In the past decade, one-way manipulation of sound has attracted rapidly growing attention with application potentials in a plethora of scenarios ranging from ultrasound imaging to noise control. Here we propose a desi...In the past decade, one-way manipulation of sound has attracted rapidly growing attention with application potentials in a plethora of scenarios ranging from ultrasound imaging to noise control. Here we propose a design of a planar device capable of unidirectionally harnessing the transmitted wavefront for broadband airborne sound. Our mechanism is to use the broken spatial symmetry to give rise to different critical angles for plane waves incident along opposite directions.Along the positive direction, the incoming sound is allowed to pass with high efficiency and be arbitrarily molded into the desired shape while any reversed wave undergoes a total reflection. We analytically derive the working bandwidth and incident angle range, and present a practical implementation of our strategy. The performance of our proposed device is demonstrated both theoretically and numerically via distinct examples of production of broadband anomalous refraction,acoustic focusing and non-diffractive beams for forward transmitted wave while virtually blocking the reversed waves.Bearing advantages of simple design, planar profile, broad bandwidth and high efficiency, our design opens the possibility for novel one-way acoustic device and may have important impact on diverse applications in need of special control of airborne sound.展开更多
In modern science and technology,on-demand control of the polarization and wavefront of electromagnetic(EM)waves is crucial for compact opto-electronic systems.Metasurfaces composed of subwavelength array structures i...In modern science and technology,on-demand control of the polarization and wavefront of electromagnetic(EM)waves is crucial for compact opto-electronic systems.Metasurfaces composed of subwavelength array structures inject infinite vitality to shape this fantastic concept,which has fundamentally changed the way humans engineer matter–wave interactions.However,achieving full-space arbitrarily polarized beams with independent wavefronts in broadband on a single metasurface aperture still remains challenging.Herein,the authors propose a generic method for broadband transmission-reflection-integrated wavefronts shaping with multichannel arbitrary polarization regulation from 8 to 16 GHz,which is based on the chirality effect of full-space non-interleaved tetrameric meta-molecules.Through superimposing eigen-polarization responses of the two kinds of enantiomers,the possibility for high-efficiency evolution of several typical polarization states with specific wavefronts is demonstrated.As proofs-of-concept,the feasibility of our methodology is validated via implementing miscellaneous functionalities,including circularly polarized(CP)beam splitting,linearly polarized(LP)vortex beams generation,and CP and LP multifoci.Meanwhile,numerous simulated and experimental results are in excellent agreement with the theoretical predictions.Encouragingly,this proposed approach imaginatively merges broadband polarization and phase control into one single full-space and shared-aperture EM device,which can extremely enhance the functional richness and information capacity in advanced integrated systems.展开更多
Nonlinear wavefront shaping is crucial for advancing optical technologies,enabling applications in optical computation,information processing,and imaging.However,a significant challenge is that once a metasurface is f...Nonlinear wavefront shaping is crucial for advancing optical technologies,enabling applications in optical computation,information processing,and imaging.However,a significant challenge is that once a metasurface is fabricated,the nonlinear wavefront it generates is fixed,offering little flexibility.This limitation often necessitates the fabrication of different metasurfaces for different wavefronts,which is both time-consuming and inefficient.To address this,we combine evolutionary algorithms with spatial light modulators(SLMs)to dynamically control wavefronts using a single metasurface,reducing the need for multiple fabrications and enabling the generation of arbitrary nonlinear wavefront patterns without requiring complicated optical alignment.We demonstrate this approach by introducing a genetic algorithm(GA)to manipulate visible wavefronts converted from near-infrared light via third-harmonic generation(THG)in a silicon metasurface.The Si metasurface supports multipolar Mie resonances that strongly enhance light-matter interactions,thereby significantly boosting THG emission at resonant positions.Additionally,the cubic relationship between THG emission and the infrared input reduces noise in the diffractive patterns produced by the SLM.This allows for precise experimental engineering of the nonlinear emission patterns with fewer alignment constraints.Our approach paves the way for self-optimized nonlinear wavefront shaping,advancing optical computation and information processing techniques.展开更多
Independent manipulation of orthogonal circularly polarized wavefronts is one of the important goals for metaoptics,and chiral nanophotonics is one of the crucial approaches.In this article,we propose a new scheme for...Independent manipulation of orthogonal circularly polarized wavefronts is one of the important goals for metaoptics,and chiral nanophotonics is one of the crucial approaches.In this article,we propose a new scheme for spin-dependent terahertz wavefront shaping based on chiral metasurfaces,which involves a hybrid design of the propagation phase,chirality induced phase,and Pancharatnam-Berry phase in all-silicon meta-atoms.A controllable linear polarization conversion effect in the transmitted wave is obtained via breaking the mirror symmetry and preserving the C_(2)symmetry of the resonator,which causes a different form of the Jones matrix.By simultaneously adjusting the in-plane geometric dimensions and azimuth angle of chiral units,and utilizing the evolution characteristics of circularly polarized components in parameter space and polarization space,spin-dependent phase responses have been observed.We provide the main theoretical analysis and demonstrate the functional design of circularly polarized multiplexed beam deflection or vortex beam generation,through the expected simulation and experimental results near the operating frequency of 0.6 THz.Our results may enrich the design of terahertz polarization-multiplexed devices.展开更多
The conventional generalized Snell’s law(GSL),derived from classical laws of optical reflection and refraction,governs wavefront manipulation via phase gradients but neglects higher-order spatial harmonics inherently...The conventional generalized Snell’s law(GSL),derived from classical laws of optical reflection and refraction,governs wavefront manipulation via phase gradients but neglects higher-order spatial harmonics inherently excited by the mutual coupling among meta-atoms on a metasurface.Here,we introduce a spatial harmonic-expanded GSL(SH-GSL)framework by unifying phase-gradient control with Floquet periodicity,establishing spatial harmonics as independent degrees of freedom rather than conventional parasitic disturbances.The SH-GSL framework rigorously identifies the intrinsic harmonic dynamics inherent to metasurfaces,which is a critical feature absent in GSL.Furthermore,this framework further reveals that all gradient-phase metasurfaces inherently function as multichannel platforms due to full spatial harmonics,with this multifunctionality rooted in nonlocal Floquet-Bloch modal interactions.Experimental validation demonstrates:abnormal spatial-harmonic reflection with angular precision(<5°deviation),multi-beam splitting(dual/quad configurations)via the relationship between specific harmonics and compensation wave vectors,and a perfect three-channel retroreflector achieving up to 99%efficiency,where parasitic harmonics are confined to near-field plasmonic regimes.This framework establishes a deterministic Floquet-engineered momentum compensation mechanism to simultaneously activate target harmonic channels while confining parasitic harmonics to near-field plasmonic regimes.Experimental validation confirms the framework’s accuracy and scalability,bridging momentum-space physics with practical meta-plasmon systems.This work redefines metasurface engineering paradigms,unlocking advancements in ultra-dense beamforming,sensing,and meta-photonics through harmonic-division multiplexing.展开更多
In the past two decades,metamaterials and metasurfaces[1,2]have been providing a new playground for light manipulation,establishing concepts and experimental platforms that enable structuring light in compact footprin...In the past two decades,metamaterials and metasurfaces[1,2]have been providing a new playground for light manipulation,establishing concepts and experimental platforms that enable structuring light in compact footprints with exceptional benefits for a wide range of technologies.Metasurfaces,in particular,have been developing a paradigm of compactification of optical components,enabling manipulation of the optical wavefront within subwavelength footprints and unprecedented control over all properties of light,from spectrum to polarization,from wavefront shaping to spatial and temporal coherence[3].The progress in the past few years has been truly impressive,bringing many of these concepts from proof-of-concept ideas to practical demonstrations ready for commercialization and deployment.As such,it has become imperative to explore ways to integrate metamaterial and metasurface devices into photonic platforms and enable platforms compatible with existing photonic circuits and systems.展开更多
Lens is a basic optical element that is widely used in daily life,such as in cameras,glasses,and microscopes.Conventional lenses are designed based on the classical refractive optics,which results in inevitable imagin...Lens is a basic optical element that is widely used in daily life,such as in cameras,glasses,and microscopes.Conventional lenses are designed based on the classical refractive optics,which results in inevitable imaging aberrations,such as chromatic aberration,spherical aberration and coma.To solve these problems,conventional imaging systems impose multiple curved lenses with different thicknesses and materials to eliminate these aberrations.As a unique photonic technology,metasurfaces can accurately manipulate the wavefront of light to produce fascinating and peculiar optical phenomena,which has stimulated researchers9 extensive interests in the field of planar optics.Starting from the introduction of phase modulation methods,this review summarizes the design principles and characteristics of metalenses.Although the imaging quality of existing metalenses is not necessarily better than that of conventional lenses,the multi-dimensional and multi-degree-of-freedom control of metasurfaces provides metalenses with novel functions that are extremely challenging or impossible to achieve with conventional lenses.展开更多
Controlling the phase of an electromagnetic field using plasmonic nanostructures provides a versatile way to manipulate light at the nanoscale.Broadband phase modulation has been demonstrated using inhomogeneous metas...Controlling the phase of an electromagnetic field using plasmonic nanostructures provides a versatile way to manipulate light at the nanoscale.Broadband phase modulation has been demonstrated using inhomogeneous metasurfaces with different geometries;however,for many applications such as filtering,hyperspectral imaging and color holography,narrowband frequency selectivity is a key functionality.In this work,we demonstrate,both theoretically and experimentally,a narrowband metasurface that relies on Fano resonances to control the propagation of light.By geometrically tuning the sub-radiant modes with respect to a fixed super-radiant resonance,we can create a phase modulation along the surface within a narrow spectral range.The resulting anomalous reflection measured for such a Fano-resonant metasurface exhibits a 100 nm bandwidth and a color routing efficiency of up to 81%at a central wavelength ofλ=750 nm.The design flexibility provided by this Fano-assisted metasurface for colorselective light manipulation is further illustrated by demonstrating a highly directional color-routing effect between two channels,atλ=532 and 660 nm,without any crosstalk.展开更多
Metasurfaces offer unprecedented flexibility in the design and control of light propagation,replacing bulk optical components and exhibiting exotic optical effects.One of the basic properties of the metasurfaces,which...Metasurfaces offer unprecedented flexibility in the design and control of light propagation,replacing bulk optical components and exhibiting exotic optical effects.One of the basic properties of the metasurfaces,which renders them as frequency selective surfaces,is the ability to transmit or reflect radiation within a narrow frequency band that can be engineered on demand.Here we introduce and demonstrate experimentally in the THz domain the concept of wavevector selective surfaces–metasurfaces transparent only within a narrow range of light propagation directions operating effectively as tunnel vision filters.Practical implementations of the new concept include applications in wavefront manipulation,observational instruments,vision and free-space communication in light-scattering environments.展开更多
We report on the first demonstration of a proof-of-principle optical fiber‘meta-tip’,which integrates a phase-gradient plasmonic metasurface on the fiber tip.For illustration and validation purposes,we present numer...We report on the first demonstration of a proof-of-principle optical fiber‘meta-tip’,which integrates a phase-gradient plasmonic metasurface on the fiber tip.For illustration and validation purposes,we present numerical and experimental results pertaining to various prototypes implementing generalized forms of the Snell’s transmission/reflection laws at near-infrared wavelengths.In particular,we demonstrate several examples of beam steering and coupling with surface waves,in fairly good agreement with theory.Our results constitute a first step toward the integration of unprecedented(metasurface-enabled)light-manipulation capabilities in optical-fiber technology.By further enriching the emergent‘lab-on-fiber’framework,this may pave the way for the widespread diffusion of optical metasurfaces in real-world applications to communications,signal processing,imaging and sensing.展开更多
Vector vortex beams(VVBs), novel structured optical fields that combine the polarization properties of vector beams and phase characteristics of vortex beams, have garnered widespread attention in the photonics commun...Vector vortex beams(VVBs), novel structured optical fields that combine the polarization properties of vector beams and phase characteristics of vortex beams, have garnered widespread attention in the photonics community. Capitalizing on recently developed metasurfaces, miniaturized VVB generators with advanced properties have been implemented. However,metasurface-empowered VVB generators remain static and can only generate one pre-designed structured light. Here, we propose a kind of phase change metasurface for tunable vector beam generation by utilizing anisotropic Ge2Sb2Se4Te1(GSST) unit cells with tunable phase retardation when GSST transits between two different phase states. By properly rotating the orientations of the tunable GSST unit structures that transit between quarter-wave plates and half-wave plates, we can effectively transform incident plane waves into vector beams with distinct topological charges and polarization states.When GSST is in the amorphous state, the designed metasurface can transmit circularly polarized light into VVBs. In the crystalline state, the same GSST metasurface converts linearly polarized light into second-order radially polarized(RP) and azimuthally polarized(AP) beams. Our phase-change metasurface paves the way for precise control over the polarization patterns and vortex characteristics of beams, thereby enabling the exact manipulation of beam structures through the alteration of their phase states.展开更多
基金Project supported by National Key R&D Program of China (Grant No. 2017YFA0303700)the National Natural Science Foundation of China (Grant Nos. 11634006, 11374157, and 81127901)+1 种基金a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutionsthe Innovation Special Zone of National Defense Science and Technology and High-Performance Computing Center of Collaborative Innovation Center of Advanced Microstructures。
文摘In the past decade, one-way manipulation of sound has attracted rapidly growing attention with application potentials in a plethora of scenarios ranging from ultrasound imaging to noise control. Here we propose a design of a planar device capable of unidirectionally harnessing the transmitted wavefront for broadband airborne sound. Our mechanism is to use the broken spatial symmetry to give rise to different critical angles for plane waves incident along opposite directions.Along the positive direction, the incoming sound is allowed to pass with high efficiency and be arbitrarily molded into the desired shape while any reversed wave undergoes a total reflection. We analytically derive the working bandwidth and incident angle range, and present a practical implementation of our strategy. The performance of our proposed device is demonstrated both theoretically and numerically via distinct examples of production of broadband anomalous refraction,acoustic focusing and non-diffractive beams for forward transmitted wave while virtually blocking the reversed waves.Bearing advantages of simple design, planar profile, broad bandwidth and high efficiency, our design opens the possibility for novel one-way acoustic device and may have important impact on diverse applications in need of special control of airborne sound.
基金National Key Research and Development Program of China(SQ2022YFB3806200)National Natural Science Foundation of China(62301596,62101588)+1 种基金Young Talent Fund of Association for Science and Technology in Shaanxi(20240129)Postdoctoral Fellowship Program of CPSF(GZC20242285)。
文摘In modern science and technology,on-demand control of the polarization and wavefront of electromagnetic(EM)waves is crucial for compact opto-electronic systems.Metasurfaces composed of subwavelength array structures inject infinite vitality to shape this fantastic concept,which has fundamentally changed the way humans engineer matter–wave interactions.However,achieving full-space arbitrarily polarized beams with independent wavefronts in broadband on a single metasurface aperture still remains challenging.Herein,the authors propose a generic method for broadband transmission-reflection-integrated wavefronts shaping with multichannel arbitrary polarization regulation from 8 to 16 GHz,which is based on the chirality effect of full-space non-interleaved tetrameric meta-molecules.Through superimposing eigen-polarization responses of the two kinds of enantiomers,the possibility for high-efficiency evolution of several typical polarization states with specific wavefronts is demonstrated.As proofs-of-concept,the feasibility of our methodology is validated via implementing miscellaneous functionalities,including circularly polarized(CP)beam splitting,linearly polarized(LP)vortex beams generation,and CP and LP multifoci.Meanwhile,numerous simulated and experimental results are in excellent agreement with the theoretical predictions.Encouragingly,this proposed approach imaginatively merges broadband polarization and phase control into one single full-space and shared-aperture EM device,which can extremely enhance the functional richness and information capacity in advanced integrated systems.
基金support from the Biotechnology and Biological Council Doctoral Training Programme(BBSRC DTP)the support from the Royal Society and Wolfson Foundation(RSWF\FT\191022).
文摘Nonlinear wavefront shaping is crucial for advancing optical technologies,enabling applications in optical computation,information processing,and imaging.However,a significant challenge is that once a metasurface is fabricated,the nonlinear wavefront it generates is fixed,offering little flexibility.This limitation often necessitates the fabrication of different metasurfaces for different wavefronts,which is both time-consuming and inefficient.To address this,we combine evolutionary algorithms with spatial light modulators(SLMs)to dynamically control wavefronts using a single metasurface,reducing the need for multiple fabrications and enabling the generation of arbitrary nonlinear wavefront patterns without requiring complicated optical alignment.We demonstrate this approach by introducing a genetic algorithm(GA)to manipulate visible wavefronts converted from near-infrared light via third-harmonic generation(THG)in a silicon metasurface.The Si metasurface supports multipolar Mie resonances that strongly enhance light-matter interactions,thereby significantly boosting THG emission at resonant positions.Additionally,the cubic relationship between THG emission and the infrared input reduces noise in the diffractive patterns produced by the SLM.This allows for precise experimental engineering of the nonlinear emission patterns with fewer alignment constraints.Our approach paves the way for self-optimized nonlinear wavefront shaping,advancing optical computation and information processing techniques.
基金National Natural Science Foundation of China(12404484)Science and Technology Department of Sichuan Province(2025ZNSFSC0846,2025ZNSFSC0847,2022Z091,2023ZYD0175)+1 种基金Scientific Research Foundation of Chengdu University of Information Technology(KYTZ202245)Sichuan Meteorological Optoelectronic Sensor Technology and Application Engineering Research Center(2024GCZX001)。
文摘Independent manipulation of orthogonal circularly polarized wavefronts is one of the important goals for metaoptics,and chiral nanophotonics is one of the crucial approaches.In this article,we propose a new scheme for spin-dependent terahertz wavefront shaping based on chiral metasurfaces,which involves a hybrid design of the propagation phase,chirality induced phase,and Pancharatnam-Berry phase in all-silicon meta-atoms.A controllable linear polarization conversion effect in the transmitted wave is obtained via breaking the mirror symmetry and preserving the C_(2)symmetry of the resonator,which causes a different form of the Jones matrix.By simultaneously adjusting the in-plane geometric dimensions and azimuth angle of chiral units,and utilizing the evolution characteristics of circularly polarized components in parameter space and polarization space,spin-dependent phase responses have been observed.We provide the main theoretical analysis and demonstrate the functional design of circularly polarized multiplexed beam deflection or vortex beam generation,through the expected simulation and experimental results near the operating frequency of 0.6 THz.Our results may enrich the design of terahertz polarization-multiplexed devices.
基金supported by the National Natural Science Foundation of China(62271011)and(62405009)the National Science Key Lab Fund(2024CXPTGFJJ020010401)+1 种基金the National Key Research and Development Program of China(2021YFA1600302)the Beijing Science Foundation for Distinguished Young Scholars(JQ21011).
文摘The conventional generalized Snell’s law(GSL),derived from classical laws of optical reflection and refraction,governs wavefront manipulation via phase gradients but neglects higher-order spatial harmonics inherently excited by the mutual coupling among meta-atoms on a metasurface.Here,we introduce a spatial harmonic-expanded GSL(SH-GSL)framework by unifying phase-gradient control with Floquet periodicity,establishing spatial harmonics as independent degrees of freedom rather than conventional parasitic disturbances.The SH-GSL framework rigorously identifies the intrinsic harmonic dynamics inherent to metasurfaces,which is a critical feature absent in GSL.Furthermore,this framework further reveals that all gradient-phase metasurfaces inherently function as multichannel platforms due to full spatial harmonics,with this multifunctionality rooted in nonlocal Floquet-Bloch modal interactions.Experimental validation demonstrates:abnormal spatial-harmonic reflection with angular precision(<5°deviation),multi-beam splitting(dual/quad configurations)via the relationship between specific harmonics and compensation wave vectors,and a perfect three-channel retroreflector achieving up to 99%efficiency,where parasitic harmonics are confined to near-field plasmonic regimes.This framework establishes a deterministic Floquet-engineered momentum compensation mechanism to simultaneously activate target harmonic channels while confining parasitic harmonics to near-field plasmonic regimes.Experimental validation confirms the framework’s accuracy and scalability,bridging momentum-space physics with practical meta-plasmon systems.This work redefines metasurface engineering paradigms,unlocking advancements in ultra-dense beamforming,sensing,and meta-photonics through harmonic-division multiplexing.
文摘In the past two decades,metamaterials and metasurfaces[1,2]have been providing a new playground for light manipulation,establishing concepts and experimental platforms that enable structuring light in compact footprints with exceptional benefits for a wide range of technologies.Metasurfaces,in particular,have been developing a paradigm of compactification of optical components,enabling manipulation of the optical wavefront within subwavelength footprints and unprecedented control over all properties of light,from spectrum to polarization,from wavefront shaping to spatial and temporal coherence[3].The progress in the past few years has been truly impressive,bringing many of these concepts from proof-of-concept ideas to practical demonstrations ready for commercialization and deployment.As such,it has become imperative to explore ways to integrate metamaterial and metasurface devices into photonic platforms and enable platforms compatible with existing photonic circuits and systems.
基金the National Key R&D Program of China(No.2020YFC2007102)the National Natural Science Foundation of China(Grant No.12074444)+1 种基金Guangdong Basic and Applied Basic Research Foundation(No.2020A1515011184)Innovation Group Project of Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai).
文摘Lens is a basic optical element that is widely used in daily life,such as in cameras,glasses,and microscopes.Conventional lenses are designed based on the classical refractive optics,which results in inevitable imaging aberrations,such as chromatic aberration,spherical aberration and coma.To solve these problems,conventional imaging systems impose multiple curved lenses with different thicknesses and materials to eliminate these aberrations.As a unique photonic technology,metasurfaces can accurately manipulate the wavefront of light to produce fascinating and peculiar optical phenomena,which has stimulated researchers9 extensive interests in the field of planar optics.Starting from the introduction of phase modulation methods,this review summarizes the design principles and characteristics of metalenses.Although the imaging quality of existing metalenses is not necessarily better than that of conventional lenses,the multi-dimensional and multi-degree-of-freedom control of metasurfaces provides metalenses with novel functions that are extremely challenging or impossible to achieve with conventional lenses.
基金supported by the Swiss National Science Foundation(grants 200020_153662 and 200021_162453).
文摘Controlling the phase of an electromagnetic field using plasmonic nanostructures provides a versatile way to manipulate light at the nanoscale.Broadband phase modulation has been demonstrated using inhomogeneous metasurfaces with different geometries;however,for many applications such as filtering,hyperspectral imaging and color holography,narrowband frequency selectivity is a key functionality.In this work,we demonstrate,both theoretically and experimentally,a narrowband metasurface that relies on Fano resonances to control the propagation of light.By geometrically tuning the sub-radiant modes with respect to a fixed super-radiant resonance,we can create a phase modulation along the surface within a narrow spectral range.The resulting anomalous reflection measured for such a Fano-resonant metasurface exhibits a 100 nm bandwidth and a color routing efficiency of up to 81%at a central wavelength ofλ=750 nm.The design flexibility provided by this Fano-assisted metasurface for colorselective light manipulation is further illustrated by demonstrating a highly directional color-routing effect between two channels,atλ=532 and 660 nm,without any crosstalk.
基金This work is supported by the UK’s Engineering and Physical Sciences Research Council through Career Acceleration Fellowship EP/G00515X/1(V.A.F.)Programme grant EP/G060363/1,by the Royal Society,and by the MOE Singapore grant MOE2011-T3-1-005
文摘Metasurfaces offer unprecedented flexibility in the design and control of light propagation,replacing bulk optical components and exhibiting exotic optical effects.One of the basic properties of the metasurfaces,which renders them as frequency selective surfaces,is the ability to transmit or reflect radiation within a narrow frequency band that can be engineered on demand.Here we introduce and demonstrate experimentally in the THz domain the concept of wavevector selective surfaces–metasurfaces transparent only within a narrow range of light propagation directions operating effectively as tunnel vision filters.Practical implementations of the new concept include applications in wavefront manipulation,observational instruments,vision and free-space communication in light-scattering environments.
文摘We report on the first demonstration of a proof-of-principle optical fiber‘meta-tip’,which integrates a phase-gradient plasmonic metasurface on the fiber tip.For illustration and validation purposes,we present numerical and experimental results pertaining to various prototypes implementing generalized forms of the Snell’s transmission/reflection laws at near-infrared wavelengths.In particular,we demonstrate several examples of beam steering and coupling with surface waves,in fairly good agreement with theory.Our results constitute a first step toward the integration of unprecedented(metasurface-enabled)light-manipulation capabilities in optical-fiber technology.By further enriching the emergent‘lab-on-fiber’framework,this may pave the way for the widespread diffusion of optical metasurfaces in real-world applications to communications,signal processing,imaging and sensing.
基金supported by the Natural Science Foundation of Zhejiang Province (No.LY24A040001)the Ningbo Youth Science and Technology Innovation Leading Talent Project (No.2023QL001)+2 种基金the Villum Fonden (No.37372)the Danmarks Frie Forskningsfond (No.1134-00010B)the Fundamental Research Funds of Shaanxi Key Laboratory of Artificially Structured Functional Materials and Devices。
文摘Vector vortex beams(VVBs), novel structured optical fields that combine the polarization properties of vector beams and phase characteristics of vortex beams, have garnered widespread attention in the photonics community. Capitalizing on recently developed metasurfaces, miniaturized VVB generators with advanced properties have been implemented. However,metasurface-empowered VVB generators remain static and can only generate one pre-designed structured light. Here, we propose a kind of phase change metasurface for tunable vector beam generation by utilizing anisotropic Ge2Sb2Se4Te1(GSST) unit cells with tunable phase retardation when GSST transits between two different phase states. By properly rotating the orientations of the tunable GSST unit structures that transit between quarter-wave plates and half-wave plates, we can effectively transform incident plane waves into vector beams with distinct topological charges and polarization states.When GSST is in the amorphous state, the designed metasurface can transmit circularly polarized light into VVBs. In the crystalline state, the same GSST metasurface converts linearly polarized light into second-order radially polarized(RP) and azimuthally polarized(AP) beams. Our phase-change metasurface paves the way for precise control over the polarization patterns and vortex characteristics of beams, thereby enabling the exact manipulation of beam structures through the alteration of their phase states.
