to that produced by the periodic metasurface in the visible light band,and a variety of abnormal manipulation behaviors of incident light are researched through these dendritic metasurfaces;an easily prepared and reflective mathematical metasurface with quasi-periodic silver dendritic structures is proposed according to the metasurface model raised by our group.The differential operation and integral operation properties of the metasurfaces are investigated through simulations and experiments in the visible band;based on the 3D ball-thorn shaped metamaterial cluster(meta-cluster)structure model,the low-loss negative refraction characteristics of isotropic meta-clusters in visible light band are simulated by Mie theory,and a 2D metamaterial photonic topological insulator(PTI)operating in the visible band is proposed.The main work of this paper is as follows:1.Study on the quasi-periodic silver dendritic metasurface in visible band.(1)Based on dendritic metasurface,a quasi-periodic dendritic cluster metasurface model in the visible band is proposed.In the simulation,the periodic structure metasurface tends to be a quasi-periodic dendritic cluster metasurface by gradually adjusting the state of the dendritic structure in the periodic structure unit.Simulation results show that the quasi-periodic cluster metasurfaces can produce nearly the same abnormal optical responses as those produced by the periodic metasurfaces.This kind of quasi-periodic dendritic cluster metasurface provides a new scheme for the development of visible light metasurface from the design principle.(2)A variety of quasi-periodic dendritic cluster set metasurfaces responding in the visible band are designed.The designed dendritic cluster set metasurfaces are used to study the reflection and transmission response to visible light.Simulation results demonstrate that abnormal reflection and refraction behaviors occur when visible light is obliquely incident on these metasurfaces at a large angle(88°).Additionally,a variety of quasi-periodic asymmetric dendritic cluster set metasurfaces are designed and used to study the manipulation of incident light polarization in the visible band.The simulation results show that cross-polarized light can be generated when the linearly polarized light is normally incident on these asymmetric metasurfaces,and the anomalous refraction behaviors of the cross-polarized light occur.The easy-to-prepare quasi-periodic dendritic cluster set metasurface provides a new method to break through the bottleneck of visible light metasurface preparation.2.Study on differential and integral operation properties of quasi-periodic silver dendritic metasurface in visible band.(1)First-order differential metasurfaces which are composed of silver dendritic structures and respond in visible light band are proposed.The position-dependent reflection coefficients obtained by simulation are in agreement with those predicted by theory.By using the prepared silver dendritic metasurface samples,the position-dependent reflectivity curves of the metasurfaces are measured in green and red bands respectively,and the trend of the curves are consistent with those predicted by simulation and theory.The easy-to-prepare silver dendritic differential metasurface provides the possibility to break through the bottleneck of the preparation of the visible light mathematical metasurface.(2)A silver dendritic integral metasurface that can work in visible light band is proposed.The position-dependent reflection coefficients obtained by simulation are in agreement with the theoretical prediction.The position-dependent reflectivity curve of the prepared metasurface sample is measured at red wavelength,and the trend of the curve is consistent with that predicted by simulation and theory.The silver dendritic metasurface that can conduct the integral operation in visible light band provides the possibility for the realization of miniaturized and integrated all-optical information processing system.3.Study on ball-thorn shaped composite metamaterials responding to visible light.(1)Based on the 3D ball-thorn shaped meta-cluster structure model,the low-loss negative refraction characteristics of isotropic meta-clusters in red and green light bands are simulated by Mie theory.In addition,the effects of various factors on the optical response behaviors of the meta-cluster structures are investigated.This kind of low-loss meta-cluster structure composed of metal and dielectric provides a new method for the design of 3D isotropic visible light metamaterials.(2)A 2D valley-Hall PTI working in the red band is proposed according to the 3D ball-thorn shaped metamaterial.Simulation results show that there is a TPEW with transmission robustness at the interface of two different PTIs.This metamaterial PTI provides a new method for efficient and free control of visible light.