Phase singularities(PSs)in topological darkness-based sensors have received significant attention in optical sensing due to their rapid,ultra-sensitive,and label-free detection capabilities.Here,we present both experi...Phase singularities(PSs)in topological darkness-based sensors have received significant attention in optical sensing due to their rapid,ultra-sensitive,and label-free detection capabilities.Here,we present both experimental and theoretical investigations of an ultrasensitive and multiplexed phase-sensitive sensor utilizing dual topological PSs in the visible and near-infrared regions.This sensor uses a simple structure,which consists of an ultra-thin highly absorbing film deposited on a metal substrate.We demonstrate the achievement of dual-polarization darkness points for s-and p-polarizations at different incident angles.Furthermore,we theoretically explain the double topological PSs accompanied by a perfect±π-jump near a zero-reflection point,based on the temporal coupled-mode formalism.To validate its multifunctional capabilities,humidity sensing tests were carried out.The results demonstrate that the sensor has a detection limit reaching the level of 0.12‰.These findings go beyond the scope of conventional interference optical coatings and highlight the potential applications of this technology in gas sensing and biosensing domains.展开更多
Microstructure regulation via short-time heat treatment is conducive to the optimization in the microstructure and properties of precipitable magnesium(Mg)alloys,but there is currently a lack of relevant studies.In th...Microstructure regulation via short-time heat treatment is conducive to the optimization in the microstructure and properties of precipitable magnesium(Mg)alloys,but there is currently a lack of relevant studies.In this work,the microstructure evolution of a Mg-RE-Ag alloy during different short-time heat treatments was characterized and discussed.The results show that extreme short-time heat treatment(ESHT,e.g.,2 min)at 450-480℃can greatly increase solute concentration in Mg matrix through the rapid re-dissolution of the second-phase and simultaneously maintain fine grains,while the ESHT at a too high temperature(e.g.,510℃)is not suitable due to excessive grain growth and coarse second phase regenerated at grain boundaries.It is found that 480℃is the approximate critical temperature for appropriate ESHT,and further prolongation of the time will lead to excessive grain growth.It is suggested that in addition to grain boundary migration,grain rotation is activated,resulting in the annihilation of high-angle grain boundaries with relatively low misorientation,as well as the reduction in the ability of the residual second phase to pin grain boundaries.In addition,the reasons for the abnormal grain boundary segregation and grain boundary continuous phase were analyzed from the perspective of interfacial energy.This study provides a basis for effective microstructure regulation of Mg-RE alloys.展开更多
The importance of tunable subwavelength optical devices in modern electromagnetic and photonic systems is indisputable.Herein,a lithography-free,wide-angle,and reconfigurable subwavelength optical device with high tun...The importance of tunable subwavelength optical devices in modern electromagnetic and photonic systems is indisputable.Herein,a lithography-free,wide-angle,and reconfigurable subwavelength optical device with high tunability operating in the near-infrared regions is proposed and experimentally demonstrated,based on a reversible nanochemistry approach.The reconfigurable subwavelength optical device basically comprises an ultrathin copper oxide(CuO)thin film on an optical thick gold substrate by utilizing the reversible chemical conversion of CuO to sulfides upon exposure to hydrogen sulfide gas.Proof-of-concept experimental results show that the maximal modulation depth of reflectance can be as high as 90%at the wavelength of 1.79μm with the initial thickness of CuO taken as 150 nm.Partially reflected wave calculations combined with the transfer matrix method are employed to analytically investigate the optical properties of the structure,which show good agreement with experimental results.We believe that the proposed versatile approaches can be implemented for dynamic control management,allowing applications in tunable photonics,active displays,optical encryption,and gas sensing.展开更多
Fabry-Perot(F-P)nanocavity-type electrochromic devices with multicolor tunability have attracted significant interest in the past two years for their potential uses in a wide variety of applications,such as electronic...Fabry-Perot(F-P)nanocavity-type electrochromic devices with multicolor tunability have attracted significant interest in the past two years for their potential uses in a wide variety of applications,such as electronic display,military camouflage,and dynamic decoration.However,challenges such as insufficient brightness,lengthy switching times,and poor cycling stability have yet to be overcome.Herein,we demonstrate electrochromic electrodes based on ITO/Cu as both the current collector and the reflective layer,with WO_(3 )as the electrochromic material,forming a unique three-layered structure.The constituted WO_(3 )/ITO/Cu films present a high brightness value of about 84%before coloration,and a decent brightness value of 48%after coloration at−0.8V.Moreover,a fast switching time between different coloration states(tc=2.2s;tb=1s)is recorded,attributed to the extremely low sheet resistivity of the ITO/Cu current collector.The films also reveal excellent electrochemical cycling stability across 2000 cycles.展开更多
基金supported by the National Key R&D Program of China(2022YFA1404701)Program of Shanghai Academic Research Leader under Grant(22XD1422100)+4 种基金National Natural Science Foundation of China(62075231,12141303,12073018)Shanghai Science and Technology Committee(20JC1414603,23dz2260100)Shanghai Pujiang Program(21PJ1411400)China Postdoctoral Science Foundation(2021M703335)Young Elite Scientists Sponsorship Program by CAST(YESS20220355).
文摘Phase singularities(PSs)in topological darkness-based sensors have received significant attention in optical sensing due to their rapid,ultra-sensitive,and label-free detection capabilities.Here,we present both experimental and theoretical investigations of an ultrasensitive and multiplexed phase-sensitive sensor utilizing dual topological PSs in the visible and near-infrared regions.This sensor uses a simple structure,which consists of an ultra-thin highly absorbing film deposited on a metal substrate.We demonstrate the achievement of dual-polarization darkness points for s-and p-polarizations at different incident angles.Furthermore,we theoretically explain the double topological PSs accompanied by a perfect±π-jump near a zero-reflection point,based on the temporal coupled-mode formalism.To validate its multifunctional capabilities,humidity sensing tests were carried out.The results demonstrate that the sensor has a detection limit reaching the level of 0.12‰.These findings go beyond the scope of conventional interference optical coatings and highlight the potential applications of this technology in gas sensing and biosensing domains.
基金Project supported by the National Natural Science Foundation of China(52071093,52071175)the Natural Science Foundation of Heilongjiang Province of China(LH2023E059)the Opening Project of Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology(ASMA202205)。
文摘Microstructure regulation via short-time heat treatment is conducive to the optimization in the microstructure and properties of precipitable magnesium(Mg)alloys,but there is currently a lack of relevant studies.In this work,the microstructure evolution of a Mg-RE-Ag alloy during different short-time heat treatments was characterized and discussed.The results show that extreme short-time heat treatment(ESHT,e.g.,2 min)at 450-480℃can greatly increase solute concentration in Mg matrix through the rapid re-dissolution of the second-phase and simultaneously maintain fine grains,while the ESHT at a too high temperature(e.g.,510℃)is not suitable due to excessive grain growth and coarse second phase regenerated at grain boundaries.It is found that 480℃is the approximate critical temperature for appropriate ESHT,and further prolongation of the time will lead to excessive grain growth.It is suggested that in addition to grain boundary migration,grain rotation is activated,resulting in the annihilation of high-angle grain boundaries with relatively low misorientation,as well as the reduction in the ability of the residual second phase to pin grain boundaries.In addition,the reasons for the abnormal grain boundary segregation and grain boundary continuous phase were analyzed from the perspective of interfacial energy.This study provides a basis for effective microstructure regulation of Mg-RE alloys.
基金National Key Research and Development Program of China(2017YFA0205800)National Natural Science Foundation of China(61471345,62075231)+3 种基金Science and Technology Commission of Shanghai Municipality(20JC1414603)Shanghai Municipal Science and Technology Major Project(2019SHZDZX01)Shanghai Innovation Project(2021-cyxt1-kj04)Fundamental Research Funds for the Central Universities.
文摘The importance of tunable subwavelength optical devices in modern electromagnetic and photonic systems is indisputable.Herein,a lithography-free,wide-angle,and reconfigurable subwavelength optical device with high tunability operating in the near-infrared regions is proposed and experimentally demonstrated,based on a reversible nanochemistry approach.The reconfigurable subwavelength optical device basically comprises an ultrathin copper oxide(CuO)thin film on an optical thick gold substrate by utilizing the reversible chemical conversion of CuO to sulfides upon exposure to hydrogen sulfide gas.Proof-of-concept experimental results show that the maximal modulation depth of reflectance can be as high as 90%at the wavelength of 1.79μm with the initial thickness of CuO taken as 150 nm.Partially reflected wave calculations combined with the transfer matrix method are employed to analytically investigate the optical properties of the structure,which show good agreement with experimental results.We believe that the proposed versatile approaches can be implemented for dynamic control management,allowing applications in tunable photonics,active displays,optical encryption,and gas sensing.
基金National Key Research and Development Program of China(2020YFB1505703)This work is supported by the National Natural Science Foundation of China(52172299,22175198,51972331)+2 种基金Z.G.Z would like to acknowledge the support from the External Cooperation Program of the Chinese Academy of Sciences(121E32KYSB20190008)Six Talent Peaks Project of Jiangsu Province(XCL-170).S.C would like to acknowledge the support from the Youth Innovation Promotion Association,CAS(2018356)Outstanding Youth Fund of Jiangxi(20192BCBL23027).
文摘Fabry-Perot(F-P)nanocavity-type electrochromic devices with multicolor tunability have attracted significant interest in the past two years for their potential uses in a wide variety of applications,such as electronic display,military camouflage,and dynamic decoration.However,challenges such as insufficient brightness,lengthy switching times,and poor cycling stability have yet to be overcome.Herein,we demonstrate electrochromic electrodes based on ITO/Cu as both the current collector and the reflective layer,with WO_(3 )as the electrochromic material,forming a unique three-layered structure.The constituted WO_(3 )/ITO/Cu films present a high brightness value of about 84%before coloration,and a decent brightness value of 48%after coloration at−0.8V.Moreover,a fast switching time between different coloration states(tc=2.2s;tb=1s)is recorded,attributed to the extremely low sheet resistivity of the ITO/Cu current collector.The films also reveal excellent electrochemical cycling stability across 2000 cycles.
