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
Overcoming chromatic aberrations is a vital concern in imaging systems in order to facilitate fullcolor and hyperspectral imaging.By contrast,large dispersion holds opportunities for spectroscopy and tomography.Combin...Overcoming chromatic aberrations is a vital concern in imaging systems in order to facilitate fullcolor and hyperspectral imaging.By contrast,large dispersion holds opportunities for spectroscopy and tomography.Combining both functions into a single component will significantly enhance its versatility.A strategy is proposed to delicately integrate two lenses with a static resonant phase and a switchable geometric phase separately.The former is a metasurface lens with a linear phase dispersion.The latter is composed of liquid crystals(LCs)with space-variant orientations with a phase profile that is frequency independent.By this means,a broadband achromatic focusing from 0.9 to 1.4 THz is revealed.When a saturated bias is applied on LCs,the geometric phase modulation vanishes,leaving only the resonant phase of the metalens.Correspondingly,the device changes from achromatic to dispersive.Furthermore,a metadeflector with tunable dispersion is demonstrated to verify the universality of the proposed method.Our work may pave a way toward active metaoptics,promoting various imaging applications.展开更多
Monochromatic light can be characterized by its three fun dame ntal properties:amplitude,phase,and polarization.In this work,we propose a versatile,transmission-mode all-dielectric metasurface platform that can indepe...Monochromatic light can be characterized by its three fun dame ntal properties:amplitude,phase,and polarization.In this work,we propose a versatile,transmission-mode all-dielectric metasurface platform that can independently manipulate the phase and amplitude for two orthogonal states of polarization in the visible frequency range.For proof-o仁concept experimental demonstration,various single-layer metasurfaces composed of subwavelength-spaced titanium-dioxide nanopillars are designed,fabricated,and characterized to exhibit the ability of polarization-switchable multidimensional light-field manipulation,including polarization-switchable grayscale nanoprinting,nonuniform cylindrical lensing,and complex-amplitude holography.We envision the metasurface platform dem on strated here to open new possibilities toward creating compact multifunctional optical devices for applications in polarization optics,information encoding,optical data storage,and security.展开更多
Corrugated silicon nanocone(SiNC)arrays have been fabricated on a silicon wafer by two polystyrene-sphere-monolayer-masked etching steps in order to create high-performance antireflective coatings.The reflectance was ...Corrugated silicon nanocone(SiNC)arrays have been fabricated on a silicon wafer by two polystyrene-sphere-monolayer-masked etching steps in order to create high-performance antireflective coatings.The reflectance was reduced from above 35%to less than 0.7%in the range 400-1050 nm,and it remained below 0.5%at incidence angles up to 70°at 632.8 nm for both s-and p-polarized light.The fluorinated corrugated SiNC array surface exhibits superhydrophobic properties with a water contact angle of 164°.展开更多
The achievement of functional nanomodules for subcellular label-free measurement has long been pursued in order to fully understand cellular functions.Here,a compact label-free nanosensor based on a fiber taper and zi...The achievement of functional nanomodules for subcellular label-free measurement has long been pursued in order to fully understand cellular functions.Here,a compact label-free nanosensor based on a fiber taper and zinc oxide nanogratings is designed and applied for the early monitoring of apoptosis in individual living cells.Because of its nanoscale dimensions,mechanical flexibility,and minimal cytotoxicity to cells,the sensing module can be loaded in cells for long term in situ tracking with high sensitivity.A gradual increase in the nuclear refractive index during the apoptosis process is observed,revealing the increase in molecular density and the decrease in cell volume.The strategy used in our study not only contributes to the understanding of internal environmental variations during cellular apoptosis but also provides a new platform for nonfluorescent fiber devices for investigation of cellular events and understanding fundamental cell biochemical engineering.展开更多
Close-packed Ag pyramidal arrays have been fabricated by using inverted pyramidal pits on Si as a template and used to generate plentiful and homogeneous surface-enhanced Raman scattering （SERS） hot sites. The sharp...Close-packed Ag pyramidal arrays have been fabricated by using inverted pyramidal pits on Si as a template and used to generate plentiful and homogeneous surface-enhanced Raman scattering （SERS） hot sites. The sharp nanotip and the four edges of the Ag pyramid result in strong electromagnetic field enhancement with an average enhancement factor （EF） of 2.84 × 10^7. Moreover, the features of the close-packed Ag pyramidal array can be well controlled, which allows SERS substrates with good reproducibility to be obtained. The relative standard deviation （RSD） was lower than 8.78% both across a single substrate and different batches of substrates.展开更多
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The authors gratefully acknowledge the support of the National Key Research and Development Program of China(No.2017YFA0303700)the National Natural Science Foundation of China(NSFC)(No.61922038)+1 种基金the Distinguished Young Scholars Fund of Jiangsu Province(No.BK20180004)the Fundamental Research Funds for the Central Universities(No.021014380118).W.H.gratefully acknowledges the support of the Tang Scholar Program.The authors declare no conflicts of interest。
文摘Overcoming chromatic aberrations is a vital concern in imaging systems in order to facilitate fullcolor and hyperspectral imaging.By contrast,large dispersion holds opportunities for spectroscopy and tomography.Combining both functions into a single component will significantly enhance its versatility.A strategy is proposed to delicately integrate two lenses with a static resonant phase and a switchable geometric phase separately.The former is a metasurface lens with a linear phase dispersion.The latter is composed of liquid crystals(LCs)with space-variant orientations with a phase profile that is frequency independent.By this means,a broadband achromatic focusing from 0.9 to 1.4 THz is revealed.When a saturated bias is applied on LCs,the geometric phase modulation vanishes,leaving only the resonant phase of the metalens.Correspondingly,the device changes from achromatic to dispersive.Furthermore,a metadeflector with tunable dispersion is demonstrated to verify the universality of the proposed method.Our work may pave a way toward active metaoptics,promoting various imaging applications.
基金the Key Research and Development Program from Ministry of Science and Technology of China(2017YFA0303700 and 2016YFA0202100)National Natural Science Foundation of China(11774163)+1 种基金Fundamental Research Funds for the Central Universities(0213-14380194).M.L.and T.Xu ack no wledge tech nical support from micro-fabricati on and in teg rati on technology center from Nanji ng Un iversity.W.Z.L.C.and A.A.acknowledge support under the Cooperative Research Agreement between the University of Maryland and the National Institute of Standards and Technology,Award#70-NANB14H209,through the University of Maryland.M.L.,W.Z.and P.H.contributed equally to this work.
文摘Monochromatic light can be characterized by its three fun dame ntal properties:amplitude,phase,and polarization.In this work,we propose a versatile,transmission-mode all-dielectric metasurface platform that can independently manipulate the phase and amplitude for two orthogonal states of polarization in the visible frequency range.For proof-o仁concept experimental demonstration,various single-layer metasurfaces composed of subwavelength-spaced titanium-dioxide nanopillars are designed,fabricated,and characterized to exhibit the ability of polarization-switchable multidimensional light-field manipulation,including polarization-switchable grayscale nanoprinting,nonuniform cylindrical lensing,and complex-amplitude holography.We envision the metasurface platform dem on strated here to open new possibilities toward creating compact multifunctional optical devices for applications in polarization optics,information encoding,optical data storage,and security.
基金This work was supported by the National Natural Science Foundation of China(No.20373019)the Program for New Century Excellent Talents in University,and the National Basic Research Program(Nos.2007CB808003 and 2009CB939701).
文摘Corrugated silicon nanocone(SiNC)arrays have been fabricated on a silicon wafer by two polystyrene-sphere-monolayer-masked etching steps in order to create high-performance antireflective coatings.The reflectance was reduced from above 35%to less than 0.7%in the range 400-1050 nm,and it remained below 0.5%at incidence angles up to 70°at 632.8 nm for both s-and p-polarized light.The fluorinated corrugated SiNC array surface exhibits superhydrophobic properties with a water contact angle of 164°.
基金sponsored by the National Natural Science Foundation of China (Nos. 61925502 and 62135007)
文摘The achievement of functional nanomodules for subcellular label-free measurement has long been pursued in order to fully understand cellular functions.Here,a compact label-free nanosensor based on a fiber taper and zinc oxide nanogratings is designed and applied for the early monitoring of apoptosis in individual living cells.Because of its nanoscale dimensions,mechanical flexibility,and minimal cytotoxicity to cells,the sensing module can be loaded in cells for long term in situ tracking with high sensitivity.A gradual increase in the nuclear refractive index during the apoptosis process is observed,revealing the increase in molecular density and the decrease in cell volume.The strategy used in our study not only contributes to the understanding of internal environmental variations during cellular apoptosis but also provides a new platform for nonfluorescent fiber devices for investigation of cellular events and understanding fundamental cell biochemical engineering.
文摘Close-packed Ag pyramidal arrays have been fabricated by using inverted pyramidal pits on Si as a template and used to generate plentiful and homogeneous surface-enhanced Raman scattering （SERS） hot sites. The sharp nanotip and the four edges of the Ag pyramid result in strong electromagnetic field enhancement with an average enhancement factor （EF） of 2.84 × 10^7. Moreover, the features of the close-packed Ag pyramidal array can be well controlled, which allows SERS substrates with good reproducibility to be obtained. The relative standard deviation （RSD） was lower than 8.78% both across a single substrate and different batches of substrates.
