Artificial microstructures,which allow us to control and change the properties of wave fields through changing the geometrical parameters and the arrangements of microstructures,have attracted plenty of attentions in ...Artificial microstructures,which allow us to control and change the properties of wave fields through changing the geometrical parameters and the arrangements of microstructures,have attracted plenty of attentions in the past few decades.Some artificial microstructure based research areas,such as metamaterials,metasurfaces and phononic topological insulators,have seen numerous novel applications and phenomena.The manipulation of different dimensions(phase,amplitude,frequency or polarization)of wave fields,particularly,can be easily achieved at subwavelength scales by metasurfaces.In this review,we focus on the recent developments of wave field manipulations based on artificial microstructures and classify some important applications from the viewpoint of different dimensional manipulations of wave fields.The development tendency of wave field manipulation from single-dimension to multidimensions provides a useful guide for researchers to realize miniaturized and integrated optical and acoustic devices.展开更多
Nonlinear metasurfaces and photonic crystals provide a significant way to generate and manipulate nonlinear signals owing to the resonance-and symmetry-based light-matter interactions supported by the artificial struc...Nonlinear metasurfaces and photonic crystals provide a significant way to generate and manipulate nonlinear signals owing to the resonance-and symmetry-based light-matter interactions supported by the artificial structures.However,the nonlinear conversion efficiency is generally limited by the angular dispersion of optical resonances especially in nonparaxial photonics.Here,we propose a metagrating realizing a quasi-bound-state in the continuum in a flat band to dramatically improve the third harmonic generation(THG)efficiency.A superior operating angular range is achieved based on the interlayer and intralayer couplings,which are introduced by breaking the mirror symmetry of the metagrating.We demonstrate the relation of angular dispersion between the nonlinear and linear responses at different incident angles.We also elucidate the mechanism of these offaxis flat-band-based nonlinear conversions through different mode decomposition.Our scheme provides a robust and analytical way for nonparaxial nonlinear generation and paves the way for further applications such as wide-angle nonlinear information transmission and enhanced nonlinear generation under tight focusing.展开更多
Optical activity is the rotation of the plane of linearly polarized light along the propagation direction as the light travels through optically active materials.In existing methods,the strength of the optical activit...Optical activity is the rotation of the plane of linearly polarized light along the propagation direction as the light travels through optically active materials.In existing methods,the strength of the optical activity is determined by the chirality of the materials,which is difficult to control quantitatively.Here we numerically and experimentally investigated an alternative approach to realize and control the optical activity with non-chiral plasmonic metasurfaces.Through judicious design of the structural units of the metasurfaces,the right and left circular polarization components of the linearly polarized light have different phase retardations after transmitting through the metasurfaces,leading to large optical activity.Moreover,the strength of the optical activity can be easily and accurately tuned by directly adjusting the phase difference.The proposed approach based on non-chiral plasmonic metasurfaces exhibits large optical activity with a high controllable degree of freedom,which may provide more possibilities for applications in photonics.展开更多
Metasurfaces,which are planar arrays of subwavelength artificial structures,have emerged as excellent platforms for the integration and miniaturization of electromagnetic devices and provided ample possibilities for s...Metasurfaces,which are planar arrays of subwavelength artificial structures,have emerged as excellent platforms for the integration and miniaturization of electromagnetic devices and provided ample possibilities for single-dimensional and multi-dimensional manipulations of electromagnetic waves.However,owing to the limited interactions between planar thin metallic nanostructures and electromagnetic waves as well as intrinsic losses in metals,metasurfaces exhibit disadvantages in terms of efficiency,controllability,and functionality.Recent advances in this field show that few-layer metasurfaces can overcome these drawbacks.Few-layer metasurfaces composed of more than one functional layer enable more degrees of design freedom.Hence,they possess unprecedented capabilities for electromagnetic wave manipulation,which have considerable impact in the area of nanophotonics.This article reviews recent advances in few-layer metasurfaces from the viewpoint of their scattering properties.The scattering matrix theory is briefly introduced,and the advantages and drawbacks of few-layer metasurfaces for the realization of arbitrary scattering properties are discussed.Then,a detailed overview of typical few-layer metasurfaces with various scattering properties and their design principles is provided.Finally,an outlook on the future directions and challenges in this promising research area is presented.展开更多
Polarization as an important degree of freedom for light plays a key role in optics.Structured beams with controlled polarization profles have diverse applications,such as information encoding,display,medical and biol...Polarization as an important degree of freedom for light plays a key role in optics.Structured beams with controlled polarization profles have diverse applications,such as information encoding,display,medical and biological imaging,and manipulation of microparticles.However,conventional polarization optics can only realize two-dimensional polarization structures in a transverse plane.The emergent ultrathin optical devices consisting of planar nanostructures,so-called metasurfaces,have shown much promise for polarization manipulation.Here we propose and experimentally demonstrate color-selective three-dimensional(3D)polarization structures with a single metasurface.The geometric metasurfaces are designed based on color and phase multiplexing and polarization rotation,creating various 3D polarization knots.Remarkably,different 3D polarization knots in the same observation region can be achieved by controlling the incident wavelengths,providing unprecedented polarization control with color information in 3D space.Our research findings may be of interest to many practical applications such as vector beam generation,virtual reality,volumetric displays,security,and anti-counterfeiting.展开更多
Metasurfaces are planar arrays composed of artificial nanostructures at the subwavelength scale.Since the first demonstration of their excellent capacity in the phase manipulation of optical waves,metasurfaces have at...Metasurfaces are planar arrays composed of artificial nanostructures at the subwavelength scale.Since the first demonstration of their excellent capacity in the phase manipulation of optical waves,metasurfaces have attracted increasing attention in optics and other disciplines,with extraordinary progress over the past decade.The unique capabilities of metasurfaces in the multidimensional manipulation of optical waves have made them versatile and powerful platforms for integrating and minimizing optical devices[1,2].展开更多
A four-fold-degenerate three-dimensional(3D)Dirac point,represents a degenerate pair of Weyl points carrying opposite chiralities.Moreover,3D Dirac crystals have shown many exotic features different from those of Weyl...A four-fold-degenerate three-dimensional(3D)Dirac point,represents a degenerate pair of Weyl points carrying opposite chiralities.Moreover,3D Dirac crystals have shown many exotic features different from those of Weyl crystals.How these features evolve from 3D Dirac to Weyl crystals is important in research on 3D topological matter.Here,we realized a pair of 3D acoustic Dirac points from band inversion in a hexagonal sonic crystal and observed the surface states and helical interface states connecting the Dirac points.Furthermore,each Dirac point can transition into a pair of Weyl points with the introduction of chiral hopping.The exotic features of the surface states and interface states are inherited by the resulting Weyl crystal.Our work may serve as an ideal platform for exploring exotic physical phenomena in 3D topological semimetals.展开更多
Metasurfaces are ultrathin structured interfaces consisting of planar arrays of subwavelength artificial nanostructures, which emerge as excellent platforms for optical wave manipulation. Owing to their unprecedented ...Metasurfaces are ultrathin structured interfaces consisting of planar arrays of subwavelength artificial nanostructures, which emerge as excellent platforms for optical wave manipulation. Owing to their unprecedented capacities to manipulate the polarization, amplitude, phase and frequency of optical waves at the subwavelength scale, metasurfaces enable various novel optical functionalities that go beyond which can be attained from conventional optical elements.展开更多
The study of topological semimetals hosting spin-1 Weyl points(WPs)beyond Dirac points and WPs has attracted a great deal of attention.However,a spin-1 Weyl semimetal that exclusively possesses spin-1 WPs in a clean f...The study of topological semimetals hosting spin-1 Weyl points(WPs)beyond Dirac points and WPs has attracted a great deal of attention.However,a spin-1 Weyl semimetal that exclusively possesses spin-1 WPs in a clean frequency window without being shadowed by any other nodal points is yet to be discovered.This study reports a spin-1 Weyl semimetal in a phononic crystal.Its spin-1 WPs are touched by two linear dispersions and an additional flat band and carry monopole charges(-2,0,2)or(2,0,-2)for the three bands from the bottom to the top.They result in double Fermi arcs,which occur between the first and second bands,as well as between the second and third bands.Further robust propagation is observed against the multiple joints and topological negative refraction of the acoustic surface arc wave.The results of this study create the basis for the exploration of the unusual properties of spin-1 Weyl physics on a macroscopic scale.展开更多
Metasurfaces,whose electromagnetic(EM)responses can be artificially designed,are two-dimensional arrays composed of subwavelength nanostructures.Accompanied by various fascinating developments in the past decade,metas...Metasurfaces,whose electromagnetic(EM)responses can be artificially designed,are two-dimensional arrays composed of subwavelength nanostructures.Accompanied by various fascinating developments in the past decade,metasurfaces have been proved as a powerful platform for the implementation of EM wave manipula-tion.However,the planar monoatomic metasurfaces widely used in previous works have limited design freedoms,resulting in some disadvantages for the realization of high-performance and new functional EM wave control.The latest developments show that few-layer metasurfaces and polyatomic metasurfaces are good alternatives to overcome the drawbacks of planar monoatomic metasurfaces and realize high-efficient,multi-band and broad-band EM functionalities.They provide additional degrees of design freedom via introducing multilayer layouts or combining multiple meta-atoms into a unit cell respectively.Here,recent advances of few-layer and polyatomic metasurfaces are reviewed.The design strategies,EM properties and main advantages of few-layer metasurfaces and polyatomic metasurfaces are overviewed firstly.Then,few-layer metasurfaces and polyatomic metasurfaces in recent progress for EM wave manipulation are classified and discussed from the viewpoint of their design strategy.At last,an outlook on future development trends and potential applications in these fast-developing research areas is presented.展开更多
基金This work was supported by the National Key Research and Development Program of China(2016YFA0301102 and 2017YFA0303800)the National Natural Science Fund for Distinguished Young Scholar(11925403)+2 种基金the National Natural Science Foundation of China(11974193,91856101,and 11774186)Natural Science Foundation of Tianjin for Distinguished Young Scientists(18JCJQJC45700)the China Postdoctoral Science Foundation(2020M680851).
文摘Artificial microstructures,which allow us to control and change the properties of wave fields through changing the geometrical parameters and the arrangements of microstructures,have attracted plenty of attentions in the past few decades.Some artificial microstructure based research areas,such as metamaterials,metasurfaces and phononic topological insulators,have seen numerous novel applications and phenomena.The manipulation of different dimensions(phase,amplitude,frequency or polarization)of wave fields,particularly,can be easily achieved at subwavelength scales by metasurfaces.In this review,we focus on the recent developments of wave field manipulations based on artificial microstructures and classify some important applications from the viewpoint of different dimensional manipulations of wave fields.The development tendency of wave field manipulation from single-dimension to multidimensions provides a useful guide for researchers to realize miniaturized and integrated optical and acoustic devices.
基金supported by the National Key Research and Development Program of China(Grant Nos.2021YFA1400601,and 2022YFA1404501)the National Natural Science Fund for Distinguished Young Scholar(Grant No.11925403)the National Natural Science Foundation of China(Grant Nos.12122406,12192253,12274239,12274237,and U22A20258)。
文摘Nonlinear metasurfaces and photonic crystals provide a significant way to generate and manipulate nonlinear signals owing to the resonance-and symmetry-based light-matter interactions supported by the artificial structures.However,the nonlinear conversion efficiency is generally limited by the angular dispersion of optical resonances especially in nonparaxial photonics.Here,we propose a metagrating realizing a quasi-bound-state in the continuum in a flat band to dramatically improve the third harmonic generation(THG)efficiency.A superior operating angular range is achieved based on the interlayer and intralayer couplings,which are introduced by breaking the mirror symmetry of the metagrating.We demonstrate the relation of angular dispersion between the nonlinear and linear responses at different incident angles.We also elucidate the mechanism of these offaxis flat-band-based nonlinear conversions through different mode decomposition.Our scheme provides a robust and analytical way for nonparaxial nonlinear generation and paves the way for further applications such as wide-angle nonlinear information transmission and enhanced nonlinear generation under tight focusing.
基金supported by the National Basic Research Program(973 Program)of China(2012CB921900)the Chinese National Key Basic Research Special Fund(2011CB922003)+3 种基金the Natural Science Foundation of China(11574163,61378006,11304163 and 91323304)the Program for New Century Excellent Talents in University(NCET-13-0294)the 111 project(B07013)the National Science Fund for Talent Training in Basic Sciences(J1103208).
文摘Optical activity is the rotation of the plane of linearly polarized light along the propagation direction as the light travels through optically active materials.In existing methods,the strength of the optical activity is determined by the chirality of the materials,which is difficult to control quantitatively.Here we numerically and experimentally investigated an alternative approach to realize and control the optical activity with non-chiral plasmonic metasurfaces.Through judicious design of the structural units of the metasurfaces,the right and left circular polarization components of the linearly polarized light have different phase retardations after transmitting through the metasurfaces,leading to large optical activity.Moreover,the strength of the optical activity can be easily and accurately tuned by directly adjusting the phase difference.The proposed approach based on non-chiral plasmonic metasurfaces exhibits large optical activity with a high controllable degree of freedom,which may provide more possibilities for applications in photonics.
基金supported by the National Key Research and Development Program of China(Grant Nos.2016YFA0301102,and 2017YFA0303800)the National Natural Science Fund for Distinguished Young Scholar(Grant No.11925403)+3 种基金the National Natural Science Foundation of China(Grant Nos.11974193,11904181,11904183,91856101,and 11774186)the Natural Science Foundation of Tianjin for Distinguished Young Scientists(Grant No.18JCJQJC45700)the National Postdoctoral Program for Innovative Talents(Grant No.BX20180148)the China Postdoctoral Science Foundation(Grant Nos.2018M640224,and 2018M640229)。
文摘Metasurfaces,which are planar arrays of subwavelength artificial structures,have emerged as excellent platforms for the integration and miniaturization of electromagnetic devices and provided ample possibilities for single-dimensional and multi-dimensional manipulations of electromagnetic waves.However,owing to the limited interactions between planar thin metallic nanostructures and electromagnetic waves as well as intrinsic losses in metals,metasurfaces exhibit disadvantages in terms of efficiency,controllability,and functionality.Recent advances in this field show that few-layer metasurfaces can overcome these drawbacks.Few-layer metasurfaces composed of more than one functional layer enable more degrees of design freedom.Hence,they possess unprecedented capabilities for electromagnetic wave manipulation,which have considerable impact in the area of nanophotonics.This article reviews recent advances in few-layer metasurfaces from the viewpoint of their scattering properties.The scattering matrix theory is briefly introduced,and the advantages and drawbacks of few-layer metasurfaces for the realization of arbitrary scattering properties are discussed.Then,a detailed overview of typical few-layer metasurfaces with various scattering properties and their design principles is provided.Finally,an outlook on the future directions and challenges in this promising research area is presented.
基金the Engineering and Physical Sciences Research Council(EP/P029892/1)the Leverhulme Trust(RPG-2021-145)the Royal Society International Exchanges(IES\R3\193046).
文摘Polarization as an important degree of freedom for light plays a key role in optics.Structured beams with controlled polarization profles have diverse applications,such as information encoding,display,medical and biological imaging,and manipulation of microparticles.However,conventional polarization optics can only realize two-dimensional polarization structures in a transverse plane.The emergent ultrathin optical devices consisting of planar nanostructures,so-called metasurfaces,have shown much promise for polarization manipulation.Here we propose and experimentally demonstrate color-selective three-dimensional(3D)polarization structures with a single metasurface.The geometric metasurfaces are designed based on color and phase multiplexing and polarization rotation,creating various 3D polarization knots.Remarkably,different 3D polarization knots in the same observation region can be achieved by controlling the incident wavelengths,providing unprecedented polarization control with color information in 3D space.Our research findings may be of interest to many practical applications such as vector beam generation,virtual reality,volumetric displays,security,and anti-counterfeiting.
文摘Metasurfaces are planar arrays composed of artificial nanostructures at the subwavelength scale.Since the first demonstration of their excellent capacity in the phase manipulation of optical waves,metasurfaces have attracted increasing attention in optics and other disciplines,with extraordinary progress over the past decade.The unique capabilities of metasurfaces in the multidimensional manipulation of optical waves have made them versatile and powerful platforms for integrating and minimizing optical devices[1,2].
基金supported by the National Key Research and Development Program of China(2016YFA0301102 and 2017YFA0303800)the National Natural Science Fund for Distinguished Young Scholars(11925403)+2 种基金the National Natural Science Foundation of China(11974193,91856101,11774186,and 21421001)the Natural Science Foundation of Tianjin for Distinguished Young Scientists(18JCJQJC45700)the Fundamental Research Funds for the Central Universities,Nankai University(63201005).
文摘A four-fold-degenerate three-dimensional(3D)Dirac point,represents a degenerate pair of Weyl points carrying opposite chiralities.Moreover,3D Dirac crystals have shown many exotic features different from those of Weyl crystals.How these features evolve from 3D Dirac to Weyl crystals is important in research on 3D topological matter.Here,we realized a pair of 3D acoustic Dirac points from band inversion in a hexagonal sonic crystal and observed the surface states and helical interface states connecting the Dirac points.Furthermore,each Dirac point can transition into a pair of Weyl points with the introduction of chiral hopping.The exotic features of the surface states and interface states are inherited by the resulting Weyl crystal.Our work may serve as an ideal platform for exploring exotic physical phenomena in 3D topological semimetals.
文摘Metasurfaces are ultrathin structured interfaces consisting of planar arrays of subwavelength artificial nanostructures, which emerge as excellent platforms for optical wave manipulation. Owing to their unprecedented capacities to manipulate the polarization, amplitude, phase and frequency of optical waves at the subwavelength scale, metasurfaces enable various novel optical functionalities that go beyond which can be attained from conventional optical elements.
基金supported by the National Key Research and Development Program of China(Grant No.2018FYA0305800)the National Natural Science Foundation of China(Grant Nos.11890701,11704128,11774275,11804101,11974005,and 11974120)+2 种基金the Guangdong Innovative and Entrepreneurial Research Team Program(Grant No.2016ZT06C594)the Guangdong Basic and Applied Basic Research Foundation(Grant No.2019B151502012)the Fundamental Research Funds for the Central Universities(Grant Nos.2018MS93,2019JQ07,and 2019ZD49)。
文摘The study of topological semimetals hosting spin-1 Weyl points(WPs)beyond Dirac points and WPs has attracted a great deal of attention.However,a spin-1 Weyl semimetal that exclusively possesses spin-1 WPs in a clean frequency window without being shadowed by any other nodal points is yet to be discovered.This study reports a spin-1 Weyl semimetal in a phononic crystal.Its spin-1 WPs are touched by two linear dispersions and an additional flat band and carry monopole charges(-2,0,2)or(2,0,-2)for the three bands from the bottom to the top.They result in double Fermi arcs,which occur between the first and second bands,as well as between the second and third bands.Further robust propagation is observed against the multiple joints and topological negative refraction of the acoustic surface arc wave.The results of this study create the basis for the exploration of the unusual properties of spin-1 Weyl physics on a macroscopic scale.
基金This work was supported by the National Key Research and Devel-opment Program of China(2017YFA0303800 and 2016YFA0301102)the National Natural Science Fund for Distinguished Young Scholar(11925403)+2 种基金the National Natural Science Foundation of China(11974193,11904181,11904183,91856101,and 11774186)Natu-ral Science Foundation of Tianjin for Distinguished Young Scientists(18JCJQJC45700)and the China Postdoctoral Science Foundation(2018M640224 and 2021M690084).
文摘Metasurfaces,whose electromagnetic(EM)responses can be artificially designed,are two-dimensional arrays composed of subwavelength nanostructures.Accompanied by various fascinating developments in the past decade,metasurfaces have been proved as a powerful platform for the implementation of EM wave manipula-tion.However,the planar monoatomic metasurfaces widely used in previous works have limited design freedoms,resulting in some disadvantages for the realization of high-performance and new functional EM wave control.The latest developments show that few-layer metasurfaces and polyatomic metasurfaces are good alternatives to overcome the drawbacks of planar monoatomic metasurfaces and realize high-efficient,multi-band and broad-band EM functionalities.They provide additional degrees of design freedom via introducing multilayer layouts or combining multiple meta-atoms into a unit cell respectively.Here,recent advances of few-layer and polyatomic metasurfaces are reviewed.The design strategies,EM properties and main advantages of few-layer metasurfaces and polyatomic metasurfaces are overviewed firstly.Then,few-layer metasurfaces and polyatomic metasurfaces in recent progress for EM wave manipulation are classified and discussed from the viewpoint of their design strategy.At last,an outlook on future development trends and potential applications in these fast-developing research areas is presented.