Although metasurfaces have shown great potential for manipulating light,most previously realized meta-devices suffer from uncontrolled angular dispersions,making them unfavorable for many applications.Here,we propose ...Although metasurfaces have shown great potential for manipulating light,most previously realized meta-devices suffer from uncontrolled angular dispersions,making them unfavorable for many applications.Here,we propose a general strategy to realize optical metasurfaces with desired angular dispersions based on carefully controlling both the near-field couplings between meta-atoms and the radiation pattern of a single meta-atom.Utilizing such a strategy,we experimentally demonstrate a series of optical meta-devices with predesigned angular dispersions,including two incident-angle-insensitive absorbers,one incident-angle-selective absorber,and one multifunctional meta-polarizer whose functionality changes from a perfect mirror to a half-waveplate as the excitation angle varies.Finally,we design a gradient meta-device using meta-atom arrays with purposely controlled angular dispersions and numerically demonstrate that it can exhibit distinct wavefront-control functionalities when illuminated at different incident angles.Our findings establish a new platform for achieving angle-multiplexed functional meta-devices,significantly expanding the wave-manipulation capabilities of optical metasurfaces.展开更多
Nonlinear metasurfaces and photonic crystals provide a significant way to generate and manipulate nonlinear signals owing to the resonance-and symmetry-based light-matter interactions supported by the artificial struc...Nonlinear metasurfaces and photonic crystals provide a significant way to generate and manipulate nonlinear signals owing to the resonance-and symmetry-based light-matter interactions supported by the artificial structures.However,the nonlinear conversion efficiency is generally limited by the angular dispersion of optical resonances especially in nonparaxial photonics.Here,we propose a metagrating realizing a quasi-bound-state in the continuum in a flat band to dramatically improve the third harmonic generation(THG)efficiency.A superior operating angular range is achieved based on the interlayer and intralayer couplings,which are introduced by breaking the mirror symmetry of the metagrating.We demonstrate the relation of angular dispersion between the nonlinear and linear responses at different incident angles.We also elucidate the mechanism of these offaxis flat-band-based nonlinear conversions through different mode decomposition.Our scheme provides a robust and analytical way for nonparaxial nonlinear generation and paves the way for further applications such as wide-angle nonlinear information transmission and enhanced nonlinear generation under tight focusing.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
The linear angular dispersion of a self-diffraction(SD) pulse, from a femtosecond laser pulse cleaning device, is compensated for by the use of a single prism. More than 500 μJ first-order SD pulse has a contrast of ...The linear angular dispersion of a self-diffraction(SD) pulse, from a femtosecond laser pulse cleaning device, is compensated for by the use of a single prism. More than 500 μJ first-order SD pulse has a contrast of 1012, which is about five orders of magnitude improvement from the input fundamental pulse. The wings of the distribution away from the main pulse in ±1 ps are cleaned with a contrast improvement of about 107, which verifies the pulse cleaning ability of the SD process.展开更多
Three coupling coefficients are defined to describe spatiotemporal coupling in ultrashort pulses. With these coupling coefficients, the first-order spatiotemporal couplings of Gaussian pulse and beam are described ana...Three coupling coefficients are defined to describe spatiotemporal coupling in ultrashort pulses. With these coupling coefficients, the first-order spatiotemporal couplings of Gaussian pulse and beam are described analytically. Also, the first-order and the second-order spatiotemporal couplings caused by angular dispersion elements are studied using these coupling coefficients. It can be shown that these coupling coefficients are dimensionless and normalized, and readily indicate the severity of spatiotemporal coupling.展开更多
基金funded by the National Natural Science Foundation of China(Nos.91850101,11734007,11674068,and 11874118)the National Key Research and Development Program of China(Nos.2017YFA0303504 and 2017YFA0700201)+2 种基金the Natural Science Foundation of Shanghai(No.18ZR1403400)the Fudan University-CIOMP Joint Fund(No.FC2018-006)the technical support from the Fudan Nanofabrication Laboratory for sample fabrication.
文摘Although metasurfaces have shown great potential for manipulating light,most previously realized meta-devices suffer from uncontrolled angular dispersions,making them unfavorable for many applications.Here,we propose a general strategy to realize optical metasurfaces with desired angular dispersions based on carefully controlling both the near-field couplings between meta-atoms and the radiation pattern of a single meta-atom.Utilizing such a strategy,we experimentally demonstrate a series of optical meta-devices with predesigned angular dispersions,including two incident-angle-insensitive absorbers,one incident-angle-selective absorber,and one multifunctional meta-polarizer whose functionality changes from a perfect mirror to a half-waveplate as the excitation angle varies.Finally,we design a gradient meta-device using meta-atom arrays with purposely controlled angular dispersions and numerically demonstrate that it can exhibit distinct wavefront-control functionalities when illuminated at different incident angles.Our findings establish a new platform for achieving angle-multiplexed functional meta-devices,significantly expanding the wave-manipulation capabilities of optical metasurfaces.
基金supported by the National Key Research and Development Program of China(Grant Nos.2021YFA1400601,and 2022YFA1404501)the National Natural Science Fund for Distinguished Young Scholar(Grant No.11925403)the National Natural Science Foundation of China(Grant Nos.12122406,12192253,12274239,12274237,and U22A20258)。
文摘Nonlinear metasurfaces and photonic crystals provide a significant way to generate and manipulate nonlinear signals owing to the resonance-and symmetry-based light-matter interactions supported by the artificial structures.However,the nonlinear conversion efficiency is generally limited by the angular dispersion of optical resonances especially in nonparaxial photonics.Here,we propose a metagrating realizing a quasi-bound-state in the continuum in a flat band to dramatically improve the third harmonic generation(THG)efficiency.A superior operating angular range is achieved based on the interlayer and intralayer couplings,which are introduced by breaking the mirror symmetry of the metagrating.We demonstrate the relation of angular dispersion between the nonlinear and linear responses at different incident angles.We also elucidate the mechanism of these offaxis flat-band-based nonlinear conversions through different mode decomposition.Our scheme provides a robust and analytical way for nonparaxial nonlinear generation and paves the way for further applications such as wide-angle nonlinear information transmission and enhanced nonlinear generation under tight focusing.
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.
基金supported by the National Natural Science Foundation of China(NSFC)(Nos.11274327,61521093,and 61527821)the Instrument Developing Project of the Chinese Academy of Sciences(No.YZ201538)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB16)
文摘The linear angular dispersion of a self-diffraction(SD) pulse, from a femtosecond laser pulse cleaning device, is compensated for by the use of a single prism. More than 500 μJ first-order SD pulse has a contrast of 1012, which is about five orders of magnitude improvement from the input fundamental pulse. The wings of the distribution away from the main pulse in ±1 ps are cleaned with a contrast improvement of about 107, which verifies the pulse cleaning ability of the SD process.
基金supported by the Program for New Century Excellent Talents in University(NCET),China(Grant No.NCET-05-0784)
文摘Three coupling coefficients are defined to describe spatiotemporal coupling in ultrashort pulses. With these coupling coefficients, the first-order spatiotemporal couplings of Gaussian pulse and beam are described analytically. Also, the first-order and the second-order spatiotemporal couplings caused by angular dispersion elements are studied using these coupling coefficients. It can be shown that these coupling coefficients are dimensionless and normalized, and readily indicate the severity of spatiotemporal coupling.
