Metasurfaces,ultrathin metamaterials constructed by planar meta-atoms with tailored electromagnetic(EM)responses,have attracted tremendous attention due to their exotic abilities to freely control EM waves.With active...Metasurfaces,ultrathin metamaterials constructed by planar meta-atoms with tailored electromagnetic(EM)responses,have attracted tremendous attention due to their exotic abilities to freely control EM waves.With active elements incorporated into metasurface designs,one can realize tunable and/or reconfgurable metadevices with functionalities controlled by external stimuli,opening a new platform to dynamically manipulate EM waves.In this article,we briefy review recent progress on tunable/reconfgurable metasurfaces,focusing on their working mechanisms and practical applications.We frst describe available approaches,categorized into diferent classes based on external stimuli applied,to realize homogeneous tunable/reconfgurable metasurfaces,which can ofer uniform manipulations on EM waves.We next summarize recent achievements on inhomogeneous tunable/reconfgurable metasurfaces with constitutional meta-atoms locally tuned by external knobs,which can dynamically control the wave-fronts of EM waves.We conclude this review by presenting our own perspectives on possible future directions and existing challenges in this fast developing feld.展开更多
In the present review,the formation of superhydrophobic(SHP)structures on the surface of Mg alloys was investigated.Different methods including hydrothermal technique,chemical and electrochemical deposition,conversion...In the present review,the formation of superhydrophobic(SHP)structures on the surface of Mg alloys was investigated.Different methods including hydrothermal technique,chemical and electrochemical deposition,conversion and polymer coating,and etching routes were discussed.The superhydrophobicity could form on the surface of Mg alloys by the application of different chemical,electrochemical,and physical methods followed by the immersion of these alloys in the solution containing modifying agents including fatty acids or long-chain molecules.The formed morphology,composition,and contact angle were reported and the effect of synthesis route on these characteristics was reviewed.展开更多
Metasurfaces enable the design of optical elements by engineering the wavefront of light at the subwavelength scale.Due to their ultrathin and compact characteristics,metasurfaces possess great potential to integrate ...Metasurfaces enable the design of optical elements by engineering the wavefront of light at the subwavelength scale.Due to their ultrathin and compact characteristics,metasurfaces possess great potential to integrate multiple functions in optoelectronic systems for optical device miniaturisation.However,current research based on multiplexing in the 2D plane has not fully utilised the capabilities of metasurfaces for multi-tasking applications.Here,we demonstrate a 3D-integrated metasurface device by stacking a hologram metasurface on a monolithic Fabry–Pérot cavity-based colour filter microarray to simultaneously achieve low-crosstalk,polarisation-independent,high-efficiency,full-colour holography,and microprint.The dual functions of the device outline a novel scheme for data recording,security encryption,colour displays,and information processing.Our 3D integration concept can be extended to achieve multi-tasking flat optical systems by including a variety of functional metasurface layers,such as polarizers,metalenses,and others.展开更多
An important Moebius invariant in the theory of Moebius surfaces in S^n inthe so-called Moebius form. In this paper, we give a complete classification of surfaces in S^n withvanishing Moebius form under the Moebius tr...An important Moebius invariant in the theory of Moebius surfaces in S^n inthe so-called Moebius form. In this paper, we give a complete classification of surfaces in S^n withvanishing Moebius form under the Moebius transformation group.展开更多
基金This work was funded by the National Key Research and Development Program of China[Grant Nos.2017YFA0700201 and 2017YFA0303504]National Natural Science Foundation of China[Grant Nos.11734007,91850101,11674068,11874118,and 11474057]Natural Science Foundation of Shanghai[Grant Nos.16ZR1445200,16JC1403100,and 18ZR1403400].
文摘Metasurfaces,ultrathin metamaterials constructed by planar meta-atoms with tailored electromagnetic(EM)responses,have attracted tremendous attention due to their exotic abilities to freely control EM waves.With active elements incorporated into metasurface designs,one can realize tunable and/or reconfgurable metadevices with functionalities controlled by external stimuli,opening a new platform to dynamically manipulate EM waves.In this article,we briefy review recent progress on tunable/reconfgurable metasurfaces,focusing on their working mechanisms and practical applications.We frst describe available approaches,categorized into diferent classes based on external stimuli applied,to realize homogeneous tunable/reconfgurable metasurfaces,which can ofer uniform manipulations on EM waves.We next summarize recent achievements on inhomogeneous tunable/reconfgurable metasurfaces with constitutional meta-atoms locally tuned by external knobs,which can dynamically control the wave-fronts of EM waves.We conclude this review by presenting our own perspectives on possible future directions and existing challenges in this fast developing feld.
文摘In the present review,the formation of superhydrophobic(SHP)structures on the surface of Mg alloys was investigated.Different methods including hydrothermal technique,chemical and electrochemical deposition,conversion and polymer coating,and etching routes were discussed.The superhydrophobicity could form on the surface of Mg alloys by the application of different chemical,electrochemical,and physical methods followed by the immersion of these alloys in the solution containing modifying agents including fatty acids or long-chain molecules.The formed morphology,composition,and contact angle were reported and the effect of synthesis route on these characteristics was reviewed.
基金the financial support of the National Natural Science Foundation of China under contract nos.51722503,51621004 and 11574078.
文摘Metasurfaces enable the design of optical elements by engineering the wavefront of light at the subwavelength scale.Due to their ultrathin and compact characteristics,metasurfaces possess great potential to integrate multiple functions in optoelectronic systems for optical device miniaturisation.However,current research based on multiplexing in the 2D plane has not fully utilised the capabilities of metasurfaces for multi-tasking applications.Here,we demonstrate a 3D-integrated metasurface device by stacking a hologram metasurface on a monolithic Fabry–Pérot cavity-based colour filter microarray to simultaneously achieve low-crosstalk,polarisation-independent,high-efficiency,full-colour holography,and microprint.The dual functions of the device outline a novel scheme for data recording,security encryption,colour displays,and information processing.Our 3D integration concept can be extended to achieve multi-tasking flat optical systems by including a variety of functional metasurface layers,such as polarizers,metalenses,and others.
文摘An important Moebius invariant in the theory of Moebius surfaces in S^n inthe so-called Moebius form. In this paper, we give a complete classification of surfaces in S^n withvanishing Moebius form under the Moebius transformation group.
