Optical whispering gallery mode （WGM） microresonators have attracted great attention due to their remarkable proper- ties such as extremely high quality factor, small mode volume, tight confinement of modes, and str...Optical whispering gallery mode （WGM） microresonators have attracted great attention due to their remarkable proper- ties such as extremely high quality factor, small mode volume, tight confinement of modes, and strong evanescent field. All these properties of WGM microresonators have ensured their great potentials for applications, such as physical sen- sors, bio/chemical sensors and microlasers. In this mini-review, the key parameters and coupling conditions of WGM microresonators are firstly introduced. The geometries of WGM optical microcavities are presented based on their fabri- cation methods. This is followed by the discussion on the state-of-the-art applications of WGM microresonators in sen- sors and microlasers.展开更多
Transition metal oxides hold great promise for lithium-ion batteries(LIBs)and electrocatalytic water splitting because of their high abundance and high energy density.However,designing and fabrication of efficient,sta...Transition metal oxides hold great promise for lithium-ion batteries(LIBs)and electrocatalytic water splitting because of their high abundance and high energy density.However,designing and fabrication of efficient,stable,high power density electrode materials are challenging.Herein,we report rambutan-like hollow carbon spheres formed by carbon nanosheet decorated with nickel oxide(NiO)rich inmetal vacancies(denoted as h-NiO/C)as a bifunctional electrode material for LIBs and electrocatalytic oxygen evolution reaction(OER).When being used as the anode of LIBs,the h-NiO/C electrode shows a large initial capacity of 885mAh g−1,a robust stability with a high capacity of 817mAh g−1 after 400 cycles,and great rate capability with a high reversible capacity of 523mAh g−1 at 10Ag−1 after 600 cycles.Moreover,working as an OER electrocatalyst,the h-NiO/C electrode shows a small overpotential of 260mV at 10mAcm−2,a Tafel slope of 37.6mVdec−1 along with good stability.Our work offers a cost-effective method for the fabrication of efficient electrode for LIBs and OER.展开更多
The rapid advancement of renewable energy technologies is essential for combating global climate change and achieving energy sustainability.Among the various renewable sources,solar energy stands out,with silicon play...The rapid advancement of renewable energy technologies is essential for combating global climate change and achieving energy sustainability.Among the various renewable sources,solar energy stands out,with silicon playing a pivotal role in solar energy conversion.However,traditional silicon-based devices often face challenges due to high surface reflectance,which limits their efficiency.The emergence of black silicon(b-Si)offers a transformative solution,thanks to its micro-and nanoscale structures that provide ultra-low reflectivity and enhanced light absorption.This makes b-Si an ideal candidate for improving solar energy devices.Beyond solar energy applications,b-Si has drawn notable interest in photonics,including applications in photodetectors,surface-enhanced Raman scattering,and imaging.This review explores b-Si comprehensively,discussing its fabrication processes,distinctive properties,and contributions to both solar energy conversion and photonic technologies.Key topics include its roles in solar cells,photoelectrochemical systems,solar thermal energy conversion,and advanced photonic devices.Furthermore,the review addresses the challenges and future directions for optimizing b-Si to facilitate its practical deployment across a range of energy and photonic applications.展开更多
The Sabatier principle—which states that the best catalyst should be at the peak of the volcano plot,with neither too strong nor too weak intermediate binding strength—plays the golden rule in designing highly activ...The Sabatier principle—which states that the best catalyst should be at the peak of the volcano plot,with neither too strong nor too weak intermediate binding strength—plays the golden rule in designing highly active electrocatalysts.For instance,Pt with a“just right”hydrogen adsorption free energy(ΔG_(H^(*))=~0 eV)is the most efficient catalyst for hydrogen evolution reaction(HER).^(1)Nevertheless,the pressing demand for renewable energy has sparked a quest beyond the top of the volcano plot,driving the innovation towards more effective,economical.展开更多
Pyroelectric(PE)detection technologies have attracted extensive attention due to the cooling-free,bias-free,and broadband properties.However,the PE signals are generated by the continuous energy conversion processes f...Pyroelectric(PE)detection technologies have attracted extensive attention due to the cooling-free,bias-free,and broadband properties.However,the PE signals are generated by the continuous energy conversion processes from light,heat,to electricity,normally leading to very slow response speeds.Herein,we design and fabricate a PE detector which shows extremely fast response in near-infrared(NIR)band by combining with the inhomogeneous plasmonic metasurface.The plasmonic effect dramatically accelerates the light-heat conversion process,unprecedentedly improving the NIR response speed by 2−4 orders of magnitude to 22μs,faster than any reported infrared(IR)PE detector.We also innovatively introduce the concept of time resolution into the field of PE detection,which represents the detector’s ability to distinguish multiple fast-moving targets.Furthermore,the spatially inhomogeneous design overcomes the traditional narrowband constraint of plasmonic systems and thus ensures a wideband response from visible to NIR.This study provides a promising approach to develop next-generation IR PE detectors with ultrafast and broadband responses.展开更多
Nonlinear optical activities,especially second harmonic generation(SHG),are key phenomena in inversion-symmetrybroken two-dimensional(2D)transition metal dichalcogenides(TMDCs).On the other hand,anisotropic nonlinear ...Nonlinear optical activities,especially second harmonic generation(SHG),are key phenomena in inversion-symmetrybroken two-dimensional(2D)transition metal dichalcogenides(TMDCs).On the other hand,anisotropic nonlinear optical processes are important for unique applications in nano-nonlinear photonic devices with polarization functions,having become one of focused research topics in the field of nonlinear photonics.However,the strong nonlinearity and strong optical anisotropy do not exist simultaneously in common 2D materials.Here,we demonstrate strong secondorder and third-order susceptibilities of 64 pm/V and 6.2×10^(-19)m^(2)/V^(2),respectively,in the even-layer PdPSe,which has not been discovered in other common TMDCs(e.g.,MoS2).Strikingly,it also simultaneously exhibited strong SHG anisotropy with an anisotropic ratio of~45,which is the largest reported among all 2D materials to date,to the best of our knowledge.In addition,the SHG anisotropy ratio can be harnessed from 0.12 to 45(375 times)by varying the excitation wavelength due to the dispersion ofχ^(2)values.As an illustrative example,we further demonstrate polarized SHG imaging for potential applications in crystal orientation identification and polarization-dependent spatial encoding.These findings in 2D PdPSe are promising for nonlinear nanophotonic and optoelectronic applications.展开更多
Two-dimensional transition metal dichalcogenides(2D TMDs)are promising as sensing materials for flexible electronics and wearable systems in artificial intelligence,tele-medicine,and internet of things(IoT).Currently,...Two-dimensional transition metal dichalcogenides(2D TMDs)are promising as sensing materials for flexible electronics and wearable systems in artificial intelligence,tele-medicine,and internet of things(IoT).Currently,the study of 2D TMDs-based flexible strain sensors mainly focuses on improving the performance of sensitivity,response,detection resolution,cyclic stability,and so on.There are few reports on power consumption despite that it is of significant importance for wearable electronic systems.It is still challenging to effectively reduce the power consumption for prolonging the endurance of electronic systems.Herein,we propose a novel approach to realize ultra-low power consumption strain sensors by reducing the contact resistance between metal electrodes and 2D MoS_(2).A dendritic bilayer MoS_(2) has been designed and synthesized by a modified CVD method.Large-area edge contact has been introduced in the dendritic MoS_(2),resulting in decreased the contact resistance significantly.The contact resistance can be down to 5.4 kΩμm,which is two orders of magnitude lower than the conventional MoS_(2) devices.We fabricate a flexible strain sensor,exhibiting superior sensitivity in detecting strains with high resolution(0.04%)and an ultra-low power consumption(33.0 pW).This study paves the way for future wearable and flexible sensing electronics with high sensitivity and ultra-low power consumption.展开更多
Achieving strong coupling between plasmonic oscillators can significantly modulate their intrinsic optical properties.Here,we report the direct observation of ultrafast plasmonic hot electron transfer from an Au grati...Achieving strong coupling between plasmonic oscillators can significantly modulate their intrinsic optical properties.Here,we report the direct observation of ultrafast plasmonic hot electron transfer from an Au grating array to an MoS_(2) monolayer in the strong coupling regime between localized surface plasmons(LSPs)and surface plasmon polaritons(SPPs).By means of femtosecond pump-probe spectroscopy,the measured hot electron transfer time is approximately 40 fs with a maximum external quantum yield of 1.65%.Our results suggest that strong coupling between LSPs and SPPs has synergetic effects on the generation of plasmonic hot carriers,where SPPs with a unique nonradiative feature can act as an‘energy recycle bin’to reuse the radiative energy of LSPs and contribute to hot carrier generation.Coherent energy exchange between plasmonic modes in the strong coupling regime can further enhance the vertical electric field and promote the transfer of hot electrons between the Au grating and the MoS_(2) monolayer.Our proposed plasmonic strong coupling configuration overcomes the challenge associated with utilizing hot carriers and is instructive in terms of improving the performance of plasmonic opto-electronic devices.展开更多
The evolution of soliton molecules emphasizes the complex soliton dynamics akin to matter molecules.Beyond the simplest soliton molecule-a soliton pair constituted by two bound pulses-soliton molecules with more const...The evolution of soliton molecules emphasizes the complex soliton dynamics akin to matter molecules.Beyond the simplest soliton molecule-a soliton pair constituted by two bound pulses-soliton molecules with more constituents have more degrees of freedom because of the temporal pulse separations and relative phases.Here we detailedly characterize the transient dynamics of soliton triplets in fiber lasers by using the dispersive Fourier transform measurement.A particular form of leading,central,and tailing pulses is constructed to shed new light on more intriguing scenarios and fuel the molecular analogy.Especially the vibrating dynamics of the central and tailing pulses are captured near the regime of equally spaced soliton triplets,which is reminiscent of the recurrent timing jitters within multi-pulse structures.Further insights enable acess into a universal form of unequally spaced soliton triplets interpreted as 2+1 soliton molecules.Different binding strengths of intramo-lecular and intermolecular bonds are validated with respect to the diverse internal motions involved in this soliton triplet molcule.All these findings unveil the transient dynamics with more degrees of freedom as well as highlight the possible application for all-optical bit storage.展开更多
Elastic and stretchable functional fibers have drawn attentions from wide research field because of their unique advantages including high dynamic bending elasticity,stretchability and high mechanic strength.Lots of e...Elastic and stretchable functional fibers have drawn attentions from wide research field because of their unique advantages including high dynamic bending elasticity,stretchability and high mechanic strength.Lots of efforts have been made to find promising soft materials and improve the processing methods to fabricate the elastomer fibers with controllable fiber geometries and designable functionalities.Significant progress has been made and various interdisciplinary applications have been demonstrated based on their unique mechanical performance.A series of remarkable applications,involving biomedicine,optics,electronics,human machine interfaces etc.,have been successfully achieved.Here,we summarize main processing methods to fabricate soft and stretchable functional fibers using different types of elastic materials,which are either widely used or specifically developed.We also introduce some representative applications of multifunctional elastic fibers to reveal this promising research area.All these reported applications indicate that the fast innovated interdisciplinary area is of great potential and inspire more remarkable ideas in fiber sensing,soft electronics,functional fiber integration and other related research fields.展开更多
Our theoretical findings demonstrate for the first time a possibility of band-gap engineering of monolayer MoS2 crystals by oxygen and the presence of vacancies. Oxygen atoms are revealed to substitute sulfur ones, fo...Our theoretical findings demonstrate for the first time a possibility of band-gap engineering of monolayer MoS2 crystals by oxygen and the presence of vacancies. Oxygen atoms are revealed to substitute sulfur ones, forming stable MoS2-xOx ternary compounds, or adsorb on top of the sulfur atoms. The substituting oxygen provides a decrease of the band gap from 1.86 to 1.64 eV and transforms the material from a direct-gap to an indirect-gap semiconductor. The surface adsorbed oxygen atoms decrease the band gap up to 0.98 eV depending on their location tending to the metallic character of the electron energy bands at a high concentration of the adsorbed atoms. Oxygen plasma processing is proposed as an effective technology for such band-gap modifications.展开更多
Super-oscillation is a counterintuitive phenomenon describing localized fast variations of functions and fields that happen at frequencies higher than the highest Fourier component of their spectra.The physical implic...Super-oscillation is a counterintuitive phenomenon describing localized fast variations of functions and fields that happen at frequencies higher than the highest Fourier component of their spectra.The physical implications of this effect have been studied in information theory and optics of classical fields,and have been used in super-resolution imaging.As a general phenomenon of wave dynamics,super-oscillations have also been predicted to exist in quantum wavefunctions.Here we report the experimental demonstration of super-oscillatory behavior of a single-quantum object,a photon.The super-oscillatory behavior is demonstrated by tight localization of the photon wavefunction after focusing with an appropriately designed slit mask to create an interference pattern with a sub-diffraction hotspot(~0.45λ).Such quantum super-oscillation can be used for low-intensity far-field super-resolution imaging techniques even down to single-photon counting regime,which would be of interest to quantum physics and non-invasive and label-free biological studies.展开更多
Optical barcodes have demonstrated a great potential in multiplexed bioassays and cell tracking for their distinctive spectral fingerprints.The vast majority of optical barcodes were designed to identify a specific ta...Optical barcodes have demonstrated a great potential in multiplexed bioassays and cell tracking for their distinctive spectral fingerprints.The vast majority of optical barcodes were designed to identify a specific target by fluorescence emission spectra,without being able to characterize dynamic changes in response to analytes through time.To overcome these limitations,the concept of the bioresponsive dynamic photonic barcode was proposed by exploiting interfacial energy transfer between a microdroplet cavity and binding molecules.Whispering-gallery modes resulting from cavity-enhanced energy transfer were therefore converted into photonic barcodes to identify binding activities,in which more than trillions of distinctive barcodes could be generated by a single droplet.Dynamic spectral barcoding was achieved by a significant improvement in terms of signal-to-noise ratio upon binding to target molecules.Theoretical studies and experiments were conducted to elucidate the effect of different cavity sizes and analyte concentrations.Timeresolved fluorescence lifetime was implemented to investigate the role of radiative and non-radiative energy transfer.Finally,microdroplet photonic barcodes were employed in biodetection to exhibit great potential in fulfilling biomedical applications.展开更多
In recent years,two-dimensional(2D)ternary materials have attracted wide attention due to their novel properties which can be achieved by regulating their chemical composition with a very great degree of freedom and a...In recent years,two-dimensional(2D)ternary materials have attracted wide attention due to their novel properties which can be achieved by regulating their chemical composition with a very great degree of freedom and adjustable space.However,as for the precise synthesis of 2D ternary materials,great challenges still lie ahead that hinder their further development.In this work,we demonstrated a simple and reliable approach to synthesize 2D ternary-layered BiOCl crystals through a microwave-assisted space-confined process in a short time(<3 minutes).Their ultraviolet(UV)detection performance was analyzed systematically.The photodetectors based on the as-obtained BiOCl platelets demonstrate high sensitivity to 266-nm laser illumination.The responsivity is calculated to be8 A/W and the response time is up to be18 ps.On the other hand,the device is quite stable after being exposed in the ambient air within 3 weeks and the response is almost unchanged during the measurement.The facile and fast synthesis of single crystalline BiOCl platelets and its high sensitivity to UV light irradiation indicate the potential optoelectronic applications of 2D BiOCl photodetectors.展开更多
Manipulation of valley pseudospins is crucial for future valleytronics. lhe emerging transition metal dichalcogenides （TMDs） provide new possibilities for exploring the interplay among the quantum degrees of freedom...Manipulation of valley pseudospins is crucial for future valleytronics. lhe emerging transition metal dichalcogenides （TMDs） provide new possibilities for exploring the interplay among the quantum degrees of freedom, including real spin, valley pseudospin, and layer pseudospin. For example, spin-valley coupling results in valley-dependent circular dichroism in which electrons with particular spin （up or down） can be selectively excited by chiral optical pumping in monolayer TMDs, whereas in few-layer TMDs, the interlayer hopping further affects the spin-valley coupling. In addition to valley and layer pseudospins, here we propose a new degree of freedom--stacking pseudospin--and demonstrate new phenomena correlated to this new stacking freedom that otherwise require the application of external electrical or magnetic field. We investigated all possible stacking configurations of chemical-vapor-deposition-grown trilayer MoS2 （AAA, ABB, AAB, ABA, and 3R）. Although the AAA, ABA, 3R stackings possess a sole peak with lower degree of valley polarization than that in monolayer samples, the AAB （ABB） stackings exhibit two distinct peaks, one similar to that observed in monolayer MoS2 and findings provide a more future valleytronics. an additional unpolarized complete understanding of peak at lower energy. Our valley quantum control for展开更多
The continuous downscaling(sub 5-nm nodes) of the processing technology is severely hampered by the shortchannel effects of the silicon(Si) material, which degrade the transistor's performance and raise the demand...The continuous downscaling(sub 5-nm nodes) of the processing technology is severely hampered by the shortchannel effects of the silicon(Si) material, which degrade the transistor's performance and raise the demand in the development of new device structures and materials to overcome them. Two-dimensional(2D) semiconductors are promising candidates for next-generation electronic materials owing to their atomic thickness and van der Waals(vdW) surface.展开更多
基金This work is partially supported by National Natural Science Foundation of China （11774102）, the Scientific Research Funds and Promotion Program for Young and Middle-aged Teacher in Science ＆ Technology Research of Huaqiao University （ZQN-YXS04, 17BS412）, Open Fund of IPOC （BUPT）, National Research Foundation Singapore （NRF） （NRF-CRP13-2014-05）, European Union＇s Horizon 2020 Research and Innovation Programme under the Marie Sklodowska-Curie Grant Agreement （No. 798916） and Singapore Ministry of Education Academic Research Fund Tier 1 （RG89/16）.
文摘Optical whispering gallery mode （WGM） microresonators have attracted great attention due to their remarkable proper- ties such as extremely high quality factor, small mode volume, tight confinement of modes, and strong evanescent field. All these properties of WGM microresonators have ensured their great potentials for applications, such as physical sen- sors, bio/chemical sensors and microlasers. In this mini-review, the key parameters and coupling conditions of WGM microresonators are firstly introduced. The geometries of WGM optical microcavities are presented based on their fabri- cation methods. This is followed by the discussion on the state-of-the-art applications of WGM microresonators in sen- sors and microlasers.
基金supported by Singapore Ministry of Education Ac RF Tier 2 (MOE2019-T2-2-105), Ac RF Tier 1 RG4/17 and RG161/19。
文摘二维(2D)过渡金属氧化物(TMO)的地球丰度高,并且具有独特的物理化学性质和较好的催化性能,是新能源工业领域中非常有应用前景的电催化剂.然而,由于合成高质量和可控厚度的2D TMO具有一定的难度,目前有关2D TMO的微观电化学研究的报道较少.本文采用化学气相沉积法直接合成了2D钴铁氧体(CoFeO),所制得的2D CoFeO呈现结晶性良好的超薄尖晶石结构,其最薄厚度可达到6.8 nm.采用超微电极测试平台考察了碱性条件下2DCoFeO催化析氧反应(OER)的性能.结果表明,2D CoFeO(111)面在10 m Acm^(-2)的电流密度下表现出330 m V的低过电位,在570 m V的过电位下表现出142 m Acm^(-2)的高电流密度.密度泛函理论计算发现2DCoFeO表面上的双金属位点降低了反应能垒.此外,2DCoFeO的超薄厚度使体电阻率降低,同时增加了活性位点的利用率,进而提高了对OER的催化活性,这与在超微电极平台上测得的2D CoFeO厚度-OER活性依赖关系的结果一致.本研究还合成了大面积的2D CoFeO薄膜,其标准三电极体系研究表明2D CoFeO样品仍然表现出较高的催化OER活性和较好的寿命,说明所制备的2D CoFeO具有较好的实际应用潜力.综上,本文采用气相化学沉积法直接合成了超薄2DCoFeO纳米片,其最薄厚度可达6.8 nm,2DCoFeO表现出良好的OER性能,为2DTMOs电催化剂的可控合成开辟了新途径.此外,本文还分析了2DCoFeO电催化OER反应的机理,为二维电催化剂设计提供了新思路.
基金We acknowledge Dr Hangjun Ying from Ningbo Institute of Materials Technology and Engineering,Chinese Academy of Sciences for TEM characterizations.This study was supported by Nanyang Technological University under NAP award(M408050000)Singapore Ministry of Education Tier 1 program(2018-T1-001-051).We acknowledge Dr Hangjun Ying from Ningbo Institute of Materials Technology and Engineering,Chinese Academy of Sciences for TEM characterizations.This study was supported by Nanyang Technological University under NAP award(M408050000Singapore Ministry of Education Tier 1 program(2018-T1-001-051).
文摘Transition metal oxides hold great promise for lithium-ion batteries(LIBs)and electrocatalytic water splitting because of their high abundance and high energy density.However,designing and fabrication of efficient,stable,high power density electrode materials are challenging.Herein,we report rambutan-like hollow carbon spheres formed by carbon nanosheet decorated with nickel oxide(NiO)rich inmetal vacancies(denoted as h-NiO/C)as a bifunctional electrode material for LIBs and electrocatalytic oxygen evolution reaction(OER).When being used as the anode of LIBs,the h-NiO/C electrode shows a large initial capacity of 885mAh g−1,a robust stability with a high capacity of 817mAh g−1 after 400 cycles,and great rate capability with a high reversible capacity of 523mAh g−1 at 10Ag−1 after 600 cycles.Moreover,working as an OER electrocatalyst,the h-NiO/C electrode shows a small overpotential of 260mV at 10mAcm−2,a Tafel slope of 37.6mVdec−1 along with good stability.Our work offers a cost-effective method for the fabrication of efficient electrode for LIBs and OER.
基金supported by the Research Grants Council(RGC)of Hong Kong(Grant Nos.15215620 and N_PolyU511/20)the Innovation and Technology Commission(ITC)of Hong Kong(Grant Nos.ITF-MHKJFS,MHP/085/22,and PiH/236/24)+2 种基金The Hong Kong Polytechnic University(Grant Nos.1-CD4V,1-CD6U,G-SB6C,1-CD8U,1-BBEN,1-W28S,1-CD9Q,1-SBVB,1-CDJW,1-CDJ8,and 1-W32A)the BROMEDIR European project(Grant No.101092697)the National Natural Science Foundation of China(Grant No.62405257).
文摘The rapid advancement of renewable energy technologies is essential for combating global climate change and achieving energy sustainability.Among the various renewable sources,solar energy stands out,with silicon playing a pivotal role in solar energy conversion.However,traditional silicon-based devices often face challenges due to high surface reflectance,which limits their efficiency.The emergence of black silicon(b-Si)offers a transformative solution,thanks to its micro-and nanoscale structures that provide ultra-low reflectivity and enhanced light absorption.This makes b-Si an ideal candidate for improving solar energy devices.Beyond solar energy applications,b-Si has drawn notable interest in photonics,including applications in photodetectors,surface-enhanced Raman scattering,and imaging.This review explores b-Si comprehensively,discussing its fabrication processes,distinctive properties,and contributions to both solar energy conversion and photonic technologies.Key topics include its roles in solar cells,photoelectrochemical systems,solar thermal energy conversion,and advanced photonic devices.Furthermore,the review addresses the challenges and future directions for optimizing b-Si to facilitate its practical deployment across a range of energy and photonic applications.
基金Z.L.acknowledges funding from the Singapore Ministry of Education(AcRF MOE2019-362 T2-2-105 and AcRF Tier 1 RG7/21)Z.L.also acknowledges funding from the Ministry of Education,Singapore,under its Research Centre of Excellence award to the Institute for Functional Intelligent Materials(Project No.EDUNC-33-18-279-V12).
文摘The Sabatier principle—which states that the best catalyst should be at the peak of the volcano plot,with neither too strong nor too weak intermediate binding strength—plays the golden rule in designing highly active electrocatalysts.For instance,Pt with a“just right”hydrogen adsorption free energy(ΔG_(H^(*))=~0 eV)is the most efficient catalyst for hydrogen evolution reaction(HER).^(1)Nevertheless,the pressing demand for renewable energy has sparked a quest beyond the top of the volcano plot,driving the innovation towards more effective,economical.
基金supported by the National Natural Science Foundation of China(No.62205227,No.62120106001)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(No.22KJB140005,No.23KJA510008)+2 种基金the Suzhou Science and Technology Plan Projects(No.SYG202124,No.SYG202304)the Key Lab of Advanced Optical Manufacturing Technologies of Jiangsu Province,Soochow University(No.ZZ2311,No.ZZ2112)State Key Laboratory of Silicon and Advanced Semiconductor Materials,Zhejiang University(No.SKL2023−01).
文摘Pyroelectric(PE)detection technologies have attracted extensive attention due to the cooling-free,bias-free,and broadband properties.However,the PE signals are generated by the continuous energy conversion processes from light,heat,to electricity,normally leading to very slow response speeds.Herein,we design and fabricate a PE detector which shows extremely fast response in near-infrared(NIR)band by combining with the inhomogeneous plasmonic metasurface.The plasmonic effect dramatically accelerates the light-heat conversion process,unprecedentedly improving the NIR response speed by 2−4 orders of magnitude to 22μs,faster than any reported infrared(IR)PE detector.We also innovatively introduce the concept of time resolution into the field of PE detection,which represents the detector’s ability to distinguish multiple fast-moving targets.Furthermore,the spatially inhomogeneous design overcomes the traditional narrowband constraint of plasmonic systems and thus ensures a wideband response from visible to NIR.This study provides a promising approach to develop next-generation IR PE detectors with ultrafast and broadband responses.
基金supported by the Singapore Ministry of Education(MOET2EP50120-0009)Agency for Science,Technology and Research(A*STAR)(M22K2c0080,R23I0IR041,and A2090b0144)+3 种基金National Medical Research Council(NMRC)(Award number MOH-000927)National Research Foundation Singapore(Award No.NRF-CRP22-2019-0007 and NRF-CRP23-2019-0007)National Research Foundation,Singapore under its AI Singapore Programme(AISG Award No:AISG2-GC-2023-009)National Research Foundation(Award No.NRF2020-NRF-ISF004-3520).
文摘Nonlinear optical activities,especially second harmonic generation(SHG),are key phenomena in inversion-symmetrybroken two-dimensional(2D)transition metal dichalcogenides(TMDCs).On the other hand,anisotropic nonlinear optical processes are important for unique applications in nano-nonlinear photonic devices with polarization functions,having become one of focused research topics in the field of nonlinear photonics.However,the strong nonlinearity and strong optical anisotropy do not exist simultaneously in common 2D materials.Here,we demonstrate strong secondorder and third-order susceptibilities of 64 pm/V and 6.2×10^(-19)m^(2)/V^(2),respectively,in the even-layer PdPSe,which has not been discovered in other common TMDCs(e.g.,MoS2).Strikingly,it also simultaneously exhibited strong SHG anisotropy with an anisotropic ratio of~45,which is the largest reported among all 2D materials to date,to the best of our knowledge.In addition,the SHG anisotropy ratio can be harnessed from 0.12 to 45(375 times)by varying the excitation wavelength due to the dispersion ofχ^(2)values.As an illustrative example,we further demonstrate polarized SHG imaging for potential applications in crystal orientation identification and polarization-dependent spatial encoding.These findings in 2D PdPSe are promising for nonlinear nanophotonic and optoelectronic applications.
基金National Key Research and Development Program of China,Grant/Award Number:2020YFB2008501the Joint of the National Natural Science Foundation of China,Grant/Award Numbers:62288102,62371397,61974120+3 种基金the Natural Science Foundation of Shaanxi Province,Grant/Award Numbers:2022JQ-659,2023-JC-YB-495the Fundamental Research Funds for the Central UniversitiesNorthwestern Polytechnical UniversityOpen Test Funding Project from Analytical&Testing Center of Northwestern Polytechnical University,Grant/Award Number:2023T008。
文摘Two-dimensional transition metal dichalcogenides(2D TMDs)are promising as sensing materials for flexible electronics and wearable systems in artificial intelligence,tele-medicine,and internet of things(IoT).Currently,the study of 2D TMDs-based flexible strain sensors mainly focuses on improving the performance of sensitivity,response,detection resolution,cyclic stability,and so on.There are few reports on power consumption despite that it is of significant importance for wearable electronic systems.It is still challenging to effectively reduce the power consumption for prolonging the endurance of electronic systems.Herein,we propose a novel approach to realize ultra-low power consumption strain sensors by reducing the contact resistance between metal electrodes and 2D MoS_(2).A dendritic bilayer MoS_(2) has been designed and synthesized by a modified CVD method.Large-area edge contact has been introduced in the dendritic MoS_(2),resulting in decreased the contact resistance significantly.The contact resistance can be down to 5.4 kΩμm,which is two orders of magnitude lower than the conventional MoS_(2) devices.We fabricate a flexible strain sensor,exhibiting superior sensitivity in detecting strains with high resolution(0.04%)and an ultra-low power consumption(33.0 pW).This study paves the way for future wearable and flexible sensing electronics with high sensitivity and ultra-low power consumption.
基金supported by the National Key Research and Development Program of China(Grant No.2017YFA0205700)National Basic Research Program of China(Grant Nos.2015CB932403,2017YFA0206000)+4 种基金National Science Foundation of China(Grant Nos.11674012,61422501,11374023,61521004 and 21790364)Beijing Natural Science Foundation(Grant No.L140007)Foundation for the Author of National Excellent Doctoral Dissertation of PR China(Grant No.201420)National Program for Support of Top-notch Young Professionals(Grant No.W02070003)Ministry of Education Singapore under Grant No.MOE2015-T2-2-043.
文摘Achieving strong coupling between plasmonic oscillators can significantly modulate their intrinsic optical properties.Here,we report the direct observation of ultrafast plasmonic hot electron transfer from an Au grating array to an MoS_(2) monolayer in the strong coupling regime between localized surface plasmons(LSPs)and surface plasmon polaritons(SPPs).By means of femtosecond pump-probe spectroscopy,the measured hot electron transfer time is approximately 40 fs with a maximum external quantum yield of 1.65%.Our results suggest that strong coupling between LSPs and SPPs has synergetic effects on the generation of plasmonic hot carriers,where SPPs with a unique nonradiative feature can act as an‘energy recycle bin’to reuse the radiative energy of LSPs and contribute to hot carrier generation.Coherent energy exchange between plasmonic modes in the strong coupling regime can further enhance the vertical electric field and promote the transfer of hot electrons between the Au grating and the MoS_(2) monolayer.Our proposed plasmonic strong coupling configuration overcomes the challenge associated with utilizing hot carriers and is instructive in terms of improving the performance of plasmonic opto-electronic devices.
基金National Natural Science Foundation of China(61775067,61775072)Ministry of Education-Singapore(MOE2019-T1-001-111)National Research Foundation Singapore(NRF-CRP-18-2017-02).
文摘The evolution of soliton molecules emphasizes the complex soliton dynamics akin to matter molecules.Beyond the simplest soliton molecule-a soliton pair constituted by two bound pulses-soliton molecules with more constituents have more degrees of freedom because of the temporal pulse separations and relative phases.Here we detailedly characterize the transient dynamics of soliton triplets in fiber lasers by using the dispersive Fourier transform measurement.A particular form of leading,central,and tailing pulses is constructed to shed new light on more intriguing scenarios and fuel the molecular analogy.Especially the vibrating dynamics of the central and tailing pulses are captured near the regime of equally spaced soliton triplets,which is reminiscent of the recurrent timing jitters within multi-pulse structures.Further insights enable acess into a universal form of unequally spaced soliton triplets interpreted as 2+1 soliton molecules.Different binding strengths of intramo-lecular and intermolecular bonds are validated with respect to the diverse internal motions involved in this soliton triplet molcule.All these findings unveil the transient dynamics with more degrees of freedom as well as highlight the possible application for all-optical bit storage.
基金supported by the Singapore Ministry of Education Academic Research Fund Tier 2(MOE2019-T2-2-127 and T2EP50120-0005)A*STAR under AME IRG(A2083c0062)+2 种基金the Singapore Ministry of Education Academic Research Fund Tier 1(RG90/19 and RG73/19)the Singapore National Research Foundation Competitive Research Program(NRF-CRP18-2017-02)supported by Nanyang Technological University.
文摘Elastic and stretchable functional fibers have drawn attentions from wide research field because of their unique advantages including high dynamic bending elasticity,stretchability and high mechanic strength.Lots of efforts have been made to find promising soft materials and improve the processing methods to fabricate the elastomer fibers with controllable fiber geometries and designable functionalities.Significant progress has been made and various interdisciplinary applications have been demonstrated based on their unique mechanical performance.A series of remarkable applications,involving biomedicine,optics,electronics,human machine interfaces etc.,have been successfully achieved.Here,we summarize main processing methods to fabricate soft and stretchable functional fibers using different types of elastic materials,which are either widely used or specifically developed.We also introduce some representative applications of multifunctional elastic fibers to reveal this promising research area.All these reported applications indicate that the fast innovated interdisciplinary area is of great potential and inspire more remarkable ideas in fiber sensing,soft electronics,functional fiber integration and other related research fields.
基金supported by the Joint BRFFR-CNRS Project (No. F15F-003)the Visby Program: scholarships for PhD studies and postdoctoral research in Sweden
文摘Our theoretical findings demonstrate for the first time a possibility of band-gap engineering of monolayer MoS2 crystals by oxygen and the presence of vacancies. Oxygen atoms are revealed to substitute sulfur ones, forming stable MoS2-xOx ternary compounds, or adsorb on top of the sulfur atoms. The substituting oxygen provides a decrease of the band gap from 1.86 to 1.64 eV and transforms the material from a direct-gap to an indirect-gap semiconductor. The surface adsorbed oxygen atoms decrease the band gap up to 0.98 eV depending on their location tending to the metallic character of the electron energy bands at a high concentration of the adsorbed atoms. Oxygen plasma processing is proposed as an effective technology for such band-gap modifications.
基金support from the Advanced Optics in Engineering Programme from the Agency for Science,Technology and Research of Singapore with grant number 122-360-0009Singapore Ministry of Education Academic Research Fund Tier 3 with grant number MOE2011-T3-1-005+2 种基金the UK Engineering and Physical Sciences Research Council with grant numbers EP/F040644/1 and EP/M009122/1the Royal Society of London and the University of Southampton Enterprise Fundfunding of the Labex ACTION program(contract no.ANR-11-LABX-0001-01).
文摘Super-oscillation is a counterintuitive phenomenon describing localized fast variations of functions and fields that happen at frequencies higher than the highest Fourier component of their spectra.The physical implications of this effect have been studied in information theory and optics of classical fields,and have been used in super-resolution imaging.As a general phenomenon of wave dynamics,super-oscillations have also been predicted to exist in quantum wavefunctions.Here we report the experimental demonstration of super-oscillatory behavior of a single-quantum object,a photon.The super-oscillatory behavior is demonstrated by tight localization of the photon wavefunction after focusing with an appropriately designed slit mask to create an interference pattern with a sub-diffraction hotspot(~0.45λ).Such quantum super-oscillation can be used for low-intensity far-field super-resolution imaging techniques even down to single-photon counting regime,which would be of interest to quantum physics and non-invasive and label-free biological studies.
基金We would like to thank the Centre of Bio-Devices and Bioinformatics and CNRS International—Nanyang Technological University-Thales Research Alliance(CINTRA)for lab supportWe would also like to thank NTU for the startup grant(SUG-M4082308.040).
文摘Optical barcodes have demonstrated a great potential in multiplexed bioassays and cell tracking for their distinctive spectral fingerprints.The vast majority of optical barcodes were designed to identify a specific target by fluorescence emission spectra,without being able to characterize dynamic changes in response to analytes through time.To overcome these limitations,the concept of the bioresponsive dynamic photonic barcode was proposed by exploiting interfacial energy transfer between a microdroplet cavity and binding molecules.Whispering-gallery modes resulting from cavity-enhanced energy transfer were therefore converted into photonic barcodes to identify binding activities,in which more than trillions of distinctive barcodes could be generated by a single droplet.Dynamic spectral barcoding was achieved by a significant improvement in terms of signal-to-noise ratio upon binding to target molecules.Theoretical studies and experiments were conducted to elucidate the effect of different cavity sizes and analyte concentrations.Timeresolved fluorescence lifetime was implemented to investigate the role of radiative and non-radiative energy transfer.Finally,microdroplet photonic barcodes were employed in biodetection to exhibit great potential in fulfilling biomedical applications.
基金National Research Foundation Singapore,Grant/Award Numbers:AStar QTE program.,AcRF Tier 2 MOE2017-T2-2-002,MOE Tier 2 MOE2015-T2-2-007,MOE Tier 3 MOE2018-T3-1-002,MOE2016-T2-2-153,MOE2017-T2-2-136,NRF-RF2013-08.MOE Tier 1 RG7/18,NRF2017-NRF-ANR0022DPSNatural Science Foundation of Jiangsu Province,Grant/Award Number:BK20160994+1 种基金This work was supported by the Singapore National Research Foundation under NRF RF Award No.NRF-RF2013-08.MOE Tier 1 RG7/18,MOE Tier 2 MOE2015-T2-2-007,MOE2016-T2-2-153,MOE2017-T2-2-136,MOE Tier 3 MOE2018-T3-1-002,AcRF Tier 2 MOE2017-T2-2-002,NRF2017-NRF-ANR0022DPS,and A*Star QTE program.Dan Tian thanks the National Nature Science Foundation of China(Grant No.21601086)the Natural Science Foundation of Jiangsu Province(BK20160994)for financial support.
文摘In recent years,two-dimensional(2D)ternary materials have attracted wide attention due to their novel properties which can be achieved by regulating their chemical composition with a very great degree of freedom and adjustable space.However,as for the precise synthesis of 2D ternary materials,great challenges still lie ahead that hinder their further development.In this work,we demonstrated a simple and reliable approach to synthesize 2D ternary-layered BiOCl crystals through a microwave-assisted space-confined process in a short time(<3 minutes).Their ultraviolet(UV)detection performance was analyzed systematically.The photodetectors based on the as-obtained BiOCl platelets demonstrate high sensitivity to 266-nm laser illumination.The responsivity is calculated to be8 A/W and the response time is up to be18 ps.On the other hand,the device is quite stable after being exposed in the ambient air within 3 weeks and the response is almost unchanged during the measurement.The facile and fast synthesis of single crystalline BiOCl platelets and its high sensitivity to UV light irradiation indicate the potential optoelectronic applications of 2D BiOCl photodetectors.
文摘Manipulation of valley pseudospins is crucial for future valleytronics. lhe emerging transition metal dichalcogenides （TMDs） provide new possibilities for exploring the interplay among the quantum degrees of freedom, including real spin, valley pseudospin, and layer pseudospin. For example, spin-valley coupling results in valley-dependent circular dichroism in which electrons with particular spin （up or down） can be selectively excited by chiral optical pumping in monolayer TMDs, whereas in few-layer TMDs, the interlayer hopping further affects the spin-valley coupling. In addition to valley and layer pseudospins, here we propose a new degree of freedom--stacking pseudospin--and demonstrate new phenomena correlated to this new stacking freedom that otherwise require the application of external electrical or magnetic field. We investigated all possible stacking configurations of chemical-vapor-deposition-grown trilayer MoS2 （AAA, ABB, AAB, ABA, and 3R）. Although the AAA, ABA, 3R stackings possess a sole peak with lower degree of valley polarization than that in monolayer samples, the AAB （ABB） stackings exhibit two distinct peaks, one similar to that observed in monolayer MoS2 and findings provide a more future valleytronics. an additional unpolarized complete understanding of peak at lower energy. Our valley quantum control for
基金financially supported by the National Natural Science Foundation of China(61674050,62004056,and 61874158)the Project of Distinguished Young of Hebei Province(A2018201231)+7 种基金the Support Program for the Top Young Talents of Hebei Province(70280011807)the Hundred Persons Plan of Hebei Province(E2018050004 and E2018050003)the Supporting Plan for 100 Excellent Innovative Talents in Colleges and Universities of Hebei Province(SLRC2019018)the Special Project of Strategic Leading Science and Technology of Chinese Academy of Sciences(XDB44000000-7)the Special Support Funds for National High Level Talents(041500120001)Hebei Basic Research Special Key Project(F2021201045)the Science and Technology Project of Hebei Education Department(QN2020178 and QN2021026)Singapore Ministry of Education(Ac RF TIER 2-MOE2019-T2-2-075)。
文摘The continuous downscaling(sub 5-nm nodes) of the processing technology is severely hampered by the shortchannel effects of the silicon(Si) material, which degrade the transistor's performance and raise the demand in the development of new device structures and materials to overcome them. Two-dimensional(2D) semiconductors are promising candidates for next-generation electronic materials owing to their atomic thickness and van der Waals(vdW) surface.
