Innovations in artificial intelligence have revolutionized various areas,especially optics.The rapid development of novel optoelectronic devices at nanoscale has exhibited the multiple functionalities,high integration...Innovations in artificial intelligence have revolutionized various areas,especially optics.The rapid development of novel optoelectronic devices at nanoscale has exhibited the multiple functionalities,high integration,compactness,fast modulation and scalability,showcasing new breakthroughs of digital optics and optoelectronic processors for intelligent computations.展开更多
Electromagnetic wave multiplexing,especially for that occurring at different incidences(spatial-frequency multiplexing),is pivotal for ultrathin multifunctional interfaces and high-capacity information processing and ...Electromagnetic wave multiplexing,especially for that occurring at different incidences(spatial-frequency multiplexing),is pivotal for ultrathin multifunctional interfaces and high-capacity information processing and communication.It is yet extremely challenging based on passive and compact wave elements,since the wave excitation and scattering channels are exclusively coupled through gradient phases and hence momentum matching condition at the interface.Here,we propose a spin-momentum multiplexed paradigm called a super-reflector enabling on-demand control of both retroreflections and anomalous reflections using a non-interleaved single-celled metasurface.By multiplexing four channels connecting two spin states excited onto each input of three spatial frequencies,a total of twelve channels are engineered,among which three are retroreflected channels and the residual are anomalous reflection ones.Our compound multiplexed super-reflector allows five degrees of freedom in circular polarization Jones'matrix,approaching the intrinsic upper limit of such planar metasurface.The concept has been experimentally verified by a proof-of-concept super-reflector at microwave frequency,showcasing twelve reflected beams and a high efficiency exceeding 90.6%defined as the ratio of reflected power to incidence for each channel beam.Our strategy opens a new avenue for angle multiplexing and angle-resolved metadevices toward the capacity limit of 2D planar Jones'matrix.展开更多
Microlens arrays(MLAs)based on the selective wetting have opened new avenues for developing compact and miniaturized imaging and display techniques with ultrahigh resolution beyond the traditional bulky and volumetric...Microlens arrays(MLAs)based on the selective wetting have opened new avenues for developing compact and miniaturized imaging and display techniques with ultrahigh resolution beyond the traditional bulky and volumetric optics.However,the selective wetting lenses explored so far have been constrained by the lack of precisely defined pattern for highly controllable wettability contrast,thus limiting the available droplet curvature and numerical aperture,which is a major challenge towards the practical high-performance MLAs.Here we report a mold-free and self-assembly approach of mass-production of scalable MLAs,which can also have ultrasmooth surface,ultrahigh resolution,and the large tuning range of the curvatures.The selective surface modification based on tunable oxygen plasma can facilitate the precise pattern with adjusted chemical contrast,thus creating large-scale microdroplets array with controlled curvature.The numerical aperture of the MLAs can be up to 0.26 and precisely tuned by adjusting the modification intensity or the droplet dose.The fabricated MLAs have high-quality surface with subnanometer roughness and allow for record-high resolution imaging up to equivalently 10,328 ppi,as we demonstrated.This study shows a cost-effective roadmap for mass-production of high-performance MLAs,which may find applications in the rapid proliferating integral imaging industry and high-resolution display.展开更多
Achieving simultaneous polarization and wavefront control,especially circular polarization with the auxiliary degree of freedom of light and spin angular momentum,is of fundamental importance in many optical applicati...Achieving simultaneous polarization and wavefront control,especially circular polarization with the auxiliary degree of freedom of light and spin angular momentum,is of fundamental importance in many optical applications.Interferences are typically undesirable in highly integrated photonic circuits and metasurfaces.Here,we propose an interference-assisted metasurface-multiplexer(meta-plexer)that counterintuitively exploits constructive and destructive interferences between hybrid meta-atoms and realizes independent spin-selective wavefront manipulation.Such kaleidoscopic meta-plexers are experimentally demonstrated via two types of single-layer spinwavefront multiplexers that are composed of spatially rotated anisotropic meta-atoms.One type generates a spinselective Bessel-beam wavefront for spin-down light and a low scattering cross-section for stealth for spin-up light.The other type demonstrates versatile control of the vortex wavefront,which is also characterized by the orbital angular momentum of light,with frequency-switchable numbers of beams under linearly polarized wave excitation.Our findings offer a distinct interference-assisted concept for realizing advanced multifunctional photonics with arbitrary and independent spin-wavefront features.A variety of applications can be readily anticipated in optical diodes,isolators,and spin-Hall meta-devices without cascading bulky optical elements.展开更多
With the rapid progress in computer science,including artificial intelligence,big data and cloud computing,full-space spot generation can be pivotal to many practical applications,such as facial recognition,motion det...With the rapid progress in computer science,including artificial intelligence,big data and cloud computing,full-space spot generation can be pivotal to many practical applications,such as facial recognition,motion detection,augmented reality,etc.These opportunities may be achieved by using diffractive optical elements(DOEs)or light detection and ranging(LIDAR).However,DOEs suffer from intrinsic limitations,such as demanding depth-controlled fabrication techniques,large thicknesses(more than the wavelength),Lambertian operation only in half space,etc.LIDAR nevertheless relies on complex and bulky scanning systems,which hinders the miniaturization of the spot generator.Here,inspired by a Lambertian scatterer,we report a Hermitian-conjugate metasurface scrambling the incident light to a cloud of random points in full space with compressed information density,functioning in both transmission and reflection spaces.Over 4044 random spots are experimentally observed in the entire space,covering angles at nearly 90°.Our scrambling metasurface is made of amorphous silicon with a uniform subwavelength height,a nearly continuous phase coverage,a lightweight,flexible design,and low-heat dissipation.Thus,it may be mass produced by and integrated into existing semiconductor foundry designs.Our work opens important directions for emerging 3D recognition sensors,such as motion sensing,facial recognition,and other applications.展开更多
Cylindrical vector beams(CVBs),which possess polarization distribution of rotational symmetry on the transverse plane,can be developed in many optical technologies.Conventional methods to generate CVBs contain redunda...Cylindrical vector beams(CVBs),which possess polarization distribution of rotational symmetry on the transverse plane,can be developed in many optical technologies.Conventional methods to generate CVBs contain redundant interferometers or need to switch among diverse elements,thus being inconvenient in applications containing multiple CVBs.Here we provide a passive polarization-selective device to substitute interferometers and simplify generation setup.It is accomplished by reversing topological charges of orbital angular momentum based on a polarization-selective Gouy phase.In the process,tunable input light is the only condition to generate a CVB with arbitrary topological charges.To cover both azimuthal and radial parameters of CVBs,we express the mapping between scalar Laguerre–Gaussian light on a basic Poincaré sphere and CVB on a high-order Poincaré sphere.The proposed device simplifies the generation of CVBs enormously and thus has potential in integrated devices for both quantum and classic optical experiments.展开更多
The growing demand for tailored nonlinearity calls for a structure with unusual phase discontinuity that allows the realization of nonlinear optical chirality,holographic imaging,and nonlinear wavefront control.Transi...The growing demand for tailored nonlinearity calls for a structure with unusual phase discontinuity that allows the realization of nonlinear optical chirality,holographic imaging,and nonlinear wavefront control.Transition-metal dichalcogenide(TMDC)monolayers offer giant optical nonlinearity within a few-angstrom thickness,but limitations in optical absorption and domain size impose restriction on wavefront control of nonlinear emissions using classical light sources.In contrast,noble metal-based plasmonic nanosieves support giant field enhancements and precise nonlinear phase control,with hundred-nanometer pixellevel resolution;however,they suffer from intrinsically weak nonlinear susceptibility.Here,we report a multifunctional nonlinear interface by integrating TMDC monolayers with plasmonic nanosieves,yielding drastically different nonlinear functionalities that cannot be accessed by either constituent.Such a hybrid nonlinear interface allows second-harmonic(SH)orbital angular momentum(OAM)generation,beam steering,versatile polarization control,and holograms,with an effective SH nonlinearityχ^((2))of~25 nm/V.This designer platform synergizes the TMDC monolayer and plasmonic nanosieves to empower tunable geometric phases and large field enhancement,paving the way toward multifunctional and ultracompact nonlinear optical devices.展开更多
Electromagnetic metasurface cloaks provide an alternative paradigm toward rendering arbitrarily shaped scatterers invisible.Most transformation-optics(TO)cloaks intrinsically need wavelength-scale volume/thickness,suc...Electromagnetic metasurface cloaks provide an alternative paradigm toward rendering arbitrarily shaped scatterers invisible.Most transformation-optics(TO)cloaks intrinsically need wavelength-scale volume/thickness,such that the incoming waves could have enough long paths to interact with structured meta-atoms in the cloak region and consequently restore the wavefront.Other challenges of TO cloaks include the polarization-dependent operation to avoid singular parameters of composite cloaking materials and limitations of canonical geometries,e.g.,circular,elliptical,trapezoidal,and triangular shapes.Here,we report for the first time a conformal-skin metasurface carpet cloak,enabling to work under arbitrary states of polarization(SOP)at Poincarésphere for the incident light and arbitrary conformal platform of the object to be cloaked.By exploiting the foundry three-dimensional(3D)printing techniques to fabricate judiciously designed meta-atoms on the external surface of a conformal object,the spatial distributions of intensity and polarization of its scattered lights can be reconstructed exactly the same as if the scattering wavefront were deflected from a flat ground at any SOP,concealing targets under polarization-scanning detections.Two conformal-skin carpet cloaks working for partial-and full-azimuth plane operation are respectively fabricated on trapezoid and pyramid platforms via 3D printing.Experimental results are in good agreement with numerical simulations and both demonstrate the polarization-insensitive cloaking within a desirable bandwidth.Our approach paves a deterministic and robust step forward to the realization of interfacial,free-form,and full-polarization cloaking for a realistic arbitrary-shape target in real-world applications.展开更多
Optical metamaterials have presented an innovative method of manipulating light.Hyperbolic metamaterials have an extremely high anisotropy with a hyperbolic dispersion relation.They are able to support high-k modes an...Optical metamaterials have presented an innovative method of manipulating light.Hyperbolic metamaterials have an extremely high anisotropy with a hyperbolic dispersion relation.They are able to support high-k modes and exhibit a high density of states which produce distinctive properties that have been exploited in various applications,such as super-resolution imaging,negative refraction,and enhanced emission control.Here,state-of-the-art hyperbolic metamaterials are reviewed,starting from the fundamental principles to applications of artificially structured hyperbolic media to suggest ways to fuse natural two-dimensional hyperbolic materials.The review concludes by indicating the current challenges and our vision for future applications of hyperbolic metamaterials.展开更多
Nanophotonic platforms such as metasurfaces,achieving arbitrary phase profiles within ultrathin thickness,emerge as miniaturized,ultracompact and kaleidoscopic optical vortex generators.However,it is often required to...Nanophotonic platforms such as metasurfaces,achieving arbitrary phase profiles within ultrathin thickness,emerge as miniaturized,ultracompact and kaleidoscopic optical vortex generators.However,it is often required to segment or interleave independent sub-array metasurfaces to multiplex optical vortices in a single nano-device,which in turn affects the device’s compactness and channel capacity.Here,inspired by phyllotaxis patterns in pine cones and sunflowers,we theoretically prove and experimentally report that multiple optical vortices can be produced in a single compact phyllotaxis nanosieve,both in free space and on a chip,where one meta-atom may contribute to many vortices simultaneously.The time-resolved dynamics of on-chip interference wavefronts between multiple plasmonic vortices was revealed by ultrafast time-resolved photoemission electron microscopy.Our nature-inspired optical vortex generator would facilitate various vortex-related optical applications,including structured wavefront shaping,free-space and plasmonic vortices,and high-capacity information metaphotonics.展开更多
The topological features of optical vortices have been opening opportunities for free-space and on-chip photonic technologies,e.g.,for multiplexed optical communications and robust information transport.In a parallel ...The topological features of optical vortices have been opening opportunities for free-space and on-chip photonic technologies,e.g.,for multiplexed optical communications and robust information transport.In a parallel but disjoint effort,polar anisotropic van der Waals nanomaterials supporting hyperbolic phonon polaritons(HP2s)have been leveraged to drastically boost light-matter interactions.So far HP2 studies have been mainly focusing on the control of their amplitude and scale features.Here we report the generation and observation of mid-infrared hyperbolic polariton vortices(HP2Vs)associated with reconfigurable topological charges.Spiral-shaped gold disks coated with a flake of hexagonal boron nitride are exploited to tailor spin-orbit interactions and realise deeply subwavelength HP2Vs.The complex interplay between excitation spin,spiral geometry and HP2 dispersion enables robust reconfigurability of the associated topological charges.Our results reveal unique opportunities to extend the application of HP2s into topological photonics,quantum information processing by integrating these phenomena with single-photon emitters,robust on-chip optical applications,sensing and nanoparticle manipulation.展开更多
Let be a non-normal cubic extension over Q.We study the higher moment of the coefficients aK3(n)of Dedckind zeta function over sum of two squares∑n21+n22≤xa1K3(n21+n22),where 2≤l≤8 and n1,n2,l∈Z.
Transformation optics(TO)facilitates flexible designs of spatial modulation of optical materials via coordinate transformations,thus,enabling on-demand manipulations of electromagnetic waves.However,the application of...Transformation optics(TO)facilitates flexible designs of spatial modulation of optical materials via coordinate transformations,thus,enabling on-demand manipulations of electromagnetic waves.However,the application of TO theory in control of hyperbolic waves remains elusive due to the spatial metric signature transition from(+,+)to(−,+)of a two-dimensional hyperbolic geometry.Here,we proposed a distinct Pythagorean theorem,which leads to establishing an anisotropic Fermat’s principle.It helps to construct anisotropic geometries and is a powerful tool for manipulating hyperbolic waves at the nanoscale and polaritons.Making use of absolute instruments,the excellent collimating and focusing behaviors of naturally in-plane hyperbolic polaritons in van der Waals𝛼α–MoO_(3)layers are demonstrated,which opens up a new way for polaritons manipulation.展开更多
Recently studied bound states in the continuum(BICs) enable perfect localization of light and enhance light–matter interactions although systems are optically open. They have found applications in numerous areas,incl...Recently studied bound states in the continuum(BICs) enable perfect localization of light and enhance light–matter interactions although systems are optically open. They have found applications in numerous areas,including optical nonlinearity, light emitters, and nano-sensors. However, their unidirectional nature in nonreciprocal devices is still elusive because such trapping states are easily destroyed when the symmetry of an optical system is broken. Herein, we propose nonreciprocal and dynamically tunable BICs for unidirectional confinement of light and symmetry-protected BICs at Γ-point by introducing antiparallel magnetism into the optical system. We demonstrate that such BICs can be achieved by using topological magnetic Weyl semimetals near zero-index frequency without any structural asymmetry, and are largely tunable via modifying the Fermi level.Our results reveal a regime of extreme light manipulation and interaction with emerging quantum materials for various practical applications.展开更多
Many real-world applications,including adaptive radar scanning and smart stealth,require reconfigurable multifunctional devices to simultaneously manipulate multiple degrees of freedom of electromagnetic(EM)waves in a...Many real-world applications,including adaptive radar scanning and smart stealth,require reconfigurable multifunctional devices to simultaneously manipulate multiple degrees of freedom of electromagnetic(EM)waves in an on-demand manner.Recently,kirigami technique,affording versatile and unconventional structural transformation,has been introduced to endow metamaterials with the capability of controlling EM waves in a reconfigurable manner.Here,we report for a kirigami-inspired sparse meta-architecture,with structural density of 1.5%in terms of the occupation space,for adaptive invisibility based on independent operations of frequency,bandwidth,and amplitude.Based on the general principle of dipolar management via structural reconstruction of kirigami-inspired meta-architectures,we demonstrate reconfigurable invisibility management with abundant EM functions and a wide tuning range using three enantiomers(A,B,and C)of different geometries characterized by the folding angleβ.Our strategy circumvents issues of limited abilities,narrow tuning range,extreme condition,and high cost raised by available reconfigurable metamaterials,providing a new avenue toward multifunctional smart devices.展开更多
Many real-world applications,including adaptive radar scanning and smart stealth,require reconfigurable multifunctional devices to simultaneously manipulate multiple degrees of freedom of electromagnetic(EM)waves in a...Many real-world applications,including adaptive radar scanning and smart stealth,require reconfigurable multifunctional devices to simultaneously manipulate multiple degrees of freedom of electromagnetic(EM)waves in an on-demand manner.Recently,kirigami technique,affording versatile and unconventional structural transformation,has been introduced to endow metamaterials with the capability of controlling EM waves in a reconfigurable manner.Here,we report for a kirigami-inspired sparse meta-architecture,with structural density of 1.5%in terms of the occupation space,for adaptive invisibility based on independent operations of frequency,bandwidth,and amplitude.Based on the general principle of dipolar management via structural reconstruction of kirigami-inspired meta-architectures,we demonstrate reconfigurable invisibility management with abundant EM functions and a wide tuning range using three enantiomers(A,B,and C)of different geometries characterized by the folding angleβ.Our strategy circumvents issues of limited abilities,narrow tuning range,extreme condition,and high cost raised by available reconfigurable metamaterials,providing a new avenue toward multifunctional smart devices.展开更多
Various theories have been proposed to account for second language production and the systematic variation characteristic of such production.Most of these theories,however,constitute only partial explanations because ...Various theories have been proposed to account for second language production and the systematic variation characteristic of such production.Most of these theories,however,constitute only partial explanations because they often fail to handle mixed empirical findings about factors held to affect second language output and underlie systematic variation.This paper proposes a new theoretical framework for posing and addressing research questions about second language production in general and systematic variation in particular.Building on influential cognitive models of second language learning and use,the theoretical framework comprises three cognitive dimensions,viz.knowledge representation,attentional focus,and processing automaticity,which interact with each other.The theoretical framework is justified by drawing on the cognitive literature and cumulative findings from second language acquisition(SLA)research.The paper also outlines possible applications of the framework to issues of interest to SLA researchers working on a number of different fronts.展开更多
文摘Innovations in artificial intelligence have revolutionized various areas,especially optics.The rapid development of novel optoelectronic devices at nanoscale has exhibited the multiple functionalities,high integration,compactness,fast modulation and scalability,showcasing new breakthroughs of digital optics and optoelectronic processors for intelligent computations.
基金supported by the National Natural Science Foundation of China under Grant No.62171459the National Defense Foundation of China under Grant No.2019-JCJQ-JJ-081Key Program of Natural Science Foundation of Shaanxi Province under Grant No.2020JZ-33,and also the Special Talents Support Program of Shaanxi Province for Young Top Talents.
文摘Electromagnetic wave multiplexing,especially for that occurring at different incidences(spatial-frequency multiplexing),is pivotal for ultrathin multifunctional interfaces and high-capacity information processing and communication.It is yet extremely challenging based on passive and compact wave elements,since the wave excitation and scattering channels are exclusively coupled through gradient phases and hence momentum matching condition at the interface.Here,we propose a spin-momentum multiplexed paradigm called a super-reflector enabling on-demand control of both retroreflections and anomalous reflections using a non-interleaved single-celled metasurface.By multiplexing four channels connecting two spin states excited onto each input of three spatial frequencies,a total of twelve channels are engineered,among which three are retroreflected channels and the residual are anomalous reflection ones.Our compound multiplexed super-reflector allows five degrees of freedom in circular polarization Jones'matrix,approaching the intrinsic upper limit of such planar metasurface.The concept has been experimentally verified by a proof-of-concept super-reflector at microwave frequency,showcasing twelve reflected beams and a high efficiency exceeding 90.6%defined as the ratio of reflected power to incidence for each channel beam.Our strategy opens a new avenue for angle multiplexing and angle-resolved metadevices toward the capacity limit of 2D planar Jones'matrix.
基金support from National Key R&D Program of China(2021YFB3600602,zcgx2022002L)National Natural Science Foundation of China(52175403 and 61805087)+4 种基金Natural Science Foundation of Guangdong Province(2021A1515010623)Special Program on Key Fields for Colleges and Universities of Guangdong Province(2021ZDZX1048)Science and Technology Program of Guangzhou(202102020604)Guangdong Provincial Key Laboratory of Optical Information Materials and Technology(2017B030301007)MOE International Laboratory for Optical Information Technologies,and the 111 Project.G.H acknowledges the NTU Start-up Grant.
文摘Microlens arrays(MLAs)based on the selective wetting have opened new avenues for developing compact and miniaturized imaging and display techniques with ultrahigh resolution beyond the traditional bulky and volumetric optics.However,the selective wetting lenses explored so far have been constrained by the lack of precisely defined pattern for highly controllable wettability contrast,thus limiting the available droplet curvature and numerical aperture,which is a major challenge towards the practical high-performance MLAs.Here we report a mold-free and self-assembly approach of mass-production of scalable MLAs,which can also have ultrasmooth surface,ultrahigh resolution,and the large tuning range of the curvatures.The selective surface modification based on tunable oxygen plasma can facilitate the precise pattern with adjusted chemical contrast,thus creating large-scale microdroplets array with controlled curvature.The numerical aperture of the MLAs can be up to 0.26 and precisely tuned by adjusting the modification intensity or the droplet dose.The fabricated MLAs have high-quality surface with subnanometer roughness and allow for record-high resolution imaging up to equivalently 10,328 ppi,as we demonstrated.This study shows a cost-effective roadmap for mass-production of high-performance MLAs,which may find applications in the rapid proliferating integral imaging industry and high-resolution display.
基金supported by the National Natural Science Foundation of China(61501499,11634010)Youth Talent Lifting Project of the China Association for Science and Technology(17-JCJQ-QT-003)+7 种基金National Defense Foundation of China(2201078)Key Program of Natural Science Foundation of Shaanxi Province(2017KJXX-24)China Scholarship Fund(201703170022)Aviation Science Foundation of China(20161996009)supports from the National Natural Science Foundation of China(61631007 and 61571117)the National Key Research and Development Program of China(2017YFA0700201,2017YFA0700202,2017YFA0700201)the 111 Project(111-2-05)the financial support from the National Research Foundation,Prime Minister’s Office,Singapore under its Competitive Research Program(CRP award NRF-CRP15-2015-03).
文摘Achieving simultaneous polarization and wavefront control,especially circular polarization with the auxiliary degree of freedom of light and spin angular momentum,is of fundamental importance in many optical applications.Interferences are typically undesirable in highly integrated photonic circuits and metasurfaces.Here,we propose an interference-assisted metasurface-multiplexer(meta-plexer)that counterintuitively exploits constructive and destructive interferences between hybrid meta-atoms and realizes independent spin-selective wavefront manipulation.Such kaleidoscopic meta-plexers are experimentally demonstrated via two types of single-layer spinwavefront multiplexers that are composed of spatially rotated anisotropic meta-atoms.One type generates a spinselective Bessel-beam wavefront for spin-down light and a low scattering cross-section for stealth for spin-up light.The other type demonstrates versatile control of the vortex wavefront,which is also characterized by the orbital angular momentum of light,with frequency-switchable numbers of beams under linearly polarized wave excitation.Our findings offer a distinct interference-assisted concept for realizing advanced multifunctional photonics with arbitrary and independent spin-wavefront features.A variety of applications can be readily anticipated in optical diodes,isolators,and spin-Hall meta-devices without cascading bulky optical elements.
基金supports from the National Natural Science Foundation of China(Numbers 11574240 and 11774273)the Outstanding Youth Funds of Hubei Province(Number 2016CFA034)+4 种基金the Open Foundation of State Key Laboratory of Optical Communication Technologies and Networks,Wuhan Research Institute of Posts and Telecommunications(Number OCTN-201605)the financial supports from the Postdoctoral Innovation Talent Support Program of China(BX20180221)the Global Ph.D.fellowship from the Korean government(NRF-2016H1A2A1906519)the financial support from the National Research Foundation(NRF)grants(NRF-2017R1E1A1A03070501,NRF-2017R1E1A2A01076613,NRF-2018M3D1A1058998,NRF-2015R1A5A1037668,and CAMM-2014M3A6B3063708)funded by the Ministry of Science and ICT(MSIT)of the Korean governmentthe financial support from the National Research Foundation,Prime Minister’s Office,Singapore under its Competitive Research Program(CRP award NRF CRP15-2015-03).
文摘With the rapid progress in computer science,including artificial intelligence,big data and cloud computing,full-space spot generation can be pivotal to many practical applications,such as facial recognition,motion detection,augmented reality,etc.These opportunities may be achieved by using diffractive optical elements(DOEs)or light detection and ranging(LIDAR).However,DOEs suffer from intrinsic limitations,such as demanding depth-controlled fabrication techniques,large thicknesses(more than the wavelength),Lambertian operation only in half space,etc.LIDAR nevertheless relies on complex and bulky scanning systems,which hinders the miniaturization of the spot generator.Here,inspired by a Lambertian scatterer,we report a Hermitian-conjugate metasurface scrambling the incident light to a cloud of random points in full space with compressed information density,functioning in both transmission and reflection spaces.Over 4044 random spots are experimentally observed in the entire space,covering angles at nearly 90°.Our scrambling metasurface is made of amorphous silicon with a uniform subwavelength height,a nearly continuous phase coverage,a lightweight,flexible design,and low-heat dissipation.Thus,it may be mass produced by and integrated into existing semiconductor foundry designs.Our work opens important directions for emerging 3D recognition sensors,such as motion sensing,facial recognition,and other applications.
基金National Natural Science Foundation of China(11534008,11804271,11974345,91736104).
文摘Cylindrical vector beams(CVBs),which possess polarization distribution of rotational symmetry on the transverse plane,can be developed in many optical technologies.Conventional methods to generate CVBs contain redundant interferometers or need to switch among diverse elements,thus being inconvenient in applications containing multiple CVBs.Here we provide a passive polarization-selective device to substitute interferometers and simplify generation setup.It is accomplished by reversing topological charges of orbital angular momentum based on a polarization-selective Gouy phase.In the process,tunable input light is the only condition to generate a CVB with arbitrary topological charges.To cover both azimuthal and radial parameters of CVBs,we express the mapping between scalar Laguerre–Gaussian light on a basic Poincaré sphere and CVB on a high-order Poincaré sphere.The proposed device simplifies the generation of CVBs enormously and thus has potential in integrated devices for both quantum and classic optical experiments.
基金This work was supported by the National Natural Science Foundation of China(nos.91850113 and 11774115)the 973 Programs under grant 2014CB921301+3 种基金the Fundamental Research Funds for the Central Universities(2019kfyRCPY105)the Air Force Office of Scientific Research,and the Defense Advanced Research Projects AgencyC.-W.Q.acknowledges financial support from A*STAR Pharos Program(grant number 1527000014,with project number R-263-000-B91-305)the National Research Foundation,Prime Minister’s Office,Singapore,under its Competitive Research Program(CRP award number NRFCRP 15-2015-03).
文摘The growing demand for tailored nonlinearity calls for a structure with unusual phase discontinuity that allows the realization of nonlinear optical chirality,holographic imaging,and nonlinear wavefront control.Transition-metal dichalcogenide(TMDC)monolayers offer giant optical nonlinearity within a few-angstrom thickness,but limitations in optical absorption and domain size impose restriction on wavefront control of nonlinear emissions using classical light sources.In contrast,noble metal-based plasmonic nanosieves support giant field enhancements and precise nonlinear phase control,with hundred-nanometer pixellevel resolution;however,they suffer from intrinsically weak nonlinear susceptibility.Here,we report a multifunctional nonlinear interface by integrating TMDC monolayers with plasmonic nanosieves,yielding drastically different nonlinear functionalities that cannot be accessed by either constituent.Such a hybrid nonlinear interface allows second-harmonic(SH)orbital angular momentum(OAM)generation,beam steering,versatile polarization control,and holograms,with an effective SH nonlinearityχ^((2))of~25 nm/V.This designer platform synergizes the TMDC monolayer and plasmonic nanosieves to empower tunable geometric phases and large field enhancement,paving the way toward multifunctional and ultracompact nonlinear optical devices.
基金This work was supported by the National Defense Foundation of China(2019-JCJQ-JJ-081)the Youth Talent Lifting Project of the China Association for Science and Technology(17-JCJQ-QT-003)+3 种基金the Key Program of Natural Science Foundation of Shaanxi Province(2020JZ-33)the Key Principal’s Fund of Air Force Engineering University(XNLX19030601)the National Key Research and Development Program of China(2017YFA0700202)the National Natural Science Foundation of China(61701082).
文摘Electromagnetic metasurface cloaks provide an alternative paradigm toward rendering arbitrarily shaped scatterers invisible.Most transformation-optics(TO)cloaks intrinsically need wavelength-scale volume/thickness,such that the incoming waves could have enough long paths to interact with structured meta-atoms in the cloak region and consequently restore the wavefront.Other challenges of TO cloaks include the polarization-dependent operation to avoid singular parameters of composite cloaking materials and limitations of canonical geometries,e.g.,circular,elliptical,trapezoidal,and triangular shapes.Here,we report for the first time a conformal-skin metasurface carpet cloak,enabling to work under arbitrary states of polarization(SOP)at Poincarésphere for the incident light and arbitrary conformal platform of the object to be cloaked.By exploiting the foundry three-dimensional(3D)printing techniques to fabricate judiciously designed meta-atoms on the external surface of a conformal object,the spatial distributions of intensity and polarization of its scattered lights can be reconstructed exactly the same as if the scattering wavefront were deflected from a flat ground at any SOP,concealing targets under polarization-scanning detections.Two conformal-skin carpet cloaks working for partial-and full-azimuth plane operation are respectively fabricated on trapezoid and pyramid platforms via 3D printing.Experimental results are in good agreement with numerical simulations and both demonstrate the polarization-insensitive cloaking within a desirable bandwidth.Our approach paves a deterministic and robust step forward to the realization of interfacial,free-form,and full-polarization cloaking for a realistic arbitrary-shape target in real-world applications.
基金POSCO-POSTECH-RIST Convergence Research Center program funded by POSCOPOSTECH-Samsung Semiconductor Research Center(IO201215-08187-01)funded by Samsung ElectronicsNational Research Foundation(NRF)grant(NRF-2019R1A2C3003129)funded by the Ministry of Science and ICT,Republic of Korea.
文摘Optical metamaterials have presented an innovative method of manipulating light.Hyperbolic metamaterials have an extremely high anisotropy with a hyperbolic dispersion relation.They are able to support high-k modes and exhibit a high density of states which produce distinctive properties that have been exploited in various applications,such as super-resolution imaging,negative refraction,and enhanced emission control.Here,state-of-the-art hyperbolic metamaterials are reviewed,starting from the fundamental principles to applications of artificially structured hyperbolic media to suggest ways to fuse natural two-dimensional hyperbolic materials.The review concludes by indicating the current challenges and our vision for future applications of hyperbolic metamaterials.
基金supported by the National Research Foundation,Prime Minister’s Office,Singapore under Competitive Research Program Award NRF-CRP22-2019-0006the grant(R-261-518-004-720)from Advanced Research and Technology Innovation Centre(ARTIC)+4 种基金the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)-Project-ID 278162697-SFB 1242ERC Advanced Grant Complex Plan,BMBF,DFG and BW-Stiftungthe Research Grants Council of Hong Kong(CRF Grant No.C6013-18G)the City University of Hong Kong(Project No.9610434)the support from A*STAR under its AME YIRG Grant(Award No.A2084c0172).
文摘Nanophotonic platforms such as metasurfaces,achieving arbitrary phase profiles within ultrathin thickness,emerge as miniaturized,ultracompact and kaleidoscopic optical vortex generators.However,it is often required to segment or interleave independent sub-array metasurfaces to multiplex optical vortices in a single nano-device,which in turn affects the device’s compactness and channel capacity.Here,inspired by phyllotaxis patterns in pine cones and sunflowers,we theoretically prove and experimentally report that multiple optical vortices can be produced in a single compact phyllotaxis nanosieve,both in free space and on a chip,where one meta-atom may contribute to many vortices simultaneously.The time-resolved dynamics of on-chip interference wavefronts between multiple plasmonic vortices was revealed by ultrafast time-resolved photoemission electron microscopy.Our nature-inspired optical vortex generator would facilitate various vortex-related optical applications,including structured wavefront shaping,free-space and plasmonic vortices,and high-capacity information metaphotonics.
基金Office of Naval Research(Grant No.N00014-19-1-2011)Vannevar Bush Faculty Fellowship,Air Force Office of Scientific Research MURI program,A*STAR AME Young Individual Research Grant(YIRG,No.A2084c0172)+4 种基金National Research Foundation Singapore(CRP22-2019-0006)Advanced Research and Technology Innovation Centre(No.R-261-518-004-720)National Science Foundation under Grant No.2044281Elemental Strategy Initiative conducted by MEXT,Japan,Grant Number JPMXP0112101001JSPS KAKENHI Grant Number JP20H00354。
文摘The topological features of optical vortices have been opening opportunities for free-space and on-chip photonic technologies,e.g.,for multiplexed optical communications and robust information transport.In a parallel but disjoint effort,polar anisotropic van der Waals nanomaterials supporting hyperbolic phonon polaritons(HP2s)have been leveraged to drastically boost light-matter interactions.So far HP2 studies have been mainly focusing on the control of their amplitude and scale features.Here we report the generation and observation of mid-infrared hyperbolic polariton vortices(HP2Vs)associated with reconfigurable topological charges.Spiral-shaped gold disks coated with a flake of hexagonal boron nitride are exploited to tailor spin-orbit interactions and realise deeply subwavelength HP2Vs.The complex interplay between excitation spin,spiral geometry and HP2 dispersion enables robust reconfigurability of the associated topological charges.Our results reveal unique opportunities to extend the application of HP2s into topological photonics,quantum information processing by integrating these phenomena with single-photon emitters,robust on-chip optical applications,sensing and nanoparticle manipulation.
基金the National Natural Science Foundation of China(Grant Nos.11771252,11531008).
文摘Let be a non-normal cubic extension over Q.We study the higher moment of the coefficients aK3(n)of Dedckind zeta function over sum of two squares∑n21+n22≤xa1K3(n21+n22),where 2≤l≤8 and n1,n2,l∈Z.
基金National Natural Science Foundation of China(92050102,11874311)National Key Research and Development Program of China(2020YFA0710100)+3 种基金Fundamental Research Funds for the Central Universities(20720220033,20720200074,20720220134)Shenzhen Science and Technology Program(JCYJ20210324121610028)China Scholarship Council(201906310019)Advanced Research and Technology Innovation Centre(ARTIC),National University of Singapore(A-0005947-16-00).
文摘Transformation optics(TO)facilitates flexible designs of spatial modulation of optical materials via coordinate transformations,thus,enabling on-demand manipulations of electromagnetic waves.However,the application of TO theory in control of hyperbolic waves remains elusive due to the spatial metric signature transition from(+,+)to(−,+)of a two-dimensional hyperbolic geometry.Here,we proposed a distinct Pythagorean theorem,which leads to establishing an anisotropic Fermat’s principle.It helps to construct anisotropic geometries and is a powerful tool for manipulating hyperbolic waves at the nanoscale and polaritons.Making use of absolute instruments,the excellent collimating and focusing behaviors of naturally in-plane hyperbolic polaritons in van der Waals𝛼α–MoO_(3)layers are demonstrated,which opens up a new way for polaritons manipulation.
基金National Natural Science Foundation of China(61922005,U1930105)Agency for Science,Technology and Research(1527000014)。
文摘Recently studied bound states in the continuum(BICs) enable perfect localization of light and enhance light–matter interactions although systems are optically open. They have found applications in numerous areas,including optical nonlinearity, light emitters, and nano-sensors. However, their unidirectional nature in nonreciprocal devices is still elusive because such trapping states are easily destroyed when the symmetry of an optical system is broken. Herein, we propose nonreciprocal and dynamically tunable BICs for unidirectional confinement of light and symmetry-protected BICs at Γ-point by introducing antiparallel magnetism into the optical system. We demonstrate that such BICs can be achieved by using topological magnetic Weyl semimetals near zero-index frequency without any structural asymmetry, and are largely tunable via modifying the Fermi level.Our results reveal a regime of extreme light manipulation and interaction with emerging quantum materials for various practical applications.
基金supported by the National Defense Foundation of China(2019-JCJQ-JJ-081)the Youth Talent Lifting Project of the China Association for Science and Technology(17-JCJQ-QT-003)+1 种基金the Key Program of Natural Science Foundation of Shaanxi Province(2020JZ-33)the Key Principal’s Fund of Air Force Engineering University(XNLX19030601).
文摘Many real-world applications,including adaptive radar scanning and smart stealth,require reconfigurable multifunctional devices to simultaneously manipulate multiple degrees of freedom of electromagnetic(EM)waves in an on-demand manner.Recently,kirigami technique,affording versatile and unconventional structural transformation,has been introduced to endow metamaterials with the capability of controlling EM waves in a reconfigurable manner.Here,we report for a kirigami-inspired sparse meta-architecture,with structural density of 1.5%in terms of the occupation space,for adaptive invisibility based on independent operations of frequency,bandwidth,and amplitude.Based on the general principle of dipolar management via structural reconstruction of kirigami-inspired meta-architectures,we demonstrate reconfigurable invisibility management with abundant EM functions and a wide tuning range using three enantiomers(A,B,and C)of different geometries characterized by the folding angleβ.Our strategy circumvents issues of limited abilities,narrow tuning range,extreme condition,and high cost raised by available reconfigurable metamaterials,providing a new avenue toward multifunctional smart devices.
基金supported by the National Defense Foundation of China(2019-JCJQ-JJ-081)the Youth Talent Lifting Project of the China Association for Science and Technology(17-JCJQ-QT-003)+1 种基金the Key Program of Natural Science Foundation of Shaanxi Province(2020JZ-33)the Key Principal’s Fund of Air Force Engineering University(XNLX19030601).
文摘Many real-world applications,including adaptive radar scanning and smart stealth,require reconfigurable multifunctional devices to simultaneously manipulate multiple degrees of freedom of electromagnetic(EM)waves in an on-demand manner.Recently,kirigami technique,affording versatile and unconventional structural transformation,has been introduced to endow metamaterials with the capability of controlling EM waves in a reconfigurable manner.Here,we report for a kirigami-inspired sparse meta-architecture,with structural density of 1.5%in terms of the occupation space,for adaptive invisibility based on independent operations of frequency,bandwidth,and amplitude.Based on the general principle of dipolar management via structural reconstruction of kirigami-inspired meta-architectures,we demonstrate reconfigurable invisibility management with abundant EM functions and a wide tuning range using three enantiomers(A,B,and C)of different geometries characterized by the folding angleβ.Our strategy circumvents issues of limited abilities,narrow tuning range,extreme condition,and high cost raised by available reconfigurable metamaterials,providing a new avenue toward multifunctional smart devices.
文摘Various theories have been proposed to account for second language production and the systematic variation characteristic of such production.Most of these theories,however,constitute only partial explanations because they often fail to handle mixed empirical findings about factors held to affect second language output and underlie systematic variation.This paper proposes a new theoretical framework for posing and addressing research questions about second language production in general and systematic variation in particular.Building on influential cognitive models of second language learning and use,the theoretical framework comprises three cognitive dimensions,viz.knowledge representation,attentional focus,and processing automaticity,which interact with each other.The theoretical framework is justified by drawing on the cognitive literature and cumulative findings from second language acquisition(SLA)research.The paper also outlines possible applications of the framework to issues of interest to SLA researchers working on a number of different fronts.
