Purpose:Currently,different research conclusions exist about the relationship between relational capital and corporate innovation.The research aims to(1)reveal the actual relationship between executive alumni relation...Purpose:Currently,different research conclusions exist about the relationship between relational capital and corporate innovation.The research aims to(1)reveal the actual relationship between executive alumni relations and firm innovation performance,(2)examine the moderating role of executive academic backgrounds,(3)analyze the paths for firms to leverage knowledge spillovers from regional universities to promote firm innovation by their geographic location.Design/methodology/approach:A social network approach is used to construct alumni relationship networks of A-share listed companies in Shanghai and Shenzhen,China.A two-way fixed effects model is used to assess the impact of firms’structural position in executive alumni networks on firms’innovation performance.In addition,the research also delves into the interactions between knowledge spillovers from geographic locations and executives’alumni networks,aiming to elucidate their combined effects on firms’innovation performance.Findings:This paper explores the curvilinear relationship between executive alumni networks’centrality and firm innovation within the Chinese context.It also finds that in the positive effect interval on the right side of the“U-shaped,”the industry with the highest number of occurrences is the high-tech industry.Moreover,it elucidates the moderating influence of executives’academic experience on the alumni networks-innovation nexus,offering a nuanced understanding of these dynamics.Lastly,we provide novel insights into optimizing resource allocation to leverage geographic knowledge spillovers for innovation.Research limitations:The study may not fully represent the broader population of firms,particularly small and medium-sized enterprises(SMEs)or unlisted companies.Future research could expand the sample to include a more diverse range of firms to enhance the generalizability of the findings.Practical implications:Firstly,companies can give due consideration to the alumni resources of executives in their personnel decisions,but they should pay attention to the rational use of resources.Secondly,universities should actively work with companies to promote knowledge transfer and collaboration.Originality/value:The findings help clarify the influence mechanism of firms’innovation performance,providing theoretical support and empirical evidence for firms to drive innovation at the executive alumni relationship network level.展开更多
Metasurfaces,composed of planar arrays of intricately designed meta-atom structures,possess remarkable capabilities in controlling electromagnetic waves in various ways.A critical aspect of metasurface design involves...Metasurfaces,composed of planar arrays of intricately designed meta-atom structures,possess remarkable capabilities in controlling electromagnetic waves in various ways.A critical aspect of metasurface design involves selecting suitable meta-atoms to achieve target functionalities such as phase retardation,amplitude modulation,and polarization conversion.Conventional design processes often involve extensive parameter sweeping,a laborious and computationally intensive task heavily reliant on designer expertise and judgement.Here,we present an efficient genetic algorithm assisted meta-atom optimization method for high-performance metasurface optics,which is compatible to both single-and multiobjective device design tasks.We first employ the method for a single-objective design task and implement a high-efficiency Pancharatnam-Berry phase based metalens with an average focusing efficiency exceeding 80%in the visible spectrum.We then employ the method for a dual-objective metasurface design task and construct an efficient spin-multiplexed structural beam generator.The device is capable of generating zeroth-order and first-order Bessel beams respectively under right-handed and left-handed circular polarized illumination,with associated generation efficiencies surpassing 88%.Finally,we implement a wavelength and spin co-multiplexed four-channel metahologram capable of projecting two spin-multiplexed holographic images under each operational wavelength,with efficiencies over 50%.Our work offers a streamlined and easy-to-implement approach to meta-atom design and optimization,empowering designers to create diverse high-performance and multifunctional metasurface optics.展开更多
Augmented reality(AR)display,which superimposes virtual images on ambient scene,can visually blend the physical world and the digital world and thus opens a new vista for human–machine interaction.AR display is consi...Augmented reality(AR)display,which superimposes virtual images on ambient scene,can visually blend the physical world and the digital world and thus opens a new vista for human–machine interaction.AR display is considered as one of the next-generation display technologies and has been drawing huge attention from both academia and industry.Current AR display systems operate based on a combination of various refractive,reflective,and diffractive optical elements,such as lenses,prisms,mirrors,and gratings.Constrained by the underlying physical mechanisms,these conventional elements only provide limited light-field modulation capability and suffer from issues such as bulky volume and considerable dispersion,resulting in large size,severe chromatic aberration,and narrow field of view of the composed AR display system.Recent years have witnessed the emerging of a new type of optical elements—metasurfaces,which are planar arrays of subwavelength electromagnetic structures that feature an ultracompact footprint and flexible light-field modulation capability,and are widely believed to be an enabling tool for overcoming the limitations faced by current AR displays.Here,we aim to provide a comprehensive review on the recent development of metasurface-enabled AR display technology.We first familiarize readers with the fundamentals of AR display,covering its basic working principle,existing conventional-optics-based solutions,as well as the associated pros and cons.We then introduce the concept of optical metasurfaces,emphasizing typical operating mechanisms,and representative phase modulation methods.We elaborate on three kinds of metasurface devices,namely,metalenses,metacouplers,and metaholograms,which have empowered different forms of AR displays.Their physical principles,device designs,and the performance improvement of the associated AR displays are explained in details.In the end,we discuss the existing challenges of metasurface optics for AR display applications and provide our perspective on future research endeavors.展开更多
Dielectric metasurfaces,composed of planar arrays of subwavelength dielectric structures that collectively mimic the operation of conventional bulk optical elements,have revolutionized the field of optics by their pot...Dielectric metasurfaces,composed of planar arrays of subwavelength dielectric structures that collectively mimic the operation of conventional bulk optical elements,have revolutionized the field of optics by their potential in constructing high-efficiency and multi-functional optoelectronic systems on chip.The performance of a dielectric metasurface is largely determined by its constituent material,which is highly desired to have a high refractive index,low optical loss and wide bandgap,and at the same time,be fabrication friendly.Here,we present a new material platform based on tantalum pentoxide(Ta2O5)for implementing high-performance dielectric metasurface optics over the ultraviolet and visible spectral region.This wide-bandgap dielectric,exhibiting a high refractive index exceeding 2.1 and negligible extinction coefficient across a broad spectrum,can be easily deposited over large areas with good quality using straightforward physical vapor deposition,and patterned into high-aspect-ratio subwavelength nanostructures through commonly-available fluorine-gas-based reactive ion etching.We implement a series of highefficiency ultraviolet and visible metasurfaces with representative light-field modulation functionalities including polarization-independent high-numerical-aperture lensing,spin-selective hologram projection,and vivid structural color generation,and the devices exhibit operational efficiencies up to 80%.Our work overcomes limitations faced by scalability of commonly-employed metasurface dielectrics and their operation into the visible and ultraviolet spectral range,and provides a novel route towards realization of high-performance,robust and foundry-manufacturable metasurface optics.展开更多
Dielectric nanostructures are widely embraced in the field of structural color design due to their low-cost characteristics,enabling sub-micron scale color printing.However,challenges still exist in the selection of s...Dielectric nanostructures are widely embraced in the field of structural color design due to their low-cost characteristics,enabling sub-micron scale color printing.However,challenges still exist in the selection of structures and image encryption.In this study,we propose a method for printing dual patterns using tailored scattering structures based on two-photon polymerization.We extensively analyze the color performance of each structure in zeroth-order diffraction under cross-polarized transmission and bright-field transmission illumination.By selecting appropriate structures based on their characteristics,we prepared full-color panels and successfully utilized these panels to print both color patterns and dual patterns,achieving multi-level control of color and information.Based on the above study,a large-sale color pattern with a hidden message in an area of 3.2 cm×2.4 cm is printed,which can be directly observed.Our results demonstrate a sustainable and eco-friendly approach to color preparation,offering innovative strategies and methods for the fields of color science and steganography for information security.展开更多
基金supported in part by the National Natural Science Foundation of China under Grant No.72264036,in part by the West Light Foundation of The Chinese Academy of Sciences under Grant No.2020-XBQNXZ-020Xinjiang University of Finance and Economics Postgraduate Innovation Project XJUFE2024K036.
文摘Purpose:Currently,different research conclusions exist about the relationship between relational capital and corporate innovation.The research aims to(1)reveal the actual relationship between executive alumni relations and firm innovation performance,(2)examine the moderating role of executive academic backgrounds,(3)analyze the paths for firms to leverage knowledge spillovers from regional universities to promote firm innovation by their geographic location.Design/methodology/approach:A social network approach is used to construct alumni relationship networks of A-share listed companies in Shanghai and Shenzhen,China.A two-way fixed effects model is used to assess the impact of firms’structural position in executive alumni networks on firms’innovation performance.In addition,the research also delves into the interactions between knowledge spillovers from geographic locations and executives’alumni networks,aiming to elucidate their combined effects on firms’innovation performance.Findings:This paper explores the curvilinear relationship between executive alumni networks’centrality and firm innovation within the Chinese context.It also finds that in the positive effect interval on the right side of the“U-shaped,”the industry with the highest number of occurrences is the high-tech industry.Moreover,it elucidates the moderating influence of executives’academic experience on the alumni networks-innovation nexus,offering a nuanced understanding of these dynamics.Lastly,we provide novel insights into optimizing resource allocation to leverage geographic knowledge spillovers for innovation.Research limitations:The study may not fully represent the broader population of firms,particularly small and medium-sized enterprises(SMEs)or unlisted companies.Future research could expand the sample to include a more diverse range of firms to enhance the generalizability of the findings.Practical implications:Firstly,companies can give due consideration to the alumni resources of executives in their personnel decisions,but they should pay attention to the rational use of resources.Secondly,universities should actively work with companies to promote knowledge transfer and collaboration.Originality/value:The findings help clarify the influence mechanism of firms’innovation performance,providing theoretical support and empirical evidence for firms to drive innovation at the executive alumni relationship network level.
基金support from the National Science Foundation of China(Grant Nos.62075078 and 62135004)the Knowledge Innovation Program of Wuhan-Shuguang Project(Grant No.2022010801020095).
文摘Metasurfaces,composed of planar arrays of intricately designed meta-atom structures,possess remarkable capabilities in controlling electromagnetic waves in various ways.A critical aspect of metasurface design involves selecting suitable meta-atoms to achieve target functionalities such as phase retardation,amplitude modulation,and polarization conversion.Conventional design processes often involve extensive parameter sweeping,a laborious and computationally intensive task heavily reliant on designer expertise and judgement.Here,we present an efficient genetic algorithm assisted meta-atom optimization method for high-performance metasurface optics,which is compatible to both single-and multiobjective device design tasks.We first employ the method for a single-objective design task and implement a high-efficiency Pancharatnam-Berry phase based metalens with an average focusing efficiency exceeding 80%in the visible spectrum.We then employ the method for a dual-objective metasurface design task and construct an efficient spin-multiplexed structural beam generator.The device is capable of generating zeroth-order and first-order Bessel beams respectively under right-handed and left-handed circular polarized illumination,with associated generation efficiencies surpassing 88%.Finally,we implement a wavelength and spin co-multiplexed four-channel metahologram capable of projecting two spin-multiplexed holographic images under each operational wavelength,with efficiencies over 50%.Our work offers a streamlined and easy-to-implement approach to meta-atom design and optimization,empowering designers to create diverse high-performance and multifunctional metasurface optics.
基金would like to acknowl-edge the support of the National Natural Science Foundation of China(NSFC)(Grant Nos.62075078 and 62135004)support of the Knowledge Innovation Program of Wuhan-Shuguang Project(Grant No.2022010801020095).Z.L.would like to acknowledge the support of the NSFC(Grant No.62205113)the China Postdoctoral Science Foundation(Grant No.2022M721244).
文摘Augmented reality(AR)display,which superimposes virtual images on ambient scene,can visually blend the physical world and the digital world and thus opens a new vista for human–machine interaction.AR display is considered as one of the next-generation display technologies and has been drawing huge attention from both academia and industry.Current AR display systems operate based on a combination of various refractive,reflective,and diffractive optical elements,such as lenses,prisms,mirrors,and gratings.Constrained by the underlying physical mechanisms,these conventional elements only provide limited light-field modulation capability and suffer from issues such as bulky volume and considerable dispersion,resulting in large size,severe chromatic aberration,and narrow field of view of the composed AR display system.Recent years have witnessed the emerging of a new type of optical elements—metasurfaces,which are planar arrays of subwavelength electromagnetic structures that feature an ultracompact footprint and flexible light-field modulation capability,and are widely believed to be an enabling tool for overcoming the limitations faced by current AR displays.Here,we aim to provide a comprehensive review on the recent development of metasurface-enabled AR display technology.We first familiarize readers with the fundamentals of AR display,covering its basic working principle,existing conventional-optics-based solutions,as well as the associated pros and cons.We then introduce the concept of optical metasurfaces,emphasizing typical operating mechanisms,and representative phase modulation methods.We elaborate on three kinds of metasurface devices,namely,metalenses,metacouplers,and metaholograms,which have empowered different forms of AR displays.Their physical principles,device designs,and the performance improvement of the associated AR displays are explained in details.In the end,we discuss the existing challenges of metasurface optics for AR display applications and provide our perspective on future research endeavors.
基金the National Institute of Standards and Technology(NIST)Physical Measurement Laboratory,Award No.70NANB14H209,through the University of Maryland.O.K.was supported by an appointment to the Intelligence Community Postdoctoral Research Fellowship Program at NIST administered by Oak Ridge Institute for Science and Education(ORISE)through an interagency agreement between the U.S.Department of Energy and the Office of the Director of National Intelligence(ODNI).
文摘Dielectric metasurfaces,composed of planar arrays of subwavelength dielectric structures that collectively mimic the operation of conventional bulk optical elements,have revolutionized the field of optics by their potential in constructing high-efficiency and multi-functional optoelectronic systems on chip.The performance of a dielectric metasurface is largely determined by its constituent material,which is highly desired to have a high refractive index,low optical loss and wide bandgap,and at the same time,be fabrication friendly.Here,we present a new material platform based on tantalum pentoxide(Ta2O5)for implementing high-performance dielectric metasurface optics over the ultraviolet and visible spectral region.This wide-bandgap dielectric,exhibiting a high refractive index exceeding 2.1 and negligible extinction coefficient across a broad spectrum,can be easily deposited over large areas with good quality using straightforward physical vapor deposition,and patterned into high-aspect-ratio subwavelength nanostructures through commonly-available fluorine-gas-based reactive ion etching.We implement a series of highefficiency ultraviolet and visible metasurfaces with representative light-field modulation functionalities including polarization-independent high-numerical-aperture lensing,spin-selective hologram projection,and vivid structural color generation,and the devices exhibit operational efficiencies up to 80%.Our work overcomes limitations faced by scalability of commonly-employed metasurface dielectrics and their operation into the visible and ultraviolet spectral range,and provides a novel route towards realization of high-performance,robust and foundry-manufacturable metasurface optics.
基金Natural Science Foundation of Heilongjiang Province(LH2022F017)Science and Technology Commission of Shanghai Municipality(SKLSFO2022-01,SKLSFO2022-03)+4 种基金State Key Laboratory of Advanced Optical Communication Systems and Networks(Shanghai Jiao Tong University,2023GZKF022)Henan Key Laboratory of Laser and Opto-electric Information Technology(JG2023-RF01)Exchange Project for Key Lab of Optical Fiber Sensing and Communications(Ministry of Education of China)National Natural Science Foundation of China(62075078,62135004,62174073)Knowledge Innovation Program of Wuhan-Shuguang Project(2022010801020095).
文摘Dielectric nanostructures are widely embraced in the field of structural color design due to their low-cost characteristics,enabling sub-micron scale color printing.However,challenges still exist in the selection of structures and image encryption.In this study,we propose a method for printing dual patterns using tailored scattering structures based on two-photon polymerization.We extensively analyze the color performance of each structure in zeroth-order diffraction under cross-polarized transmission and bright-field transmission illumination.By selecting appropriate structures based on their characteristics,we prepared full-color panels and successfully utilized these panels to print both color patterns and dual patterns,achieving multi-level control of color and information.Based on the above study,a large-sale color pattern with a hidden message in an area of 3.2 cm×2.4 cm is printed,which can be directly observed.Our results demonstrate a sustainable and eco-friendly approach to color preparation,offering innovative strategies and methods for the fields of color science and steganography for information security.
