Achromatic metalens composed of arrays of subwavelength nanostructures with spatially varying geometries is attractivefor a number of optical applications. However, the limited degree of freedom in the single layer ac...Achromatic metalens composed of arrays of subwavelength nanostructures with spatially varying geometries is attractivefor a number of optical applications. However, the limited degree of freedom in the single layer achromatic metasurfacedesign makes it difficult to simultaneously guarantee the sufficient phase dispersion and high diffraction efficiency,which restricts the achromatic bandwidth and efficiency of metalens. Here we propose and demonstrate a high efficiencyachromatic metalens with diffraction-limited focusing capability at the wavelength ranging from 1000 nm to 1700 nm. Themetalens comprises two stacked nanopillar metasurfaces, by which the required focusing phase and dispersion compensationcan be controlled independently. As a result, in addition to the large achromatic bandwidth, the averaged focusingefficiency of the bilayer metalens is higher than 64% at the near-infrared region. Our design opens up the possibilityto obtain the required phase dispersion and efficiency simultaneously, which is of great significance to design broadbandmetasurface-based optical devices.展开更多
Beam deflectors are important optical elements which can control the propagation direction of the beam in free space.However,with the development of miniaturization of the optical systems,conventional reflector-based ...Beam deflectors are important optical elements which can control the propagation direction of the beam in free space.However,with the development of miniaturization of the optical systems,conventional reflector-based mechanical beam deflectors confront a huge challenge due to their large sizes and incompatibility to the device integration.Here we propose an all-dielectric flat metasurface beam deflector which is composed of a single layer array of TiO_2 nanoantennas resting on a fused-silica substrate.Numerical simulations are performed to demonstrate that the proposed deflectors are able to efficiently deflect the incident beam for different angles with transmission efficiency higher than 80%at visible frequencies.This ultrathin all-dielectric metasurface deflector may have great potential applications in integrated optics.展开更多
Perception of color with our eyes is one of the major sources of information that we gain from our surround-ings.The color of an object depends on which portion of light(range of wavelengths)reaches our eyes.In nature...Perception of color with our eyes is one of the major sources of information that we gain from our surround-ings.The color of an object depends on which portion of light(range of wavelengths)reaches our eyes.In nature,struc-tura1 colors are often caused by the interaction of light with dielectric structures whose dim ensions are on the order of visible-light wavelengths.For example,in beetles,the color is originated from the microstructure of the skin which is acting as scattering center;while in some butterflies,the colorful patterns are routed from the reflection from the top of the wings.Different optical interactions,including multilayer interference,light scattering and photonic crystal eflfect,give rise to selective transmission or reflection of particular light wavelengths.which leads to the generation of structural colors.W ith the consumption of dyes and pigments,recycling of colored discarded m aterials has been a very difficult issue because of the hardships in relation to the dissociation of diverse chemica1 compounds present in the colorant agents.Plasmonic colors therefore draw attention as they enable generation of vivid colors only by geometrical arrange-ment of m etals which not only eases the recycling but also enhances the chemical stability of the colors.Plasm onic colors are structural colors that originate from the interaction between light and metallic nanostructures.Rapid development in nanofabrication and characterization of plasmonic structures provides an efficient way to control light properties at subwavelength scale,which can generate plasmonic structural colors.The engineering of plasmonic colors is a promising rapidly em erging research field that could have a large technological impact.Artiflcia1 surfaces,in particular,on which the colors are generated via a resonant interaction between light and subwavelength metallic nanostructures,have emerged as nanomaterials or metam aterials for the realization of structura1 colors.Here we introduce several representa-tive plasmonic nanostructures which can generate visible structural colors,including nanogratings,perforated metallic film s,metal-insulator-meta1 resonators,dynamically tunable color generators and perfect absorbers.w e highlight the properties of plasmonic colors and discuss the intrinsic plasmonic resonance m echanism s.Plasmonic structural colors have features of sub-diffraction localization,high-fidelity color rendering and rapid responses of external changes,which are believed to offer a promising future in the applications including ultra-high resolution color displaB spectral filtering and sensing,holography,three-dimensiona1 stereoscopic imaging and real-time colors controlling with extremely com-pact device architectures.展开更多
Transparent flow field visualization techniques play a critical role in engineering and scientific applications.They provide a clear and intuitive means to understand fluid dynamics and its complex phenomena,such as l...Transparent flow field visualization techniques play a critical role in engineering and scientific applications.They provide a clear and intuitive means to understand fluid dynamics and its complex phenomena,such as laminar flow,turbulence,and vortices.However,achieving fully two-dimensional quantitative visualization of transparent flow fields under non-invasive conditions remains a significant challenge.Here,we present an approach for achieving flow field visualization by harnessing the synergistic effects of a dielectric metasurface array endowed with photonic spindecoupled capability.This approach enables the simultaneous acquisition of light-field images containing flow field information in two orthogonal dimensions,which allows for the real-time and quantitative derivation of multiple physical parameters.As a proof-of-concept,we experimentally demonstrate the applicability of the proposed visualization technique to various scenarios,including temperature field mapping,gas leak detection,visualization of various fluid physical phenomena,and 3D morphological reconstruction of transparent phase objects.This technique not only establishes an exceptional platform for advancing research in fluid physics,but also exhibits significant potential for broad applications in industrial design and vision.展开更多
Shrinking conventional optical systems to chip-scale dimensions will benefit custom applications in imaging,displaying,sensing,spectroscopy,and metrology.Towards this goal,metasurfaces-planar arrays of subwavelength e...Shrinking conventional optical systems to chip-scale dimensions will benefit custom applications in imaging,displaying,sensing,spectroscopy,and metrology.Towards this goal,metasurfaces-planar arrays of subwavelength electromagnetic structures that collectively mimic the functionality of thicker conventional optical elements-have been exploited at frequencies ranging from the microwave range up to the visible range.Here,we demonstrate highperformance metasurface optical components that operate at ultraviolet wavelengths,including wavelengths down to the record-short deep ultraviolet range,and perform representative wavefront shaping functions,namely,highnumerical-aperture lensing,accelerating beam generation,and hologram projection.The constituent nanostructured elements of the metasurfaces are formed of hafnium oxide-a loss-less,high-refractive-index dielectric material deposited using low-temperature atomic layer deposition and patterned using high-aspect-ratio Damascene lithography.This study opens the way towards low-form factor,multifunctional ultraviolet nanophotonic platforms based on flat optical components,enabling diverse applications including lithography,imaging,spectroscopy,and quantum information processing.展开更多
Metasurface-based imaging has attracted considerable attention owing to its compactness,multifunctionality,and subwavelength coding capability.With the integration of computational imaging techniques,researchers have ...Metasurface-based imaging has attracted considerable attention owing to its compactness,multifunctionality,and subwavelength coding capability.With the integration of computational imaging techniques,researchers have actively explored the extended capabilities of metasurfaces,enabling a wide range of imaging methods.We present an overview of the recent progress in metasurface-based imaging techniques,focusing on the perspective of computational imaging.Specifically,we categorize and review existing metasurface-based imaging into three main groups,including(i)conventional metasurface design employing canonical methods,(ii)computation introduced independently in either the imaging process or postprocessing,and(iii)an end-to-end computation-optimized imaging system based upon metasurfaces.We highlight the advantages and challenges associated with each computational metasurface-based imaging technique and discuss the potential and future prospects of the computational boosted metaimager.展开更多
基金We are grateful for financial supports from National Natural Science Foundation of China(11774163)Fundamental Research Funds for Central Universities.
文摘Achromatic metalens composed of arrays of subwavelength nanostructures with spatially varying geometries is attractivefor a number of optical applications. However, the limited degree of freedom in the single layer achromatic metasurfacedesign makes it difficult to simultaneously guarantee the sufficient phase dispersion and high diffraction efficiency,which restricts the achromatic bandwidth and efficiency of metalens. Here we propose and demonstrate a high efficiencyachromatic metalens with diffraction-limited focusing capability at the wavelength ranging from 1000 nm to 1700 nm. Themetalens comprises two stacked nanopillar metasurfaces, by which the required focusing phase and dispersion compensationcan be controlled independently. As a result, in addition to the large achromatic bandwidth, the averaged focusingefficiency of the bilayer metalens is higher than 64% at the near-infrared region. Our design opens up the possibilityto obtain the required phase dispersion and efficiency simultaneously, which is of great significance to design broadbandmetasurface-based optical devices.
基金supported in part by the National Natural Science Foundation of China under Grant (61575092)support from the Thousand Talents Program for Young Professionals,Collaborative Innovations Center of Advanced Microstructures
文摘Beam deflectors are important optical elements which can control the propagation direction of the beam in free space.However,with the development of miniaturization of the optical systems,conventional reflector-based mechanical beam deflectors confront a huge challenge due to their large sizes and incompatibility to the device integration.Here we propose an all-dielectric flat metasurface beam deflector which is composed of a single layer array of TiO_2 nanoantennas resting on a fused-silica substrate.Numerical simulations are performed to demonstrate that the proposed deflectors are able to efficiently deflect the incident beam for different angles with transmission efficiency higher than 80%at visible frequencies.This ultrathin all-dielectric metasurface deflector may have great potential applications in integrated optics.
文摘Perception of color with our eyes is one of the major sources of information that we gain from our surround-ings.The color of an object depends on which portion of light(range of wavelengths)reaches our eyes.In nature,struc-tura1 colors are often caused by the interaction of light with dielectric structures whose dim ensions are on the order of visible-light wavelengths.For example,in beetles,the color is originated from the microstructure of the skin which is acting as scattering center;while in some butterflies,the colorful patterns are routed from the reflection from the top of the wings.Different optical interactions,including multilayer interference,light scattering and photonic crystal eflfect,give rise to selective transmission or reflection of particular light wavelengths.which leads to the generation of structural colors.W ith the consumption of dyes and pigments,recycling of colored discarded m aterials has been a very difficult issue because of the hardships in relation to the dissociation of diverse chemica1 compounds present in the colorant agents.Plasmonic colors therefore draw attention as they enable generation of vivid colors only by geometrical arrange-ment of m etals which not only eases the recycling but also enhances the chemical stability of the colors.Plasm onic colors are structural colors that originate from the interaction between light and metallic nanostructures.Rapid development in nanofabrication and characterization of plasmonic structures provides an efficient way to control light properties at subwavelength scale,which can generate plasmonic structural colors.The engineering of plasmonic colors is a promising rapidly em erging research field that could have a large technological impact.Artiflcia1 surfaces,in particular,on which the colors are generated via a resonant interaction between light and subwavelength metallic nanostructures,have emerged as nanomaterials or metam aterials for the realization of structura1 colors.Here we introduce several representa-tive plasmonic nanostructures which can generate visible structural colors,including nanogratings,perforated metallic film s,metal-insulator-meta1 resonators,dynamically tunable color generators and perfect absorbers.w e highlight the properties of plasmonic colors and discuss the intrinsic plasmonic resonance m echanism s.Plasmonic structural colors have features of sub-diffraction localization,high-fidelity color rendering and rapid responses of external changes,which are believed to offer a promising future in the applications including ultra-high resolution color displaB spectral filtering and sensing,holography,three-dimensiona1 stereoscopic imaging and real-time colors controlling with extremely com-pact device architectures.
基金support from the Key Research and Development Program of the Ministry of Science and Technology of China(2022YFA1205000)the National Natural Science Foundation of China(12274217,12104225)+2 种基金the Natural Science Foundation of Jiangsu Province(BK20220068)Fundamental Research Funds for the Central UniversitiesThe authors acknowledge the technique support from the microfabrication center of the National Laboratory of Solid-State Microstructures.
文摘Transparent flow field visualization techniques play a critical role in engineering and scientific applications.They provide a clear and intuitive means to understand fluid dynamics and its complex phenomena,such as laminar flow,turbulence,and vortices.However,achieving fully two-dimensional quantitative visualization of transparent flow fields under non-invasive conditions remains a significant challenge.Here,we present an approach for achieving flow field visualization by harnessing the synergistic effects of a dielectric metasurface array endowed with photonic spindecoupled capability.This approach enables the simultaneous acquisition of light-field images containing flow field information in two orthogonal dimensions,which allows for the real-time and quantitative derivation of multiple physical parameters.As a proof-of-concept,we experimentally demonstrate the applicability of the proposed visualization technique to various scenarios,including temperature field mapping,gas leak detection,visualization of various fluid physical phenomena,and 3D morphological reconstruction of transparent phase objects.This technique not only establishes an exceptional platform for advancing research in fluid physics,but also exhibits significant potential for broad applications in industrial design and vision.
基金support from The National Key R&D Program of China(Grant Nos.2017YFA0303700 and 2016YFA0202100)the National Science Foundation of China(Grant No.11774163)+1 种基金support under the Cooperative Research Agreement between the University of Maryland and the National Institute of Standards and Technology(NIST)Physical Measurement Laboratory,Award No.70NANB14H209funding from Huazhong University of Science and Technology.
文摘Shrinking conventional optical systems to chip-scale dimensions will benefit custom applications in imaging,displaying,sensing,spectroscopy,and metrology.Towards this goal,metasurfaces-planar arrays of subwavelength electromagnetic structures that collectively mimic the functionality of thicker conventional optical elements-have been exploited at frequencies ranging from the microwave range up to the visible range.Here,we demonstrate highperformance metasurface optical components that operate at ultraviolet wavelengths,including wavelengths down to the record-short deep ultraviolet range,and perform representative wavefront shaping functions,namely,highnumerical-aperture lensing,accelerating beam generation,and hologram projection.The constituent nanostructured elements of the metasurfaces are formed of hafnium oxide-a loss-less,high-refractive-index dielectric material deposited using low-temperature atomic layer deposition and patterned using high-aspect-ratio Damascene lithography.This study opens the way towards low-form factor,multifunctional ultraviolet nanophotonic platforms based on flat optical components,enabling diverse applications including lithography,imaging,spectroscopy,and quantum information processing.
基金supported by the National Key Research and Development Program of China(Grant Nos.2022YFA1205000 and 2022YFA1207200)the National Natural Science Foundation of China(Grant Nos.12274217,61971465,and 12104225)the Fundamental Research Funds for the Central Universities,China(Grant No.0210-14380184)
文摘Metasurface-based imaging has attracted considerable attention owing to its compactness,multifunctionality,and subwavelength coding capability.With the integration of computational imaging techniques,researchers have actively explored the extended capabilities of metasurfaces,enabling a wide range of imaging methods.We present an overview of the recent progress in metasurface-based imaging techniques,focusing on the perspective of computational imaging.Specifically,we categorize and review existing metasurface-based imaging into three main groups,including(i)conventional metasurface design employing canonical methods,(ii)computation introduced independently in either the imaging process or postprocessing,and(iii)an end-to-end computation-optimized imaging system based upon metasurfaces.We highlight the advantages and challenges associated with each computational metasurface-based imaging technique and discuss the potential and future prospects of the computational boosted metaimager.
