The generation of terahertz （THz） emission from air plasma induced by two-color femtosecond laser pulses is studied on the basis of a transient photocurrent model. While the gas is ionized by the two-color femtoseco...The generation of terahertz （THz） emission from air plasma induced by two-color femtosecond laser pulses is studied on the basis of a transient photocurrent model. While the gas is ionized by the two-color femtosecond laser-pulses com- posed of the fundamental and its second harmonic, a non-vanishing directional photoelectron current emerges, radiating a THz electromagnetic pulse. The gas ionization processes at three different laser-pulse energies are simulated, and the corresponding THz waveforms and spectra are plotted. The results demonstrate that, by keeping the laser-pulse width and the relative phase between two pulses invariant when the laser energy is at a moderate value, the emitted THz fields are significantly enhanced with a near-linear dependence on the optical energy.展开更多
Digital holography can be applied to ultrafast detection when a femtosecond laser pulse is used. In this paper, the interference process of two femtosecond laser pulses is studied and the recording process of the femt...Digital holography can be applied to ultrafast detection when a femtosecond laser pulse is used. In this paper, the interference process of two femtosecond laser pulses is studied and the recording process of the femtosecond laser pulsed digital hologram is simulated. Holograms at different recording angles are generated by integrating the instantaneous interference field. By analyzing the distribution of the reconstructed phase error, the characteristics of femtosecond laser pulsed digital holography are discussed.展开更多
SiC_(f)/SiC ceramic matrix composites(SiC_(f)/SiC composites)are difficult to drill small holes due to their heterogeneity,high hardness,and low electrical conductivity.In order to solve the difficulties of poor quali...SiC_(f)/SiC ceramic matrix composites(SiC_(f)/SiC composites)are difficult to drill small holes due to their heterogeneity,high hardness,and low electrical conductivity.In order to solve the difficulties of poor quality and low efficiency when drilling small holes,a novel femtosecond laser rotary drilling(FLRD)technique is proposed.Beam kinematic paths and experimental studies were carried out to analyze the effects of processing parameters on the drilling results in the two-step drilling process.In the through-hole drilling stage,the material removal rate increases with increasing laser power,decreasing feed speed and decreasing pitch.As for the finishing stage of drilling,the exit diameter increased with increasing laser power and decreasing feed speed.The drilling parameters were selected by taking the processing efficiency of through-hole and the quality of finished hole as the constraint criteria.Holes with a diameter of 500μm were drilled using FLRD in 3 mm thick SiC_(f)/SiC composites with a drilling time<150 s.The hole aspect ratio was 6,the taper<0.2°,and there was no significant thermal damage at the orifice or the wall of the hole.The FLRD provides a solution for precision machining of small holes in difficult-to-machine materials by offering the advantages of high processing quality and short drilling times.展开更多
The poor surface conditions and osseointegration capacity of 3D printed Ti6Al4V implants(3DPT)significantly influence their performance as orthopedic and dental implants.In this work,we creatively introduce a one-step...The poor surface conditions and osseointegration capacity of 3D printed Ti6Al4V implants(3DPT)significantly influence their performance as orthopedic and dental implants.In this work,we creatively introduce a one-step femtosecond laser treatment to improve the surface conditions and osteointegration.The surface characterization,mechanical properties,corrosion resistance,and biological responses were investigated.These results found that femtosecond laser eliminated defects like embedded powders and superficial cracks while forming the nano cones-like structures surface on 3DPT,leading to enhanced osseointegration,anti-corrosion,and anti-fatigue performance.Molecular dynamics simulations revealed the ablation removal mechanism and the formation of nano cone-like structures.These findings were further supported by the in vivo studies,showing that the FS-treated implants had superior bone-implant contact and osseointegration.Hence,the one-step femtosecond laser method is regarded as a promising surface modification method for improving the functional performance of Ti-based orthopedic implants.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
As an efficient passive anti-icing method,the superhydrophobic surface can reduce icing process on metals in low temperatures.However,the usual organic low-surface-energy decorations are often prone to age especially ...As an efficient passive anti-icing method,the superhydrophobic surface can reduce icing process on metals in low temperatures.However,the usual organic low-surface-energy decorations are often prone to age especially in harsh environments,leading to a decrease or complete failure of the anti-icing performance.Here,we adopt a fabrication method of femtosecond laser element-doping microstructuring to achieve inor-ganic superhydrophobic aluminum alloys surfaces through simultaneously modifying the surface profile and compositions of aluminum alloys.The obtained bionic anthill tribe structure with the low thermal conductiv-ity,exhibits the superior delayed freezing time(803.3 s)and the low ice adhesion(16μN)in comparison to the fluorosilane modified and bare Al surfaces.Moreover,such an inherently superhydrophobic metal sur-face also shows the exceptional environmental durability in anti-icing performance,which confirms the ef-fectiveness of our superhydrophobic surface without the need for organic coatings.展开更多
Aiming at the requirement for high-precision tilt monitoring in the field of structural health monitoring(SHM),this paper proposes a sensitivity-enhanced tilt sensor based on a femtosecond fiber Bragg grating(FBG).Fir...Aiming at the requirement for high-precision tilt monitoring in the field of structural health monitoring(SHM),this paper proposes a sensitivity-enhanced tilt sensor based on a femtosecond fiber Bragg grating(FBG).Firstly,structural design of the tilt sensor was conducted based on static mechanics principles.By positioning the FBG away from the beam’s neutral axis,linear strain enhancement in the FBG was achieved,thereby improving sensor sensitivity.The relationship between FBG strain,applied force,and the offset distance from the neutral axis was established,determining the optimal distance corresponding to maximum strain.Based on this optimization scheme,a prototype of the tilt sensor was designed,fabricated,and experimentally tested.Experimental results show that the FBG offset distance yielding maximum sensitivity is 4.4 mm.Within a tilt angle range of−30°to 30°,the sensor achieved a sensitivity of 129.95 pm/°and a linearity of 0.9997.Compared to conventional FBG-based tilt sensors,both sensitivity and linearity were significantly improved.Furthermore,the sensor demonstrated excellent repeatability(error<0.94%),creep resistance(error<0.30%),and temperature stability(error<0.90%).These results demonstrate the sensor’s excellent potential for SHM applications.The sensor has been successfully deployed in an underground pipeline project,conducting long-term monitoring of tilt and deformation in the steel support structures,further proving its value for engineering safety monitoring.展开更多
Gallium nitride(GaN),as a third-generation semiconductor,is highly attractive due to its exceptional physical and chemical properties.Laser direct writing offers an efficient method for the precise processing of hard ...Gallium nitride(GaN),as a third-generation semiconductor,is highly attractive due to its exceptional physical and chemical properties.Laser direct writing offers an efficient method for the precise processing of hard and brittle materials.In this work,various types of surface microtexture were processed on GaN epilayers using a femtosecond laser with a wavelength of 1030 nm.The effects of the laser energy,singlepulse interval,number of pulses,and number of scan passes on groove machining were investigated with a view to achieving high-quality micromachining.The depth,width,surface morphology,and roughness of the grooves were analyzed using scanning electron microscopy,laser scanning confocal microscopy,and atomic force microscopy.Damage and stress were characterized at the microscale using Raman spectroscopy.High-quality precision machining of different types of periodic surface microtexture at 40 mW laser power was achieved by controlling the process parameters and laser trajectory.Finally,an initial exploration was conducted to examine vector-light-based microand nanostructure processing.The findings demonstrate the potential of femtosecond lasers for efficient micromachining of hard and brittle materials without the creation of heat-affected zones or microcracks.The high-quality textured structures achieved through this processing technique have broad and promising applications in optoelectronic devices and tribology.展开更多
Smart windows(SWs)garner significant potential in green buildings owing to their capability of on-demand tuning the solar gains.Apart from solar regulation,people always desire a type of slippery SW which can repel th...Smart windows(SWs)garner significant potential in green buildings owing to their capability of on-demand tuning the solar gains.Apart from solar regulation,people always desire a type of slippery SW which can repel the surface hydrous contaminants for anti-fouling application.Unfortunately,the up-to-date slippery SWs that respond to electrical/thermal stimuli have drawbacks of inferior durability and high energy-consumption,which greatly constrain their practical usability.This article presents our current work on an ultra-robust and energy-efficient near-infrared-responsive smart window(NIR-SW)which can regulate the optical transmittance and droplet’s adhesion in synergy.Significantly,laser-printing strategy enables us to seed the shape-memory photothermal microwalls on a transparent substrate,which can promote daylighting while maintaining privacy by near-infrared(NIR)switching between being transparent and opaque.As a light manipulator,it turns transparent with NIR-activated erect microwalls like an open louver;however,it turns opaque with the pressure-fixed bent microwalls akin to a closed louver.Simultaneously,the droplets can easily slip on the surface of erect microwalls similar to a classical lotus effect;by contrast,the droplets will tightly pin on the surface of bent microwalls analogous to the prevalent rose effect.Owing to shape-memory effect,this optical/wettability regulation is thus reversible and reconfigurable in response to the alternate NIR/pressure trigger.Moreover,NIR-SW unfolds a superior longevity despite suffering from the raindrop’s impacting more than 10000 cycles.Remarkably,such a new-type SW is competent for thermal management,anti-icing system,peep-proof screen,and programmable optics.This work renders impetus for the researchers striving for self-cleaning intelligent windows,energy-efficient greenhouse,and so forth.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
High-energy continuous wave(CW)lasers are mostly used in laser damage applications,but efficient laser ablation of transparent materials is challenging due to low optical absorption.Considering the potential of femtos...High-energy continuous wave(CW)lasers are mostly used in laser damage applications,but efficient laser ablation of transparent materials is challenging due to low optical absorption.Considering the potential of femtosecond(fs)laser-induced air filament for high-peak laser transmission over long distances,femtosecond(fs)laser-induced air filaments are combined with a millisecond(ms)laser to form an fs-ms CPL,enhancing the efficiency of sapphire ablation through synchronized spatial-temporal focusing.Experimental results show that ablation efficiency increases with the ms peak power and duty ratio.Excessive thermal stress leads to fragmentation of the sapphire when the ms duty ratio is over 30%at the peak power of 800 W,or when the peak power is over 500 W at a duty ratio of 100%.Also,the mechanism of high-efficiency damage is revealed through in-situ high-speed imaging.According to it,the ablation process went through 4 stages within 1.5 ms:defect-creating,melting and ablation,spattering,and fragmentation.Finally,the equivalent ablation efficiency of the fs-ms CPL is as high as 1.73×10^(7)μm^(3)/J,about 28 times higher compared to the fs laser only.The CPL damage method explored in this paper can provide theoretical guidance for efficient laser damage of transparent materials.展开更多
Ultrafast phenomena induced by femtosecond laser irradiation encompass a range of highly dynamic physical processes,including but not limited to electron excitation,material ablation,plasma generation,and shock wave p...Ultrafast phenomena induced by femtosecond laser irradiation encompass a range of highly dynamic physical processes,including but not limited to electron excitation,material ablation,plasma generation,and shock wave propagation.Unveiling the dynamics of these ultrafast processes is crucial for effectively controlling laser processing.However,many of these phenomena occur on timescales ranging from femtoseconds(fs) to nanoseconds(ns),which presents significant challenges in monitoring and interpretation;thus,ultrafast optical imaging techniques are often required.This paper comprehensively reviews the ultrafast optical imaging methods employed in recent years to monitor various ultrafast processes such as electron excitation,ultrafast ablation,plasma ejection,and shock wave propagation during femtosecond laser processing of metallic,composite,and ceramic materials.These methods can be categorized into two primary types:pump-probe ultrafast optical imaging and single-shot ultrafast optical imaging techniques.The working principles and key findings associated with each type of ultrafast optical imaging technique are described in detail.Finally,the imaging principles,advantages and disadvantages,and application scenarios of various ultrafast imaging technologies are summarized,along with a discussion of future challenges and development directions in this field.展开更多
To enhance the adhesion of ceramic coatings in turbine blade Thermal Barrier Coatings(TBCs)systems,Laser Surface Texturing(LST)was employed to create microstructures on the metal bond coat.The bonding conditions and f...To enhance the adhesion of ceramic coatings in turbine blade Thermal Barrier Coatings(TBCs)systems,Laser Surface Texturing(LST)was employed to create microstructures on the metal bond coat.The bonding conditions and failure mechanisms of the ceramic coatings within these microstructures were thoroughly investigated.Femtosecond laser technology was used to fabricate three types of high-quality microstructure grooves:linear,sine wave,and grid patterns.These grooves exhibit uniform morphology,well-defined edges,and smooth inner walls.After ceramic coating deposition,columnar crystal structures grew perpendicularly along the groove walls,completely filling the microstructures and forming an arched support structure that significantly enhances mechanical interlocking and adhesion.Among the different microstructures,grid patterns demonstrated the best adhesion performance.In scratch tests,grid-patterned microstructures exhibited only localized small block spalling under high load conditions,avoiding large-scale delamination.This superior performance is attributed to the ability of grid pattern to effectively distribute stress in multiple directions and prevent crack propagation.By reducing stress concentration and enhancing mechanical interlocking points,grid-patterned microstructures also showed excellent resistance to spallation during thermal cycling,markedly improving the thermal resistance and adhesion of coating.展开更多
AIM:To examine how three distinct central positioning techniques for anterior capsulotomy-pupil center,limbus center,and lens apex-affect intraocular lens(IOL)placement and visual quality following femtosecond laser-a...AIM:To examine how three distinct central positioning techniques for anterior capsulotomy-pupil center,limbus center,and lens apex-affect intraocular lens(IOL)placement and visual quality following femtosecond laser-assisted cataract surgery(FLACS).METHODS:A total of 36 patients(72 eyes)with age-related cataracts who underwent FLACS and ZCB00 aspherical IOL implantation at Aier Eye Hospital Medical Center,Anhui Medical University between January and December 2023 were included in this prospective study.Patients were divided into three groups based on the central positioning mode for anterior capsulotomy:pupil center,limbus center,and lens apex center groups.IOL alignment and displacement were evaluated using the Casia2 device,and the postoperative visual quality was assessed.RESULTS:At 1 d postoperatively,the IOL tilt for the pupil,limbus,and apex groups were 3.96°±1.51°,4.63°±1.87°,and 3.90°±2.24°,respectively(F=1.07,P=0.35);IOL decentration values were 0.21±0.10 mm,0.23±0.16 mm,and 0.21±0.12 mm,respectively(F=0.14,P=0.87);total higher-order aberrations were 0.32±0.40μm,0.56±0.61μm,and 0.53±0.60μm,respectively(F=1.38,P=0.26);and coma aberrations values were 0.13±0.10μm,0.16±0.15μm,and 0.14±0.15μm,respectively(F=0.3,P=0.74).All results obtained postoperative day 1 did not differ significantly.At 3 mo postoperatively,IOL tilt values were 5.42°±2.00°,3.96°±1.44°,and 3.20°±1.19°,respectively(F=12.40,P<0.001);IOL decentration values were 0.33±0.07 mm,0.23±0.11 mm,and 0.21±0.11 mm,respectively(F=4.99,P=0.008);total higher-order aberrations were 0.67±0.29μm,0.44±0.37μm,and 0.42±0.19μm,respectively(F=5.50,P=0.006);and coma aberrations values were 0.21±0.12μm,0.19±0.12μm,and 0.12±0.11μm,respectively(F=3.87,P=0.03).All results obtained 3 mo postoperatively were statistically significant.CONCLUSION:Using the lens apex as the central positioning mode for anterior capsulotomy in FLACS improves postoperative IOL stability and reduces postoperative IOL tilt and decentration.If the lens apex cannot be determined intraoperatively,the limbus center-positioning mode is recommended.展开更多
We theoretically investigate the feasibility of reconstructing the transverse structures of femtosecond laser filaments in air by photoacoustic tomography.To simulate the emission and transmission of filament-induced ...We theoretically investigate the feasibility of reconstructing the transverse structures of femtosecond laser filaments in air by photoacoustic tomography.To simulate the emission and transmission of filament-induced ultrasonic signals more truly,a series of experimentally recorded cross-sectional images are used to simulate the initial pressure rise from multiple filaments(MFs).The aperture size and sensitivity of the detector was incorporated into the reconstruction algorithm.The results show that frequency of acoustic signals induced by MFs with maximum volumetric energy density~100 k J/m^(3)is about 2 MHz below.The initial spatial distribution of optical filaments can be clearly reconstructed with the back projection based algorithm.We recommend a PAT system with transducers of a lower central frequency and a stronger apodization working at a longer scanning radius can be used in photoacoustic image reconstruction of femtosecond laser multifilaments.This study demonstrates the feasibility of using photoacoustic tomography to reconstruct femtosecond multifilament images,which is helpful for studying the complex dynamic processes of multifilament and multifilament manipulation and is also valuable for the remote applications of laser filaments.展开更多
Ionization and dissociation are fundamental processes that molecules undergo in intense femtosecond laser fields.Professor Fanao Kong is a pioneering researcher in this field within China.He has developed an orbital-b...Ionization and dissociation are fundamental processes that molecules undergo in intense femtosecond laser fields.Professor Fanao Kong is a pioneering researcher in this field within China.He has developed an orbital-based molecular ionization model and a laser field-assisted molecular dissociation model to elucidate experimental observations and predict potential applications.The predictions of these models have been corroborated by subsequent theoretical and experimental studies.This review highlights Professor Kong’s significant contributions to the study of molecular ionization and dissociation in intense femtosecond laser fields,emphasizing key advancements and outlining future directions in the field of strong-field laser chemistry.展开更多
Chitosan(CS)-based nanocomposites have been studied in various fields,requiring a more facile and efficient technique to fabricate nanoparticles with customized structures.In this study,Ag@methacrylamide CS/poly(ethyl...Chitosan(CS)-based nanocomposites have been studied in various fields,requiring a more facile and efficient technique to fabricate nanoparticles with customized structures.In this study,Ag@methacrylamide CS/poly(ethylene glycol)diacrylate(Ag@MP)micropatterns are successfully fabricated by femtosecond laser maskless optical projection lithography(Fs-MOPL)for the first time.The formation mechanism of core-shell nanomaterial is demonstrated by the local surface plasmon resonances and the nucleation and growth theory.Amino and hydroxyl groups greatly affect the number of Ag@MP nanocomposites,which is further verified by replacing MCS with methacrylated bovine serum albumin and hyaluronic acid methacryloyl,respectively.Besides,the performance of the surface-enhanced Raman scattering,cytotoxicity,cell proliferation,and antibacterial was investigated on Ag@MP micropatterns.Therefore,the proposed protocol to prepare hydrogel core-shell micropattern by the home-built Fs-MOPL technique is prospective for potential applications in the biomedical and biotechnological fields,such as biosensors,cell imaging,and antimicrobial.展开更多
The electrochemical conversion of CO_(2) into value-added chemicals presents an environmentally sustainable alternative to conventional fossil-derived processes,yet achieving high selectivity remains challenging due t...The electrochemical conversion of CO_(2) into value-added chemicals presents an environmentally sustainable alternative to conventional fossil-derived processes,yet achieving high selectivity remains challenging due to competing reaction pathways.Here,we demonstrate precise tuning of CO_(2) electroreduction pathways through femtosecond laser-driven surface doping of Cu with targeted metals,achieving Faradaic efficiencies of 58.9%for CO,67.9%for formate,and 37.8%for ethylene.This spatially shaping laser technique enables nanoscale deposition of any metal(including Sb,Sn,Re,La,In,Co,Ni,Ag,and Pt)onto Cu foil,forming compositionally graded Cu-based bimetallic surfaces with controlled atomic ratios.Systematic electronic structure analysis reveals that secondary metals induce d-band center shifts spanning−0.21 to+0.78 eV,governing intermediate adsorption energetics-upward shifts strengthen*CO binding via enhanced back-donation,while downward shifts generally weaken adsorbate interactions.Through precise control of Cu/Sn and Cu/Sb atomic ratios,we manipulate electronic structures of CuSn and CuSb catalysts and consequently demonstrate continuous tuning of formate(19.0%-67.9%)and CO(18.8%-58.9%)selectivity.In-situ Raman spectroscopy and valence band X-ray photoelectron spectroscopy(XPS)elucidate dual modulation mechanisms.Sn enhances CO desorption by weakening*CO adsorption,whereas La promotes ethylene formation through optimized CO absorption and dimerization.The tunability of the reaction pathways aligns with metal-dependent stabilization of critical intermediates(CO and*OCHO).This work introduces a nanoscale-depth and trace-level multi-elemental loading strategy with tunable ratios on copper electrodes,enabling precise electronic structure manipulation of Cu-based electrocatalysts to mechanistically elucidate the correlation between surface electronic states and product selectivity,offering a roadmap to design and modulate Cu-based catalysts for selective CO_(2)-to-chemical conversion and beyond via low-cost laser processing techniques.展开更多
Integrating the magneto-optical effect into a waveguide-based photonic device becomes more and more interesting.In the work,the planar optical waveguide firstly was prepared in a terbium gallium garnet crystal(TGG)via...Integrating the magneto-optical effect into a waveguide-based photonic device becomes more and more interesting.In the work,the planar optical waveguide firstly was prepared in a terbium gallium garnet crystal(TGG)via the proton implantation with the energy of 4×10^(-1)MeV and the fluence of 6×10^(8)ions/μm^(2).Subsequently,a femtosecond laser with a central wavelength of 800 nm and a power of 3 mW was used to ablate the surface of the planar waveguide,forming the ridge optical waveguide.The dark-mode curve of the planar waveguide was measured by a prism coupling technique.The top-view morphology of the ridge waveguide was observed via a Nikon microscope.The mode field distributions of the planar and ridge waveguides were obtained by an end-face coupling system,and the propagation losses of the two waveguides were measured to be 2.26 dB/cm and 2.58 dB/cm,respectively.The Verdet constants were measured to be-72.7°/T·cm for the TGG substrate and-60.7°/T·cm for the ridge waveguide.The TGG waveguides have a potential in the fabrication of magneto-optical waveguide devices.展开更多
Able to precisely control and manipulate materials'states at micro/nano-scale level,femtosecond(fs)laser micro/nano processing technology has undergone tremendous development over the past three decades.Free-formi...Able to precisely control and manipulate materials'states at micro/nano-scale level,femtosecond(fs)laser micro/nano processing technology has undergone tremendous development over the past three decades.Free-forming three-dimensional(3D)microscale functional devices and inducing fascinating and unique physical or chemical phenomena have granted this technology powerful versatility that no other technology can match.As this technology advances rapidly in various fields of application,some key challenges have emerged and remain to be urgently addressed.This review firstly introduces the fundamental principles for understanding how fs laser pulses interact with materials and the associated unique phenomena in section 2.Then micro/nano-fabrication in transparent materials by fs laser processing is presented in section 3.Thereafter,several high efficiency/throughput fabrication methods as well as pulse-shaping techniques are listed in sections 4 and 5 reviews four-dimensional(4D)and nanoscale printing realized by fs laser processing technology.Special attention is paid to the heterogeneous integration(HI)of functional materials enabled by fs laser processing in section 6.Several intriguing examples of 3D functional micro-devices created by fs laser-based manufacturing methods such as microfluidics,lab-on-chip,micro-optics,micro-mechanics,micro-electronics,micro-bots and micro-biodevices are reviewed in section 7.Finally,a summary of the review and a perspective are proposed to explore the challenges and future opportunities for further betterment of fs laser micro/nano processing technology.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No.61177095)the Natural Science Foundation of Hubei Province,China(Grant No.2012FFA074)+1 种基金the Ph.D.Programs Foundation of Ministry of Education of China (Grant No.20100142110042)the Fundamental Research Funds for the Central Universities (Grant Nos.2012QN094 and 2012QN097)
文摘The generation of terahertz （THz） emission from air plasma induced by two-color femtosecond laser pulses is studied on the basis of a transient photocurrent model. While the gas is ionized by the two-color femtosecond laser-pulses com- posed of the fundamental and its second harmonic, a non-vanishing directional photoelectron current emerges, radiating a THz electromagnetic pulse. The gas ionization processes at three different laser-pulse energies are simulated, and the corresponding THz waveforms and spectra are plotted. The results demonstrate that, by keeping the laser-pulse width and the relative phase between two pulses invariant when the laser energy is at a moderate value, the emitted THz fields are significantly enhanced with a near-linear dependence on the optical energy.
基金supported by the National Natural Science Foundation of China(Grant No.61275133)
文摘Digital holography can be applied to ultrafast detection when a femtosecond laser pulse is used. In this paper, the interference process of two femtosecond laser pulses is studied and the recording process of the femtosecond laser pulsed digital hologram is simulated. Holograms at different recording angles are generated by integrating the instantaneous interference field. By analyzing the distribution of the reconstructed phase error, the characteristics of femtosecond laser pulsed digital holography are discussed.
基金the support of the Xingliao Talent Program of Liaoning Province(No.XLYC2001004)the High Level Talents Innovation Plan of Dalian(No.2020RD02)the Fundamental Research Funds for the Central Universities(No.DUT22LAB501).
文摘SiC_(f)/SiC ceramic matrix composites(SiC_(f)/SiC composites)are difficult to drill small holes due to their heterogeneity,high hardness,and low electrical conductivity.In order to solve the difficulties of poor quality and low efficiency when drilling small holes,a novel femtosecond laser rotary drilling(FLRD)technique is proposed.Beam kinematic paths and experimental studies were carried out to analyze the effects of processing parameters on the drilling results in the two-step drilling process.In the through-hole drilling stage,the material removal rate increases with increasing laser power,decreasing feed speed and decreasing pitch.As for the finishing stage of drilling,the exit diameter increased with increasing laser power and decreasing feed speed.The drilling parameters were selected by taking the processing efficiency of through-hole and the quality of finished hole as the constraint criteria.Holes with a diameter of 500μm were drilled using FLRD in 3 mm thick SiC_(f)/SiC composites with a drilling time<150 s.The hole aspect ratio was 6,the taper<0.2°,and there was no significant thermal damage at the orifice or the wall of the hole.The FLRD provides a solution for precision machining of small holes in difficult-to-machine materials by offering the advantages of high processing quality and short drilling times.
基金supported by the National Natural Science Foundation of China(No.U21A2055),Natural Science Foundation of Tianjin of China(No.21JCQNJC01280)Tianjin Key R&D Program Beijing-Tianjin-Hebei Collaborative Innovation Project(No.22YFXTHZ00120).
文摘The poor surface conditions and osseointegration capacity of 3D printed Ti6Al4V implants(3DPT)significantly influence their performance as orthopedic and dental implants.In this work,we creatively introduce a one-step femtosecond laser treatment to improve the surface conditions and osteointegration.The surface characterization,mechanical properties,corrosion resistance,and biological responses were investigated.These results found that femtosecond laser eliminated defects like embedded powders and superficial cracks while forming the nano cones-like structures surface on 3DPT,leading to enhanced osseointegration,anti-corrosion,and anti-fatigue performance.Molecular dynamics simulations revealed the ablation removal mechanism and the formation of nano cone-like structures.These findings were further supported by the in vivo studies,showing that the FS-treated implants had superior bone-implant contact and osseointegration.Hence,the one-step femtosecond laser method is regarded as a promising surface modification method for improving the functional performance of Ti-based orthopedic implants.
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.
文摘As an efficient passive anti-icing method,the superhydrophobic surface can reduce icing process on metals in low temperatures.However,the usual organic low-surface-energy decorations are often prone to age especially in harsh environments,leading to a decrease or complete failure of the anti-icing performance.Here,we adopt a fabrication method of femtosecond laser element-doping microstructuring to achieve inor-ganic superhydrophobic aluminum alloys surfaces through simultaneously modifying the surface profile and compositions of aluminum alloys.The obtained bionic anthill tribe structure with the low thermal conductiv-ity,exhibits the superior delayed freezing time(803.3 s)and the low ice adhesion(16μN)in comparison to the fluorosilane modified and bare Al surfaces.Moreover,such an inherently superhydrophobic metal sur-face also shows the exceptional environmental durability in anti-icing performance,which confirms the ef-fectiveness of our superhydrophobic surface without the need for organic coatings.
文摘Aiming at the requirement for high-precision tilt monitoring in the field of structural health monitoring(SHM),this paper proposes a sensitivity-enhanced tilt sensor based on a femtosecond fiber Bragg grating(FBG).Firstly,structural design of the tilt sensor was conducted based on static mechanics principles.By positioning the FBG away from the beam’s neutral axis,linear strain enhancement in the FBG was achieved,thereby improving sensor sensitivity.The relationship between FBG strain,applied force,and the offset distance from the neutral axis was established,determining the optimal distance corresponding to maximum strain.Based on this optimization scheme,a prototype of the tilt sensor was designed,fabricated,and experimentally tested.Experimental results show that the FBG offset distance yielding maximum sensitivity is 4.4 mm.Within a tilt angle range of−30°to 30°,the sensor achieved a sensitivity of 129.95 pm/°and a linearity of 0.9997.Compared to conventional FBG-based tilt sensors,both sensitivity and linearity were significantly improved.Furthermore,the sensor demonstrated excellent repeatability(error<0.94%),creep resistance(error<0.30%),and temperature stability(error<0.90%).These results demonstrate the sensor’s excellent potential for SHM applications.The sensor has been successfully deployed in an underground pipeline project,conducting long-term monitoring of tilt and deformation in the steel support structures,further proving its value for engineering safety monitoring.
基金supported by the Henan Key Laboratory of Intelligent Manufacturing Equipment Integration for Superhard Materials(Grant No.JDKJ2022-01)the National Natural Science Foundation of China(Grant Nos.52035009 and 51761135106)+1 种基金the 2020 Mobility Programme of the Sino-German Center for Research Promotion(Grant No.M-0396)the“111”project by the State Administration of Foreign Experts Affairs and the Ministry of Education of China(Grant No.B07014).
文摘Gallium nitride(GaN),as a third-generation semiconductor,is highly attractive due to its exceptional physical and chemical properties.Laser direct writing offers an efficient method for the precise processing of hard and brittle materials.In this work,various types of surface microtexture were processed on GaN epilayers using a femtosecond laser with a wavelength of 1030 nm.The effects of the laser energy,singlepulse interval,number of pulses,and number of scan passes on groove machining were investigated with a view to achieving high-quality micromachining.The depth,width,surface morphology,and roughness of the grooves were analyzed using scanning electron microscopy,laser scanning confocal microscopy,and atomic force microscopy.Damage and stress were characterized at the microscale using Raman spectroscopy.High-quality precision machining of different types of periodic surface microtexture at 40 mW laser power was achieved by controlling the process parameters and laser trajectory.Finally,an initial exploration was conducted to examine vector-light-based microand nanostructure processing.The findings demonstrate the potential of femtosecond lasers for efficient micromachining of hard and brittle materials without the creation of heat-affected zones or microcracks.The high-quality textured structures achieved through this processing technique have broad and promising applications in optoelectronic devices and tribology.
基金supported by the National Natural Science Foundation of China(No.52005475,62305321)the Natural Science Foundation of Anhui Province(No.JZ2024AKZR0561,2308085QE167)Opening Project of the Key Laboratory of Bionic Engineering(Ministry of Education),Jilin University(K202204).
文摘Smart windows(SWs)garner significant potential in green buildings owing to their capability of on-demand tuning the solar gains.Apart from solar regulation,people always desire a type of slippery SW which can repel the surface hydrous contaminants for anti-fouling application.Unfortunately,the up-to-date slippery SWs that respond to electrical/thermal stimuli have drawbacks of inferior durability and high energy-consumption,which greatly constrain their practical usability.This article presents our current work on an ultra-robust and energy-efficient near-infrared-responsive smart window(NIR-SW)which can regulate the optical transmittance and droplet’s adhesion in synergy.Significantly,laser-printing strategy enables us to seed the shape-memory photothermal microwalls on a transparent substrate,which can promote daylighting while maintaining privacy by near-infrared(NIR)switching between being transparent and opaque.As a light manipulator,it turns transparent with NIR-activated erect microwalls like an open louver;however,it turns opaque with the pressure-fixed bent microwalls akin to a closed louver.Simultaneously,the droplets can easily slip on the surface of erect microwalls similar to a classical lotus effect;by contrast,the droplets will tightly pin on the surface of bent microwalls analogous to the prevalent rose effect.Owing to shape-memory effect,this optical/wettability regulation is thus reversible and reconfigurable in response to the alternate NIR/pressure trigger.Moreover,NIR-SW unfolds a superior longevity despite suffering from the raindrop’s impacting more than 10000 cycles.Remarkably,such a new-type SW is competent for thermal management,anti-icing system,peep-proof screen,and programmable optics.This work renders impetus for the researchers striving for self-cleaning intelligent windows,energy-efficient greenhouse,and so forth.
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Project(52105498) supported by the National Natural Science Foundation of ChinaProject(2021RC3074) supported by the Science and Technology Innovation Program of Hunan Province,China+2 种基金Project(2023YFB4605500) supported by the National Key Research and Development Program of ChinaProject(AHL2022KF04) supported by the Advanced Laser Technology Laboratory of Anhui Province,ChinaProject(kq2402089) supported by the Changsha Natural Science Foundation,China。
文摘High-energy continuous wave(CW)lasers are mostly used in laser damage applications,but efficient laser ablation of transparent materials is challenging due to low optical absorption.Considering the potential of femtosecond(fs)laser-induced air filament for high-peak laser transmission over long distances,femtosecond(fs)laser-induced air filaments are combined with a millisecond(ms)laser to form an fs-ms CPL,enhancing the efficiency of sapphire ablation through synchronized spatial-temporal focusing.Experimental results show that ablation efficiency increases with the ms peak power and duty ratio.Excessive thermal stress leads to fragmentation of the sapphire when the ms duty ratio is over 30%at the peak power of 800 W,or when the peak power is over 500 W at a duty ratio of 100%.Also,the mechanism of high-efficiency damage is revealed through in-situ high-speed imaging.According to it,the ablation process went through 4 stages within 1.5 ms:defect-creating,melting and ablation,spattering,and fragmentation.Finally,the equivalent ablation efficiency of the fs-ms CPL is as high as 1.73×10^(7)μm^(3)/J,about 28 times higher compared to the fs laser only.The CPL damage method explored in this paper can provide theoretical guidance for efficient laser damage of transparent materials.
基金supported by the National Key R&D Program of China(No.2022YFB4601601)the Key R&D Program of Guangxi Province,China(No.GKAB23026101)+1 种基金the Base,Talent Special Project of the Guangxi Science and Technology Plan Project(No.Gui Ke AD23026149)Guangxi Natural Science Foundation,China(No.2023GXNSFBA026287)
文摘Ultrafast phenomena induced by femtosecond laser irradiation encompass a range of highly dynamic physical processes,including but not limited to electron excitation,material ablation,plasma generation,and shock wave propagation.Unveiling the dynamics of these ultrafast processes is crucial for effectively controlling laser processing.However,many of these phenomena occur on timescales ranging from femtoseconds(fs) to nanoseconds(ns),which presents significant challenges in monitoring and interpretation;thus,ultrafast optical imaging techniques are often required.This paper comprehensively reviews the ultrafast optical imaging methods employed in recent years to monitor various ultrafast processes such as electron excitation,ultrafast ablation,plasma ejection,and shock wave propagation during femtosecond laser processing of metallic,composite,and ceramic materials.These methods can be categorized into two primary types:pump-probe ultrafast optical imaging and single-shot ultrafast optical imaging techniques.The working principles and key findings associated with each type of ultrafast optical imaging technique are described in detail.Finally,the imaging principles,advantages and disadvantages,and application scenarios of various ultrafast imaging technologies are summarized,along with a discussion of future challenges and development directions in this field.
基金supported by the National Science and Technology Major Project,China(No.J2019-VII-0013-0153)the Sichuan Science and Technology Program,China(Nos.2021ZDZX0001 and 2021ZDZX0002)。
文摘To enhance the adhesion of ceramic coatings in turbine blade Thermal Barrier Coatings(TBCs)systems,Laser Surface Texturing(LST)was employed to create microstructures on the metal bond coat.The bonding conditions and failure mechanisms of the ceramic coatings within these microstructures were thoroughly investigated.Femtosecond laser technology was used to fabricate three types of high-quality microstructure grooves:linear,sine wave,and grid patterns.These grooves exhibit uniform morphology,well-defined edges,and smooth inner walls.After ceramic coating deposition,columnar crystal structures grew perpendicularly along the groove walls,completely filling the microstructures and forming an arched support structure that significantly enhances mechanical interlocking and adhesion.Among the different microstructures,grid patterns demonstrated the best adhesion performance.In scratch tests,grid-patterned microstructures exhibited only localized small block spalling under high load conditions,avoiding large-scale delamination.This superior performance is attributed to the ability of grid pattern to effectively distribute stress in multiple directions and prevent crack propagation.By reducing stress concentration and enhancing mechanical interlocking points,grid-patterned microstructures also showed excellent resistance to spallation during thermal cycling,markedly improving the thermal resistance and adhesion of coating.
文摘AIM:To examine how three distinct central positioning techniques for anterior capsulotomy-pupil center,limbus center,and lens apex-affect intraocular lens(IOL)placement and visual quality following femtosecond laser-assisted cataract surgery(FLACS).METHODS:A total of 36 patients(72 eyes)with age-related cataracts who underwent FLACS and ZCB00 aspherical IOL implantation at Aier Eye Hospital Medical Center,Anhui Medical University between January and December 2023 were included in this prospective study.Patients were divided into three groups based on the central positioning mode for anterior capsulotomy:pupil center,limbus center,and lens apex center groups.IOL alignment and displacement were evaluated using the Casia2 device,and the postoperative visual quality was assessed.RESULTS:At 1 d postoperatively,the IOL tilt for the pupil,limbus,and apex groups were 3.96°±1.51°,4.63°±1.87°,and 3.90°±2.24°,respectively(F=1.07,P=0.35);IOL decentration values were 0.21±0.10 mm,0.23±0.16 mm,and 0.21±0.12 mm,respectively(F=0.14,P=0.87);total higher-order aberrations were 0.32±0.40μm,0.56±0.61μm,and 0.53±0.60μm,respectively(F=1.38,P=0.26);and coma aberrations values were 0.13±0.10μm,0.16±0.15μm,and 0.14±0.15μm,respectively(F=0.3,P=0.74).All results obtained postoperative day 1 did not differ significantly.At 3 mo postoperatively,IOL tilt values were 5.42°±2.00°,3.96°±1.44°,and 3.20°±1.19°,respectively(F=12.40,P<0.001);IOL decentration values were 0.33±0.07 mm,0.23±0.11 mm,and 0.21±0.11 mm,respectively(F=4.99,P=0.008);total higher-order aberrations were 0.67±0.29μm,0.44±0.37μm,and 0.42±0.19μm,respectively(F=5.50,P=0.006);and coma aberrations values were 0.21±0.12μm,0.19±0.12μm,and 0.12±0.11μm,respectively(F=3.87,P=0.03).All results obtained 3 mo postoperatively were statistically significant.CONCLUSION:Using the lens apex as the central positioning mode for anterior capsulotomy in FLACS improves postoperative IOL stability and reduces postoperative IOL tilt and decentration.If the lens apex cannot be determined intraoperatively,the limbus center-positioning mode is recommended.
基金Project supported by the National Natural Science Foundation of China(Grant No.42105176)the National University of Defense Technology Independent Research Project(Grant No.ZK21-40)。
文摘We theoretically investigate the feasibility of reconstructing the transverse structures of femtosecond laser filaments in air by photoacoustic tomography.To simulate the emission and transmission of filament-induced ultrasonic signals more truly,a series of experimentally recorded cross-sectional images are used to simulate the initial pressure rise from multiple filaments(MFs).The aperture size and sensitivity of the detector was incorporated into the reconstruction algorithm.The results show that frequency of acoustic signals induced by MFs with maximum volumetric energy density~100 k J/m^(3)is about 2 MHz below.The initial spatial distribution of optical filaments can be clearly reconstructed with the back projection based algorithm.We recommend a PAT system with transducers of a lower central frequency and a stronger apodization working at a longer scanning radius can be used in photoacoustic image reconstruction of femtosecond laser multifilaments.This study demonstrates the feasibility of using photoacoustic tomography to reconstruct femtosecond multifilament images,which is helpful for studying the complex dynamic processes of multifilament and multifilament manipulation and is also valuable for the remote applications of laser filaments.
基金supported by the National Key R&D Program of China(No.2023YFA1406801)the National Natural Science Foundation of China(Nos.12174011,12434013).
文摘Ionization and dissociation are fundamental processes that molecules undergo in intense femtosecond laser fields.Professor Fanao Kong is a pioneering researcher in this field within China.He has developed an orbital-based molecular ionization model and a laser field-assisted molecular dissociation model to elucidate experimental observations and predict potential applications.The predictions of these models have been corroborated by subsequent theoretical and experimental studies.This review highlights Professor Kong’s significant contributions to the study of molecular ionization and dissociation in intense femtosecond laser fields,emphasizing key advancements and outlining future directions in the field of strong-field laser chemistry.
基金the National Natural Science Foundation of China(NSFC,Grant Nos.61975213,61475164,51901234,and 61205194)National Key R&D Program of China(Grant Nos.2017YFB1104300and 2016YFA0200500)+2 种基金International Partnership Program of Chinese Academy of Sciences(GJHZ2021130)Cooperative R&D Projects between Austria,FFG and China,CAS(GJHZ1720)supported by JSPS Bilateral Program Number JPJSBP120217203。
文摘Chitosan(CS)-based nanocomposites have been studied in various fields,requiring a more facile and efficient technique to fabricate nanoparticles with customized structures.In this study,Ag@methacrylamide CS/poly(ethylene glycol)diacrylate(Ag@MP)micropatterns are successfully fabricated by femtosecond laser maskless optical projection lithography(Fs-MOPL)for the first time.The formation mechanism of core-shell nanomaterial is demonstrated by the local surface plasmon resonances and the nucleation and growth theory.Amino and hydroxyl groups greatly affect the number of Ag@MP nanocomposites,which is further verified by replacing MCS with methacrylated bovine serum albumin and hyaluronic acid methacryloyl,respectively.Besides,the performance of the surface-enhanced Raman scattering,cytotoxicity,cell proliferation,and antibacterial was investigated on Ag@MP micropatterns.Therefore,the proposed protocol to prepare hydrogel core-shell micropattern by the home-built Fs-MOPL technique is prospective for potential applications in the biomedical and biotechnological fields,such as biosensors,cell imaging,and antimicrobial.
基金supported by the National Key R&D Program of China(No.2022YFB4601300)Aeronautical Science Fund(No.3030021252404)+2 种基金the National Natural Science Foundation of China(NSFC,No.52475425)the NSFC Basic Sciences Center Program(Extreme Light Field Manufacturing,No.52488301)We thank the Analytical&Testing Center of Beijing Institute of Technology for providing XPS and valence band measurements.We thank the BL02B01 and BL01B Beamlines at Shanghai Synchrotron Radiation Facility(SSRF),supported by the NSFC(No.11227902),for photoelectron spectroscopy and vibrational spectroscopy studies.We thank the support from beamline BL11U and BL10B at the National Synchrotron Radiation Laboratory(NSRL)in Hefei,China,for the synchrotron radiation and X-ray spectroscopic measurements.
文摘The electrochemical conversion of CO_(2) into value-added chemicals presents an environmentally sustainable alternative to conventional fossil-derived processes,yet achieving high selectivity remains challenging due to competing reaction pathways.Here,we demonstrate precise tuning of CO_(2) electroreduction pathways through femtosecond laser-driven surface doping of Cu with targeted metals,achieving Faradaic efficiencies of 58.9%for CO,67.9%for formate,and 37.8%for ethylene.This spatially shaping laser technique enables nanoscale deposition of any metal(including Sb,Sn,Re,La,In,Co,Ni,Ag,and Pt)onto Cu foil,forming compositionally graded Cu-based bimetallic surfaces with controlled atomic ratios.Systematic electronic structure analysis reveals that secondary metals induce d-band center shifts spanning−0.21 to+0.78 eV,governing intermediate adsorption energetics-upward shifts strengthen*CO binding via enhanced back-donation,while downward shifts generally weaken adsorbate interactions.Through precise control of Cu/Sn and Cu/Sb atomic ratios,we manipulate electronic structures of CuSn and CuSb catalysts and consequently demonstrate continuous tuning of formate(19.0%-67.9%)and CO(18.8%-58.9%)selectivity.In-situ Raman spectroscopy and valence band X-ray photoelectron spectroscopy(XPS)elucidate dual modulation mechanisms.Sn enhances CO desorption by weakening*CO adsorption,whereas La promotes ethylene formation through optimized CO absorption and dimerization.The tunability of the reaction pathways aligns with metal-dependent stabilization of critical intermediates(CO and*OCHO).This work introduces a nanoscale-depth and trace-level multi-elemental loading strategy with tunable ratios on copper electrodes,enabling precise electronic structure manipulation of Cu-based electrocatalysts to mechanistically elucidate the correlation between surface electronic states and product selectivity,offering a roadmap to design and modulate Cu-based catalysts for selective CO_(2)-to-chemical conversion and beyond via low-cost laser processing techniques.
基金supported by the Postgraduate Research and Innovation Program of Jiangsu Province,China(Grant No.KYCX241133)the National Natural Science Foundation of China(Grant No.11405041)+1 种基金the Key Research and Development Program of Jiangxi Province,China(Grant No.20223BBE51020)the Opening Fund of Key Laboratory of Rare Earths(Chinese Academy of Sciences).
文摘Integrating the magneto-optical effect into a waveguide-based photonic device becomes more and more interesting.In the work,the planar optical waveguide firstly was prepared in a terbium gallium garnet crystal(TGG)via the proton implantation with the energy of 4×10^(-1)MeV and the fluence of 6×10^(8)ions/μm^(2).Subsequently,a femtosecond laser with a central wavelength of 800 nm and a power of 3 mW was used to ablate the surface of the planar waveguide,forming the ridge optical waveguide.The dark-mode curve of the planar waveguide was measured by a prism coupling technique.The top-view morphology of the ridge waveguide was observed via a Nikon microscope.The mode field distributions of the planar and ridge waveguides were obtained by an end-face coupling system,and the propagation losses of the two waveguides were measured to be 2.26 dB/cm and 2.58 dB/cm,respectively.The Verdet constants were measured to be-72.7°/T·cm for the TGG substrate and-60.7°/T·cm for the ridge waveguide.The TGG waveguides have a potential in the fabrication of magneto-optical waveguide devices.
基金supported by National Key R&D Program of China(Grant Nos.2021YFB2802000 and 2022YFB2804300)Science and Technology Commission of Shanghai Municipality(Grant No.21DZ1100500)+3 种基金Shanghai Municipal Science and Technology Major Projectthe Shanghai Frontiers Science Center Program(2021-2025 No.20)National Natural Science Foundation of China(Grant No.61975123)Shanghai Scienceand Technology Innovation Action Plan(Grant No.23JC1403100)。
文摘Able to precisely control and manipulate materials'states at micro/nano-scale level,femtosecond(fs)laser micro/nano processing technology has undergone tremendous development over the past three decades.Free-forming three-dimensional(3D)microscale functional devices and inducing fascinating and unique physical or chemical phenomena have granted this technology powerful versatility that no other technology can match.As this technology advances rapidly in various fields of application,some key challenges have emerged and remain to be urgently addressed.This review firstly introduces the fundamental principles for understanding how fs laser pulses interact with materials and the associated unique phenomena in section 2.Then micro/nano-fabrication in transparent materials by fs laser processing is presented in section 3.Thereafter,several high efficiency/throughput fabrication methods as well as pulse-shaping techniques are listed in sections 4 and 5 reviews four-dimensional(4D)and nanoscale printing realized by fs laser processing technology.Special attention is paid to the heterogeneous integration(HI)of functional materials enabled by fs laser processing in section 6.Several intriguing examples of 3D functional micro-devices created by fs laser-based manufacturing methods such as microfluidics,lab-on-chip,micro-optics,micro-mechanics,micro-electronics,micro-bots and micro-biodevices are reviewed in section 7.Finally,a summary of the review and a perspective are proposed to explore the challenges and future opportunities for further betterment of fs laser micro/nano processing technology.
