Stirred reactors are key equipment in production,and unpredictable failures will result in significant economic losses and safety issues.Therefore,it is necessary to monitor its health state.To achieve this goal,in th...Stirred reactors are key equipment in production,and unpredictable failures will result in significant economic losses and safety issues.Therefore,it is necessary to monitor its health state.To achieve this goal,in this study,five states of the stirred reactor were firstly preset:normal,shaft bending,blade eccentricity,bearing wear,and bolt looseness.Vibration signals along x,y and z axes were collected and analyzed in both the time domain and frequency domain.Secondly,93 statistical features were extracted and evaluated by ReliefF,Maximal Information Coefficient(MIC)and XGBoost.The above evaluation results were then fused by D-S evidence theory to extract the final 16 features that are most relevant to the state of the stirred reactor.Finally,the CatBoost algorithm was introduced to establish the stirred reactor health monitoring model.The validation results showed that the model achieves 100%accuracy in detecting the fault/normal state of the stirred reactor and 98%accuracy in diagnosing the type of fault.展开更多
Modeling soil salinity in an arid salt-affected ecosystem is a difficult task when using remote sensing data because of the complicated soil context(vegetation cover,moisture,surface roughness,and organic matter)and t...Modeling soil salinity in an arid salt-affected ecosystem is a difficult task when using remote sensing data because of the complicated soil context(vegetation cover,moisture,surface roughness,and organic matter)and the weak spectral features of salinized soil.Therefore,an index such as the salinity index(SI)that only uses soil spectra may not detect soil salinity effectively and quantitatively.The use of vegetation reflectance as an indirect indicator can avoid limitations associated with the direct use of soil reflectance.The normalized difference vegetation index(NDVI),as the most common vegetation index,was found to be responsive to salinity but may not be available for retrieving sparse vegetation due to its sensitivity to background soil in arid areas.Therefore,the arid fraction integrated index(AFII)was created as supported by the spectral mixture analysis(SMA),which is more appropriate for analyzing variations in vegetation cover(particularly halophytes)than NDVI in the study area.Using soil and vegetation separately for detecting salinity perhaps is not feasible.Then,we developed a new and operational model,the soil salinity detecting model(SDM)that combines AFII and SI to quantitatively estimate the salt content in the surface soil.SDMs,including SDM1 and SDM2,were constructed through analyzing the spatial characteristics of soils with different salinization degree by integrating AFII and SI using a scatterplot.The SDMs were then compared to the combined spectral response index(COSRI)from field measurements with respect to the soil salt content.The results indicate that the SDM values are highly correlated with soil salinity,in contrast to the performance of COSRI.Strong exponential relationships were observed between soil salinity and SDMs(R2>0.86,RMSE<6.86)compared to COSRI(R2=0.71,RMSE=16.21).These results suggest that the feature space related to biophysical properties combined with AFII and SI can effectively provide information on soil salinity.展开更多
The use of low-coherence light is expected to be one of the effective ways to suppress or even eliminate the laser–plasma instabilities that arise in attempts to achieve inertial confinement fusion.In this paper,a re...The use of low-coherence light is expected to be one of the effective ways to suppress or even eliminate the laser–plasma instabilities that arise in attempts to achieve inertial confinement fusion.In this paper,a review of low-coherence high-power laser drivers and related key techniques is first presented.Work at typical low-coherence laser facilities,including Gekko XII,PHEBUS,Pharos III,and Kanal-2 is described.The many key techniques that are used in the research and development of low-coherence laser drivers are described and analyzed,including low-coherence source generation,amplification,harmonic conversion,and beam smoothing of low-coherence light.Then,recent progress achieved by our group in research on a broadband low-coherence laser driver is presented.During the development of our low-coherence high-power laser facility,we have proposed and implemented many key techniques for working with low-coherence light,including source generation,efficient amplification and propagation,harmonic conversion,beam smoothing,and precise beam control.Based on a series of technological breakthroughs,a kilojoule low-coherence laser driver named Kunwu with a coherence time of only 300 fs has been built,and the first round of physical experiments has been completed.This high-power laser facility provides not only a demonstration and verification platform for key techniques and system integration of a low-coherence laser driver,but also a new type of experimental platform for research into,for example,high-energy-density physics and,in particular,laser–plasma interactions.展开更多
A simple,convenient,and highly sensitive bio-interface for graphene field-effect transistors(GFETs) based on multifunctional nano-denatured bovine serum albumin(nano-dBSA) functionalization was developed to target can...A simple,convenient,and highly sensitive bio-interface for graphene field-effect transistors(GFETs) based on multifunctional nano-denatured bovine serum albumin(nano-dBSA) functionalization was developed to target cancer bio-markers.The novel graphene–protein bioelectronic interface was constructed by heating to denature native BSA on the graphene substrate surface.The formed nano-d BSA film served as the cross-linker to immobilize monoclonal antibody against car-cinoembryonic antigen(anti-CEA mAb) on the graphene channel activated by EDC and Sulfo-NHS.The nano-dBSA film worked as a self-protecting layer of graphene to prevent surface contamination by lithographic processing.The improved GFETbiosensor exhibited good specificity and high sensitivity toward the target at an ultralow concentration of 337.58 fg mL-1.The electrical detection of the binding of CEA followed the Hill model for ligand–receptor interaction,indicating the negative binding cooperativity between CEA and anti-CEA mAb with a dissociation constant of 6.82×10-10M.The multifunctional nano-dBSA functionalization can confer a new function to graphene-like 2D nanomaterials and provide a promising bio-functionalization method for clinical application in biosensing,nanomedicine,and drug delivery.展开更多
Hydrogen has been recently utilized in many fields due to its recyclability and non-pollution characteristics.Hydrogen fuel cell vehicles and hydrogen refueling stations have become the main carrier of hydrogen energy...Hydrogen has been recently utilized in many fields due to its recyclability and non-pollution characteristics.Hydrogen fuel cell vehicles and hydrogen refueling stations have become the main carrier of hydrogen energy application.However,due to the inflammable and explosive characteristics,the safety problems of hydrogen became indispensable.This paper introduces the safety problems and countermeasures of hydrogen fuel cell vehicles and hydrogen refueling stations.The research progress and achievements of hydrogen energy standards are then comprehensively discussed.Finally,the development status,existing problems and future development direction of five kinds of optical fiber sensors are pointed out.展开更多
Omicron,the new mutant coronavirus,has spread rapidly globally,attracting close attention from different stakeholders worldwide.The complex and constantly changing epidemic situation has had a new impact on the world....Omicron,the new mutant coronavirus,has spread rapidly globally,attracting close attention from different stakeholders worldwide.The complex and constantly changing epidemic situation has had a new impact on the world.Therefore,this paper focuses on the characteristics of the rapid spread of the COVID-19 variant strain.Generally,epidemic prevention experts conduct preliminary screening as part of the existing epidemic plan database according to the current local situation,after which they sort the alternatives deemed more suitable for the situation.Then the decision-makers identify the most divergent expert group,plan for consultation and adjustments,and finally obtain the plan with the smallest divergence.This article aims to integrate the experts'opinions with the method of minimizing the differences,which can maximize the expert consensus and help organize the schemes that best meet the epidemic situation.The experts'negotiation and iteration of the differences in the initial plan align with the current complex and dynamic epidemic situation and are of great significance to the rapid formulation of plans to achieve effective prevention and control.展开更多
In this paper,we demonstrate efficient spontaneous quasi-phase matched(SQPM)second harmonic generation(SHG)in a microracetrack resonator on X-cut thin film lithium niobate.Our approach does not involve poling,but expl...In this paper,we demonstrate efficient spontaneous quasi-phase matched(SQPM)second harmonic generation(SHG)in a microracetrack resonator on X-cut thin film lithium niobate.Our approach does not involve poling,but exploits the anisotropy of the crystals to allow the phase-matching condition to be fulfilled spontaneously as the TE-polarized light circulates in a specifically designed racetrack resonator.In experiment,normalized on-chip conversion efficiencies of 1.01×10-4/W and 0.43×10-4/W are achieved by 37th-order and 111th-order SQPM,respectively.The configurable SQPM will benefit the application of nonlinear frequency conversion and quantum source generation in chip-scale integrated photonics compatible with standard CMOS fabrication processes.展开更多
Relativistic electrons moving over a periodic metal grating can lead to an intriguing emission of light,known as Smith–Purcell radiation[SPR],the precursor of the free-electron laser.The speed of light plays a critic...Relativistic electrons moving over a periodic metal grating can lead to an intriguing emission of light,known as Smith–Purcell radiation[SPR],the precursor of the free-electron laser.The speed of light plays a critical role in the far-field emission spectrum.Inspired by this photonic SPR,here we experimentally demonstrate a photoacoustic phased array using laser-induced shock waves.We observe acoustic radiation spectrum in the far field,perfectly predicted by a universal theory for the SPR.This scheme provides a tool to control the acoustic radiation in the near field,paving the way toward coherent acoustic wave generation and microstructure metrology.展开更多
Scattering of waves, e.g., light, due to medium inhomogeneity is ubiquitous in physics and isconsidered detrimental for many applications. Wavefront shaping technology is a powerful tool to defeatscattering and focus ...Scattering of waves, e.g., light, due to medium inhomogeneity is ubiquitous in physics and isconsidered detrimental for many applications. Wavefront shaping technology is a powerful tool to defeatscattering and focus light through inhomogeneous media, which is vital for optical imaging, communication,therapy, etc. Wavefront shaping based on the scattering matrix (SM) is extremely useful in handling dynamicprocesses in the linear regime. However, the implementation of such a method for controlling light in nonlinearmedia is still a challenge and has been unexplored until now. We report a method to determine the SM ofnonlinear scattering media with second-order nonlinearity. We experimentally demonstrate its feasibility inwavefront control and realize focusing of nonlinear signals through strongly scattering quadratic media.Moreover, we show that statistical properties of this SM still follow the random matrix theory. The scattering-matrix approach of nonlinear scattering medium opens a path toward nonlinear signal recovery, nonlinearimaging, microscopic object tracking, and complex environment quantum information processing.展开更多
Measuring topological invariants is an essential task in characterizing topological phases of matter.They are usually obtained from the number of edge states due to the bulk-edge correspondence or from interference si...Measuring topological invariants is an essential task in characterizing topological phases of matter.They are usually obtained from the number of edge states due to the bulk-edge correspondence or from interference since they are integrals of the geometric phases in the energy band.It is commonly believed that the bulk band structures could not be directly used to obtain the topological invariants.Here,we implement the experimental extraction of Zak phase from the bulk band structures of a Su-Schrieffer-Heeger(SSH)model in the synthetic frequency dimension.Such synthetic SSH lattices are constructed in the frequency axis of light,by controlling the coupling strengths between the symmetric and antisymmetric supermodes of two bichromatically driven rings.We measure the transmission spectra and obtain the projection of the time-resolved band structure on lattice sites,where a strong contrast between the non-trivial and trivial topological phases is observed.The topological Zak phase is naturally encoded in the bulk band structures of the synthetic SSH lattices,which can hence be experimentally extracted from the transmission spectra in a fiber-based modulated ring platform using a laser with telecom wavelength.Our method of extracting topological phases from the bulk band structure can be further extended to characterize topological invariants in higher dimensions,while the exhibited trivial and non-trivial transmission spectra from the topological transition may find future applications in optical communications.展开更多
The commercialization of lithium niobate on insulator(LNOI) wafer has resulted in significant on-chip photonic integration application owing to its remarkable photonic,acousto-optic,electro-optic,and piezoelectric nat...The commercialization of lithium niobate on insulator(LNOI) wafer has resulted in significant on-chip photonic integration application owing to its remarkable photonic,acousto-optic,electro-optic,and piezoelectric nature.In recent years,a variety of high-performance on-chip LNOI-based photonic devices have been realized.In this study,we developed a 1-mol% erbium-doped lithium niobate crystal and its LNOI on a silicon substrate and fabricated an erbium-doped LNOI microdisk with high quality factor(~1.05×105).C-band laser emission at ~1530 and ~1560 nm(linewidth 0.12 nm) from the high-Q erbium-doped LNOI microdisk was demonstrated with 974-and 1460-nm pumping,with the latter having better thermal stability.This microlaser would play an important role in the photonic integrated circuits of the lithium niobate platform.展开更多
The generation and manipulation of optical vortices are of fundamental importance in a variety of promising applications. Here, we develop a nonlinear optical paradigm to implement self-and cross-convolution of optica...The generation and manipulation of optical vortices are of fundamental importance in a variety of promising applications. Here, we develop a nonlinear optical paradigm to implement self-and cross-convolution of optical vortex arrays, demonstrating the features of a vortex copier and regenerator. We use a phase-only spatial light modulator to prepare the 1064 nm invisible fundamental light to carry special optical vortex arrays and use a potassium titanyl phosphate crystal to perform type Ⅱ second-harmonic generation in the Fourier domain to achieve 532 nm visible structured vortices. Based on pure cross-convolution, we succeed in copying arbitrary-order single vortices as well as their superposition states onto a prearranged array of fundamental Gaussian spots. Also, based on the simultaneous effect of self-and cross-convolutions, we can expand the initial vortex lattices to regenerate more vortices carrying various higher topological charges. Our presented method of realizing an optical vortex copier and regenerator could find direct applications in optical manipulation, optical imaging, optical communication, and quantum information processing with structured vortex arrays.展开更多
Abbe’s resolution limit,one of the best-known physical limitations,poses a great challenge for any wave system in imaging,wave transport,and dynamics.Originally formulated in linear optics,the Abbe limit can be broke...Abbe’s resolution limit,one of the best-known physical limitations,poses a great challenge for any wave system in imaging,wave transport,and dynamics.Originally formulated in linear optics,the Abbe limit can be broken using nonlinear optical interactions.We extend the Abbe theory into a nonlinear regime and experimentally demonstrate a far-field,label-free,and scan-free super-resolution imaging technique based on nonlinear four-wave mixing to retrieve near-field scattered evanescent waves,achieving a sub-wavelength resolution ofλ∕5.6.This method paves the way for numerous new applications in biomedical imaging,semiconductor metrology,and photolithography.展开更多
Metal-free, organic-dye-based fluorescent nanorods were fabricated through a simple solvent-exchange procedure. The as-prepared nanorods exhibit low toxicity to living cells and excellent photostability. Furthermore, ...Metal-free, organic-dye-based fluorescent nanorods were fabricated through a simple solvent-exchange procedure. The as-prepared nanorods exhibit low toxicity to living cells and excellent photostability. Furthermore, they are stable in solutions of various pHs and high ionic strength and in solutions with interfering metal ions. Compared with the free DPP-Br molecules in THF, these nanorods exhibit larger Stokes shift, broader absorption spectra, and greatly improved photostability. We successfully demonstrated the application of the nanorods, including their aforementioned beneficial characteristics, as a good fluorescence probe for bio-imaging.展开更多
All-optical logic gates including AND, XOR, and NOT gates, as well as a half-adder, are realized based on twodimensional lithium niobate photonic crystal(PhC) circuits with Ph C micro-cavities.The proposed all-optical...All-optical logic gates including AND, XOR, and NOT gates, as well as a half-adder, are realized based on twodimensional lithium niobate photonic crystal(PhC) circuits with Ph C micro-cavities.The proposed all-optical devices have an extinction ratio as high as 23 dB due to the effective all-optical switch function induced by twomissing-hole micro-cavities.These proposed devices can have potential implementation of complex integrated optical functionalities including all-optical computing in a lithium niobate slab or thin film.展开更多
Future quantum information networks operated on telecom channels require qubit transfer between different wavelengths while preserving quantum coherence and entanglement. Qubit transfer is a nonlinear optical process,...Future quantum information networks operated on telecom channels require qubit transfer between different wavelengths while preserving quantum coherence and entanglement. Qubit transfer is a nonlinear optical process,but currently the types of atoms used for quantum information processing and storage are limited by the narrow bandwidth of upconversion available. Here we present the first experimental demonstration of broadband and high-efficiency quasi-phase matching second-harmonic generation(SHG) in a chip-scale periodically poled lithium niobate thin film. We achieve a large bandwidth of up to 2 THz for SHG by satisfying quasi-phase matching and group-velocity matching simultaneously. Furthermore, by changing the film thickness, the central wavelength of the quasi-phase matching SHG bandwidth can be modulated from 2.70 μm to 1.44 μm. The reconfigurable quasi-phase matching lithium niobate thin film provides a significant on-chip integrated platform for photonics and quantum optics.展开更多
Recently, the perfect vector(PV) beam has sparked considerable interest because its radius is independent of the topological charge(TC), which has demonstrated special capabilities in optical manipulation, microscopy ...Recently, the perfect vector(PV) beam has sparked considerable interest because its radius is independent of the topological charge(TC), which has demonstrated special capabilities in optical manipulation, microscopy imaging, and laser micromachining. Previous research about the generation and manipulation of such PV beams only focuses on the linear optical fields. Therefore, the generation of nonlinear PV beams is still lacking. Here, we propose a dual waveband generator to simultaneously generate the PV beams in linear and nonlinear wavebands.In our experiment, PV beams with different polarization states are realized. It is proved that the polarization states of the generated PV beams can be flexibly adjusted by changing the axis direction of a half wave plate. The experimental results show that the radii of the generated PV beams are equal and independent of the TCs.With proper alteration of the nonlinear crystals, this approach could be further extended to other nonlinear processes, such as sum-frequency generation and difference-frequency generation.展开更多
Electromagnetically induced transparency has the unique ability to optically control transparency windows with low light in atomic systems.However,its practical applications in quantum physics and information science ...Electromagnetically induced transparency has the unique ability to optically control transparency windows with low light in atomic systems.However,its practical applications in quantum physics and information science are limited due to rigid experimental requirements.Here we demonstrate a new mechanism of optically induced transparency in a micro-cavity by introducing a four-wave mixing gain to nonlinearly couple two separated resonances of the micro-cavity in an ambient environment.A signature Fano-like resonance was observed owing to the nonlinear interference of the two coupled resonances.Moreover,we show that the unidirectional gain of the four-wave mixing can lead to the remarkable effect of non-reciprocal transmission at the transparency windows.Optically induced transparency may offer a unique platform for a compact,integrated solution to all-optical and quantum information.展开更多
基金supported by the China Postdoctoral Science Foundation(Grant Number 2023M742598).
文摘Stirred reactors are key equipment in production,and unpredictable failures will result in significant economic losses and safety issues.Therefore,it is necessary to monitor its health state.To achieve this goal,in this study,five states of the stirred reactor were firstly preset:normal,shaft bending,blade eccentricity,bearing wear,and bolt looseness.Vibration signals along x,y and z axes were collected and analyzed in both the time domain and frequency domain.Secondly,93 statistical features were extracted and evaluated by ReliefF,Maximal Information Coefficient(MIC)and XGBoost.The above evaluation results were then fused by D-S evidence theory to extract the final 16 features that are most relevant to the state of the stirred reactor.Finally,the CatBoost algorithm was introduced to establish the stirred reactor health monitoring model.The validation results showed that the model achieves 100%accuracy in detecting the fault/normal state of the stirred reactor and 98%accuracy in diagnosing the type of fault.
基金financially supported by the National Basic Research Program of China (2009CB825105)the National Natural Science Foundation of China (41261090)
文摘Modeling soil salinity in an arid salt-affected ecosystem is a difficult task when using remote sensing data because of the complicated soil context(vegetation cover,moisture,surface roughness,and organic matter)and the weak spectral features of salinized soil.Therefore,an index such as the salinity index(SI)that only uses soil spectra may not detect soil salinity effectively and quantitatively.The use of vegetation reflectance as an indirect indicator can avoid limitations associated with the direct use of soil reflectance.The normalized difference vegetation index(NDVI),as the most common vegetation index,was found to be responsive to salinity but may not be available for retrieving sparse vegetation due to its sensitivity to background soil in arid areas.Therefore,the arid fraction integrated index(AFII)was created as supported by the spectral mixture analysis(SMA),which is more appropriate for analyzing variations in vegetation cover(particularly halophytes)than NDVI in the study area.Using soil and vegetation separately for detecting salinity perhaps is not feasible.Then,we developed a new and operational model,the soil salinity detecting model(SDM)that combines AFII and SI to quantitatively estimate the salt content in the surface soil.SDMs,including SDM1 and SDM2,were constructed through analyzing the spatial characteristics of soils with different salinization degree by integrating AFII and SI using a scatterplot.The SDMs were then compared to the combined spectral response index(COSRI)from field measurements with respect to the soil salt content.The results indicate that the SDM values are highly correlated with soil salinity,in contrast to the performance of COSRI.Strong exponential relationships were observed between soil salinity and SDMs(R2>0.86,RMSE<6.86)compared to COSRI(R2=0.71,RMSE=16.21).These results suggest that the feature space related to biophysical properties combined with AFII and SI can effectively provide information on soil salinity.
基金The authors thank Professor Yongxiang Hu for the ns-LSP experiment on Mg-3Gd alloy and his useful discussion.The research was supported by the National Key R&D Program of China(2017YFA0303700)the National Natural Science Foundation of China(NSFC)(11574208).
文摘The use of low-coherence light is expected to be one of the effective ways to suppress or even eliminate the laser–plasma instabilities that arise in attempts to achieve inertial confinement fusion.In this paper,a review of low-coherence high-power laser drivers and related key techniques is first presented.Work at typical low-coherence laser facilities,including Gekko XII,PHEBUS,Pharos III,and Kanal-2 is described.The many key techniques that are used in the research and development of low-coherence laser drivers are described and analyzed,including low-coherence source generation,amplification,harmonic conversion,and beam smoothing of low-coherence light.Then,recent progress achieved by our group in research on a broadband low-coherence laser driver is presented.During the development of our low-coherence high-power laser facility,we have proposed and implemented many key techniques for working with low-coherence light,including source generation,efficient amplification and propagation,harmonic conversion,beam smoothing,and precise beam control.Based on a series of technological breakthroughs,a kilojoule low-coherence laser driver named Kunwu with a coherence time of only 300 fs has been built,and the first round of physical experiments has been completed.This high-power laser facility provides not only a demonstration and verification platform for key techniques and system integration of a low-coherence laser driver,but also a new type of experimental platform for research into,for example,high-energy-density physics and,in particular,laser–plasma interactions.
基金the support of grants from the National Key R&D Program of China(Nos.2018YFA0108202 and 2017YFA0205300)the National Natural Science Foundation of China(Nos.61571429,61801464,61801465,and 81471748)+1 种基金the STS Project of the Chinese Academy of Sciences(NO.KFJ-STS-SCYD-120)the Science and Technology Commission of Shanghai Municipality(Nos.16410711800 and 14391901900)
文摘A simple,convenient,and highly sensitive bio-interface for graphene field-effect transistors(GFETs) based on multifunctional nano-denatured bovine serum albumin(nano-dBSA) functionalization was developed to target cancer bio-markers.The novel graphene–protein bioelectronic interface was constructed by heating to denature native BSA on the graphene substrate surface.The formed nano-d BSA film served as the cross-linker to immobilize monoclonal antibody against car-cinoembryonic antigen(anti-CEA mAb) on the graphene channel activated by EDC and Sulfo-NHS.The nano-dBSA film worked as a self-protecting layer of graphene to prevent surface contamination by lithographic processing.The improved GFETbiosensor exhibited good specificity and high sensitivity toward the target at an ultralow concentration of 337.58 fg mL-1.The electrical detection of the binding of CEA followed the Hill model for ligand–receptor interaction,indicating the negative binding cooperativity between CEA and anti-CEA mAb with a dissociation constant of 6.82×10-10M.The multifunctional nano-dBSA functionalization can confer a new function to graphene-like 2D nanomaterials and provide a promising bio-functionalization method for clinical application in biosensing,nanomedicine,and drug delivery.
基金the National Key Research and Development Program of China(Grant No.2021YFB4000902)the Key Research and Development Project of Hubei Province(Grant No.2021BCA216)are both highly appreciated。
文摘Hydrogen has been recently utilized in many fields due to its recyclability and non-pollution characteristics.Hydrogen fuel cell vehicles and hydrogen refueling stations have become the main carrier of hydrogen energy application.However,due to the inflammable and explosive characteristics,the safety problems of hydrogen became indispensable.This paper introduces the safety problems and countermeasures of hydrogen fuel cell vehicles and hydrogen refueling stations.The research progress and achievements of hydrogen energy standards are then comprehensively discussed.Finally,the development status,existing problems and future development direction of five kinds of optical fiber sensors are pointed out.
基金This study was supported by the Key Scientific Research Project of Henan Province(Nos.22A630004 and 21A790002)the 2021 Project of Huamao Finance Research Institute of Henan University of Economics and Law and the Key Fields Special Project(Digital Economy)of Guangdong Universities(No.2021ZDZX3010).
文摘Omicron,the new mutant coronavirus,has spread rapidly globally,attracting close attention from different stakeholders worldwide.The complex and constantly changing epidemic situation has had a new impact on the world.Therefore,this paper focuses on the characteristics of the rapid spread of the COVID-19 variant strain.Generally,epidemic prevention experts conduct preliminary screening as part of the existing epidemic plan database according to the current local situation,after which they sort the alternatives deemed more suitable for the situation.Then the decision-makers identify the most divergent expert group,plan for consultation and adjustments,and finally obtain the plan with the smallest divergence.This article aims to integrate the experts'opinions with the method of minimizing the differences,which can maximize the expert consensus and help organize the schemes that best meet the epidemic situation.The experts'negotiation and iteration of the differences in the initial plan align with the current complex and dynamic epidemic situation and are of great significance to the rapid formulation of plans to achieve effective prevention and control.
基金supported by the National Key R&D Program of China(Grant No.2019YFB2203501)National Natural Science Foundation of China(Grant Nos.12134009,and 91950107)+1 种基金Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01-ZX06)Shanghai Jiao Tong University(SJTU)(Grant No.21X010200828)。
文摘In this paper,we demonstrate efficient spontaneous quasi-phase matched(SQPM)second harmonic generation(SHG)in a microracetrack resonator on X-cut thin film lithium niobate.Our approach does not involve poling,but exploits the anisotropy of the crystals to allow the phase-matching condition to be fulfilled spontaneously as the TE-polarized light circulates in a specifically designed racetrack resonator.In experiment,normalized on-chip conversion efficiencies of 1.01×10-4/W and 0.43×10-4/W are achieved by 37th-order and 111th-order SQPM,respectively.The configurable SQPM will benefit the application of nonlinear frequency conversion and quantum source generation in chip-scale integrated photonics compatible with standard CMOS fabrication processes.
基金supported by the National Natural Science Foundation of China(Nos.92050113 and 11674228)the National Key Research and Development Program of China(Nos.2016YFA0302500 and 2017YFA0303700)the Shanghai MEC Scientific Innovation Program(No.E00075)。
文摘Relativistic electrons moving over a periodic metal grating can lead to an intriguing emission of light,known as Smith–Purcell radiation[SPR],the precursor of the free-electron laser.The speed of light plays a critical role in the far-field emission spectrum.Inspired by this photonic SPR,here we experimentally demonstrate a photoacoustic phased array using laser-induced shock waves.We observe acoustic radiation spectrum in the far field,perfectly predicted by a universal theory for the SPR.This scheme provides a tool to control the acoustic radiation in the near field,paving the way toward coherent acoustic wave generation and microstructure metrology.
基金supported in part by the National Key R&D Program of China (No. 2018YFA0306301)the National Natural Science Foundation of China (Nos. 12192252, 62022058, 12074252, and 12004245)+2 种基金the Shanghai Municipal Science and Technology Major Project (No. 2019SHZDZX01ZX06)the Shanghai Rising-Star Program (No. 20QA1405400)the Yangyang Development Fund.
文摘Scattering of waves, e.g., light, due to medium inhomogeneity is ubiquitous in physics and isconsidered detrimental for many applications. Wavefront shaping technology is a powerful tool to defeatscattering and focus light through inhomogeneous media, which is vital for optical imaging, communication,therapy, etc. Wavefront shaping based on the scattering matrix (SM) is extremely useful in handling dynamicprocesses in the linear regime. However, the implementation of such a method for controlling light in nonlinearmedia is still a challenge and has been unexplored until now. We report a method to determine the SM ofnonlinear scattering media with second-order nonlinearity. We experimentally demonstrate its feasibility inwavefront control and realize focusing of nonlinear signals through strongly scattering quadratic media.Moreover, we show that statistical properties of this SM still follow the random matrix theory. The scattering-matrix approach of nonlinear scattering medium opens a path toward nonlinear signal recovery, nonlinearimaging, microscopic object tracking, and complex environment quantum information processing.
基金supported by National Natural Science Foundation of China(12104297,12122407,11974245,11825401,12192252,12204304)National Key Research and Development Program of China(2021YFA1400900)+1 种基金Shanghai Municipal Science and Technology Major Project(2019SHZDZX01-Zx06)the Innovation Program for Quantum Science and Technology(2021ZD0302000)。
文摘Measuring topological invariants is an essential task in characterizing topological phases of matter.They are usually obtained from the number of edge states due to the bulk-edge correspondence or from interference since they are integrals of the geometric phases in the energy band.It is commonly believed that the bulk band structures could not be directly used to obtain the topological invariants.Here,we implement the experimental extraction of Zak phase from the bulk band structures of a Su-Schrieffer-Heeger(SSH)model in the synthetic frequency dimension.Such synthetic SSH lattices are constructed in the frequency axis of light,by controlling the coupling strengths between the symmetric and antisymmetric supermodes of two bichromatically driven rings.We measure the transmission spectra and obtain the projection of the time-resolved band structure on lattice sites,where a strong contrast between the non-trivial and trivial topological phases is observed.The topological Zak phase is naturally encoded in the bulk band structures of the synthetic SSH lattices,which can hence be experimentally extracted from the transmission spectra in a fiber-based modulated ring platform using a laser with telecom wavelength.Our method of extracting topological phases from the bulk band structure can be further extended to characterize topological invariants in higher dimensions,while the exhibited trivial and non-trivial transmission spectra from the topological transition may find future applications in optical communications.
基金supported by the National Key R&D Program of China (Grant Nos. 2019YFB2203500, and 2017YFA0303700)the National Natural Science Foundation of China (Grant No. 91950107)the Foundation for Development of Science and Technology of Shanghai (Grant No. 17JC1400400)。
文摘The commercialization of lithium niobate on insulator(LNOI) wafer has resulted in significant on-chip photonic integration application owing to its remarkable photonic,acousto-optic,electro-optic,and piezoelectric nature.In recent years,a variety of high-performance on-chip LNOI-based photonic devices have been realized.In this study,we developed a 1-mol% erbium-doped lithium niobate crystal and its LNOI on a silicon substrate and fabricated an erbium-doped LNOI microdisk with high quality factor(~1.05×105).C-band laser emission at ~1530 and ~1560 nm(linewidth 0.12 nm) from the high-Q erbium-doped LNOI microdisk was demonstrated with 974-and 1460-nm pumping,with the latter having better thermal stability.This microlaser would play an important role in the photonic integrated circuits of the lithium niobate platform.
基金National Natural Science Foundation of China(NSFC)(11474238,11734011,91636109)Fundamental Research Funds for the Central Universities at Xiamen University(20720160040)+2 种基金Natural Science Foundation of Fujian Province(2015J06002)Program for New Century Excellent Talents in University(NCET)(NCET-13-0495)National Key R&D Program of China(2017YFA0303700)
文摘The generation and manipulation of optical vortices are of fundamental importance in a variety of promising applications. Here, we develop a nonlinear optical paradigm to implement self-and cross-convolution of optical vortex arrays, demonstrating the features of a vortex copier and regenerator. We use a phase-only spatial light modulator to prepare the 1064 nm invisible fundamental light to carry special optical vortex arrays and use a potassium titanyl phosphate crystal to perform type Ⅱ second-harmonic generation in the Fourier domain to achieve 532 nm visible structured vortices. Based on pure cross-convolution, we succeed in copying arbitrary-order single vortices as well as their superposition states onto a prearranged array of fundamental Gaussian spots. Also, based on the simultaneous effect of self-and cross-convolutions, we can expand the initial vortex lattices to regenerate more vortices carrying various higher topological charges. Our presented method of realizing an optical vortex copier and regenerator could find direct applications in optical manipulation, optical imaging, optical communication, and quantum information processing with structured vortex arrays.
基金This work was supported by the National Key Research and Development Program(Grant Nos.2016YFA0302500 and 2017YFA0303700)National Natural Science Foundation of China(Grant Nos.92050113 and 11674228)Shanghai MEC Scientific Innovation Program(Grant No.E00075).
文摘Abbe’s resolution limit,one of the best-known physical limitations,poses a great challenge for any wave system in imaging,wave transport,and dynamics.Originally formulated in linear optics,the Abbe limit can be broken using nonlinear optical interactions.We extend the Abbe theory into a nonlinear regime and experimentally demonstrate a far-field,label-free,and scan-free super-resolution imaging technique based on nonlinear four-wave mixing to retrieve near-field scattered evanescent waves,achieving a sub-wavelength resolution ofλ∕5.6.This method paves the way for numerous new applications in biomedical imaging,semiconductor metrology,and photolithography.
基金This work was supported by General Research Fund of Hong Kong （CityU 104911） and National Natural Science Foundation of China （NSFC 51372213 and NSFC 61176007）.
文摘Metal-free, organic-dye-based fluorescent nanorods were fabricated through a simple solvent-exchange procedure. The as-prepared nanorods exhibit low toxicity to living cells and excellent photostability. Furthermore, they are stable in solutions of various pHs and high ionic strength and in solutions with interfering metal ions. Compared with the free DPP-Br molecules in THF, these nanorods exhibit larger Stokes shift, broader absorption spectra, and greatly improved photostability. We successfully demonstrated the application of the nanorods, including their aforementioned beneficial characteristics, as a good fluorescence probe for bio-imaging.
基金the National Natural Science Foundation of China(11822410,12034013,11734009,and 11974245)the National Key R&D Program of China(2017YFA0303701 and 2019YFA0705000)+10 种基金the Shanghai Municipal Science and Technology Major Project(2019SHZDZX01)the Program of Shanghai Academic Research Leader(20XD1424200)the Natural Science Foundation of Shanghai(19ZR1475700)the Strategic Priority Research Program of Chinese Academy of Sciences(XDB16030300)the Key Research Program of Frontier Sciences of Chinese Academy of Sciences(QYZDJ-SSW-SLH010)the Youth Innovation Promotion Association of Chinese Academy of Sciences(2018284)NSF(ECCS-1509268,and CMMI-1826078)AFOSR(FA9550-20-1-0366)partially supported by the Fundamental Research Funds for the Central Universitiesthe support from the Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learningthe support from Shandong Quancheng Scholarship(00242019024)。
基金supported by the National Key R&D Program of China(No.2017YFA0303700)the National Natural Science Foundation of China(NFSC)(No.11574208)
文摘All-optical logic gates including AND, XOR, and NOT gates, as well as a half-adder, are realized based on twodimensional lithium niobate photonic crystal(PhC) circuits with Ph C micro-cavities.The proposed all-optical devices have an extinction ratio as high as 23 dB due to the effective all-optical switch function induced by twomissing-hole micro-cavities.These proposed devices can have potential implementation of complex integrated optical functionalities including all-optical computing in a lithium niobate slab or thin film.
基金National Key R&D Program of China(2017YFA0303700)National Natural Science Foundation of China(NSFC)(11574208)
文摘Future quantum information networks operated on telecom channels require qubit transfer between different wavelengths while preserving quantum coherence and entanglement. Qubit transfer is a nonlinear optical process,but currently the types of atoms used for quantum information processing and storage are limited by the narrow bandwidth of upconversion available. Here we present the first experimental demonstration of broadband and high-efficiency quasi-phase matching second-harmonic generation(SHG) in a chip-scale periodically poled lithium niobate thin film. We achieve a large bandwidth of up to 2 THz for SHG by satisfying quasi-phase matching and group-velocity matching simultaneously. Furthermore, by changing the film thickness, the central wavelength of the quasi-phase matching SHG bandwidth can be modulated from 2.70 μm to 1.44 μm. The reconfigurable quasi-phase matching lithium niobate thin film provides a significant on-chip integrated platform for photonics and quantum optics.
基金National Key R&D Program of China(2017YFA0303700,2018YFA0306300)National Natural Science Foundation of China(11734011)Foundation for Development of Science and Technology of Shanghai(17JC1400400)
文摘Recently, the perfect vector(PV) beam has sparked considerable interest because its radius is independent of the topological charge(TC), which has demonstrated special capabilities in optical manipulation, microscopy imaging, and laser micromachining. Previous research about the generation and manipulation of such PV beams only focuses on the linear optical fields. Therefore, the generation of nonlinear PV beams is still lacking. Here, we propose a dual waveband generator to simultaneously generate the PV beams in linear and nonlinear wavebands.In our experiment, PV beams with different polarization states are realized. It is proved that the polarization states of the generated PV beams can be flexibly adjusted by changing the axis direction of a half wave plate. The experimental results show that the radii of the generated PV beams are equal and independent of the TCs.With proper alteration of the nonlinear crystals, this approach could be further extended to other nonlinear processes, such as sum-frequency generation and difference-frequency generation.
基金supported by the National Natural Science Foundation of China(grant nos 11304201 and 61475100)the National 1000-plan Program(Youth),the Shanghai Pujiang Talent Program(grant no.12PJ1404700)the Shanghai Scientific Innovation Program(grant no.14JC1402900).
文摘Electromagnetically induced transparency has the unique ability to optically control transparency windows with low light in atomic systems.However,its practical applications in quantum physics and information science are limited due to rigid experimental requirements.Here we demonstrate a new mechanism of optically induced transparency in a micro-cavity by introducing a four-wave mixing gain to nonlinearly couple two separated resonances of the micro-cavity in an ambient environment.A signature Fano-like resonance was observed owing to the nonlinear interference of the two coupled resonances.Moreover,we show that the unidirectional gain of the four-wave mixing can lead to the remarkable effect of non-reciprocal transmission at the transparency windows.Optically induced transparency may offer a unique platform for a compact,integrated solution to all-optical and quantum information.
