Despite the promising progress in conductive hydrogels made with pure conducting polymer,great challenges remain in the interface adhesion and robustness in longterm monitoring.To address these challenges,Prof.Seung H...Despite the promising progress in conductive hydrogels made with pure conducting polymer,great challenges remain in the interface adhesion and robustness in longterm monitoring.To address these challenges,Prof.Seung Hwan Ko and Taek-Soo Kim’s team introduced a laserinduced phase separation and adhesion method for fabricating conductive hydrogels consisting of pure poly(3,4-ethylenedioxythiophene):polystyrene sulfonate on polymer substrates.The laser-induced phase separation and adhesion treated conducting polymers can be selectively transformed into conductive hydrogels that exhibit wet conductivities of 101.4 S cm^(−1) with a spatial resolution down to 5μm.Moreover,they maintain impedance and charge-storage capacity even after 1 h of sonication.The micropatterned electrode arrays demonstrate their potential in long-term in vivo signal recordings,highlighting their promising role in the field of bioelectronics.展开更多
This paper describes what is thought to be the first generation of a continuous wave deep ultraviolet laser at 275 nm by efficient frequency doubling of a blue-diode-pumped Pr:YLF laser at 550 nm.By employing a novel ...This paper describes what is thought to be the first generation of a continuous wave deep ultraviolet laser at 275 nm by efficient frequency doubling of a blue-diode-pumped Pr:YLF laser at 550 nm.By employing a novel fast-axis collimated blue semiconductor laser as the pump source,combined with a folded cavity and innovation coating technology,and utilizing a Brewster-cut BBO crystal for intracavity frequency doubling,TEM00 mode deep UV laser radiation at 275 nm with an output power of 351 mW is obtained.This marks the first report of achieving 275 nm laser generation based on Pr:LiYF4 to date.展开更多
In-situ formed high Mn steel coating reinforced by carbides was formed by laser surface alloying(LSA).Laser alloyed layers on 1Cr18Ni9Ti steel with Mn+W_(2)C(specimen A),Mn+NiWC(specimen B)and Mn+SiC(specimen C)powder...In-situ formed high Mn steel coating reinforced by carbides was formed by laser surface alloying(LSA).Laser alloyed layers on 1Cr18Ni9Ti steel with Mn+W_(2)C(specimen A),Mn+NiWC(specimen B)and Mn+SiC(specimen C)powders were fabricated to improve the wear and corrosion behavior of 1Cr18Ni9Ti steel blades in high speed mixers.Microstructure evolution,phases,element distribution,microhardness,wear and corrosion behavior of the laser alloyed layers were investigated.Results indicated that high Mn steel matrix composites with undissolved W_(2)C,WC and other in-situ formed carbides were formed by LSA with Mn+W_(2)C and Mn+NiWC while SiC totally dissolved into the high Mn matrix when adding Mn+SiC.Ni as the binding phase in Ni-WC powder decreased the crack sensitivity of the alloyed layer as compared with the addition of W_(2)C powder.An improvement in average microhardness was achieved in the matrix in specimen A,B and C,with the value of 615,602 and 277 HV_(0.5),while that of the substrate was 212 HV_(0.5).The increase of microhardness,wear and corrosion resistance is highly corelated to microstructure,formed phases,type and content of carbides,micro-hardness and toughness of the alloyed layers.展开更多
The accuracy of spot centroid positioning has a significant impact on the tracking accuracy of the system and the stability of the laser link construction.In satellite laser communication systems,the use of short-wave...The accuracy of spot centroid positioning has a significant impact on the tracking accuracy of the system and the stability of the laser link construction.In satellite laser communication systems,the use of short-wave infrared wavelengths as beacon light can reduce atmospheric absorption and signal attenuation.However,there are strong non-uniformity and blind pixels in the short-wave infrared image,which makes the image distorted and leads to the decrease of spot centroid positioning accuracy.Therefore,the high-precision localization of the spot centroid of the short-wave infrared images is of great research significance.A high-precision spot centroid positioning model for short-wave infrared is proposed to correct for non-uniformity and blind pixels in short-wave infrared images and quantify the localization errors caused by the two,further model-based localization error simulations are performed,and a novel spot centroid positioning payload for satellite laser communications has been designed using the latest 640×512 planar array InGaAs shortwave infrared detector.The experimental results show that the non-uniformity of the corrected image is reduced from 7%to 0.6%,the blind pixels rejection rate reaches 100%,the frame rate can be up to 2000 Hz,and the spot centroid localization accuracy is as high as 0.1 pixel point,which realizes high-precision spot centroid localization of high-frame-frequency short-wave infrared images.展开更多
Laser etching and laser chemical vapor deposition(LCVD)techniques were proposed for the rapid preparation of high-purity,strongly bonded SiC porous micro-nano-coatings on quartz substrates.The laser serves as an exter...Laser etching and laser chemical vapor deposition(LCVD)techniques were proposed for the rapid preparation of high-purity,strongly bonded SiC porous micro-nano-coatings on quartz substrates.The laser serves as an external driving force for the vertical growth of SiC whiskers,facilitating the formation of a porous nanostructure that resembles coral models found in the macroscopic biological world.The porous nanostructures are beneficial for reducing thermal expansion mismatch and relieving residual stress.It is capable of eliminating the cracks on the surface of SiC coatings as well as enhancing the bonding of SiC coatings with quartz substrates to avoid coating detachment.展开更多
Laser shock peening(LSP)was used to enhance the high-temperature oxidation resistance of laser melting deposited Ti45Al8Nb alloy.The microstructure and high-temperature oxidation behavior of the as-deposited Ti45Al8Nb...Laser shock peening(LSP)was used to enhance the high-temperature oxidation resistance of laser melting deposited Ti45Al8Nb alloy.The microstructure and high-temperature oxidation behavior of the as-deposited Ti45Al8Nb alloy before and after LSP were investigated by scanning electron microscopy,X-ray diffraction,and electron backscatter diffraction.The results indicated that the rate of mass gain in the as-deposited sample after LSP exhibited a decrease when exposed to an oxidation temperature of 900℃,implying that LSP-treated samples exhibited superior oxidation resistance at high temperatures.A gradient structure with a fine-grain layer,a deformed-grain layer,and a coarse-grain layer was formed in the LSP-treated sample,which facilitated the diffusion of the Al atom during oxidation,leading to the formation of a dense Al_(2)O_(3)layer on the surface.The mechanism of improvement in the oxidation resistance of the as-deposited Ti45Al8Nb alloy via LSP was discussed.展开更多
While laser surface texturing(LST)is a promising manufacturing technique for surface functionalization,simultaneously realizing high precision and high efficiency in the LST of complex curved surface is challenging,du...While laser surface texturing(LST)is a promising manufacturing technique for surface functionalization,simultaneously realizing high precision and high efficiency in the LST of complex curved surface is challenging,due to continuously varied geometries of laser-matter incidence.In the present work,we propose a novel manufacturing system of 7-axis on-the-fly LST for complex curved surface,based on the integrated synchronization of 5-axis linkage motion platform with 2-axis galvanometer.Specifically,the algorithm for decomposing spatial texture trajectory on curved surface into low-frequency and high-frequency parts is established,based on which the kinematic model of synchronized 7-axis system is developed to derive the motion of each axis in both 5-axis linkage motion platform and 2-axis galvanometer simultaneously.Subsequently,the synchronized 7-axis LST system is experimentally realized,including the setup of mechanical stages integrated with optical path,the configuration of numerical control unit,and the development of processing software.Finally,case study of 7-axis on-the-fly LST of freeform aluminum surface is performed,and the advantages in terms of processing efficiency and texturing accuracy over 5-axis linkage LST are demonstrated.The correlation of reduced following errors between mechanical stages with the promoted performance of curved surface texturing by the 7-axis on-the-fly LST is further analyzed.Current work provides a feasible solution for establishing the manufacturing system for high performance LST of complex curved surface.展开更多
The topic of improving the mechanical stability of external cavity diode lasers(ECDLs)has recently attracted widespread attention and interest.The use of corner-cube-array(CCA)-based resonators provides a potential so...The topic of improving the mechanical stability of external cavity diode lasers(ECDLs)has recently attracted widespread attention and interest.The use of corner-cube-array(CCA)-based resonators provides a potential solution for this purpose,although continuous oscillation at super large incident angle remains challenging.In this work,we employ the CCA resonator to generate continuous oscillation within±20°angular misalignment of cavity mirror in experiment.On the basis of retroreflection theory,the retroreflectivity of a CCA is analyzed by using optical simulation software.Notably,the experiment verifies the advantage of using a CCA over a plane mirror in laser resonator,thereby providing a promising approach for ECDLs.The threshold characteristic curves measured at different incident angles in the experiment verify that the CCA possesses an obvious anti-angle misalignment performance.This research introduces an alternative solution of using CCA resonator instead of parallel plane cavity,thereby realizing an adjustment-free ECDL with enhanced mechanical stability.展开更多
The intrusion of obstacles onto railway tracks presents a significant threat to train safety,characterized by sudden and unpredictable occurrences.With China leading the world in high-speed rail mileage,ensuring railw...The intrusion of obstacles onto railway tracks presents a significant threat to train safety,characterized by sudden and unpredictable occurrences.With China leading the world in high-speed rail mileage,ensuring railway security is paramount.The current laser monitoring technologies suffer from high false alarm rates and unreliable intrusion identification.This study addresses these issues by investigating high-resolution laser monitoring technology for railway obstacles,focusing on key parameters such as monitoring range and resolution.We propose an enhanced non-uniform laser scanning method,developing a laser monitoring system that reduces the obstacle false alarm rate to 2.00%,significantly lower than the 20%standard(TJ/GW135-2015).This rate is the best record for laser monitoring systems on China Railway.Our system operates seamlessly in all weather conditions,providing superior accuracy,resolution,and identification efficiency.It is the only 3D LiDAR system certified by the China State Railway Group Co.,Ltd.(Certificate No.[2023]008).Over three years,our system has been deployed at numerous points along various lines managed by the China State Railway Group,accumulating a dataset of 300,000 observations.This extensive deployment has significantly enhanced railway safety.The development and implementation of our railway laser monitoring system represent a substantial advancement in railway safety technology.Its low false alarm rate(2.00%),high accuracy(20 cm×20 cm×20 cm),and robust performance in diverse conditions underscore its potential for widespread adoption,promising to enhance railway safety in China and internationally.展开更多
Two-plasmon-decay instability(TPD)poses a critical target preheating risk in direct-drive inertial confinement fusion.In this paper,TPD collectively driven by dual laser beams consisting of a normal-incidence laser be...Two-plasmon-decay instability(TPD)poses a critical target preheating risk in direct-drive inertial confinement fusion.In this paper,TPD collectively driven by dual laser beams consisting of a normal-incidence laser beam(Beam-N)and a large-angle-incidence laser beam(Beam-L)is investigated via particle-in-cell simulations.It is found that significant TPD growth can develop in this regime at previously unexpected low laser intensities if the intensity of Beam-L exceeds the large-angle-incidence threshold.Both beams contribute to the growth of TPD in a“seed-amplification”manner in which the absolute instability driven by Beam-L provides the seeds that are convectively amplified by Beam-N,making TPD energetically important and causing significant pump depletion and hot-electron generation.展开更多
Broad area quantum cascade lasers(BA QCLs)have significant applications in many areas,but suffer from demanding pulse operating conditions and poor beam quality due to heat accumulation and generation of high order mo...Broad area quantum cascade lasers(BA QCLs)have significant applications in many areas,but suffer from demanding pulse operating conditions and poor beam quality due to heat accumulation and generation of high order modes.A structure of mini-array is adopted to improve the heat dissipation capacity and beam quality of BA QCLs.The active region is etched to form a multi-emitter and the channels are filled with In P:Fe,which acts as a lateral heat dissipation channel to improve the lateral heat dissipation efficiency.A device withλ~4.8μm,a peak output power of 122 W at 1.2%duty cycle with a pulse of 1.5μs is obtained in room temperature,with far-field single-lobed distribution.This result allows BA QCLs to obtain high peak power at wider pump pulse widths and higher duty cycle conditions,promotes the application of the mid-infrared laser operating in pulsed mode in th e field of standoff photoacoustic chemical detection,space optical communication,and so on.展开更多
High-power laser technology is widely used in manufacturing processing,medical diagnosis,and treatment,and is one of the important fields of strategic high-tech competition in China at the moment.In the context of ind...High-power laser technology is widely used in manufacturing processing,medical diagnosis,and treatment,and is one of the important fields of strategic high-tech competition in China at the moment.In the context of industrial upgrading,high-power laser technology plays an important role in leading the development of the manufacturing industry and industrial intelligence.Based on this,this paper carries out research on high-power laser technology and industry,summarizes the basic principle and classification of high-power laser technology,analyzes the current status of high-power laser technology industry,points out the opportunities and challenges faced by the industry development,puts forward suggestions to promote the development of high-power laser technology industry,and to provide an effective reference for the application and development of high-power laser technology.展开更多
Controllable rock cracking technology is crucial for the exploration and exploitation of deep underground resources.Many existing studies have been dedicated to the laser-assisted rock-weakening technology.It has been...Controllable rock cracking technology is crucial for the exploration and exploitation of deep underground resources.Many existing studies have been dedicated to the laser-assisted rock-weakening technology.It has been proved that laser irradiation can improve drilling and blasting efficiency when combined with mechanical rock fracturing methods,which are irrelevant for borehole stabilization.To improve the latter,this study used laser ablation for borehole reinforcement.The high-power laser was applied to typical rock samples(sandstone,mudstone and coal)in both dry and saturated conditions.Multi-technique observations and measurements were used to fully understand the peculiar modifications of the specimens under laser treatment,i.e.mechanical loading,acoustic emission(AE)monitoring,digital image correlation(DIC)strain field evaluation,infrared thermography(IRT)monitoring and X-ray computed tomography(CT)scanning.The results showed that,in addition to the effects already demonstrated,laser irradiation can improve the strength of the soft rock,especially in the saturated state.The process involved a complicated phase change including melting and evaporation of the matrix under high-temperature and high-pressure to form a glassy high strength silicate material.This process is similar to the reaction between molten lava and water,or the impact of an asteroid on the earth.Inspired by the results,a conceptual path for a new borehole stabilization technology using laser ablation was outlined.展开更多
Transparent materials utilized as underwater optical windows are highly vulnerable to various forms of pollution or abrasion due to their intrinsic hydrophilic properties.This susceptibility is particularly pronounced...Transparent materials utilized as underwater optical windows are highly vulnerable to various forms of pollution or abrasion due to their intrinsic hydrophilic properties.This susceptibility is particularly pronounced in underwater environments where pollutants can impede the operation of these optical devices,significantly degrading or even compromising their optical properties.The glass catfish,known for its remarkable transparency in water,maintains surface cleanliness and clarity despite exposure to contaminants,impurities abrasion,and hydraulic pressure.Inspired by the glass catfish’s natural attributes,this study introduces a new solution named subaquatic abrasion-resistant and anti-fouling window(SAAW).Utilizing femtosecond laser ablation and electrodeposition,the SAAW is engineered by embedding fine metal bone structures into a transparent substrate and anti-fouling sliding layer,akin to the sturdy bones among catfish’s body.This approach significantly bolsters the window’s abrasion resistance and anti-fouling performance while maintaining high light transmittance.The sliding layer on the SAAW’s surface remarkably reduces the friction of various liquids,which is the reason that SAAW owns the great anti-fouling property.The SAAW demonstrates outstanding optical clarity even after enduring hundreds of sandpaper abrasions,attributing to the fine metal bone structures bearing all external forces and protecting the sliding layer of SAAW.Furthermore,it exhibits exceptional resistance to biological adhesion and underwater pressure.In a green algae environment,the window remains clean with minimal change in transmittance over one month.Moreover,it retains its wettability and anti-fouling properties when subjected to a depth of 30 m of underwater pressure for 30 d.Hence,the SAAW prepared by femtosecond laser ablation and electrodeposition presents a promising strategy for developing stable optical windows in liquid environments.展开更多
We demonstrate an integrating sphere to cool~(87)Rb atoms and measure the recoil-induced resonance and electromagnetically induced absorption spectrum.We measure the relationship between their linewidth and light shif...We demonstrate an integrating sphere to cool~(87)Rb atoms and measure the recoil-induced resonance and electromagnetically induced absorption spectrum.We measure the relationship between their linewidth and light shift with variation of the detuning and power of the cooling laser and study the performance of the diffuse laser cooling mechanism by the absorption linewidth radio?ν_E/?ν_R and light shift|?_R-?_E|using nonlinear spectroscopy.Specifically,when?ν_E/?ν_R reaches a value of 1.57,the temperature and number of cold atoms achieve the optimal cooling effect.This characterization of absorption linewidth and light shift will provide a method to estimate whether diffuse light cooling achieves the best cooling effect,contributing to the future development of isotropic laser cooling for application in quantum sensing.展开更多
We investigated the ionization and dissociation processes of ammonia clusters ranging from dimer to pentamer induced by 800-nm femtosecond laser fields.Time-of-flight(TOF)mass spectra of the ammonia clusters were reco...We investigated the ionization and dissociation processes of ammonia clusters ranging from dimer to pentamer induced by 800-nm femtosecond laser fields.Time-of-flight(TOF)mass spectra of the ammonia clusters were recorded over a range of laser intensities from 2.1×10^(12)W/cm^(2) to 5.6×10^(12)W/cm^(2).The protonated ion signals dominate the spectra,which is consistent with the stability of the geometric structures.The ionization and dissociation channels of ammonia clusters are discussed.The competition and switching among observed dissociation channels are revealed by analyzing the variations in the relative ionic yields of specific protonated and unprotonated clusters under different laser intensities.These results indicate that the ionization of the neutral multiple-ammonia units,produced through the dissociation of cluster ions,may start to contribute,as well as the additional processes to consume protonated ions and/or produce unprotonated ions induced by the femtosecond laser fields when the laser intensity is above^4×10^(12)W/cm^(2).These findings provide deeper insights into the ionization and dissociation dynamics in multi-photon ionization experiments involving ammonia clusters.展开更多
Surface tension-induced shrinkage of heterogeneously bonded interfaces is a key factor in limiting the performance of nanostructures.Herein,we demonstrate a laser-induced thermo-compression bonding technology to suppr...Surface tension-induced shrinkage of heterogeneously bonded interfaces is a key factor in limiting the performance of nanostructures.Herein,we demonstrate a laser-induced thermo-compression bonding technology to suppress surface tension-induced shrinkage of Cu-Au bonded interface.A focused laser beam is used to apply localized heating and scattering force to the exposed Cu nanowire.The laser-induced scattering force and the heating can be adjusted by regulating the exposure intensity.When the ratio of scattering forces to the gravity of the exposed nanowire reaches 3.6×10^(3),the molten Cu nanowire is compressed into flattened shape rather than shrinking into nanosphere by the surface tension.As a result,the Cu-Au bonding interface is broadened fourfold by the scattering force,leading to a reduction in contact resistance of approximately 56%.This noncontact thermo-compression bonding technology provides significant possibilities for the interconnect packaging and integration of nanodevices.展开更多
Conventional Fe-C alloy parts used in mechanical transmission and braking systems exposed to the external environment often suffer from wear and corrosion failures.Surface coating strengthening technologies have been ...Conventional Fe-C alloy parts used in mechanical transmission and braking systems exposed to the external environment often suffer from wear and corrosion failures.Surface coating strengthening technologies have been explored to improve the surface performance and prolong service life of these parts.Among these technologies,laser cladding has shown promise in producing Fe-based alloy coatings with superior interfacial bonding properties to the Fe-C alloy substrate.Additionally,the microstructure of the Fe-based alloy coating is more uniform and the grain size is finer than that of surfacing welding,thermal spraying,and plasma cladding,and the oxide film of alloying elements on the coating surface can improve the coating performance.However,Fe-based alloy coatings produced by laser cladding typically exhibit lower hardness,lower wear resistance,corrosion resistance,and oxidation resistance compared to coatings based on Co and Ni alloys.Moreover,these coatings are susceptible to defects such as pores and cracks.To address these limitations,the incorporation of rare-earth oxides through doping in the laser cladding process has garnered significant attention.This approach has demonstrated substantial improvements in the microstructure and properties of Fe-based alloy coatings.This paper reviewed recent research on the structure and properties of laser-cladded Fe-based alloy coatings doped with various rare earth oxides,including La_(2)O_(3),CeO_(2),and Y_(2)O_(3).Specifically,it discussed the effects of rare earth oxides and their concentrations on the structure,hardness,friction,wear,corrosion,and oxidation characteristics of these coatings.Furthermore,the mechanisms by which rare earth oxides influence the coating’s structure and properties were summarized.This review aimed to serve as a valuable reference for the application and advancement of laser cladding technology for rare earth modified Fe-based alloy coatings.展开更多
In this study,we explore the impact of state-of-the-art laser fields on theαdecay half-life of deformed ground-state odd-A nuclei within the proton number range of 52–107.The calculations show that the presence of a...In this study,we explore the impact of state-of-the-art laser fields on theαdecay half-life of deformed ground-state odd-A nuclei within the proton number range of 52–107.The calculations show that the presence of a laser field modulates theαdecay half-life by altering theαdecay penetration probability within a limited range.Moreover,the variance in the penetration probability rate of change between even–odd and odd–even nuclei is investigated.Furthermore,we investigate the rate of change of the penetration probability for the same parent nucleus with different neutron numbers,based on the characteristics of the odd-A nucleus.We found that the influence of the laser field on the penetration probability is determined by both the shell effect and odd–even staggering.This research contributes to the understanding of nuanced interactions between laser fields and nuclear decay processes.Therefore,valuable insights for future experiments in laser–nuclear physics are attainable using this study.展开更多
The low-melting glass of Bi2O_(3)-B2O_(3)-SiO_(2)(BiBSi)system was used for the first time for laser sealing of vacuum glazing.Under the condition of constant boron content,how the structure and properties vary with B...The low-melting glass of Bi2O_(3)-B2O_(3)-SiO_(2)(BiBSi)system was used for the first time for laser sealing of vacuum glazing.Under the condition of constant boron content,how the structure and properties vary with Bi/Si ratio in low-melting glass was investigated.In addition,the relationships between laser power,low-melting glass solder with different Bi/Si ratios and laser sealing shear strength were revealed.The results show that a decrease in the Bi/Si ratio can cause a contraction of the glass network of the low-melting glass,leading to an increase of its characteristic temperature and a decrease of its coefficient of thermal expansion.During laser sealing,the copper ions in the low-melting glass play an endothermic role.A change in the Bi/Si ratio will affect the valence state transition of the copper ions in the low-melting glass.The absorbance of the low-melting glass does not follow the expected correlation with the Bi/Si ratio,but shows a linear correlation with the content of divalent copper ions.The greater the concentration of divalent copper ions,the greater the absorbance of the low-melting glass,and the lower the laser power required for laser sealing.The shear strength of the low melting glass solder after laser sealing was tested,and it was found that the maximum shear strength of Z1 glass sample was the highest up to 2.67 MPa.展开更多
基金supported by the National Natural Science Foundation of China(52475610)Zhejiang Provincial Natural Science Foundation of China(LDQ24E050001).
文摘Despite the promising progress in conductive hydrogels made with pure conducting polymer,great challenges remain in the interface adhesion and robustness in longterm monitoring.To address these challenges,Prof.Seung Hwan Ko and Taek-Soo Kim’s team introduced a laserinduced phase separation and adhesion method for fabricating conductive hydrogels consisting of pure poly(3,4-ethylenedioxythiophene):polystyrene sulfonate on polymer substrates.The laser-induced phase separation and adhesion treated conducting polymers can be selectively transformed into conductive hydrogels that exhibit wet conductivities of 101.4 S cm^(−1) with a spatial resolution down to 5μm.Moreover,they maintain impedance and charge-storage capacity even after 1 h of sonication.The micropatterned electrode arrays demonstrate their potential in long-term in vivo signal recordings,highlighting their promising role in the field of bioelectronics.
文摘This paper describes what is thought to be the first generation of a continuous wave deep ultraviolet laser at 275 nm by efficient frequency doubling of a blue-diode-pumped Pr:YLF laser at 550 nm.By employing a novel fast-axis collimated blue semiconductor laser as the pump source,combined with a folded cavity and innovation coating technology,and utilizing a Brewster-cut BBO crystal for intracavity frequency doubling,TEM00 mode deep UV laser radiation at 275 nm with an output power of 351 mW is obtained.This marks the first report of achieving 275 nm laser generation based on Pr:LiYF4 to date.
文摘In-situ formed high Mn steel coating reinforced by carbides was formed by laser surface alloying(LSA).Laser alloyed layers on 1Cr18Ni9Ti steel with Mn+W_(2)C(specimen A),Mn+NiWC(specimen B)and Mn+SiC(specimen C)powders were fabricated to improve the wear and corrosion behavior of 1Cr18Ni9Ti steel blades in high speed mixers.Microstructure evolution,phases,element distribution,microhardness,wear and corrosion behavior of the laser alloyed layers were investigated.Results indicated that high Mn steel matrix composites with undissolved W_(2)C,WC and other in-situ formed carbides were formed by LSA with Mn+W_(2)C and Mn+NiWC while SiC totally dissolved into the high Mn matrix when adding Mn+SiC.Ni as the binding phase in Ni-WC powder decreased the crack sensitivity of the alloyed layer as compared with the addition of W_(2)C powder.An improvement in average microhardness was achieved in the matrix in specimen A,B and C,with the value of 615,602 and 277 HV_(0.5),while that of the substrate was 212 HV_(0.5).The increase of microhardness,wear and corrosion resistance is highly corelated to microstructure,formed phases,type and content of carbides,micro-hardness and toughness of the alloyed layers.
基金Supported by the Short-wave Infrared Camera Systems(B025F40622024)。
文摘The accuracy of spot centroid positioning has a significant impact on the tracking accuracy of the system and the stability of the laser link construction.In satellite laser communication systems,the use of short-wave infrared wavelengths as beacon light can reduce atmospheric absorption and signal attenuation.However,there are strong non-uniformity and blind pixels in the short-wave infrared image,which makes the image distorted and leads to the decrease of spot centroid positioning accuracy.Therefore,the high-precision localization of the spot centroid of the short-wave infrared images is of great research significance.A high-precision spot centroid positioning model for short-wave infrared is proposed to correct for non-uniformity and blind pixels in short-wave infrared images and quantify the localization errors caused by the two,further model-based localization error simulations are performed,and a novel spot centroid positioning payload for satellite laser communications has been designed using the latest 640×512 planar array InGaAs shortwave infrared detector.The experimental results show that the non-uniformity of the corrected image is reduced from 7%to 0.6%,the blind pixels rejection rate reaches 100%,the frame rate can be up to 2000 Hz,and the spot centroid localization accuracy is as high as 0.1 pixel point,which realizes high-precision spot centroid localization of high-frame-frequency short-wave infrared images.
基金Funded by the International Science&Technology Cooperation Program of Hubei Province of China(No.2022EHB024)the National Key Research and Development Plan(Nos.2018YFE0103600 and 2021YFB3703100)+1 种基金the National Natural Science Foundation of China(Nos.51872212,51972244,52002075,and 52102066)the 111 Project(No.B13035)。
文摘Laser etching and laser chemical vapor deposition(LCVD)techniques were proposed for the rapid preparation of high-purity,strongly bonded SiC porous micro-nano-coatings on quartz substrates.The laser serves as an external driving force for the vertical growth of SiC whiskers,facilitating the formation of a porous nanostructure that resembles coral models found in the macroscopic biological world.The porous nanostructures are beneficial for reducing thermal expansion mismatch and relieving residual stress.It is capable of eliminating the cracks on the surface of SiC coatings as well as enhancing the bonding of SiC coatings with quartz substrates to avoid coating detachment.
基金supported by the Class Ⅲ Peak Discipline of Shanghai,China-Materials Science and Engineering(High-Energy Beam Intelligent Processing and Green Manufacturing).
文摘Laser shock peening(LSP)was used to enhance the high-temperature oxidation resistance of laser melting deposited Ti45Al8Nb alloy.The microstructure and high-temperature oxidation behavior of the as-deposited Ti45Al8Nb alloy before and after LSP were investigated by scanning electron microscopy,X-ray diffraction,and electron backscatter diffraction.The results indicated that the rate of mass gain in the as-deposited sample after LSP exhibited a decrease when exposed to an oxidation temperature of 900℃,implying that LSP-treated samples exhibited superior oxidation resistance at high temperatures.A gradient structure with a fine-grain layer,a deformed-grain layer,and a coarse-grain layer was formed in the LSP-treated sample,which facilitated the diffusion of the Al atom during oxidation,leading to the formation of a dense Al_(2)O_(3)layer on the surface.The mechanism of improvement in the oxidation resistance of the as-deposited Ti45Al8Nb alloy via LSP was discussed.
基金the support by the Harbin Manufacturing Science and Technology Innovation Talent Project(No.2023CXRCGD035)the Open Research Foundation of State Key Laboratory of Digital Manufacturing Equipment and Technology in Huazhong University of Science and Technology,China(No.IMETKF2023012).
文摘While laser surface texturing(LST)is a promising manufacturing technique for surface functionalization,simultaneously realizing high precision and high efficiency in the LST of complex curved surface is challenging,due to continuously varied geometries of laser-matter incidence.In the present work,we propose a novel manufacturing system of 7-axis on-the-fly LST for complex curved surface,based on the integrated synchronization of 5-axis linkage motion platform with 2-axis galvanometer.Specifically,the algorithm for decomposing spatial texture trajectory on curved surface into low-frequency and high-frequency parts is established,based on which the kinematic model of synchronized 7-axis system is developed to derive the motion of each axis in both 5-axis linkage motion platform and 2-axis galvanometer simultaneously.Subsequently,the synchronized 7-axis LST system is experimentally realized,including the setup of mechanical stages integrated with optical path,the configuration of numerical control unit,and the development of processing software.Finally,case study of 7-axis on-the-fly LST of freeform aluminum surface is performed,and the advantages in terms of processing efficiency and texturing accuracy over 5-axis linkage LST are demonstrated.The correlation of reduced following errors between mechanical stages with the promoted performance of curved surface texturing by the 7-axis on-the-fly LST is further analyzed.Current work provides a feasible solution for establishing the manufacturing system for high performance LST of complex curved surface.
基金supported by the Natural Science Foundation of Jiangsu Province(Grant No.BK20240613)Jiangsu Province’s“Innovation and Entrepreneurship Doctor”Program(Grant No.JSSCBS20230088)+4 种基金Natural Science Foundation of Nanjing University of Posts and Telecommunications(Grant No.NY224123)Natural Science Research Start-up Foundation of Recruiting Talents of Nanjing University of Posts and Telecommunications(Grant No.NY222112)Beijing Nova Program(Grant No.20240484696)Wenzhou Major Science and Technology Innovation Key Project(Grant No.ZG2020046)INNOVATION Program for Quantum Science and Technology(Grant No.2021ZD0303200)。
文摘The topic of improving the mechanical stability of external cavity diode lasers(ECDLs)has recently attracted widespread attention and interest.The use of corner-cube-array(CCA)-based resonators provides a potential solution for this purpose,although continuous oscillation at super large incident angle remains challenging.In this work,we employ the CCA resonator to generate continuous oscillation within±20°angular misalignment of cavity mirror in experiment.On the basis of retroreflection theory,the retroreflectivity of a CCA is analyzed by using optical simulation software.Notably,the experiment verifies the advantage of using a CCA over a plane mirror in laser resonator,thereby providing a promising approach for ECDLs.The threshold characteristic curves measured at different incident angles in the experiment verify that the CCA possesses an obvious anti-angle misalignment performance.This research introduces an alternative solution of using CCA resonator instead of parallel plane cavity,thereby realizing an adjustment-free ECDL with enhanced mechanical stability.
基金financially supported by the National Natural Science Foundation of China(Nos.62275244,62375258,62225507,U2033211,62175230,and 62175232)the CAS Project for Young Scientists in Basic Research(No.YSBR-065)+2 种基金Scientific Instrument Developing Project of the Chinese Academy of Sciences(No.YJKYYQ20200001)National Key R&D Program of China(No.2022YFB3607800,No.2022YFB3605800,and No.2022YFB4601501)Key Program of the Chinese Academy of Sciences(ZDBS-ZRKJZ-TLC018)。
文摘The intrusion of obstacles onto railway tracks presents a significant threat to train safety,characterized by sudden and unpredictable occurrences.With China leading the world in high-speed rail mileage,ensuring railway security is paramount.The current laser monitoring technologies suffer from high false alarm rates and unreliable intrusion identification.This study addresses these issues by investigating high-resolution laser monitoring technology for railway obstacles,focusing on key parameters such as monitoring range and resolution.We propose an enhanced non-uniform laser scanning method,developing a laser monitoring system that reduces the obstacle false alarm rate to 2.00%,significantly lower than the 20%standard(TJ/GW135-2015).This rate is the best record for laser monitoring systems on China Railway.Our system operates seamlessly in all weather conditions,providing superior accuracy,resolution,and identification efficiency.It is the only 3D LiDAR system certified by the China State Railway Group Co.,Ltd.(Certificate No.[2023]008).Over three years,our system has been deployed at numerous points along various lines managed by the China State Railway Group,accumulating a dataset of 300,000 observations.This extensive deployment has significantly enhanced railway safety.The development and implementation of our railway laser monitoring system represent a substantial advancement in railway safety technology.Its low false alarm rate(2.00%),high accuracy(20 cm×20 cm×20 cm),and robust performance in diverse conditions underscore its potential for widespread adoption,promising to enhance railway safety in China and internationally.
基金supported by the National Natural Science Foundation of China (NSFC) under Grant Nos. 12375243 and 12388101the Strategic Priority Research Program of the Chinese Academy of Sciences under Grant Nos. XDA25050400, XDA25010200, and XDA25010100+1 种基金the Science Challenge Projectthe Fundamental Research Funds for the Central Universities。
文摘Two-plasmon-decay instability(TPD)poses a critical target preheating risk in direct-drive inertial confinement fusion.In this paper,TPD collectively driven by dual laser beams consisting of a normal-incidence laser beam(Beam-N)and a large-angle-incidence laser beam(Beam-L)is investigated via particle-in-cell simulations.It is found that significant TPD growth can develop in this regime at previously unexpected low laser intensities if the intensity of Beam-L exceeds the large-angle-incidence threshold.Both beams contribute to the growth of TPD in a“seed-amplification”manner in which the absolute instability driven by Beam-L provides the seeds that are convectively amplified by Beam-N,making TPD energetically important and causing significant pump depletion and hot-electron generation.
文摘Broad area quantum cascade lasers(BA QCLs)have significant applications in many areas,but suffer from demanding pulse operating conditions and poor beam quality due to heat accumulation and generation of high order modes.A structure of mini-array is adopted to improve the heat dissipation capacity and beam quality of BA QCLs.The active region is etched to form a multi-emitter and the channels are filled with In P:Fe,which acts as a lateral heat dissipation channel to improve the lateral heat dissipation efficiency.A device withλ~4.8μm,a peak output power of 122 W at 1.2%duty cycle with a pulse of 1.5μs is obtained in room temperature,with far-field single-lobed distribution.This result allows BA QCLs to obtain high peak power at wider pump pulse widths and higher duty cycle conditions,promotes the application of the mid-infrared laser operating in pulsed mode in th e field of standoff photoacoustic chemical detection,space optical communication,and so on.
文摘High-power laser technology is widely used in manufacturing processing,medical diagnosis,and treatment,and is one of the important fields of strategic high-tech competition in China at the moment.In the context of industrial upgrading,high-power laser technology plays an important role in leading the development of the manufacturing industry and industrial intelligence.Based on this,this paper carries out research on high-power laser technology and industry,summarizes the basic principle and classification of high-power laser technology,analyzes the current status of high-power laser technology industry,points out the opportunities and challenges faced by the industry development,puts forward suggestions to promote the development of high-power laser technology industry,and to provide an effective reference for the application and development of high-power laser technology.
基金supported by the National Natural Science Foundation of China(Grant No.51804296)China Scholarship Council Grant(Grant No.CSC#202006425019).
文摘Controllable rock cracking technology is crucial for the exploration and exploitation of deep underground resources.Many existing studies have been dedicated to the laser-assisted rock-weakening technology.It has been proved that laser irradiation can improve drilling and blasting efficiency when combined with mechanical rock fracturing methods,which are irrelevant for borehole stabilization.To improve the latter,this study used laser ablation for borehole reinforcement.The high-power laser was applied to typical rock samples(sandstone,mudstone and coal)in both dry and saturated conditions.Multi-technique observations and measurements were used to fully understand the peculiar modifications of the specimens under laser treatment,i.e.mechanical loading,acoustic emission(AE)monitoring,digital image correlation(DIC)strain field evaluation,infrared thermography(IRT)monitoring and X-ray computed tomography(CT)scanning.The results showed that,in addition to the effects already demonstrated,laser irradiation can improve the strength of the soft rock,especially in the saturated state.The process involved a complicated phase change including melting and evaporation of the matrix under high-temperature and high-pressure to form a glassy high strength silicate material.This process is similar to the reaction between molten lava and water,or the impact of an asteroid on the earth.Inspired by the results,a conceptual path for a new borehole stabilization technology using laser ablation was outlined.
基金supported by the National Science Foundation of China under Grant Nos(Nos.12127806,62175195)the International Joint Research Laboratory for Micro/Nano Manufacturing and Measurement Technologies。
文摘Transparent materials utilized as underwater optical windows are highly vulnerable to various forms of pollution or abrasion due to their intrinsic hydrophilic properties.This susceptibility is particularly pronounced in underwater environments where pollutants can impede the operation of these optical devices,significantly degrading or even compromising their optical properties.The glass catfish,known for its remarkable transparency in water,maintains surface cleanliness and clarity despite exposure to contaminants,impurities abrasion,and hydraulic pressure.Inspired by the glass catfish’s natural attributes,this study introduces a new solution named subaquatic abrasion-resistant and anti-fouling window(SAAW).Utilizing femtosecond laser ablation and electrodeposition,the SAAW is engineered by embedding fine metal bone structures into a transparent substrate and anti-fouling sliding layer,akin to the sturdy bones among catfish’s body.This approach significantly bolsters the window’s abrasion resistance and anti-fouling performance while maintaining high light transmittance.The sliding layer on the SAAW’s surface remarkably reduces the friction of various liquids,which is the reason that SAAW owns the great anti-fouling property.The SAAW demonstrates outstanding optical clarity even after enduring hundreds of sandpaper abrasions,attributing to the fine metal bone structures bearing all external forces and protecting the sliding layer of SAAW.Furthermore,it exhibits exceptional resistance to biological adhesion and underwater pressure.In a green algae environment,the window remains clean with minimal change in transmittance over one month.Moreover,it retains its wettability and anti-fouling properties when subjected to a depth of 30 m of underwater pressure for 30 d.Hence,the SAAW prepared by femtosecond laser ablation and electrodeposition presents a promising strategy for developing stable optical windows in liquid environments.
基金Project supported by Shandong Provincial Natural Science Foundation(Grant No.ZR2023LLZ003)the National Natural Science Foundation of China(Grant No.62005145)Fundamental Research Fund of Shandong University,and Shandong Provincial Postdoctoral Science Foundation(Grant No.SDBX202302002)。
文摘We demonstrate an integrating sphere to cool~(87)Rb atoms and measure the recoil-induced resonance and electromagnetically induced absorption spectrum.We measure the relationship between their linewidth and light shift with variation of the detuning and power of the cooling laser and study the performance of the diffuse laser cooling mechanism by the absorption linewidth radio?ν_E/?ν_R and light shift|?_R-?_E|using nonlinear spectroscopy.Specifically,when?ν_E/?ν_R reaches a value of 1.57,the temperature and number of cold atoms achieve the optimal cooling effect.This characterization of absorption linewidth and light shift will provide a method to estimate whether diffuse light cooling achieves the best cooling effect,contributing to the future development of isotropic laser cooling for application in quantum sensing.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.92261201,12134005,12334011)。
文摘We investigated the ionization and dissociation processes of ammonia clusters ranging from dimer to pentamer induced by 800-nm femtosecond laser fields.Time-of-flight(TOF)mass spectra of the ammonia clusters were recorded over a range of laser intensities from 2.1×10^(12)W/cm^(2) to 5.6×10^(12)W/cm^(2).The protonated ion signals dominate the spectra,which is consistent with the stability of the geometric structures.The ionization and dissociation channels of ammonia clusters are discussed.The competition and switching among observed dissociation channels are revealed by analyzing the variations in the relative ionic yields of specific protonated and unprotonated clusters under different laser intensities.These results indicate that the ionization of the neutral multiple-ammonia units,produced through the dissociation of cluster ions,may start to contribute,as well as the additional processes to consume protonated ions and/or produce unprotonated ions induced by the femtosecond laser fields when the laser intensity is above^4×10^(12)W/cm^(2).These findings provide deeper insights into the ionization and dissociation dynamics in multi-photon ionization experiments involving ammonia clusters.
基金supported by the National Natural Science Foundation of China(Nos.52305612 and U20A6004)Open Fund of Hubei Key Laboratory of Electronic Manufacturing and Packaging Integration(Wuhan University)(NO.EMPI2023015).
文摘Surface tension-induced shrinkage of heterogeneously bonded interfaces is a key factor in limiting the performance of nanostructures.Herein,we demonstrate a laser-induced thermo-compression bonding technology to suppress surface tension-induced shrinkage of Cu-Au bonded interface.A focused laser beam is used to apply localized heating and scattering force to the exposed Cu nanowire.The laser-induced scattering force and the heating can be adjusted by regulating the exposure intensity.When the ratio of scattering forces to the gravity of the exposed nanowire reaches 3.6×10^(3),the molten Cu nanowire is compressed into flattened shape rather than shrinking into nanosphere by the surface tension.As a result,the Cu-Au bonding interface is broadened fourfold by the scattering force,leading to a reduction in contact resistance of approximately 56%.This noncontact thermo-compression bonding technology provides significant possibilities for the interconnect packaging and integration of nanodevices.
基金supported by the Jiangxi Provincial Natural Science Foundation of China(Grant number 20224BAB204049)the National Natural Science Foundation of China(Grant number 52205194)the Fund Project of Jiangxi Provincial Department of Education(Grant number GJJ2200602)。
文摘Conventional Fe-C alloy parts used in mechanical transmission and braking systems exposed to the external environment often suffer from wear and corrosion failures.Surface coating strengthening technologies have been explored to improve the surface performance and prolong service life of these parts.Among these technologies,laser cladding has shown promise in producing Fe-based alloy coatings with superior interfacial bonding properties to the Fe-C alloy substrate.Additionally,the microstructure of the Fe-based alloy coating is more uniform and the grain size is finer than that of surfacing welding,thermal spraying,and plasma cladding,and the oxide film of alloying elements on the coating surface can improve the coating performance.However,Fe-based alloy coatings produced by laser cladding typically exhibit lower hardness,lower wear resistance,corrosion resistance,and oxidation resistance compared to coatings based on Co and Ni alloys.Moreover,these coatings are susceptible to defects such as pores and cracks.To address these limitations,the incorporation of rare-earth oxides through doping in the laser cladding process has garnered significant attention.This approach has demonstrated substantial improvements in the microstructure and properties of Fe-based alloy coatings.This paper reviewed recent research on the structure and properties of laser-cladded Fe-based alloy coatings doped with various rare earth oxides,including La_(2)O_(3),CeO_(2),and Y_(2)O_(3).Specifically,it discussed the effects of rare earth oxides and their concentrations on the structure,hardness,friction,wear,corrosion,and oxidation characteristics of these coatings.Furthermore,the mechanisms by which rare earth oxides influence the coating’s structure and properties were summarized.This review aimed to serve as a valuable reference for the application and advancement of laser cladding technology for rare earth modified Fe-based alloy coatings.
基金supported by the National Natural Science Foundation of China(Nos.12375244 and 12135009)the Hunan Provincial Innovation Foundation for Postgraduate(Nos.CX20210007 and CX20230008)。
文摘In this study,we explore the impact of state-of-the-art laser fields on theαdecay half-life of deformed ground-state odd-A nuclei within the proton number range of 52–107.The calculations show that the presence of a laser field modulates theαdecay half-life by altering theαdecay penetration probability within a limited range.Moreover,the variance in the penetration probability rate of change between even–odd and odd–even nuclei is investigated.Furthermore,we investigate the rate of change of the penetration probability for the same parent nucleus with different neutron numbers,based on the characteristics of the odd-A nucleus.We found that the influence of the laser field on the penetration probability is determined by both the shell effect and odd–even staggering.This research contributes to the understanding of nuanced interactions between laser fields and nuclear decay processes.Therefore,valuable insights for future experiments in laser–nuclear physics are attainable using this study.
基金Funded by the National Natural Science Foundation of China(No.52472012)Opening Project of State Silica-Based Materials Laboratory of Anhui Province(No.2022KF11)the Research and Development of Glass Powder for Laser Sealing and Its Sealing Technology(No.K24556)。
文摘The low-melting glass of Bi2O_(3)-B2O_(3)-SiO_(2)(BiBSi)system was used for the first time for laser sealing of vacuum glazing.Under the condition of constant boron content,how the structure and properties vary with Bi/Si ratio in low-melting glass was investigated.In addition,the relationships between laser power,low-melting glass solder with different Bi/Si ratios and laser sealing shear strength were revealed.The results show that a decrease in the Bi/Si ratio can cause a contraction of the glass network of the low-melting glass,leading to an increase of its characteristic temperature and a decrease of its coefficient of thermal expansion.During laser sealing,the copper ions in the low-melting glass play an endothermic role.A change in the Bi/Si ratio will affect the valence state transition of the copper ions in the low-melting glass.The absorbance of the low-melting glass does not follow the expected correlation with the Bi/Si ratio,but shows a linear correlation with the content of divalent copper ions.The greater the concentration of divalent copper ions,the greater the absorbance of the low-melting glass,and the lower the laser power required for laser sealing.The shear strength of the low melting glass solder after laser sealing was tested,and it was found that the maximum shear strength of Z1 glass sample was the highest up to 2.67 MPa.
