Biopolymeric nanocomposites have attracted considerable attention because of their biocompatibility,biodegradability,and unique physicochemical properties.It is essential to manufacture three-dimensional(3D)biocompati...Biopolymeric nanocomposites have attracted considerable attention because of their biocompatibility,biodegradability,and unique physicochemical properties.It is essential to manufacture three-dimensional(3D)biocompatible micro/nanostructures using biopolymeric nanocomposites.Herein,we demonstrate the high-fidelity fabrication of biocompatible 3D features with sub-50 nm resolution using femtosecond laser direct writing(FsLDW)of a biopolymeric nanocomposite composed of egg white and sulfonated graphene(S-graphene).The biopolymer nanocomposite acts as a negative photoresist suitable for water-based lithography.The introduction of S-graphene not only dramatically lowered the laser power threshold but also significantly modulated the morphology of the 3D features constructed by FsLDW.Microstructures with porous,rough,or smooth morphologies were obtained by optimizing the S-graphene concentration and laser scanning speed.The fabricated egg-white/S-graphene microstructures exhibited biocompatibility and environmental degradability.Egg white/S-graphene was also employed to fabricate diffractive gratings with superior optical quality.This study provides a promising method to manufacture biocompatible 3D features with controllable morphology,which has potential applications in biological and photonic fields.展开更多
Objective: To investigate whether attaching a free lens anterior capsular disc to the corneal endothelial surface during femtosecond laser-assisted cataract surgery (FLACS) can effectively reduce postoperative corneal...Objective: To investigate whether attaching a free lens anterior capsular disc to the corneal endothelial surface during femtosecond laser-assisted cataract surgery (FLACS) can effectively reduce postoperative corneal endothelial cell loss. Methods: This prospective study included 97 cataract patients. Among them, 33 patients served as the experimental group, where a free lens anterior capsular disc was applied for corneal endothelial protection during FLACS. The remaining 64 patients formed the control group and underwent conventional FLACS. Changes in corneal endothelial cell density were compared between the two groups before surgery and one month postoperatively. Results: One month after surgery, corneal endothelial cell counts in both groups were lower than preoperative levels. However, the experimental group exhibited higher corneal endothelial cell counts than the control group, with a smaller reduction in cell counts (p < 0.05). The corneal endothelial cell loss rate in the experimental group was lower than that in the control group one month postoperatively (p < 0.05). At the one-month follow-up, there were no significant differences in LogMAR visual acuity or non-contact intraocular pressure between the two groups compared to preoperative values (p > 0.05). Additionally, no significant differences were observed between the experimental and control groups in terms of LogMAR visual acuity, non-contact intraocular pressure, improvements in LogMAR visual acuity, or changes in non-contact intraocular pressure (p > 0.05). Conclusion: Attaching a free lens anterior capsular disc to the corneal endothelial surface during FLACS can effectively reduce intraoperative corneal endothelial cell loss.展开更多
White Cyphochilus insulanus beetles,exhibiting both environmental camouflage display and radiative cooling functions,serve as a good prototype for biomimetic fabrication.As inspired,this work presents a femtosecond(fs...White Cyphochilus insulanus beetles,exhibiting both environmental camouflage display and radiative cooling functions,serve as a good prototype for biomimetic fabrication.As inspired,this work presents a femtosecond(fs)laser-based biomimetic fabrication strategy that takes full use of the synthesized radiative cooling nanomaterials for a groundbreaking stimuli-responsive infrared(IR)impressionistic camouflage display.The proposed technique is capable of readily transforming various substrates(quartz glass and metals including Ti,Al,Zr,and W)into self-assembled porous networks(aerogels)consisting of oxygen-vacancy-rich oxide nanoparticles.Surprisingly,the emissions of all as-prepared porous particle-networks in the radiative-cooling long-wavelength infrared(LWIR)band are above 95%,with the SiO_(2) aerogels reaching a maximum of 99.6%.Benefiting from the far-from-equilibrium thermodynamic kinetics,metastable phases of anatase TiO_(2),tetragonal zirconia(t-ZrO_(2)),and monoclinic WO_(3)(Pc)are synthesizable,opening up opportunities for exploring their optical applications.Taking the low-temperature metastable phase WO_(3)(Pc)as representative for systematic studies,it is found that(1)the ratio WO_(3)(Pc)phase to that of room-temperature phase of WO_(3)(P2_(1)/n)can be tailored by modulation of processing parameters;(2)laser synthesized aerogels with hybrid phases of WO_(3)(Pc)and WO_(3)(P2_(1)/n)have a brighter visible whiteness,higher visible/nearinfrared(NIR)spectral selectivity than the natural prototype of white Cyphochilus insulanus beetles but with comparable LWIR emittance.White WO_(3) aerogel in situ deposited during flexibly fs laser artistic patterning can blur the painting features due to its radiative cooling effect,allowing a colorful impressionistic IR display in the heating mode.What's more,invisible painting features concealed by the white deposited WO_(3) aerogel are clearly/faintly distinguishable by introducing external stimuli of a human hand and sample heating,respectively,catalyzing progress in optical encryption and selectively stimuli-responsive decryption display in the infrared band.展开更多
Laser-induced periodic surface structures(LIPSS)have gained increasing attention in the field of micro/nano fabrication,although achieving sub-100-nm period LIPSS with high uniformity remains a significant challenge.I...Laser-induced periodic surface structures(LIPSS)have gained increasing attention in the field of micro/nano fabrication,although achieving sub-100-nm period LIPSS with high uniformity remains a significant challenge.In this work,towards deep-subwavelength LIPSS on highly oriented pyrolytic graphite(HOPG),we demonstrate that ultra-uniform nanogratings of sub-50-nm periods and near-10-nm groove widths can be stably prepared via 800-nm femtosecond laser scanning irradiation with a high-NA objective lens under water immersion.The resulting nanogratings of strong polarization dependence,exhibiting exceptional surface flatness,period stability,and structural integrity,tend to appear at near-damage-threshold fluence regime with an appropriate effective pulse number.It turns out that the water immersion condition can significantly reduce the thermal effects of femtosecond laser ablation on HOPG,and thus via a mild,incubation-like scanning ablation process occurring in the nanogrooves with a continuous or jumping manner,this deep-subwavelength grating can achieve robust elongation growth,ensuring its long-range uniformity as well as minimal deposited debris and structural defects.Interestingly,the different incubation extension mechanisms for the mutually perpendicular and parallel settings between scanning direction and laser polarization bring not only distinct effective-pulse-number windows and somewhat different grating qualities,but also different extension stabilities in nanograting stitching via overlapping scanning lines and thus the optimal scanning strategy of parallel setting for large-area processing.In short,this study presents a convenient laser-processing approach for high precision fabrication of sub-50-nm gratings on HOPG,which would provide new insights into micro/nano-fabrication for optoelectronic metasurfaces and physics of the interaction between ultrafast laser and graphite.展开更多
We demonstrate a high-speed rotating slit beam shaping method for femtosecond(fs)laser three-dimensional(3D)isotropic inscription in glass materials.By integrating fs laser direct writing with a real-time rotating sli...We demonstrate a high-speed rotating slit beam shaping method for femtosecond(fs)laser three-dimensional(3D)isotropic inscription in glass materials.By integrating fs laser direct writing with a real-time rotating slit mechanism,a 3D symmetric spherical focal field distribution is created in the laser-irradiated regions of transparent substrates.The corresponding focal field distribution is theoretically calculated and validated by examining the features of laser-inscribed lines in glass samples.Moreover,we investigate the influences of laser writing speed and slit rotational speed on the fabrication resolution in glass,and discuss the formation mechanism of the generated periodic microstructures.To showcase its powerful capability for3D isotropic fabrication,the high-speed rotating slit beam shaping method is applied to create straight optical waveguides,bending optical waveguides,and hollow microchannels in the glass.The proposed method holds great potential for the facile manufacture of diverse 3D isotropic microstructures and devices within transparent materials across various applications,including advanced photonics,microoptics,micro-electromechanical systems,and microfluidics.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
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
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
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
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
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
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
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
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
The femtosecond laser is commonly used for high-quality micromachining of materials.However,the interaction time between the femtosecond laser and the substrate material is extremely short,making it difficult for quan...The femtosecond laser is commonly used for high-quality micromachining of materials.However,the interaction time between the femtosecond laser and the substrate material is extremely short,making it difficult for quantitative measurements and analysis through experiments.In this work,we use a two-temperature model for simulation to study the ablation process of aluminum alloy and aluminum/titanium alloy under femtosecond laser pulse mode.The temperature changes and ablation process of both alloys under femtosecond laser burst irradiation were studied.The study found that when the separation time of sub-pulses was 1 ps,the surface temperature and ablation depth rised with the increase of sub-pulse numbers.A comparison was made between these two alloy types,and enhanced ablation was observed with the heterogeneous aluminum/titanium alloy,up to 34.7%deeper compared to aluminum alloy.Moreover,the detailed theoretical explanation was also discussed.This work provided a basis for efficient ablation of materials with low laser fluence.展开更多
Silicon carbide(SiC)is widely used in fields such as new energy,military radar,and aerospace due to its outstanding physical and chemical properties.The surface micro-grooves of SiC can enhance the performance of micr...Silicon carbide(SiC)is widely used in fields such as new energy,military radar,and aerospace due to its outstanding physical and chemical properties.The surface micro-grooves of SiC can enhance the performance of micro-electromechanical systems,micro-sensors,and field-effect transistors.However,SiC,being a brittle and hard material,poses challenges for traditional machining methods like micro-groove machining and chemical etching,including subsurface damage,short tool life,and low processing efficiency.This paper investigates the processing characteristics of femtosecond laser machining of SiC micro-grooves and compares them with those of single-crystal Si.The results indicate that femtosecond laser ablation of SiC primarily leads to melting and vaporization,forming modification,melted,and ablation areas in the affected area.Femtosecond laser processing of SiC micro-grooves involves three processes:heat absorption and melting,vaporization,and chipping,with vaporization as the primary material removal mechanism.The depth and width of SiC micro-grooves are positively correlated with pulse energy(E_(p)),pulse overlap rate(PO),and number of passes(N_(pass)).The bottom roughness of the micro-grooves is positively correlated with E_(p),negatively correlated with PO,and less affected by changes in the N_(pass).These findings further elucidate the material removal and micro-groove formation mechanisms of SiC under femtosecond laser irradiation,providing theoretical insights for high-quality and high-efficiency processing of SiC micro-grooves.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
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
基金financially supported by the National Key Research and Development Program of China(Nos.2024YFB4607402 and 2016YFC1100502)the National Natural Science Foundation of China(Nos.51673208 and 61975213)。
文摘Biopolymeric nanocomposites have attracted considerable attention because of their biocompatibility,biodegradability,and unique physicochemical properties.It is essential to manufacture three-dimensional(3D)biocompatible micro/nanostructures using biopolymeric nanocomposites.Herein,we demonstrate the high-fidelity fabrication of biocompatible 3D features with sub-50 nm resolution using femtosecond laser direct writing(FsLDW)of a biopolymeric nanocomposite composed of egg white and sulfonated graphene(S-graphene).The biopolymer nanocomposite acts as a negative photoresist suitable for water-based lithography.The introduction of S-graphene not only dramatically lowered the laser power threshold but also significantly modulated the morphology of the 3D features constructed by FsLDW.Microstructures with porous,rough,or smooth morphologies were obtained by optimizing the S-graphene concentration and laser scanning speed.The fabricated egg-white/S-graphene microstructures exhibited biocompatibility and environmental degradability.Egg white/S-graphene was also employed to fabricate diffractive gratings with superior optical quality.This study provides a promising method to manufacture biocompatible 3D features with controllable morphology,which has potential applications in biological and photonic fields.
基金Task Contract for the 2022 Dongguan Social Development Science and Technology Project,Project Name:Clinical Study on the Protection of Corneal Endothelium by the Anterior Capsular Flap in LenSx Femtosecond Laser-Assisted Cataract Surgery(Project No.:20221800901212)。
文摘Objective: To investigate whether attaching a free lens anterior capsular disc to the corneal endothelial surface during femtosecond laser-assisted cataract surgery (FLACS) can effectively reduce postoperative corneal endothelial cell loss. Methods: This prospective study included 97 cataract patients. Among them, 33 patients served as the experimental group, where a free lens anterior capsular disc was applied for corneal endothelial protection during FLACS. The remaining 64 patients formed the control group and underwent conventional FLACS. Changes in corneal endothelial cell density were compared between the two groups before surgery and one month postoperatively. Results: One month after surgery, corneal endothelial cell counts in both groups were lower than preoperative levels. However, the experimental group exhibited higher corneal endothelial cell counts than the control group, with a smaller reduction in cell counts (p < 0.05). The corneal endothelial cell loss rate in the experimental group was lower than that in the control group one month postoperatively (p < 0.05). At the one-month follow-up, there were no significant differences in LogMAR visual acuity or non-contact intraocular pressure between the two groups compared to preoperative values (p > 0.05). Additionally, no significant differences were observed between the experimental and control groups in terms of LogMAR visual acuity, non-contact intraocular pressure, improvements in LogMAR visual acuity, or changes in non-contact intraocular pressure (p > 0.05). Conclusion: Attaching a free lens anterior capsular disc to the corneal endothelial surface during FLACS can effectively reduce intraoperative corneal endothelial cell loss.
基金financial support received from the Shanghai Pujiang Program(23PJ1406500)。
文摘White Cyphochilus insulanus beetles,exhibiting both environmental camouflage display and radiative cooling functions,serve as a good prototype for biomimetic fabrication.As inspired,this work presents a femtosecond(fs)laser-based biomimetic fabrication strategy that takes full use of the synthesized radiative cooling nanomaterials for a groundbreaking stimuli-responsive infrared(IR)impressionistic camouflage display.The proposed technique is capable of readily transforming various substrates(quartz glass and metals including Ti,Al,Zr,and W)into self-assembled porous networks(aerogels)consisting of oxygen-vacancy-rich oxide nanoparticles.Surprisingly,the emissions of all as-prepared porous particle-networks in the radiative-cooling long-wavelength infrared(LWIR)band are above 95%,with the SiO_(2) aerogels reaching a maximum of 99.6%.Benefiting from the far-from-equilibrium thermodynamic kinetics,metastable phases of anatase TiO_(2),tetragonal zirconia(t-ZrO_(2)),and monoclinic WO_(3)(Pc)are synthesizable,opening up opportunities for exploring their optical applications.Taking the low-temperature metastable phase WO_(3)(Pc)as representative for systematic studies,it is found that(1)the ratio WO_(3)(Pc)phase to that of room-temperature phase of WO_(3)(P2_(1)/n)can be tailored by modulation of processing parameters;(2)laser synthesized aerogels with hybrid phases of WO_(3)(Pc)and WO_(3)(P2_(1)/n)have a brighter visible whiteness,higher visible/nearinfrared(NIR)spectral selectivity than the natural prototype of white Cyphochilus insulanus beetles but with comparable LWIR emittance.White WO_(3) aerogel in situ deposited during flexibly fs laser artistic patterning can blur the painting features due to its radiative cooling effect,allowing a colorful impressionistic IR display in the heating mode.What's more,invisible painting features concealed by the white deposited WO_(3) aerogel are clearly/faintly distinguishable by introducing external stimuli of a human hand and sample heating,respectively,catalyzing progress in optical encryption and selectively stimuli-responsive decryption display in the infrared band.
基金supported by grants from Natural Science Foundation of Guangdong Province(Grant No.2021A1515012335)National Natural Science Foundation of China(NSFC)(Grant No.11274400)+2 种基金Pearl River S&T Nova Program of Guangzhou(Grant No.201506010059)State Key Laboratory of Optoelectronic Materials and Technologies(Sun Yat-Sen University)(Grant No.OEMT-2024-ZTS-01)State Key Laboratory of High Field Laser Physics(Shanghai Institute of Optics and Fine Mechanics)。
文摘Laser-induced periodic surface structures(LIPSS)have gained increasing attention in the field of micro/nano fabrication,although achieving sub-100-nm period LIPSS with high uniformity remains a significant challenge.In this work,towards deep-subwavelength LIPSS on highly oriented pyrolytic graphite(HOPG),we demonstrate that ultra-uniform nanogratings of sub-50-nm periods and near-10-nm groove widths can be stably prepared via 800-nm femtosecond laser scanning irradiation with a high-NA objective lens under water immersion.The resulting nanogratings of strong polarization dependence,exhibiting exceptional surface flatness,period stability,and structural integrity,tend to appear at near-damage-threshold fluence regime with an appropriate effective pulse number.It turns out that the water immersion condition can significantly reduce the thermal effects of femtosecond laser ablation on HOPG,and thus via a mild,incubation-like scanning ablation process occurring in the nanogrooves with a continuous or jumping manner,this deep-subwavelength grating can achieve robust elongation growth,ensuring its long-range uniformity as well as minimal deposited debris and structural defects.Interestingly,the different incubation extension mechanisms for the mutually perpendicular and parallel settings between scanning direction and laser polarization bring not only distinct effective-pulse-number windows and somewhat different grating qualities,but also different extension stabilities in nanograting stitching via overlapping scanning lines and thus the optimal scanning strategy of parallel setting for large-area processing.In short,this study presents a convenient laser-processing approach for high precision fabrication of sub-50-nm gratings on HOPG,which would provide new insights into micro/nano-fabrication for optoelectronic metasurfaces and physics of the interaction between ultrafast laser and graphite.
基金supported by the National Key Research and Development Program of China(2022YFA1404800)National Natural Science Foundation of China(12174107,12004221,12192254,92250304,W2441005,12334014,12192251)+4 种基金Natural Science Foundation of Shandong Province(ZR2024QA024,ZR2021ZD02)Postdoctoral Innovation Talents Support Program of Shandong Province(No.SDBX2019005)Shanghai Municipal Science and Technology Major ProjectFundamental Research Funds for the Central UniversitiesEngineering Research Center for Nanophotonics&Advanced Instrument,Ministry of Education,East China Normal University(No.2023nmc005)。
文摘We demonstrate a high-speed rotating slit beam shaping method for femtosecond(fs)laser three-dimensional(3D)isotropic inscription in glass materials.By integrating fs laser direct writing with a real-time rotating slit mechanism,a 3D symmetric spherical focal field distribution is created in the laser-irradiated regions of transparent substrates.The corresponding focal field distribution is theoretically calculated and validated by examining the features of laser-inscribed lines in glass samples.Moreover,we investigate the influences of laser writing speed and slit rotational speed on the fabrication resolution in glass,and discuss the formation mechanism of the generated periodic microstructures.To showcase its powerful capability for3D isotropic fabrication,the high-speed rotating slit beam shaping method is applied to create straight optical waveguides,bending optical waveguides,and hollow microchannels in the glass.The proposed method holds great potential for the facile manufacture of diverse 3D isotropic microstructures and devices within transparent materials across various applications,including advanced photonics,microoptics,micro-electromechanical systems,and microfluidics.
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 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.
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.
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.
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.
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Project(2023YFB4604200)supported by National Key R&D Program of ChinaProjects(52475499,52222513,52075557)supported by National Natural Science Foundation of China+5 种基金Project(2021RC3011)supported by Science and Technology Innovation Program of Hunan Province,ChinaProject(2024JJ5426)supported by Natural Science Foundation of Hunan Province,ChinaProject(2023CXQD019)supported by the Central South University Innovation-Driven Research Programme,ChinaProject(ZZYJKT2023-12)supported by the State Key Laboratory of Precision Manufacturing for Extreme Service Performance,Central South University,ChinaProject(IMETKF2024018)supported by the State Key Laboratory of Intelligent Manufacturing Equipment and Technology,Huazhong University of Science and Technology,ChinaProject(2024ZZTS0102)supported by the Fundamental Research Funds for the Central Universities,China。
文摘The femtosecond laser is commonly used for high-quality micromachining of materials.However,the interaction time between the femtosecond laser and the substrate material is extremely short,making it difficult for quantitative measurements and analysis through experiments.In this work,we use a two-temperature model for simulation to study the ablation process of aluminum alloy and aluminum/titanium alloy under femtosecond laser pulse mode.The temperature changes and ablation process of both alloys under femtosecond laser burst irradiation were studied.The study found that when the separation time of sub-pulses was 1 ps,the surface temperature and ablation depth rised with the increase of sub-pulse numbers.A comparison was made between these two alloy types,and enhanced ablation was observed with the heterogeneous aluminum/titanium alloy,up to 34.7%deeper compared to aluminum alloy.Moreover,the detailed theoretical explanation was also discussed.This work provided a basis for efficient ablation of materials with low laser fluence.
基金Supported by National Natural Science Foundation of China(Grant No.52122510)the School-enterprise Cooperation Project Funded by Dongguan Strong Laser Advanced Equipment Co.,Ltd.(Grant No.21HK0214)。
文摘Silicon carbide(SiC)is widely used in fields such as new energy,military radar,and aerospace due to its outstanding physical and chemical properties.The surface micro-grooves of SiC can enhance the performance of micro-electromechanical systems,micro-sensors,and field-effect transistors.However,SiC,being a brittle and hard material,poses challenges for traditional machining methods like micro-groove machining and chemical etching,including subsurface damage,short tool life,and low processing efficiency.This paper investigates the processing characteristics of femtosecond laser machining of SiC micro-grooves and compares them with those of single-crystal Si.The results indicate that femtosecond laser ablation of SiC primarily leads to melting and vaporization,forming modification,melted,and ablation areas in the affected area.Femtosecond laser processing of SiC micro-grooves involves three processes:heat absorption and melting,vaporization,and chipping,with vaporization as the primary material removal mechanism.The depth and width of SiC micro-grooves are positively correlated with pulse energy(E_(p)),pulse overlap rate(PO),and number of passes(N_(pass)).The bottom roughness of the micro-grooves is positively correlated with E_(p),negatively correlated with PO,and less affected by changes in the N_(pass).These findings further elucidate the material removal and micro-groove formation mechanisms of SiC under femtosecond laser irradiation,providing theoretical insights for high-quality and high-efficiency processing of SiC micro-grooves.
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(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.
