Research On Design And Dynamic Regulation Of Optical Metasurfaces

Metasurface is a new type of ultra-thin planar optical element that controls the phase,polarization,and amplitude of the wavefront by manipulating the resonance of incident electromagnetic waves through artificially designed micro-nano structures.Its novel working mechanism and flexible structure design form provides broad prospects for its application in the field of optoelectronics.However,the prepared optical devices will have a fixed optical response range due to the fixed structure size,which will greatly limit the practical application of metastructured surfaces.Therefore,the study of dynamically adjustable metasurfaces is particularly important.Adding active factors that can make electromagnetic waves sensitive to the design of metasurfaces can cause sensitive regulation of structural systems,and the macroscopic response of structures to electromagnetic wave regulation is reflected in changes in the optical response of functional devices.The research content of this article is the design and dynamic regulation of optical metasurfaces.During the research process,a metasurface structure system with corresponding functions was designed.The three kinds of regulation methods are changed by external refractive index changes,stress tensile deformation,and chemical methods to regulate the electromagnetic wave formation.Although different control methods correspond to different structural designs and different application fields,the overall dynamic control is generated based on the coupling mechanism.The metasurface structure system designed in this paper can be coupled by multiple bodies and structural units between modes.Coupling with incident electromagnetic waves produces work.How to use the external active factors to produce the most sensitive and efficient regulation of the coupling mechanism of the designed structural system is the main content of the research on the dynamic regulation of optical metasurfaces.Of course,with the continuous deepening of the research work in this article,the developed structural system is more and more flexible in the regulation of electromagnetic waves,and the application of the device is also more portable and practical.This article designs a simple grating structure composed of metal-dielectric-metal materials is designed in this paper.Surface and plasmonic modes(SPPs)and structural magnetic resonance modes(MPPs)generate a strong coupling mode.The strengthens of the magnetic field by nearly 500 times in a coupled mode through a simple plasmonic metasurface,to some extent,balances the asymmetry of electrical and magnetic conversion and greatly enhances the structure.The radiation intensity of the magnetic field in the system,while the overall structure of the device retains the characteristics of the surface plasmonic mode,and the precise adjustment of the resonance position of the structure under the external refractive index changes.The development of the device played a driving role.This article also designs a metasurface that is controlled by stress tensile deformation.When a traditional structural system applies unidirectional tensile stress,the structural device will lack information and be inefficient in a certain direction because of the polarization sensitivity band.Especially on the structural color display.The titanium dioxide metastructured surface is embedded in a polydimethylsiloxane(PDMS)flexible substrate.It can be observed in simulations and experiments that two orthogonally polarized reflection colors are simultaneously regulated in the visible light band and can respond in response.High consistency in trend,range and speed.This polarization-insensitive property is determined by two different mechanisms of near-field interaction and grating effect in the vertical and parallel polarization directions,so the overall structural color display can achieve continuous and efficient under unidirectional stretching.At the same time,due to the influence of structural parameters on the speed of regulation,based on such a regulation mechanism,structural devices can be applied in the display and hiding of information.Lead halide perovskite has high refractive index and low loss material properties,which meets the requirements of metamaterial surface design for material selection.In the end of this article,a perovskite metamorphic surface with full phase coverage and high reflection efficiency is designed in the reflection mode.The arbitrary wavefront can be adjusted from the sub-wavelength size to transform the incident beam into the required wavefront profile and reconstruct it at the far field.The structural devices based on polarization conversion,abnormal reflection and holographic imaging of lead halide perovskite were successfully designed.Among them,the absolute conversion efficiency of abnormal reflection reaches 45%,which is comparable to high-refractive transparent dielectric materials such as silicon and titanium dioxide.At the same time,lead halide perovskite also has a structural property with adjustable band gap,which can realize the structure of the device through the replacement of anions.Dynamic regulation plays a driving role in the portable application of adjustable all-dielectric metasurfaces.