A metasurface hologram combines fine spatial resolution and large viewing angles with a planar form factor and compact size.However,it suffers coherent artifacts originating from electromagnetic cross-talk between clo...A metasurface hologram combines fine spatial resolution and large viewing angles with a planar form factor and compact size.However,it suffers coherent artifacts originating from electromagnetic cross-talk between closely packed meta-atoms and fabrication defects of nanoscale features.Here,we introduce an efficient method to suppress all artifacts by fine-tuning the spatial coherence of illumination.Our method is implemented with a degenerate cavity laser,which allows a precise and continuous tuning of the spatial coherence over a wide range,with little variation in the emission spectrum and total power.We find the optimal degree of spatial coherence to suppress the coherent artifacts of a meta-hologram while maintaining the image sharpness.This work paves the way to compact and dynamical holographic displays free of coherent defects.展开更多
Imaging through scattering medium is challenging but important for different applications.Most advances rely on computational image reconstruction from scattering signals.In these conventional investigations,speckles ...Imaging through scattering medium is challenging but important for different applications.Most advances rely on computational image reconstruction from scattering signals.In these conventional investigations,speckles were always treated as scrambled grainy patterns.Directly seeing through scattering diffusers has never been realized.Here,we report a new strategy to see through random diffusers directly using self-imaging of speckles.By analyzing the physics,a direct observation strategy through scattering media is reported with improved image quality.Using this method,we experimentally demonstrated reconstruction-free real-time imaging of static and moving objects with their actual orientation information under single-wavelength and white light illumination.We also proposed a modified speckle autocorrelation imaging(SAI)method inspired by the self-imaging results.Importantly,our strategy requires no pre-calibration or acquisition of point-spread-function,no active control of wavefronts or complicated equipment,nor iterations or carefully adjusted parameters,paving the way towards rapid and high-quality imaging through scattering diffusers.展开更多
Metasurfaces,composed of two-dimensional nanostructures,exhibit remarkable capabilities in shaping wavefronts,encompassing phase,amplitude,and polarization.This unique proficiency heralds a transformative paradigm shi...Metasurfaces,composed of two-dimensional nanostructures,exhibit remarkable capabilities in shaping wavefronts,encompassing phase,amplitude,and polarization.This unique proficiency heralds a transformative paradigm shift in the domain of next-generation optics and photonics,culminating in the development of flat and ultrathin optical devices.Particularly noteworthy is the all-dielectric-based metasurface,leveraging materials such as titanium dioxide,silicon,gallium arsenide,and silicon nitride,which finds extensive application in the design and implementation of high-performance optical devices,owing to its notable advantages,including a high refractive index,low ohmic loss,and cost-effectiveness.Furthermore,the remarkable growth in nanofabrication technologies allows for the exploration of new methods in metasurface fabrication,especially through wafer-scale nanofabrication technologies,thereby facilitating the realization of commercial applications for metasurfaces.This review provides a comprehensive overview of the latest advancements in state-of-the-art fabrication technologies in dielectric metasurface areas.These technologies,including standard nanolithography[e.g.,electron beam lithography(EBL)and focused ion beam(FIB)lithography],advanced nanolithography(e.g.,grayscale and scanning probe lithography),and large-scale nanolithography[e.g.,nanoimprint and deep ultraviolet(DUV)lithography],are utilized to fabricate highresolution,high-aspect-ratio,flexible,multilayer,slanted,and wafer-scale all-dielectric metasurfaces with intricate nanostructures.Ultimately,we conclude with a perspective on current cutting-edge nanofabrication technologies.展开更多
The design and synthesis of transition metal complexes with high thermal stability in olefin polymerization have become more and more important in order to meet the need of industrial application.This review focuses o...The design and synthesis of transition metal complexes with high thermal stability in olefin polymerization have become more and more important in order to meet the need of industrial application.This review focuses on the transition metal complex catalyst with high thermal stability containing different structures,including the backbone of bis（imino）pyridine,a-diimine and other types of ligands.Besides the catalytic activity,the influence of reaction temperature on the molecular weight and molecular weight distribution of the obtained polymer was also described.The plausible mechanism on the stability of catalysts at high temperature was proposed,which may give guidance to design catalyst with good thermal stability.展开更多
基金supported by the US Office of Naval Research(ONR)under Grant No.N00014-221-1-2026support from National Key Research and Development Program of China(Grant No.2018YFB2200403)+1 种基金National Natural Science Foundation of China(Grant Nos.12025402,11974092,91850204,11934012,and 61975041)Shenzhen Fundamental research projects(Grant Nos.JCYJ20180507184613841,JCYJ20180507183532343,and JCYJ20180306172041577).
文摘A metasurface hologram combines fine spatial resolution and large viewing angles with a planar form factor and compact size.However,it suffers coherent artifacts originating from electromagnetic cross-talk between closely packed meta-atoms and fabrication defects of nanoscale features.Here,we introduce an efficient method to suppress all artifacts by fine-tuning the spatial coherence of illumination.Our method is implemented with a degenerate cavity laser,which allows a precise and continuous tuning of the spatial coherence over a wide range,with little variation in the emission spectrum and total power.We find the optimal degree of spatial coherence to suppress the coherent artifacts of a meta-hologram while maintaining the image sharpness.This work paves the way to compact and dynamical holographic displays free of coherent defects.
文摘Imaging through scattering medium is challenging but important for different applications.Most advances rely on computational image reconstruction from scattering signals.In these conventional investigations,speckles were always treated as scrambled grainy patterns.Directly seeing through scattering diffusers has never been realized.Here,we report a new strategy to see through random diffusers directly using self-imaging of speckles.By analyzing the physics,a direct observation strategy through scattering media is reported with improved image quality.Using this method,we experimentally demonstrated reconstruction-free real-time imaging of static and moving objects with their actual orientation information under single-wavelength and white light illumination.We also proposed a modified speckle autocorrelation imaging(SAI)method inspired by the self-imaging results.Importantly,our strategy requires no pre-calibration or acquisition of point-spread-function,no active control of wavefronts or complicated equipment,nor iterations or carefully adjusted parameters,paving the way towards rapid and high-quality imaging through scattering diffusers.
基金supported by the National Key Research and Development Project of China (Nos.2022YFA1404700,2023YFB2806700,and 2021YFA1400802)National Natural Science Foundation of China (Nos.6233000076,12334016,12025402,62125501,11934012,12261131500,92250302,and 62375232)+3 种基金Shenzhen Fundamental Research Project (Nos.JCYJ20210324120402006,JCYJ20220818102218040,and GXWD20220817145518001)University Grants Committee/Research Grants Council of the Hong Kong Special Administrative Region,China (Project No.AoE/P-502/20,CRF Project Nos.C5031-22G and C1015-21E,GRF Project Nos.CityU15303521 and CityU11305223and Germany/Hong Kong Joint Research Scheme:GCityU101/22)Project of City University of Hong Kong (Nos.9380131,9610628,and 7005867).
文摘Metasurfaces,composed of two-dimensional nanostructures,exhibit remarkable capabilities in shaping wavefronts,encompassing phase,amplitude,and polarization.This unique proficiency heralds a transformative paradigm shift in the domain of next-generation optics and photonics,culminating in the development of flat and ultrathin optical devices.Particularly noteworthy is the all-dielectric-based metasurface,leveraging materials such as titanium dioxide,silicon,gallium arsenide,and silicon nitride,which finds extensive application in the design and implementation of high-performance optical devices,owing to its notable advantages,including a high refractive index,low ohmic loss,and cost-effectiveness.Furthermore,the remarkable growth in nanofabrication technologies allows for the exploration of new methods in metasurface fabrication,especially through wafer-scale nanofabrication technologies,thereby facilitating the realization of commercial applications for metasurfaces.This review provides a comprehensive overview of the latest advancements in state-of-the-art fabrication technologies in dielectric metasurface areas.These technologies,including standard nanolithography[e.g.,electron beam lithography(EBL)and focused ion beam(FIB)lithography],advanced nanolithography(e.g.,grayscale and scanning probe lithography),and large-scale nanolithography[e.g.,nanoimprint and deep ultraviolet(DUV)lithography],are utilized to fabricate highresolution,high-aspect-ratio,flexible,multilayer,slanted,and wafer-scale all-dielectric metasurfaces with intricate nanostructures.Ultimately,we conclude with a perspective on current cutting-edge nanofabrication technologies.
文摘The design and synthesis of transition metal complexes with high thermal stability in olefin polymerization have become more and more important in order to meet the need of industrial application.This review focuses on the transition metal complex catalyst with high thermal stability containing different structures,including the backbone of bis（imino）pyridine,a-diimine and other types of ligands.Besides the catalytic activity,the influence of reaction temperature on the molecular weight and molecular weight distribution of the obtained polymer was also described.The plausible mechanism on the stability of catalysts at high temperature was proposed,which may give guidance to design catalyst with good thermal stability.
