1.Introduction.In recent decades,the pursuit of miniaturization has been crucial in nanofabrication,fostering innovation,and enabling novel applications in chip manufacturing,nanophotonics,and quantum devices[1,2].Adv...1.Introduction.In recent decades,the pursuit of miniaturization has been crucial in nanofabrication,fostering innovation,and enabling novel applications in chip manufacturing,nanophotonics,and quantum devices[1,2].Advancements in nanofabrication technology are driven by the demand for higher component density and performance,necessitating precise material processing in atmospheric environments.展开更多
Photonic computing has emerged as a promising technology for the ever-increasing computational demands of machine learning and artificial intelligence.Due to the advantages in computing speed,integrated photonic chips...Photonic computing has emerged as a promising technology for the ever-increasing computational demands of machine learning and artificial intelligence.Due to the advantages in computing speed,integrated photonic chips have attracted wide research attention on performing convolutional neural network algorithm.Programmable photonic chips are vital for achieving practical applications of photonic computing.Herein,a programmable photonic chip based on ultrafast laser-induced phase change is fabricated for photonic computing.Through designing the ultrafast laser pulses,the Sb film integrated into photonic waveguides can be reversibly switched between crystalline and amorphous phase,resulting in a large contrast in refractive index and extinction coefficient.As a consequence,the light transmission of waveguides can be switched between write and erase states.To determine the phase change time,the transient laser-induced phase change dynamics of Sb film are revealed at atomic scale,and the time-resolved transient reflectivity is measured.Based on the integrated photonic chip,photonic convolutional neural networks are built to implement machine learning algorithm,and images recognition task is achieved.This work paves a route for fabricating programmable photonic chips by designed ultrafast laser,which will facilitate the application of photonic computing in artificial intelligence.展开更多
The ultrafast laser-matter interaction is explored to induce new pioneering principles and technologies into the realms of fundamental science and industrial production.The local thermal melting and connection propert...The ultrafast laser-matter interaction is explored to induce new pioneering principles and technologies into the realms of fundamental science and industrial production.The local thermal melting and connection properties of the ultrafast laser welding technology offer a novel method for welding of diverse transparent materials,thus having wide range of potential applications in aerospace,opto-mechanical systems,sensors,microfluidic,optics,etc.In this comprehensive review,tuning the transient electron activation processes,high-rate laser energy deposition,and dynamic evolution of plasma morphology by the temporal/spatial shaping methods have been demonstrated to facilitate the transition from conventional homogeneous transparent material welding to the more intricate realm of transparent/metal heterogeneous material welding.The welding strength and stability are also improvable through the implementation of real-time,in-situ monitoring techniques and the prompt diagnosis of welding defects.The principles of ultrafast laser welding,bottleneck problems in the welding,novel welding methods,advances in welding performance,in-situ monitoring and diagnosis,and various applications are reviewed.Finally,we offer a forward-looking perspective on the fundamental challenges within the field of ultrafast laser welding and identify key areas for future research,underscoring the imperative need for ongoing innovation and exploration.展开更多
This review examines the state-of-the-art in spatial manipulation of ultrafast laser processing using dynamic light modulators,with a particular focus on liquid crystal-based systems.We discuss phase modulation strate...This review examines the state-of-the-art in spatial manipulation of ultrafast laser processing using dynamic light modulators,with a particular focus on liquid crystal-based systems.We discuss phase modulation strategies and highlight the current limitations and challenges in surface and bulk processing.Specifically,we emphasize the delicate balance between high-fidelity beam shaping and energy efficiency,both critical for surface and bulk processing applications.Given the inherent physical limitations of spatial light modulators such as spatial resolution,fill factor,and phase modulation range.We explore techniques developed to bridge the gap between desired intensity distributions and actual experimental beam profiles.We present various laser light modulation technologies and the main algorithmic strategies for obtaining modulation patterns.The paper includes application examples across a wide range of fields,from surgery to surface structuring,cutting,bulk photo-inscription of optical functions,and additive manufacturing,highlighting the significant enhancements in processing speed and precision due to spatial beam shaping.The diverse applications and the technological limitations underscore the need for adapted modulation pattern calculation methods.We discuss several advancements addressing these challenges,involving both experimental and algorithmic developments,including the recent incorporation of artificial intelligence.Additionally,we cover recent progress in phase and pulse front control based on spatial modulators,which introduces an extra control parameter for light excitation with high potential for achieving more controlled processing outcomes.展开更多
The exceptional photoelectric performance and high compatibility of perovskite materials render perovskite solar cells highly promising for extensive development,thus garnering significant attention.In perovskite sola...The exceptional photoelectric performance and high compatibility of perovskite materials render perovskite solar cells highly promising for extensive development,thus garnering significant attention.In perovskite solar cells,the hole transport layer plays a crucial role.For the commonly employed organic small molecule hole transport material Spiro-OMeTAD,a certain period of oxidation treatment is required to achieve complete transport performance.However,this posttreatment oxidation processes typically rely on ambient oxidation,which poses challenges in terms of precise control and leads to degradation of the perovskite light absorption layer.This approach fails to meet the demands for high efficiency and stability in practical application.Herein,the mechanism of ultrafast laser on Spiro-OMeTAD and the reaction process for laser-induced oxidation of it are investigated.PbI_(2) at Perovskite/Spiro-OMeTAD interface breaks down to produce I_(2) upon ultrafast laser irradiation and I_(2) promote the oxidation process.Through the laser irradiation oxidation processing,a higher stability of perovskite solar cells is achieved.This work establishes a new approach toward oxidation treatment of Spiro-OMeTAD.展开更多
Ultrafast laser inscription(ULI)inside semiconductors offers new perspectives for 3D monolithic structures to be fabricated and new functionalities to be added in electronic and photonic microdevices.However,important...Ultrafast laser inscription(ULI)inside semiconductors offers new perspectives for 3D monolithic structures to be fabricated and new functionalities to be added in electronic and photonic microdevices.However,important challenges remain because of nonlinear effects such as strong plasma generation that distort the energy delivery at the focal point when exposing these materials to intense infrared light.Up to now,the successful technological demonstrations have primarily concentrated on silicon(Si).In this paper,we target at another important semiconductor:gallium arsenide(GaAs).With nonlinearities higher than those of Si,3D-machining of GaAs with femtosecond pulses becomes even harder.However,we show that the difficulty can be circumvented by burst-mode irradiation.We generate and apply trains of pulses at terahertz repetition rates for efficient pulse-to-pulse accumulation of laser-induced free carriers in the focal region,while avoiding an overdose of prefocal excitations.The superior performance of burst-mode irradiation is confirmed by a comparative study conducted with infrared luminescence microscopy.The results indicate a successful reduction of the plasma density in the prefocal region so that higher pulse energy reaches the focal spot.The same method is applied to identify optimum irradiation conditions considering particular cases such as asymmetric pulse trains and aberrated beams.With 64-pulse trains,we successfully manage to cross the writing threshold providing a solution for ULI inside GaAs.The application potential is finally illustrated with a stealth dicing demonstration by taking benefit of the burst mode.The irradiation method opens wide possibilities for 3D structuring inside GaAs by ULI.展开更多
As the fundamental optical properties and novel photophysics of graphene and related two-dimensional （2D） crystals are being extensively investigated and revealed, a range of potential applications in optical and op...As the fundamental optical properties and novel photophysics of graphene and related two-dimensional （2D） crystals are being extensively investigated and revealed, a range of potential applications in optical and optoelectronic devices have been proposed and demonstrated. Of the many possibilities, the use of 2D materials as broadband, cost-effective and versatile ultrafast optical switches （or saturable absorbers） for short-pulsed lasers constitutes a rapidly developing field with not only a good number of publications, but also a promising prospect for commercial exploitation. This review primarily focuses on the recent development of pulsed lasers based on several representative 2D materials. The comparative advantages of these materials are discussed, and challenges to practical exploitation, which represent good future directions of research, are laid out.展开更多
Laser processing with high-power ultrashort pulses,which promises high precision and efficiency,is an emerging new tool for material structuring.High repetition rate ultrafast laser highlighting with a higher degree o...Laser processing with high-power ultrashort pulses,which promises high precision and efficiency,is an emerging new tool for material structuring.High repetition rate ultrafast laser highlighting with a higher degree of freedom in its burst mode is believed to be able to create micro/nanostructures with even more variety,which is promising for electrochemical applications.We employ a homemade high repetition rate ultrafast fiber laser for structuring metal nickel(Ni)and thus preparing electrocatalysts for hydrogen evolution reaction(HER)for the first time,we believe.Different processing parameters are designed to create three groups of samples with different micro/nanostructures.The various micro/nanostructures not only increase the surface area of the Ni electrode but also regulate local electric field and help discharge hydrogen bubbles,which offer more favorable conditions for HER.All groups of the laser-structured Ni exhibit enhanced electrocatalytic activity for HER in the alkaline solution.Electrochemical measurements demonstrate that the overpotential at 10 mAcm−2 can be decreased as much as 182 mV compared with the overpotential of the untreated Ni(−457 mV versus RHE).展开更多
Because poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)(PEDOT:PSS)is water processable,thermally stable,and highly conductive,PEDOT:PSS and its composites have been considered to be one of the most promising f...Because poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)(PEDOT:PSS)is water processable,thermally stable,and highly conductive,PEDOT:PSS and its composites have been considered to be one of the most promising flexible thermoelectric materials.However,the PEDOT:PSS film prepared from its commercial aqueous dispersion usually has very low conductivity,thus cannot be directly utilized for TE applications.Here,a simple environmental friendly strategy via femtosecond laser irradiation without any chemical dopants and treatments was demonstrated.Under optimal conditions,the electrical conductivity of the treated film is increased to 803.1 S cm^(-1)from 1.2 S cm^(-1)around three order of magnitude higher,and the power factor is improved to 19.0μW m^(-1)K^(-2),which is enhanced more than 200 times.The mechanism for such remarkable enhancement was attributed to the transition of the PEDOT chains from a coil to a linear or expanded coil conformation,reduction of the interplanar stacking distance,and the removal of insulating PSS with increasing the oxidation level of PEDOT,facilitating the charge transportation.This work presents an effective route for fabricating high-performance flexible conductive polymer films and wearable thermoelectric devices.展开更多
Herein,we report the victorious synthesis of metal-organic frameworks(MOFs) on TiO_2 nanotubes(NTs)using a layer-by-layer(LbL) approach.Highly crystalline and homogenous thin films of MOFs were grown and characterized...Herein,we report the victorious synthesis of metal-organic frameworks(MOFs) on TiO_2 nanotubes(NTs)using a layer-by-layer(LbL) approach.Highly crystalline and homogenous thin films of MOFs were grown and characterized using XRD,SEM,FT-IR and UV/Vis spectroscopy.Moreover,the utilization of the MOF films as sensitizers was probed in bespoke Graetzel type liquid junction solar cells.The constructed cell performance revealed an I_(sc) of 1.16 mA cm^(–2),Vocof 0.63 V,FF of 0.33,and E_(ff) of 0.42%.Further,pumpprobe transient laser spectroscopy was performed to investigate the energy and charge transfer dynamics of the MOFs/TiO_2 NTs interface.The results indicated 86% injection efficiency.The ultrafast pump-probe spectroscopy allows the investigation of this process and the differences between MOFs.It also showed that the relaxation of the MOF chromophores is in competition with electron injection in the Ti O2 motif.Thus this study provides a new insight into electron transfer from photoexcited metal-organic frameworks(MOFs) into titanium dioxide.展开更多
Materials exhibiting broadband nonlinear optical responses are critically important for ultrafast photonics applications,particularly as saturable absorbers(SAs)that facilitate broadband optical pulse generation.In th...Materials exhibiting broadband nonlinear optical responses are critically important for ultrafast photonics applications,particularly as saturable absorbers(SAs)that facilitate broadband optical pulse generation.In this study,tea polyphenolpolyvinyl alcohol(TP-PVA)composite films are synthesized via a polymer embedding method and employed as SAs to initiate ultrafast pulse operation in fiber lasers.The TP-PVA SA film exhibits excellent broadband saturable absorption performance at wavelengths of 1.0μm,1.5μm,and 2.0μm,with modulation depths of 54.21%,41.41%,and 51.16%,respectively.Stable passively mode-locked pulses with pulse widths of 588 fs,419 fs,and 743 fs are generated in Yb-,Er-,and Tm-doped fiber lasers,respectively.This work confirms the effective performance of TP-PVA as a broadband SA,and establishes a foundation for the integration of novel and sustainable materials within ultrafast photonic systems.The approach paves the way for developing compact broadband ultrafast laser systems operating in the near-infrared spectral region.展开更多
Nanometallic materials have attracted wide research attention in the fabrication of functional devices,including flexible electronics circuits and high-sensitive sensors.Sintering of nanometallic materials is generall...Nanometallic materials have attracted wide research attention in the fabrication of functional devices,including flexible electronics circuits and high-sensitive sensors.Sintering of nanometallic materials is generally thought as an effective technology for the functional manufacturing,and the controllable sintering of nanometallic materials and its major mechanisms have long been a challenge.Here,an ultrafast laser processing strategy for Ag nanoparticles(NPs)is achieved by modulating plasmonic.The excitation mode of plasmon can be designed by laser parameters,including polarization with a specific crystal size.The atomic-scale ultrafast dynamics are revealed for understanding the sintering process and design of the sintered structures.The non-equilibrium energy transfer between electron and lattice and dynamic evolution of pressure are proved to be the foremost driving forces on the motion of atomic structures.Through research of plasmonic-induced electric field enhancement and non-uniform deposition of heat and in-situ observation of relative transmittance,mapping from atomic-scale structure to micro behavior is established.Based on plasmonic modulation and processing of Ag NPs,a machine learning combined flexible gesture sensor with high recognition accuracy is displayed.This work expands the knowledge of interactions between lasers and nanometallic materials and provides a method for designing functional devices for a wide range of applications.展开更多
Single-crystal fibers(SCFs)exhibit a significant potential for high-power laser applications owing to their superior thermal management capabilities.To enhance pump power and mitigate damage at the injection end of SC...Single-crystal fibers(SCFs)exhibit a significant potential for high-power laser applications owing to their superior thermal management capabilities.To enhance pump power and mitigate damage at the injection end of SCFs,a segmented YAG/Yb:YAG/YAG SCF with a diameter of~200μm was directly grown using a one-step laserheated pedestal growth(LHPG)method.The crystallinity and uniformity of the as-grown fiber were evaluated through a real-time back-reflection Laue camera system.Employing a low-loss segmented YAG/Yb:YAG/YAG SCF as the laser gain medium,investigations were conducted on both continuous-wave(CW)oscillators and ultrafast pulse amplifiers.The CW laser operation at 1030.9 nm achieved a maximum output power of 117.6 W with a slope efficiency of~46%,while the ultrafast amplifier system generated pulses with an average power of 101.2 W at a repetition rate of 30.8 MHz.To the best of our knowledge,this represents the highest average power achieved from a single-stage amplifier based on an Yb:YAG SCF.Preliminary pulse compression was performed at a signal power of 5o.6 W using a grating pair,resulting in a compressed pulse width of 786 fs with a compression efficiency of 58%.This study highlights the potential of crystal fiber lasers for a new generation of high-power laser systems.展开更多
In this paper, we have demonstrated an Er-doped ultrafast laser with a single mode fiber-gradient index multimode fiber-single mode fiber(SMF-GIMF-SMF, SMS) structure as saturable absorber(SA), which can generate not ...In this paper, we have demonstrated an Er-doped ultrafast laser with a single mode fiber-gradient index multimode fiber-single mode fiber(SMF-GIMF-SMF, SMS) structure as saturable absorber(SA), which can generate not only stable single-pulse state, but also special mode-locked pulses with the characteristics of high energy and noisy behaviors at proper pump power and cavity polarization state. In addition, we have deeply investigated the real-time spectral evolutions of the mode-locked pulses through the dispersive Fourier transformation(DFT) technique. It can be found that the pulse regime can actually consist of a lot of small noise pulses with randomly varying intensities. We believe that these results will further enrich the nonlinear dynamical processes in the ultrafast lasers.展开更多
The size of compression gratings has become a crucial factor in achieving 100-PW level super-intense ultrafast lasers,in view of the laser-induced damage of grating compressor.To improve the output laser energy within...The size of compression gratings has become a crucial factor in achieving 100-PW level super-intense ultrafast lasers,in view of the laser-induced damage of grating compressor.To improve the output laser energy within the damage threshold of grating compressor and therefore obtain higher laser peak power,we proposed the full-aperture grating compressor(FAGC).In this work,the spatiotemporal characteristics of the output pulses from FAGC are investigated,based on the SULF-10 PW laser facility with~400-mm beam diameter.The simulation and proof-of-principle experiment show that the pulse duration and the focusing quality of the output pulses from an FAGC are basically identical with those from a conventional 4-grating compressor;meanwhile,no evident diffractions are induced by the spectral clipping of FAGC.Thus,there is no marked influence of FAGC on the spatiotemporal characteristics of output compressed pulses.This work further demonstrates the feasibility of FAGC efficiently,which should be a promising scheme for realizing single-channel 100-PW level super-intense ultrafast lasers.展开更多
The fiber-based saturable absorber(SA)that enables mode-locking within a ring cavity serves as the core component of the ultrafast all-fiber lasers.However,the integration of SAs onto fibers with high compactness suff...The fiber-based saturable absorber(SA)that enables mode-locking within a ring cavity serves as the core component of the ultrafast all-fiber lasers.However,the integration of SAs onto fibers with high compactness suffers from imbalanced saturable absorption properties and unstable mode-locking performance.Here,we present a robust mode-locking SA by integrating a nanocavity composed of a two-dimensional graphene heterostructure on the fiber end facet.We demonstrate a significant reduction in the saturation intensity(~65%)and improved soliton dynamic processes through precise modulation of the optical field within the heterostructure.The designed heterostructure facilitates the formation of a stable single-soliton state for robust mode-locking.A high tolerance to intracavity polarization variations is achieved in the heterostructure-SA(~85%compared to 20%for bare graphene).Our designed heterostructure-SA represents an important advancement in the development of ultracompact mode-locked all-fiber lasers,offering enhanced integrability and stability.展开更多
The development of micro-electro-mechanical system(MEMS)alkali metal vapor cells offers the potential for the batch fabrication of micro-quantum sensors for atomic clocks,atomic magnetometers and atomic gyroscopes.The...The development of micro-electro-mechanical system(MEMS)alkali metal vapor cells offers the potential for the batch fabrication of micro-quantum sensors for atomic clocks,atomic magnetometers and atomic gyroscopes.The sealing of MEMS vapor cells is traditionally achieved by anodic bonding.However,high-temperature and high direct-voltage conditions during anodic bonding adversely affect the performance of the vapor cell.In this study,a fabrication method based on ultrafast laser welding integrated with a microfabrication process was developed for MEMS alkali metal vapor cells,and the energy-coupling mechanism of welding was analyzed.This method confined high temperatures to a localized area during laser welding.The cross-sections of the welding samples were analyzed,the element distribution was characterized,and the results showed that this method achieved high-strength sealing.Additionally,a platform for alkali metal injection and buffer gas charging was developed to enable the fabrication of MEMS vapor cells with ultrafast laser welding.The MEMS vapor cells were tested using absorption spectra,and the leakage rate under high-temperature vacuum conditions proved that high hermeticity could be achieved by ultrafast laser welding.Finally,MEMS vapor cells were used to fabricate a single-beam magnetometer,and its measurement sensitivity was determined experimentally.This process provides a new method for the efficient fabrication of MEMS vapor cells.展开更多
The ultimate feature size is key in ultrafast laser material processing.A capacity to substantially exceed optical limits and to structure below 100 nm is essential to advance ultrafast processing into the field of me...The ultimate feature size is key in ultrafast laser material processing.A capacity to substantially exceed optical limits and to structure below 100 nm is essential to advance ultrafast processing into the field of metamaterials.Such achievement requires combining the control of optical near-fields and of material reactions while preserving the flexibility of long working distances,compatible with a mature laser process.Using subpicosecond and picosecond nondiffractive Bessel beams,we demonstrate unprecedented feature sizes below a hundredth of the incident 1-um wavelength over an extended focus depth of tens of micrometers.Record features sizes,down to 7 nm,result from self-generated near-field light components initiated by cavities induced by far-field radiation in a back-surface illumination geometry.This sustains the generation of more confined near-field evanescent components along the laser scan with a nanometer pitch,perpendicular to the incident field direction,driving a superresolved laser structuring process via local thermal ablation.The near-field pattern is replicated with high robustness,advancing toward a 10-nm nanoscribing tool with a micrometer-sized laser pen.The process is controllable by the field orientation.The nondiffractive irradiation develops evanescent fields over the focusing length,resulting in high-aspect-ratio trenching with a nanometer section and a micrometer depth.Higher energy doses trigger the self-organization of quasi-periodic patterns seeded by spatially modulated scattering,similarly to optical modelocking.A predictive multipulse simulation method validates the far-field-induced near-field electromagnetic scenario of void nanochannel growth and replication,indicating the processing range and resolution on the surface and in the depth.展开更多
Soliton molecules(SMs),bounded and self-assembled of particle-like dissipative solitons,exist with versatile mutual interactions and manifest substantial potential in soliton communication and optical data storage.How...Soliton molecules(SMs),bounded and self-assembled of particle-like dissipative solitons,exist with versatile mutual interactions and manifest substantial potential in soliton communication and optical data storage.However,controllable manipulation of the bounded molecular patterns remains challenging,as reaching a specific operation regime in lasers generally involves adjusting multiple control parameters in connection with a wide range of accessible pulse dynamics.An evolutionary algorithm is implemented for intelligent control of SMs in a 2μm ultrafast fiber laser mode locked through nonlinear polarization rotation.Depending on the specifications of the merit function used for the optimization procedure,various SM operations are obtained,including spectra shape programming and controllable deterministic switching of doublet and triplet SMs operating in stationary or pulsation states with reconfigurable temporal separations,frequency locking of pulsation SMs,doublet and SM complexes with controllable pulsation ratio,etc.Digital encoding is further demonstrated in this platform by employing the self-assembled characteristics of SMs.Our work opens up an avenue for active SM control beyond conventional telecom bands and brings useful insights into nonlinear science and applications.展开更多
Due to their unique physical properties,nonlinear materials are gradually demonstrating significant potential in the field of optics.Gold nanoparticles supported on carbon black(Au/CB),possessing low loss and high non...Due to their unique physical properties,nonlinear materials are gradually demonstrating significant potential in the field of optics.Gold nanoparticles supported on carbon black(Au/CB),possessing low loss and high nonlinear characteristics,serve as an excellent material for saturable absorber(SA) in ultrafast fiber lasers.In this study,we investigated the performance of Au/CB material and designed an ultrafast fiber laser based on Au/CB SA,successfully observing stable fundamental mode-locking and pulse bunch phenomena.Specifically,when the fiber laser operates in fundamental mode-locking state,the center wavelength of optical spectrum is 1 558.82 nm,with a 3 dB bandwidth of 2.26 nm.Additionally,to investigate the evolution of real-time spectra,the dispersive Fourier transform(DFT) technology is employed.On the other hand,the pulse bunch emitted by the laser is actually composed of numerous random sub-pulses,exhibiting high-energy characteristics.The number of sub-pulses increases with the increase of pump power.These findings contribute to further exploring the properties of Au/CB material and reveal its potential applications in ultrafast optics.展开更多
基金supported by the National Natural Science Foun-dation of China(51975017 and 52405448)the Human Resource Training Project(HRTP-[2022]-53)of Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province(IKKEM)the support by the China Postdoctoral Science Foundation(2024M750149 and GZC20240087).
文摘1.Introduction.In recent decades,the pursuit of miniaturization has been crucial in nanofabrication,fostering innovation,and enabling novel applications in chip manufacturing,nanophotonics,and quantum devices[1,2].Advancements in nanofabrication technology are driven by the demand for higher component density and performance,necessitating precise material processing in atmospheric environments.
基金supported by the National Key R&D Program of China(2024YFB4609801)the National Natural Science Foundation of China(52075289)the Tsinghua-Jiangyin Innovation Special Fund(TJISF,2023JYTH0104).
文摘Photonic computing has emerged as a promising technology for the ever-increasing computational demands of machine learning and artificial intelligence.Due to the advantages in computing speed,integrated photonic chips have attracted wide research attention on performing convolutional neural network algorithm.Programmable photonic chips are vital for achieving practical applications of photonic computing.Herein,a programmable photonic chip based on ultrafast laser-induced phase change is fabricated for photonic computing.Through designing the ultrafast laser pulses,the Sb film integrated into photonic waveguides can be reversibly switched between crystalline and amorphous phase,resulting in a large contrast in refractive index and extinction coefficient.As a consequence,the light transmission of waveguides can be switched between write and erase states.To determine the phase change time,the transient laser-induced phase change dynamics of Sb film are revealed at atomic scale,and the time-resolved transient reflectivity is measured.Based on the integrated photonic chip,photonic convolutional neural networks are built to implement machine learning algorithm,and images recognition task is achieved.This work paves a route for fabricating programmable photonic chips by designed ultrafast laser,which will facilitate the application of photonic computing in artificial intelligence.
基金supports from National Key R&D Program of China(Grant No.2023YFB4605500)National Natural Science Foundation of China(Grant No.52105498)+3 种基金Natural Science Foundation of Hunan Province(Grant No.2022JJ40597)the Science and Technology Innovation Program of Hunan Province(Grant No.2022RC1132)State Key Laboratory of Precision Manufacturing for Extreme Service Performance(Grant No.ZZYJKT2023-08)support in analyzing the status of ultrafast laser welding applications,as well as the corresponding project support(Grant No.HKF202400595).
文摘The ultrafast laser-matter interaction is explored to induce new pioneering principles and technologies into the realms of fundamental science and industrial production.The local thermal melting and connection properties of the ultrafast laser welding technology offer a novel method for welding of diverse transparent materials,thus having wide range of potential applications in aerospace,opto-mechanical systems,sensors,microfluidic,optics,etc.In this comprehensive review,tuning the transient electron activation processes,high-rate laser energy deposition,and dynamic evolution of plasma morphology by the temporal/spatial shaping methods have been demonstrated to facilitate the transition from conventional homogeneous transparent material welding to the more intricate realm of transparent/metal heterogeneous material welding.The welding strength and stability are also improvable through the implementation of real-time,in-situ monitoring techniques and the prompt diagnosis of welding defects.The principles of ultrafast laser welding,bottleneck problems in the welding,novel welding methods,advances in welding performance,in-situ monitoring and diagnosis,and various applications are reviewed.Finally,we offer a forward-looking perspective on the fundamental challenges within the field of ultrafast laser welding and identify key areas for future research,underscoring the imperative need for ongoing innovation and exploration.
基金supported by the French ANRT agence nationale de la recherche technologique under the CIFRE conventions industrielles de formation par la recherche framework.
文摘This review examines the state-of-the-art in spatial manipulation of ultrafast laser processing using dynamic light modulators,with a particular focus on liquid crystal-based systems.We discuss phase modulation strategies and highlight the current limitations and challenges in surface and bulk processing.Specifically,we emphasize the delicate balance between high-fidelity beam shaping and energy efficiency,both critical for surface and bulk processing applications.Given the inherent physical limitations of spatial light modulators such as spatial resolution,fill factor,and phase modulation range.We explore techniques developed to bridge the gap between desired intensity distributions and actual experimental beam profiles.We present various laser light modulation technologies and the main algorithmic strategies for obtaining modulation patterns.The paper includes application examples across a wide range of fields,from surgery to surface structuring,cutting,bulk photo-inscription of optical functions,and additive manufacturing,highlighting the significant enhancements in processing speed and precision due to spatial beam shaping.The diverse applications and the technological limitations underscore the need for adapted modulation pattern calculation methods.We discuss several advancements addressing these challenges,involving both experimental and algorithmic developments,including the recent incorporation of artificial intelligence.Additionally,we cover recent progress in phase and pulse front control based on spatial modulators,which introduces an extra control parameter for light excitation with high potential for achieving more controlled processing outcomes.
基金supported by the National Key Research and Development Program of China(2020YFA0715000)the Guangdong Basic and Applied Basic Research Foundation(2021B1515120041)the Hainan Provincial Joint Project of Sanya Yazhou Bay Science and Technology City(2021JJLH0058)。
文摘The exceptional photoelectric performance and high compatibility of perovskite materials render perovskite solar cells highly promising for extensive development,thus garnering significant attention.In perovskite solar cells,the hole transport layer plays a crucial role.For the commonly employed organic small molecule hole transport material Spiro-OMeTAD,a certain period of oxidation treatment is required to achieve complete transport performance.However,this posttreatment oxidation processes typically rely on ambient oxidation,which poses challenges in terms of precise control and leads to degradation of the perovskite light absorption layer.This approach fails to meet the demands for high efficiency and stability in practical application.Herein,the mechanism of ultrafast laser on Spiro-OMeTAD and the reaction process for laser-induced oxidation of it are investigated.PbI_(2) at Perovskite/Spiro-OMeTAD interface breaks down to produce I_(2) upon ultrafast laser irradiation and I_(2) promote the oxidation process.Through the laser irradiation oxidation processing,a higher stability of perovskite solar cells is achieved.This work establishes a new approach toward oxidation treatment of Spiro-OMeTAD.
基金This research has received funding from the European Research Council(ERC)under the European Union’s Horizon 2020 research and innovation program(Grant Agreement No.724480).
文摘Ultrafast laser inscription(ULI)inside semiconductors offers new perspectives for 3D monolithic structures to be fabricated and new functionalities to be added in electronic and photonic microdevices.However,important challenges remain because of nonlinear effects such as strong plasma generation that distort the energy delivery at the focal point when exposing these materials to intense infrared light.Up to now,the successful technological demonstrations have primarily concentrated on silicon(Si).In this paper,we target at another important semiconductor:gallium arsenide(GaAs).With nonlinearities higher than those of Si,3D-machining of GaAs with femtosecond pulses becomes even harder.However,we show that the difficulty can be circumvented by burst-mode irradiation.We generate and apply trains of pulses at terahertz repetition rates for efficient pulse-to-pulse accumulation of laser-induced free carriers in the focal region,while avoiding an overdose of prefocal excitations.The superior performance of burst-mode irradiation is confirmed by a comparative study conducted with infrared luminescence microscopy.The results indicate a successful reduction of the plasma density in the prefocal region so that higher pulse energy reaches the focal spot.The same method is applied to identify optimum irradiation conditions considering particular cases such as asymmetric pulse trains and aberrated beams.With 64-pulse trains,we successfully manage to cross the writing threshold providing a solution for ULI inside GaAs.The application potential is finally illustrated with a stealth dicing demonstration by taking benefit of the burst mode.The irradiation method opens wide possibilities for 3D structuring inside GaAs by ULI.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61378025 and 61427812)the Shuangchuang Team Program of Jiangsu Province,China,the National Key Basic Research Program of China(Grant No.2014CB921101)the State Key Laboratory of Advanced Optical Communication Systems Networks,China
文摘As the fundamental optical properties and novel photophysics of graphene and related two-dimensional （2D） crystals are being extensively investigated and revealed, a range of potential applications in optical and optoelectronic devices have been proposed and demonstrated. Of the many possibilities, the use of 2D materials as broadband, cost-effective and versatile ultrafast optical switches （or saturable absorbers） for short-pulsed lasers constitutes a rapidly developing field with not only a good number of publications, but also a promising prospect for commercial exploitation. This review primarily focuses on the recent development of pulsed lasers based on several representative 2D materials. The comparative advantages of these materials are discussed, and challenges to practical exploitation, which represent good future directions of research, are laid out.
基金supported by the National Natural Science Foundation of China(Grant Nos.62375087,12374304,and 62235014)the NSFC Development of National Major Scientific Research Instrument(Grant No.61927816)+3 种基金the Mobility Programme of the Sino-German(Grant No.M-0296)the Introduced Innovative Team Project of Guangdong Pearl River Talents Program(Grant No.2021ZT09Z109)the Natural Science Foundation of Guangdong Province(Grant No.2021B1515020074)the Science and Technology Project of Guangdong(Grant No.2020B1212060002).
文摘Laser processing with high-power ultrashort pulses,which promises high precision and efficiency,is an emerging new tool for material structuring.High repetition rate ultrafast laser highlighting with a higher degree of freedom in its burst mode is believed to be able to create micro/nanostructures with even more variety,which is promising for electrochemical applications.We employ a homemade high repetition rate ultrafast fiber laser for structuring metal nickel(Ni)and thus preparing electrocatalysts for hydrogen evolution reaction(HER)for the first time,we believe.Different processing parameters are designed to create three groups of samples with different micro/nanostructures.The various micro/nanostructures not only increase the surface area of the Ni electrode but also regulate local electric field and help discharge hydrogen bubbles,which offer more favorable conditions for HER.All groups of the laser-structured Ni exhibit enhanced electrocatalytic activity for HER in the alkaline solution.Electrochemical measurements demonstrate that the overpotential at 10 mAcm−2 can be decreased as much as 182 mV compared with the overpotential of the untreated Ni(−457 mV versus RHE).
基金supported by the National Key Research and Development Program of China(2020YFA0715000)the Guangdong Basic and Applied Basic Research Foundation(2020A1515110250,2021B1515120041)+1 种基金the Foshan Xianhu Laboratory of the Advanced Energy Science and Technology Guangdong Laboratory(XHT2020-005)the Fundamental Research Funds for the Central Universities(2020IVA068,2021lll007JC)
文摘Because poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)(PEDOT:PSS)is water processable,thermally stable,and highly conductive,PEDOT:PSS and its composites have been considered to be one of the most promising flexible thermoelectric materials.However,the PEDOT:PSS film prepared from its commercial aqueous dispersion usually has very low conductivity,thus cannot be directly utilized for TE applications.Here,a simple environmental friendly strategy via femtosecond laser irradiation without any chemical dopants and treatments was demonstrated.Under optimal conditions,the electrical conductivity of the treated film is increased to 803.1 S cm^(-1)from 1.2 S cm^(-1)around three order of magnitude higher,and the power factor is improved to 19.0μW m^(-1)K^(-2),which is enhanced more than 200 times.The mechanism for such remarkable enhancement was attributed to the transition of the PEDOT chains from a coil to a linear or expanded coil conformation,reduction of the interplanar stacking distance,and the removal of insulating PSS with increasing the oxidation level of PEDOT,facilitating the charge transportation.This work presents an effective route for fabricating high-performance flexible conductive polymer films and wearable thermoelectric devices.
基金funded by the Science and Technology Development Fund in Egypt (STDF),project number 12323
文摘Herein,we report the victorious synthesis of metal-organic frameworks(MOFs) on TiO_2 nanotubes(NTs)using a layer-by-layer(LbL) approach.Highly crystalline and homogenous thin films of MOFs were grown and characterized using XRD,SEM,FT-IR and UV/Vis spectroscopy.Moreover,the utilization of the MOF films as sensitizers was probed in bespoke Graetzel type liquid junction solar cells.The constructed cell performance revealed an I_(sc) of 1.16 mA cm^(–2),Vocof 0.63 V,FF of 0.33,and E_(ff) of 0.42%.Further,pumpprobe transient laser spectroscopy was performed to investigate the energy and charge transfer dynamics of the MOFs/TiO_2 NTs interface.The results indicated 86% injection efficiency.The ultrafast pump-probe spectroscopy allows the investigation of this process and the differences between MOFs.It also showed that the relaxation of the MOF chromophores is in competition with electron injection in the Ti O2 motif.Thus this study provides a new insight into electron transfer from photoexcited metal-organic frameworks(MOFs) into titanium dioxide.
基金supported by the Opening Foundation of Hubei Key Laboratory for New Textile Materials and Applications Research(Grant No.FZXCL202410)the Key Project of Science and Technology Research Program of Hubei Provincial Department of Education,China(Grant No.D20231704)+1 种基金Wuhan Textile University(Grant No.523058)the Foundation of Wuhan Textile University(Grant No.K24058)。
文摘Materials exhibiting broadband nonlinear optical responses are critically important for ultrafast photonics applications,particularly as saturable absorbers(SAs)that facilitate broadband optical pulse generation.In this study,tea polyphenolpolyvinyl alcohol(TP-PVA)composite films are synthesized via a polymer embedding method and employed as SAs to initiate ultrafast pulse operation in fiber lasers.The TP-PVA SA film exhibits excellent broadband saturable absorption performance at wavelengths of 1.0μm,1.5μm,and 2.0μm,with modulation depths of 54.21%,41.41%,and 51.16%,respectively.Stable passively mode-locked pulses with pulse widths of 588 fs,419 fs,and 743 fs are generated in Yb-,Er-,and Tm-doped fiber lasers,respectively.This work confirms the effective performance of TP-PVA as a broadband SA,and establishes a foundation for the integration of novel and sustainable materials within ultrafast photonic systems.The approach paves the way for developing compact broadband ultrafast laser systems operating in the near-infrared spectral region.
基金supported by the National Natural Science Foundation of China(52575510)the National Key R&D Program of China(2024YFB4609801).
文摘Nanometallic materials have attracted wide research attention in the fabrication of functional devices,including flexible electronics circuits and high-sensitive sensors.Sintering of nanometallic materials is generally thought as an effective technology for the functional manufacturing,and the controllable sintering of nanometallic materials and its major mechanisms have long been a challenge.Here,an ultrafast laser processing strategy for Ag nanoparticles(NPs)is achieved by modulating plasmonic.The excitation mode of plasmon can be designed by laser parameters,including polarization with a specific crystal size.The atomic-scale ultrafast dynamics are revealed for understanding the sintering process and design of the sintered structures.The non-equilibrium energy transfer between electron and lattice and dynamic evolution of pressure are proved to be the foremost driving forces on the motion of atomic structures.Through research of plasmonic-induced electric field enhancement and non-uniform deposition of heat and in-situ observation of relative transmittance,mapping from atomic-scale structure to micro behavior is established.Based on plasmonic modulation and processing of Ag NPs,a machine learning combined flexible gesture sensor with high recognition accuracy is displayed.This work expands the knowledge of interactions between lasers and nanometallic materials and provides a method for designing functional devices for a wide range of applications.
基金National Key Research and Development Program of China(2023YFB406900)National Natural Science Foundation of China(62435012,U24A20312,52202008,62175132)+1 种基金Natural Science Foundation of Shandong Province(ZR2022QE013)Outstanding Young and Middle-aged Scholars of Shandong University(Tao Li)。
文摘Single-crystal fibers(SCFs)exhibit a significant potential for high-power laser applications owing to their superior thermal management capabilities.To enhance pump power and mitigate damage at the injection end of SCFs,a segmented YAG/Yb:YAG/YAG SCF with a diameter of~200μm was directly grown using a one-step laserheated pedestal growth(LHPG)method.The crystallinity and uniformity of the as-grown fiber were evaluated through a real-time back-reflection Laue camera system.Employing a low-loss segmented YAG/Yb:YAG/YAG SCF as the laser gain medium,investigations were conducted on both continuous-wave(CW)oscillators and ultrafast pulse amplifiers.The CW laser operation at 1030.9 nm achieved a maximum output power of 117.6 W with a slope efficiency of~46%,while the ultrafast amplifier system generated pulses with an average power of 101.2 W at a repetition rate of 30.8 MHz.To the best of our knowledge,this represents the highest average power achieved from a single-stage amplifier based on an Yb:YAG SCF.Preliminary pulse compression was performed at a signal power of 5o.6 W using a grating pair,resulting in a compressed pulse width of 786 fs with a compression efficiency of 58%.This study highlights the potential of crystal fiber lasers for a new generation of high-power laser systems.
基金supported by the Guangdong Basic and Applied Basic Research Foundation (No.2023A1515010093)the Shenzhen Fundamental Research Program (Stable Support Plan Program)(Nos.JCYJ20220809170611004, 20231121110828001 and 20231121113641002)the National Taipei University of Technology-Shenzhen University Joint Research Program (No.2024001)。
文摘In this paper, we have demonstrated an Er-doped ultrafast laser with a single mode fiber-gradient index multimode fiber-single mode fiber(SMF-GIMF-SMF, SMS) structure as saturable absorber(SA), which can generate not only stable single-pulse state, but also special mode-locked pulses with the characteristics of high energy and noisy behaviors at proper pump power and cavity polarization state. In addition, we have deeply investigated the real-time spectral evolutions of the mode-locked pulses through the dispersive Fourier transformation(DFT) technique. It can be found that the pulse regime can actually consist of a lot of small noise pulses with randomly varying intensities. We believe that these results will further enrich the nonlinear dynamical processes in the ultrafast lasers.
基金supported by the National Key R&D Program of China(2020YFA0714500,2019YFF01014401)The National Natural Science Foundation of China(12388102)+2 种基金Strategic Priority Research Program of Chinese Academy of Sciences(XDB0890102)Shanghai Science and Technology Committee Program(22DZ1100300,22560780100,23560750200)The Youth Innovation Promotion Association of the Chinese Academy of Sciences.
文摘The size of compression gratings has become a crucial factor in achieving 100-PW level super-intense ultrafast lasers,in view of the laser-induced damage of grating compressor.To improve the output laser energy within the damage threshold of grating compressor and therefore obtain higher laser peak power,we proposed the full-aperture grating compressor(FAGC).In this work,the spatiotemporal characteristics of the output pulses from FAGC are investigated,based on the SULF-10 PW laser facility with~400-mm beam diameter.The simulation and proof-of-principle experiment show that the pulse duration and the focusing quality of the output pulses from an FAGC are basically identical with those from a conventional 4-grating compressor;meanwhile,no evident diffractions are induced by the spectral clipping of FAGC.Thus,there is no marked influence of FAGC on the spatiotemporal characteristics of output compressed pulses.This work further demonstrates the feasibility of FAGC efficiently,which should be a promising scheme for realizing single-channel 100-PW level super-intense ultrafast lasers.
基金supported by the National Natural Science Foundation of China(12422406,12427806,T2188101,52025023,and 12374167)National Key R&D Program of China(2022YFA1403500 and 2021YFA1400201)the New Cornerstone Science Foundation through the XPLORER PRIZE.
文摘The fiber-based saturable absorber(SA)that enables mode-locking within a ring cavity serves as the core component of the ultrafast all-fiber lasers.However,the integration of SAs onto fibers with high compactness suffers from imbalanced saturable absorption properties and unstable mode-locking performance.Here,we present a robust mode-locking SA by integrating a nanocavity composed of a two-dimensional graphene heterostructure on the fiber end facet.We demonstrate a significant reduction in the saturation intensity(~65%)and improved soliton dynamic processes through precise modulation of the optical field within the heterostructure.The designed heterostructure facilitates the formation of a stable single-soliton state for robust mode-locking.A high tolerance to intracavity polarization variations is achieved in the heterostructure-SA(~85%compared to 20%for bare graphene).Our designed heterostructure-SA represents an important advancement in the development of ultracompact mode-locked all-fiber lasers,offering enhanced integrability and stability.
基金supported in part by the National Key Research&Development(R&D)Plan(2024YFB3212500)the National Natural Science Foundation of China(62473305)+2 种基金the Chongqing Natural Science Basic Research Project(cstc2021jcyj-msxmX0801)the National Natural Science Youth Foundation of China(52305615)the National Natural Science Youth Foundation of China(52305618).
文摘The development of micro-electro-mechanical system(MEMS)alkali metal vapor cells offers the potential for the batch fabrication of micro-quantum sensors for atomic clocks,atomic magnetometers and atomic gyroscopes.The sealing of MEMS vapor cells is traditionally achieved by anodic bonding.However,high-temperature and high direct-voltage conditions during anodic bonding adversely affect the performance of the vapor cell.In this study,a fabrication method based on ultrafast laser welding integrated with a microfabrication process was developed for MEMS alkali metal vapor cells,and the energy-coupling mechanism of welding was analyzed.This method confined high temperatures to a localized area during laser welding.The cross-sections of the welding samples were analyzed,the element distribution was characterized,and the results showed that this method achieved high-strength sealing.Additionally,a platform for alkali metal injection and buffer gas charging was developed to enable the fabrication of MEMS vapor cells with ultrafast laser welding.The MEMS vapor cells were tested using absorption spectra,and the leakage rate under high-temperature vacuum conditions proved that high hermeticity could be achieved by ultrafast laser welding.Finally,MEMS vapor cells were used to fabricate a single-beam magnetometer,and its measurement sensitivity was determined experimentally.This process provides a new method for the efficient fabrication of MEMS vapor cells.
基金The National Key R&D Program of China(2022YFB4600200)the Natural Science Basic Research Program of Shaanxi Province(2022JQ-648)partially supported by the French National Research Agency(ANR)with grants ANR-19-CE30-0036 and ANR-21-CE08-0005.
文摘The ultimate feature size is key in ultrafast laser material processing.A capacity to substantially exceed optical limits and to structure below 100 nm is essential to advance ultrafast processing into the field of metamaterials.Such achievement requires combining the control of optical near-fields and of material reactions while preserving the flexibility of long working distances,compatible with a mature laser process.Using subpicosecond and picosecond nondiffractive Bessel beams,we demonstrate unprecedented feature sizes below a hundredth of the incident 1-um wavelength over an extended focus depth of tens of micrometers.Record features sizes,down to 7 nm,result from self-generated near-field light components initiated by cavities induced by far-field radiation in a back-surface illumination geometry.This sustains the generation of more confined near-field evanescent components along the laser scan with a nanometer pitch,perpendicular to the incident field direction,driving a superresolved laser structuring process via local thermal ablation.The near-field pattern is replicated with high robustness,advancing toward a 10-nm nanoscribing tool with a micrometer-sized laser pen.The process is controllable by the field orientation.The nondiffractive irradiation develops evanescent fields over the focusing length,resulting in high-aspect-ratio trenching with a nanometer section and a micrometer depth.Higher energy doses trigger the self-organization of quasi-periodic patterns seeded by spatially modulated scattering,similarly to optical modelocking.A predictive multipulse simulation method validates the far-field-induced near-field electromagnetic scenario of void nanochannel growth and replication,indicating the processing range and resolution on the surface and in the depth.
基金supported by the Research Grants Council of the Hong Kong Special Administrative Region of China(Grant Nos.HKU 17212824,HKU 17210522,HKU C7074-21G,HKU R7003-21,and HKU 17205321)the Innovation and Technology Commission of the Hong Kong SAR Government(Grant Nos.MHP/073/20 and MHP/057/21),and the Health@InnoHK program.
文摘Soliton molecules(SMs),bounded and self-assembled of particle-like dissipative solitons,exist with versatile mutual interactions and manifest substantial potential in soliton communication and optical data storage.However,controllable manipulation of the bounded molecular patterns remains challenging,as reaching a specific operation regime in lasers generally involves adjusting multiple control parameters in connection with a wide range of accessible pulse dynamics.An evolutionary algorithm is implemented for intelligent control of SMs in a 2μm ultrafast fiber laser mode locked through nonlinear polarization rotation.Depending on the specifications of the merit function used for the optimization procedure,various SM operations are obtained,including spectra shape programming and controllable deterministic switching of doublet and triplet SMs operating in stationary or pulsation states with reconfigurable temporal separations,frequency locking of pulsation SMs,doublet and SM complexes with controllable pulsation ratio,etc.Digital encoding is further demonstrated in this platform by employing the self-assembled characteristics of SMs.Our work opens up an avenue for active SM control beyond conventional telecom bands and brings useful insights into nonlinear science and applications.
基金supported by the Natural Science Foundation of Guangdong Province (No.2023A1515010093)the Shenzhen Fundamental Research Program (Nos.JCYJ20220809170611004, JCYJ20231121110828001 and JCYJ20231121113641002)。
文摘Due to their unique physical properties,nonlinear materials are gradually demonstrating significant potential in the field of optics.Gold nanoparticles supported on carbon black(Au/CB),possessing low loss and high nonlinear characteristics,serve as an excellent material for saturable absorber(SA) in ultrafast fiber lasers.In this study,we investigated the performance of Au/CB material and designed an ultrafast fiber laser based on Au/CB SA,successfully observing stable fundamental mode-locking and pulse bunch phenomena.Specifically,when the fiber laser operates in fundamental mode-locking state,the center wavelength of optical spectrum is 1 558.82 nm,with a 3 dB bandwidth of 2.26 nm.Additionally,to investigate the evolution of real-time spectra,the dispersive Fourier transform(DFT) technology is employed.On the other hand,the pulse bunch emitted by the laser is actually composed of numerous random sub-pulses,exhibiting high-energy characteristics.The number of sub-pulses increases with the increase of pump power.These findings contribute to further exploring the properties of Au/CB material and reveal its potential applications in ultrafast optics.
