Meta-devices have significantly revitalized the study of nonlinear optical phenomena.At the nanoscale,the detrimental effects of phase mismatching between fundamental and harmonic waves can be substantially reduced.Th...Meta-devices have significantly revitalized the study of nonlinear optical phenomena.At the nanoscale,the detrimental effects of phase mismatching between fundamental and harmonic waves can be substantially reduced.This review analyzes the theoretical frameworks of how plasmonic and dielectric materials induce nonlinear optical properties.Plasmonic and dielectric nonlinear meta-devices that can excite strong resonant modes for efficiency enhancement are explored.We outline different strategies designed to shape the radiation pattern in order to increase the collection capability of nonlinear signals emitted from meta-devices.In addition,we discuss how nonlinear phase manipulation in meta-devices can integrate the benefits of efficiency enhancement and radiation shaping,not only boosting the energy density of the nonlinear signal but also facilitating a wide range of applications.Finally,potential research directions within this field are discussed.展开更多
Tunable Airy beams with controllable propagation trajectories have sparked interest in various fields,such as optical manipulation and laser fabrication.Existing research approaches encounter challenges related to ins...Tunable Airy beams with controllable propagation trajectories have sparked interest in various fields,such as optical manipulation and laser fabrication.Existing research approaches encounter challenges related to insufficient compactness and integration feasibility,or they require enhanced tunability to enable real-time dynamic manipulation of the propagation trajectory.In this work,we present a novel method that utilizes a dual metasurface system to surpass these limitations,significantly enhancing the practical potential of the Airy beam.Our approach involves encoding a cubic phase profile and two off-axis Fresnel lens phase profiles across the two metasurfaces.The validity of the proposed strategy has been confirmed through simulation and experimental results.The proposed meta-device addresses the existing limitations and lays the foundation for broadening the applicability of Airy beams across diverse domains,encompassing light-sheet microscopy,laser fabrication,optical tweezers,etc.展开更多
Metasurfaces are one of the most promising devices to break through the limitations of bulky optical components.By offering a new method of light manipulation based on the light-matter interaction in subwavelength nan...Metasurfaces are one of the most promising devices to break through the limitations of bulky optical components.By offering a new method of light manipulation based on the light-matter interaction in subwavelength nanostructures,metasurfaces enable the efficient manipulation of the amplitude,phase,polarization,and frequency of light and derive a series of possibilities for important applications.However,one key challenge for the realization of applications for meta-devices is how to fabricate large-scale,uniform nanostructures with high resolution.In this review,we review the state-of-the-art nanofabrication techniques compatible with the manufacture of meta-devices.Maskless lithography,masked lithography,and other nanofabrication techniques are highlighted in detail.We also delve into the constraints and limitations of the current fabrication methods while providing some insights on solutions to overcome these challenges for advanced nanophotonic applications.展开更多
Dynamic control of Airy beam has been attracting scientists’attention due to its potential applications in imaging,optical manipulation and laser manufacturing.However,traditional way of dynamic tuning of free space ...Dynamic control of Airy beam has been attracting scientists’attention due to its potential applications in imaging,optical manipulation and laser manufacturing.However,traditional way of dynamic tuning of free space Airy beam usually requires bulky optics and will inevitably limit its practical applications.To solve this issue,a recent work proposes to use a compact meta-device which consists of two cascaded dielectric metasurfaces working in the visible regime.展开更多
Graphene,a two‐dimensional material renowned for its distinctive electronic band structure and remarkable physical properties,has garnered substantial attention in recent years.Its integration into met-amaterials(i.e...Graphene,a two‐dimensional material renowned for its distinctive electronic band structure and remarkable physical properties,has garnered substantial attention in recent years.Its integration into met-amaterials(i.e.,artificially structured materials)and metamaterial‐based devices opens up exciting possibilities for manipulating electromagnetic waves with various functionalities.These metamaterials and meta‐devices,with their strong resonances,enhance interactions with inci-dent waves,further aided by electrically tunable graphene,enabling fruitful modulation of electromagnetic waves.In this review,we present a detailed exploration of the recent advancements in graphene‐based mi-crowave meta‐devices.We first introduce the electromagnetic properties of graphene,laying the foundation for its electromagnetic modeling and characterization.The second part introduces the fabrication and transfer methods of graphene.Next,we review the passive meta‐devices con-structed with graphene,exploring how these devices leverage graphene's unique properties.We further discuss graphene‐based active meta‐devices for dynamic wave manipulations,with a focus on graphene-electrolyte-graphene sandwich structures.Lastly,the review delves into graphene‐based coding and programmable meta‐devices,highlighting their innovative applications.Each section provides a focused explora-tion of a specific aspect of the field,showcasing the diverse and expanding role of graphene in the microwave region.Through this comprehensive review,we aim to enrich our understanding and appre-ciation for the growing developments and potential of graphene in mi-crowave technology.展开更多
Focused vector vortex beams(VVBs)offer significant potential for applications in nonlinear effects,quantum optics,and communications due to their symmetric intensity patterns,phase singularities,and structured polariz...Focused vector vortex beams(VVBs)offer significant potential for applications in nonlinear effects,quantum optics,and communications due to their symmetric intensity patterns,phase singularities,and structured polarization profiles.Nevertheless,the emerging frontier of dynamically tunable VVBs in the THz regime faces critical limitations in conventional static metasurface implementations,hindering their full potential for advanced photonic applications.In this work,we propose and demonstrate a design strategy,which employs dielectric cascaded metasurfaces to generate VVBs with tunable characteristics through mechanical twisting.To achieve this,LayerⅠis constructed from birefringent silicon pillars with rectangular configurations,enabling independent encoding of orthogonal circularly polarized channels via spin-decoupled phasing techniques,while LayerⅡis composed of cylindrical silicon pillars with polarization-maintaining properties to control the focal length.The generation and modulation of VVBs are achieved by mechanically adjusting the relative angles between these two layers,allowing for dynamic tuning of the beam's properties.Experimentally,we further present the accurate generation of first-and second-order focused VVBs with a high focusing efficiency(>12.9%),consistent with theoretical predictions.Moreover,the system exhibited continuous focal length tuning across 26λ-10.4λby rotating the layers from 90°to 240°,achieving a 42.8%modulation depth,while maintaining radial symmetry,as confirmed by an absolute percentage error analysis(<9.8%).The demonstrated mechanical tuning mechanism provides a practical pathway toward adaptive THz photonic devices,bridging critical gaps in real-world applications ranging from polarization-encoded communications to depthresolved biomedical imaging.展开更多
Metasurfaces,composed of two-dimensional nanostructures,exhibit remarkable capabilities in shaping wavefronts,encompassing phase,amplitude,and polarization.This unique proficiency heralds a transformative paradigm shi...Metasurfaces,composed of two-dimensional nanostructures,exhibit remarkable capabilities in shaping wavefronts,encompassing phase,amplitude,and polarization.This unique proficiency heralds a transformative paradigm shift in the domain of next-generation optics and photonics,culminating in the development of flat and ultrathin optical devices.Particularly noteworthy is the all-dielectric-based metasurface,leveraging materials such as titanium dioxide,silicon,gallium arsenide,and silicon nitride,which finds extensive application in the design and implementation of high-performance optical devices,owing to its notable advantages,including a high refractive index,low ohmic loss,and cost-effectiveness.Furthermore,the remarkable growth in nanofabrication technologies allows for the exploration of new methods in metasurface fabrication,especially through wafer-scale nanofabrication technologies,thereby facilitating the realization of commercial applications for metasurfaces.This review provides a comprehensive overview of the latest advancements in state-of-the-art fabrication technologies in dielectric metasurface areas.These technologies,including standard nanolithography[e.g.,electron beam lithography(EBL)and focused ion beam(FIB)lithography],advanced nanolithography(e.g.,grayscale and scanning probe lithography),and large-scale nanolithography[e.g.,nanoimprint and deep ultraviolet(DUV)lithography],are utilized to fabricate highresolution,high-aspect-ratio,flexible,multilayer,slanted,and wafer-scale all-dielectric metasurfaces with intricate nanostructures.Ultimately,we conclude with a perspective on current cutting-edge nanofabrication technologies.展开更多
Chromatic aberration-free meta-devices(e.g.,achromatic meta-devices and abnormal chromatic meta-devices)play an essential role in modern science and technology.However,current efforts suffer the issues of low efficien...Chromatic aberration-free meta-devices(e.g.,achromatic meta-devices and abnormal chromatic meta-devices)play an essential role in modern science and technology.However,current efforts suffer the issues of low efficiency,narrow operating band,and limited wavefront manipulation capability.We propose a general strategy to design chromatic aberration-free meta-devices with high-efficiency and ultrabroadband properties,which is realized by satisfying the key criteria of desirable phase dispersion and high reflection amplitudes at the target frequency interval.The phase dispersion is tuned successfully based on a multiresonant Lorentz model,and high reflection is guaranteed by the presence of the metallic ground.As proof of the concept,two microwave meta-devices are designed,fabricated,and experimentally characterized.An achromatic meta-mirror is proposed within 8 to 12 GHz,and another abnormal chromatic meta-mirror can tune the reflection angle as a linear function.Both meta-mirrors exhibit very high efficiencies(85%to 94%in the frequency band).Our findings open a door to realize chromatic aberration-free meta-devices with high efficiency and wideband properties and stimulate the realizations of chromatic aberration-free metadevices with other functionalities or working at higher frequency.展开更多
Metasurfaces have exhibited great capabilities to control electromagnetic waves,and many multifunctional metasurfaces were recently proposed.However,although angle-multiplexed meta-devices were successfully realized i...Metasurfaces have exhibited great capabilities to control electromagnetic waves,and many multifunctional metasurfaces were recently proposed.However,although angle-multiplexed meta-devices were successfully realized in reflection geometries,their transmission-mode counterparts are difficult to achieve due to the additional requirements.Here,we design and fabricate a transmissive angle-multiplexed meta-polarizer in the microwave regime based on a multilayer metasurface.Coupled-mode-theory analyses reveal that the device exhibits distinct angle-dependent transmissive responses under excitations with different polarizations,and such differences are further enhanced by multiple scatterings inside the device.Microwave experimental results are in good agreement with numerical simulations and theoretical analyses.展开更多
基金supported by the University Grants Committee/Research Grants Council of the Hong Kong Special Administrative Region,China(AoE/P-502/20,C1015-21E,C5031-22G,CityU15303521,CityU11305223,CityU11310522,CityU11300123,and G-CityU 101/22)the City University of Hong Kong(9380131 and 7005867)the National Natural Science Foundation of China(62375232).
文摘Meta-devices have significantly revitalized the study of nonlinear optical phenomena.At the nanoscale,the detrimental effects of phase mismatching between fundamental and harmonic waves can be substantially reduced.This review analyzes the theoretical frameworks of how plasmonic and dielectric materials induce nonlinear optical properties.Plasmonic and dielectric nonlinear meta-devices that can excite strong resonant modes for efficiency enhancement are explored.We outline different strategies designed to shape the radiation pattern in order to increase the collection capability of nonlinear signals emitted from meta-devices.In addition,we discuss how nonlinear phase manipulation in meta-devices can integrate the benefits of efficiency enhancement and radiation shaping,not only boosting the energy density of the nonlinear signal but also facilitating a wide range of applications.Finally,potential research directions within this field are discussed.
文摘Tunable Airy beams with controllable propagation trajectories have sparked interest in various fields,such as optical manipulation and laser fabrication.Existing research approaches encounter challenges related to insufficient compactness and integration feasibility,or they require enhanced tunability to enable real-time dynamic manipulation of the propagation trajectory.In this work,we present a novel method that utilizes a dual metasurface system to surpass these limitations,significantly enhancing the practical potential of the Airy beam.Our approach involves encoding a cubic phase profile and two off-axis Fresnel lens phase profiles across the two metasurfaces.The validity of the proposed strategy has been confirmed through simulation and experimental results.The proposed meta-device addresses the existing limitations and lays the foundation for broadening the applicability of Airy beams across diverse domains,encompassing light-sheet microscopy,laser fabrication,optical tweezers,etc.
基金support from the University Grants Committee/Research Grants Council of the Hong Kong Special Administrative Region,China[Project No.AoE/P-502/20,CRF Project:C1015-21EC5031-22G,and GRF Project:CityU15303521,CityU11305223,CityU11310522,CityU11300123]+5 种基金the Department of Science and Technology of Guangdong Province[Project No.2020B1515120073]City University of Hong Kong[Project No.9380131,9610628,and 7005867]S.M.Xiao acknowledges financial support from National Key R&D Program of China(Grant Nos.2021YFA1400802)the National Natural Science Foundation of China(Grant Nos.62125501,and 6233000076)Fundamental Research Funds for the Central Universities(Grant No.2022FRRK030004Shenzhen Fundamental Research Projects(Grant Nos.JCYJ20220818102218040).
文摘Metasurfaces are one of the most promising devices to break through the limitations of bulky optical components.By offering a new method of light manipulation based on the light-matter interaction in subwavelength nanostructures,metasurfaces enable the efficient manipulation of the amplitude,phase,polarization,and frequency of light and derive a series of possibilities for important applications.However,one key challenge for the realization of applications for meta-devices is how to fabricate large-scale,uniform nanostructures with high resolution.In this review,we review the state-of-the-art nanofabrication techniques compatible with the manufacture of meta-devices.Maskless lithography,masked lithography,and other nanofabrication techniques are highlighted in detail.We also delve into the constraints and limitations of the current fabrication methods while providing some insights on solutions to overcome these challenges for advanced nanophotonic applications.
文摘Dynamic control of Airy beam has been attracting scientists’attention due to its potential applications in imaging,optical manipulation and laser manufacturing.However,traditional way of dynamic tuning of free space Airy beam usually requires bulky optics and will inevitably limit its practical applications.To solve this issue,a recent work proposes to use a compact meta-device which consists of two cascaded dielectric metasurfaces working in the visible regime.
基金National Natural Science Foundation of China,Grant/Award Number:62071291。
文摘Graphene,a two‐dimensional material renowned for its distinctive electronic band structure and remarkable physical properties,has garnered substantial attention in recent years.Its integration into met-amaterials(i.e.,artificially structured materials)and metamaterial‐based devices opens up exciting possibilities for manipulating electromagnetic waves with various functionalities.These metamaterials and meta‐devices,with their strong resonances,enhance interactions with inci-dent waves,further aided by electrically tunable graphene,enabling fruitful modulation of electromagnetic waves.In this review,we present a detailed exploration of the recent advancements in graphene‐based mi-crowave meta‐devices.We first introduce the electromagnetic properties of graphene,laying the foundation for its electromagnetic modeling and characterization.The second part introduces the fabrication and transfer methods of graphene.Next,we review the passive meta‐devices con-structed with graphene,exploring how these devices leverage graphene's unique properties.We further discuss graphene‐based active meta‐devices for dynamic wave manipulations,with a focus on graphene-electrolyte-graphene sandwich structures.Lastly,the review delves into graphene‐based coding and programmable meta‐devices,highlighting their innovative applications.Each section provides a focused explora-tion of a specific aspect of the field,showcasing the diverse and expanding role of graphene in the microwave region.Through this comprehensive review,we aim to enrich our understanding and appre-ciation for the growing developments and potential of graphene in mi-crowave technology.
基金supported by the National Natural Science Foundation of China(Grant Nos.U22A2008,and 12404484)the Sichuan Province Science and Technology Support Program(Grant No.25QNJJ2419)+1 种基金the National Key Research and Development Program of China(Grant No.2021YFB2800703)the Laoshan Laboratory Science and Technology Innovation Project(Grant No.LSKJ202200801)。
文摘Focused vector vortex beams(VVBs)offer significant potential for applications in nonlinear effects,quantum optics,and communications due to their symmetric intensity patterns,phase singularities,and structured polarization profiles.Nevertheless,the emerging frontier of dynamically tunable VVBs in the THz regime faces critical limitations in conventional static metasurface implementations,hindering their full potential for advanced photonic applications.In this work,we propose and demonstrate a design strategy,which employs dielectric cascaded metasurfaces to generate VVBs with tunable characteristics through mechanical twisting.To achieve this,LayerⅠis constructed from birefringent silicon pillars with rectangular configurations,enabling independent encoding of orthogonal circularly polarized channels via spin-decoupled phasing techniques,while LayerⅡis composed of cylindrical silicon pillars with polarization-maintaining properties to control the focal length.The generation and modulation of VVBs are achieved by mechanically adjusting the relative angles between these two layers,allowing for dynamic tuning of the beam's properties.Experimentally,we further present the accurate generation of first-and second-order focused VVBs with a high focusing efficiency(>12.9%),consistent with theoretical predictions.Moreover,the system exhibited continuous focal length tuning across 26λ-10.4λby rotating the layers from 90°to 240°,achieving a 42.8%modulation depth,while maintaining radial symmetry,as confirmed by an absolute percentage error analysis(<9.8%).The demonstrated mechanical tuning mechanism provides a practical pathway toward adaptive THz photonic devices,bridging critical gaps in real-world applications ranging from polarization-encoded communications to depthresolved biomedical imaging.
基金supported by the National Key Research and Development Project of China (Nos.2022YFA1404700,2023YFB2806700,and 2021YFA1400802)National Natural Science Foundation of China (Nos.6233000076,12334016,12025402,62125501,11934012,12261131500,92250302,and 62375232)+3 种基金Shenzhen Fundamental Research Project (Nos.JCYJ20210324120402006,JCYJ20220818102218040,and GXWD20220817145518001)University Grants Committee/Research Grants Council of the Hong Kong Special Administrative Region,China (Project No.AoE/P-502/20,CRF Project Nos.C5031-22G and C1015-21E,GRF Project Nos.CityU15303521 and CityU11305223and Germany/Hong Kong Joint Research Scheme:GCityU101/22)Project of City University of Hong Kong (Nos.9380131,9610628,and 7005867).
文摘Metasurfaces,composed of two-dimensional nanostructures,exhibit remarkable capabilities in shaping wavefronts,encompassing phase,amplitude,and polarization.This unique proficiency heralds a transformative paradigm shift in the domain of next-generation optics and photonics,culminating in the development of flat and ultrathin optical devices.Particularly noteworthy is the all-dielectric-based metasurface,leveraging materials such as titanium dioxide,silicon,gallium arsenide,and silicon nitride,which finds extensive application in the design and implementation of high-performance optical devices,owing to its notable advantages,including a high refractive index,low ohmic loss,and cost-effectiveness.Furthermore,the remarkable growth in nanofabrication technologies allows for the exploration of new methods in metasurface fabrication,especially through wafer-scale nanofabrication technologies,thereby facilitating the realization of commercial applications for metasurfaces.This review provides a comprehensive overview of the latest advancements in state-of-the-art fabrication technologies in dielectric metasurface areas.These technologies,including standard nanolithography[e.g.,electron beam lithography(EBL)and focused ion beam(FIB)lithography],advanced nanolithography(e.g.,grayscale and scanning probe lithography),and large-scale nanolithography[e.g.,nanoimprint and deep ultraviolet(DUV)lithography],are utilized to fabricate highresolution,high-aspect-ratio,flexible,multilayer,slanted,and wafer-scale all-dielectric metasurfaces with intricate nanostructures.Ultimately,we conclude with a perspective on current cutting-edge nanofabrication technologies.
基金This work was supported by the National Natural Science Foundation of China under Grant Nos.61871394,61901512,11604167,61625502,11961141010,61975176, 62071423Postdoctoral Innovation Talents Support Program of China under Grant No.BX20190293, Natural Science Foundation of Shaanxi Province under Grant No.2019JQ-013.
文摘Chromatic aberration-free meta-devices(e.g.,achromatic meta-devices and abnormal chromatic meta-devices)play an essential role in modern science and technology.However,current efforts suffer the issues of low efficiency,narrow operating band,and limited wavefront manipulation capability.We propose a general strategy to design chromatic aberration-free meta-devices with high-efficiency and ultrabroadband properties,which is realized by satisfying the key criteria of desirable phase dispersion and high reflection amplitudes at the target frequency interval.The phase dispersion is tuned successfully based on a multiresonant Lorentz model,and high reflection is guaranteed by the presence of the metallic ground.As proof of the concept,two microwave meta-devices are designed,fabricated,and experimentally characterized.An achromatic meta-mirror is proposed within 8 to 12 GHz,and another abnormal chromatic meta-mirror can tune the reflection angle as a linear function.Both meta-mirrors exhibit very high efficiencies(85%to 94%in the frequency band).Our findings open a door to realize chromatic aberration-free meta-devices with high efficiency and wideband properties and stimulate the realizations of chromatic aberration-free metadevices with other functionalities or working at higher frequency.
基金supported by the National Natural Science Foundation of China(Nos.11734007,62192771,and 91850101)National Key Research and Development Program of China(Nos.2017YFA0303504 and 2020YFA0710100)Natural Science Foundation of Shanghai(No.20JC1414601)。
文摘Metasurfaces have exhibited great capabilities to control electromagnetic waves,and many multifunctional metasurfaces were recently proposed.However,although angle-multiplexed meta-devices were successfully realized in reflection geometries,their transmission-mode counterparts are difficult to achieve due to the additional requirements.Here,we design and fabricate a transmissive angle-multiplexed meta-polarizer in the microwave regime based on a multilayer metasurface.Coupled-mode-theory analyses reveal that the device exhibits distinct angle-dependent transmissive responses under excitations with different polarizations,and such differences are further enhanced by multiple scatterings inside the device.Microwave experimental results are in good agreement with numerical simulations and theoretical analyses.
