We achieved an ultra-flat broad spectrum output with a 20-dB bandwidth of 77.85 nm in a double-clad Yb-doped fiber laser.The intensity difference between the highest and lowest points of the spectrum indicates a flatn...We achieved an ultra-flat broad spectrum output with a 20-dB bandwidth of 77.85 nm in a double-clad Yb-doped fiber laser.The intensity difference between the highest and lowest points of the spectrum indicates a flatness better than4 dB.More notably,this ultra-flat broad spectrum maintains a stable single-pulse mode-locking state.With the increase of pump power,an ultra-wide spectrum with a 20-dB bandwidth approaching 100 nm was formed at a pump power of 2.25 W.Additionally,we obtained a 9-pulse mode-locked state at another PC station with the same pump,which is the highest number of stable mode-locked pulse bursts observed so far with a first-order Raman frequency shift.This fiber laser shows its benefits of ultra-flat broad spectrum,high stability,and ease of fabrication,which provides a new method of obtaining the broadband light source for multiple practical applications.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
Currently,the performance,cost,and environmental sustainability of saturable absorbers(SAs)represent major bottlenecks in the development of ultrafast fiber lasers.However,the development of high-performance SAs remai...Currently,the performance,cost,and environmental sustainability of saturable absorbers(SAs)represent major bottlenecks in the development of ultrafast fiber lasers.However,the development of high-performance SAs remains challenging due to intricate fabrication processes and inadequate nonlinear performance.In this context,this work presents the natural alkaloid berberine as a promising alternative for mode-locked erbium-doped fiber lasers.The berberine-based SA exhibits excellent nonlinear optical properties,including a modulation depth of 24.40%and a saturation intensity of 1.281MW/cm^(2),and successfully enables stable femtosecond pulse generation.By employing time-stretched dispersive Fourier transform technology,the transient dynamics results indicate that the berberine-based SA significantly shortens the relaxation oscillation time and effectively suppresses pulse intensity fluctuations,thereby accelerating the self-starting process of mode-locking.This work provides a new strategy for developing high-performance,low-cost,and environmentally friendly ultrafast photonic devices,significantly advancing the practical application of green SAs.展开更多
Owing to the dynamic tunability and strong confinement,graphene plasmons(GPs)have emerged as an excellent candidate for the manipulation of light-matter interaction.Surface plasmons(SPs)have been admitted as another e...Owing to the dynamic tunability and strong confinement,graphene plasmons(GPs)have emerged as an excellent candidate for the manipulation of light-matter interaction.Surface plasmons(SPs)have been admitted as another effective way allowing strong confinement of light at the nanoscale.The combination of GPs and SPs like localized surface plasmons(LSPs)and propagating surface plasmon polaritons(SPPs)will lead to a synergistic effect that could remarkably improve light-matter interactions,showing great potential for many applications for the improvement of solar cell efficiency,biosensor sensitivity,and the performance of photonic devices.In this study,the GPs were activated by placing graphene film onto a two-dimensional(2D)phase-changing crystalline Ge_(2)Sb_(1.5)Bi_(0.5)Te_(5)(cGSBT)nanograting structure,which also acts as an original source generating LSPs.The SPPs originated by laying the above structure onto an Au mirror.The combined effects of GPs,LSPs,and SPPs are epitomized in such a simple Gr/2D cGSBT gratings/Au heterostructure,which allows easy realization of an ultrafast mode-locked laser quite stable working at 1550 nm range due to the strong nonlinear optical absorption capability.This approach overcomes the heat and energy loss in metallic gratings or a Gr-based heterostructure,exhibiting great potential for applications in the design and fabrication of photonic devices.展开更多
As a representative transition metal dichalcogenides(TMD),NiTe_(2)has an ultra-fast optical response,high carrier mobility,and excellent environmental stability.It has a broad application prospect in the fields of ene...As a representative transition metal dichalcogenides(TMD),NiTe_(2)has an ultra-fast optical response,high carrier mobility,and excellent environmental stability.It has a broad application prospect in the fields of ener-gy,biomedicine,optoelectronic devices,and so on.At present,there have been scant reports on the application of NiTe_(2)in the field of ultrafast photonics.In this work,NiTe_(2)was synthesized by chemical vapor deposition(CVD)and integrated with a tapered optical fiber to achieve mode-locking in an erbium-doped fiber laser(EDFL)and a thu-lium-doped fiber laser(TDFL).The mode-locked EDFL exhibited a pulse width of 678 fs and an output power of 3.92 mW.The pulse width of mode-locked TDFL was estimated to have a pulse width of 694 fs with an output power of 21.64 mW.These results demonstrate that NiTe_(2)is an effective saturable absorber material with potential applica-tions in the field of ultrafast optics.展开更多
We realize a stable self-starting passively mode-locking all-solid-state laser by using novel GaAs mirrors as the absorber and output coupler. The GaAs mirror is grown by the technology of metal organic chemical vapou...We realize a stable self-starting passively mode-locking all-solid-state laser by using novel GaAs mirrors as the absorber and output coupler. The GaAs mirror is grown by the technology of metal organic chemical vapour deposition at low temperature. With such an absorber as the output coupler in the laser resonator, laser pulses with duration of 42ps were generated at a repetition rate of 400MHz, corresponding to the average power of 590mW.展开更多
Ytterbium(Yb)-based mode-locked fiber lasers have undergone significant development and found widespread applications owing to their high efficiency,compact size,and low cost.However,these lasers typically operate wit...Ytterbium(Yb)-based mode-locked fiber lasers have undergone significant development and found widespread applications owing to their high efficiency,compact size,and low cost.However,these lasers typically operate within the 1030 to 1080 nm range,and expanding their operational wavelength is crucial for applications across various fields.We present the direct generation of a mode-locked laser at 1120.06 nm using an all-polarization-maintaining structure,establishing the longest wavelength reported to date for Yb-doped fiber-based mode-locked lasers.A stable picosecond pulse laser at 1120 nm was realized by combining high-concentration Yb-doping and phase-biasing technology within a figure-9 cavity configuration.The laser delivers a pulse duration of 6.20 ps,a spectral width of 0.19 nm centered at 1120.06 nm,and a repetition rate of 21.52 MHz and reaches a maximum output power of 1.39 W via a double-cladding Yb fiber power amplifier in a master oscillator power amplifier configuration.Furthermore,we present a theoretical investigation of the laser performance,with simulation results aligning well with experimental findings.In addition,a 560.06-nm ultrafast yellow-green laser was generated through frequency doubling in a lithium triborate crystal.We present an approach for long-wavelength Yb-doped mode-locked lasers,with the potential to advance the development and application of Yb-based fiber lasers.展开更多
Ultra-narrow bandwidth mode-locked lasers with tunable pulse duration can be versatile light sources for diverse applications.However,the spectral-temporal control of a narrow bandwidth mode-locked laser is challengin...Ultra-narrow bandwidth mode-locked lasers with tunable pulse duration can be versatile light sources for diverse applications.However,the spectral-temporal control of a narrow bandwidth mode-locked laser is challenging due to limited gain and nonlinearity,hindering practical applications of such lasers.We demonstrate a pulse duration widely tunable mode-locked ultra-narrow bandwidth laser using a composite filtering mechanism and a single-wall carbon nanotube.The laser pulse duration can be adjusted from 481 ps to 1.38 ns,which is the widest tuning range achieved in narrow-bandwidth passively mode-locked lasers.When the pulse duration is 1.38 ns,the corresponding spectral width reaches 4 pm(502 MHz).Numerical simulations support the experimental results and show that the evolution of long pulses in the laser cavity behaves similarly to a quasi-continuous wave with a low breathing ratio.We have not only designed a simple and flexible tunable scheme for the dilemma of spectral-temporal control in narrow-bandwidth mode-locked fiber lasers but also provided a unique and idealized light source for various applications that takes into account robust output.展开更多
We report on a Kerr-lens mode-locked(KLM)femtosecond Yb:CaYAlO_(4)(Yb:CYA)laser operating at a repetition rate of 1.04 GHz,pumped by a single-mode fiber laser.The laser delivers an average output power of 1.37 W with ...We report on a Kerr-lens mode-locked(KLM)femtosecond Yb:CaYAlO_(4)(Yb:CYA)laser operating at a repetition rate of 1.04 GHz,pumped by a single-mode fiber laser.The laser delivers an average output power of 1.37 W with a pulse duration of 109 fs.Potential improvements,including scaling the pump power,increasing the repetition rate,and further reducing the pulse duration,are discussed.This study contributes to the advancement of Watt-level GHz femtosecond laser generation and its applications.展开更多
CsPbBr3 nanocrystal is used as the saturable absorber(SA) for mode-locking Tm-doped fiber laser in a ring fiber cavity.The modulation depth, saturable intensity, and non-saturable loss of the fabricated SA are 14.1%, ...CsPbBr3 nanocrystal is used as the saturable absorber(SA) for mode-locking Tm-doped fiber laser in a ring fiber cavity.The modulation depth, saturable intensity, and non-saturable loss of the fabricated SA are 14.1%, 2.5 MW/cm^2,and 5.9%, respectively.In the mode-locking operation, the mode-locked pulse train has a repetition rate of 16.6 MHz with pulse width of 24.2 ps.The laser wavelength is centered at 1992.9 nm with 3-dB spectrum width of 2.5 nm.The maximum output power is 110 mW with slope efficiency of 7.1%.Our experiment shows that CsPbBr3 nanocrystal can be used as an efficient SA in the 2-μm wavelength region.展开更多
Passive harmonic mode locking of an erbium-doped fiber laser based on few-layer molybdenum disulfide(MoS2)saturable absorber(SA) is demonstrated. The few-layer MoS2 is prepared by the chemical vapor deposition(CVD) me...Passive harmonic mode locking of an erbium-doped fiber laser based on few-layer molybdenum disulfide(MoS2)saturable absorber(SA) is demonstrated. The few-layer MoS2 is prepared by the chemical vapor deposition(CVD) method and then transferred onto the end face of a fiber connector to form a fiber-compatible Mo S2SA. The 20 th harmonic modelocked pulses at 216-MHz repetition rate are stably generated with a pulse duration of 1.42 ps and side-mode suppression ratio(SMSR) of 36.1dB. The results confirm that few-layer MoS2 can serve as an effective SA for mode-locked fiber lasers.展开更多
In the last few years,research on advanced ultrafast photonic devices has attracted great interest from laser physicists.As a semiconductor material with excellent nonlinear saturation absorption characteristics,Ga As...In the last few years,research on advanced ultrafast photonic devices has attracted great interest from laser physicists.As a semiconductor material with excellent nonlinear saturation absorption characteristics,Ga As has been used in solidstate and fiber lasers as a mode-locker.However,the pulse widths that have been reported in the searchable published literature are all long and the shortest is tens of picoseconds.Femtosecond pulse widths,desired for a variety of applications,have not yet been reported in Ga As-based pulsed lasers.In this work,we further explore the nonlinear characteristics of Ga As that has been magnetron sputtered onto the surface of a tapered fiber and its application in the generation of femtosecond lasing via effective dispersion optimization and nonlinearity management.With the enhanced interaction between evanescent waves and Ga As nanosheets,mode-locked soliton pulses as short as 830 fs are generated at repetition rates of 4.64 MHz.As far as we know,this is the first time that femtosecond-level pulses have been generated with a Ga As-based saturable absorber.In addition,soliton molecules,including in the dual-pulse state,are also realized under stronger pumping.This work demonstrates that Ga As-based photonic devices have good application prospects in effective polymorphous ultrashort pulsed laser generation.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 pulse generation from active mode-locking terahertz quantum cascade laser is studied by Maxwell-Bloch equations.It is shown that longer dephasing time will lead to multiple pulses generation from the laser.The dep...The pulse generation from active mode-locking terahertz quantum cascade laser is studied by Maxwell-Bloch equations.It is shown that longer dephasing time will lead to multiple pulses generation from the laser.The dependence of output field on modulation length and radio-frequency parameters is obtained.In order to achieve short pulse generation,the DC bias should close to threshold value and modulation length should be shorter than 0.256 mm.The output pulse is unstable and the envelope shows many oscillations in the presence of spatial hole burning,resulting destabilization of mode-locking.展开更多
Synchronized dual-wavelength mode-locked laser is investigated numerically and experimentally in the normal dispersion regime.A programmable optical processor is introduced to shape the spectral profile and adjust the...Synchronized dual-wavelength mode-locked laser is investigated numerically and experimentally in the normal dispersion regime.A programmable optical processor is introduced to shape the spectral profile and adjust the net dispersion,which is demonstrated be a convenient and reliable approach to generate dual-color solitons.The time-stretch dispersive Fourier transform and frequency-resolved optical grating techniques are utilized to measure the spectral and temporal characteristics of dual-color solitons,respectively.The numerical results are consistent with experimental results.This work may facilitate the development of filter-based mode-locked laser and the understanding of multi-wavelength soliton dynamics.展开更多
A compact,intracavity optical deposition of graphene saturable absorber(SA)for low-threshold passively mode-locked fiber laser is proposed and demonstrated.The optical deposition is implemented in the laser cavity by ...A compact,intracavity optical deposition of graphene saturable absorber(SA)for low-threshold passively mode-locked fiber laser is proposed and demonstrated.The optical deposition is implemented in the laser cavity by using a slot collimator.Utilizing the fabricated graphene SA,the fiber laser achieves self-starting,passively mode-locked operation at a low threshold of 32 mW pump power,delivering a 13.1-MHz 2.36-ps pulse train.展开更多
A dual-phase synergistic enhancement method was adopted to strengthen the Al-Mn-Mg-Sc-Zr alloy fabricated by laser powder bed fusion(LPBF)by leveraging the unique advantages of Er and TiB_(2).Spherical powders of 0.5w...A dual-phase synergistic enhancement method was adopted to strengthen the Al-Mn-Mg-Sc-Zr alloy fabricated by laser powder bed fusion(LPBF)by leveraging the unique advantages of Er and TiB_(2).Spherical powders of 0.5wt%Er-1wt%TiB_(2)/Al-Mn-Mg-Sc-Zr nanocomposite were prepared using vacuum homogenization technique,and the density of samples prepared through the LPBF process reached 99.8%.The strengthening and toughening mechanisms of Er-TiB_(2)were investigated.The results show that Al_(3)Er diffraction peaks are detected by X-ray diffraction analysis,and texture strength decreases according to electron backscatter diffraction results.The added Er and TiB_(2)nano-reinforcing phases act as heterogeneous nucleation sites during the LPBF forming process,hindering grain growth and effectively refining the grains.After incorporating the Er-TiB_(2)dual-phase nano-reinforcing phases,the tensile strength and elongation at break of the LPBF-deposited samples reach 550 MPa and 18.7%,which are 13.4%and 26.4%higher than those of the matrix material,respectively.展开更多
To explore the formation mechanism of anisotropy in Ti-6Al-4V alloy fabricated by selective laser melting(SLM),the compressive mechanical properties,microhardness,microstructure,and crystallographic orientation of the...To explore the formation mechanism of anisotropy in Ti-6Al-4V alloy fabricated by selective laser melting(SLM),the compressive mechanical properties,microhardness,microstructure,and crystallographic orientation of the alloy across different planes were investigated.The anisotropy of SLM-fabricated Ti-6Al-4V alloys was analyzed,and the electron backscatter diffraction technique was used to investigate the influence of different grain types and orientations on the stress-strain distribution at various scales.Results reveal that in room-temperature compression tests at a strain rate of 10^(-3) s^(-1),both the compressive yield strength and microhardness vary along the deposition direction,indicating a certain degree of mechanical property anisotropy.The alloy exhibits a columnar microstructure;along the deposition direction,the grains appear equiaxed,and they have internal hexagonal close-packed(hcp)α/α'martensitic structure.α'phase has a preferential orientation approximately along the<0001>direction.Anisotropy arises from the high aspect ratio of columnar grains,along with the weak texture of the microstructure and low symmetry of the hcp crystal structure.展开更多
Conventional ignition methods are proving to be ineffective for low-sensitivity energetic materials,highlighting the need to investigate alternative ignition systems,such as laser-based techniques.Over the past decade...Conventional ignition methods are proving to be ineffective for low-sensitivity energetic materials,highlighting the need to investigate alternative ignition systems,such as laser-based techniques.Over the past decade,lasers have emerged as a promising solution,providing focused energy beams for controllable,efficient,and reliable ignition in the field of energetic materials.This study presents a comparative analysis of two state-of-the-art ignition approaches:direct laser ignition and laser-driven flyer ignition.Experiments were performed using a Neodymium-doped Yttrium Aluminum Garnet(Nd:YAG)laser at different energy beam levels to systematically evaluate ignition onset.In the direct laser ignition test setup,the laser beam was applied directly to the energetic tested material,while laserdriven flyer ignition utilized 40 and 100μm aluminum foils,propelled at velocities ranging from 300 to 1250 m/s.Comparative analysis with the Lawrence and Trott model substantiated the velocity data and provided insight into the ignition mechanisms.Experimental results indicate that the ignition time for the laser-driven flyer method was significantly shorter,with the pyrotechnic composition achieving complete combustion faster compared to direct laser ignition.Moreover,precise ignition thresholds were determined for both methods,providing critical parameters for optimizing ignition systems in energetic materials.This work elucidates the advantages and limitations of each technique while advancing next-generation ignition technology,enhancing the reliability and safety of propulsion systems.展开更多
The effects of initial spin orientation on the final electron beam polarization in laser wakefield acceleration in a pre-polarized plasma are investigated theoretically and numerically.From the results of variation of...The effects of initial spin orientation on the final electron beam polarization in laser wakefield acceleration in a pre-polarized plasma are investigated theoretically and numerically.From the results of variation of the initial spin direction,the spin dynamics of the electron beam are found to depend on the self-injection mechanism.The effects of wakefields and laser fields are studied using test particle dynamics and particle-in-cell simulations based on the Thomas-Bargmann-Michel-Telegdi equation.Compared with transverse injection,longitudinal injection is found to be preferable for obtaining a highly polarized electron beam.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.12204132)the Natural Science Foundation of Shandong Province,China(Grant No.ZR2021MF122)+1 种基金Shandong Province TechnologyBased SME Innovation Enhancement Project(Grant No.2024TSGC0715)the Postgraduate Education Reform Project of Shandong Province,China(Grant No.SDYJSJGC2024107)。
文摘We achieved an ultra-flat broad spectrum output with a 20-dB bandwidth of 77.85 nm in a double-clad Yb-doped fiber laser.The intensity difference between the highest and lowest points of the spectrum indicates a flatness better than4 dB.More notably,this ultra-flat broad spectrum maintains a stable single-pulse mode-locking state.With the increase of pump power,an ultra-wide spectrum with a 20-dB bandwidth approaching 100 nm was formed at a pump power of 2.25 W.Additionally,we obtained a 9-pulse mode-locked state at another PC station with the same pump,which is the highest number of stable mode-locked pulse bursts observed so far with a first-order Raman frequency shift.This fiber laser shows its benefits of ultra-flat broad spectrum,high stability,and ease of fabrication,which provides a new method of obtaining the broadband light source for multiple practical applications.
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 Key Project of Science and Technology Research Program of Hubei Provincial Department of Education,China(D20231704)the Opening Foundation of Hubei Key Laboratory for New Textile Materials and Applications Research(FZXCL202410)the Wuhan Textile University Special Fund Project。
文摘Currently,the performance,cost,and environmental sustainability of saturable absorbers(SAs)represent major bottlenecks in the development of ultrafast fiber lasers.However,the development of high-performance SAs remains challenging due to intricate fabrication processes and inadequate nonlinear performance.In this context,this work presents the natural alkaloid berberine as a promising alternative for mode-locked erbium-doped fiber lasers.The berberine-based SA exhibits excellent nonlinear optical properties,including a modulation depth of 24.40%and a saturation intensity of 1.281MW/cm^(2),and successfully enables stable femtosecond pulse generation.By employing time-stretched dispersive Fourier transform technology,the transient dynamics results indicate that the berberine-based SA significantly shortens the relaxation oscillation time and effectively suppresses pulse intensity fluctuations,thereby accelerating the self-starting process of mode-locking.This work provides a new strategy for developing high-performance,low-cost,and environmentally friendly ultrafast photonic devices,significantly advancing the practical application of green SAs.
基金National Natural Science Foundation of China(62404116)Natural Science Foundation of Shandong Province(ZR2023QE216)Youth Innovation Team Project of Shandong Province(2023KJ235)。
文摘Owing to the dynamic tunability and strong confinement,graphene plasmons(GPs)have emerged as an excellent candidate for the manipulation of light-matter interaction.Surface plasmons(SPs)have been admitted as another effective way allowing strong confinement of light at the nanoscale.The combination of GPs and SPs like localized surface plasmons(LSPs)and propagating surface plasmon polaritons(SPPs)will lead to a synergistic effect that could remarkably improve light-matter interactions,showing great potential for many applications for the improvement of solar cell efficiency,biosensor sensitivity,and the performance of photonic devices.In this study,the GPs were activated by placing graphene film onto a two-dimensional(2D)phase-changing crystalline Ge_(2)Sb_(1.5)Bi_(0.5)Te_(5)(cGSBT)nanograting structure,which also acts as an original source generating LSPs.The SPPs originated by laying the above structure onto an Au mirror.The combined effects of GPs,LSPs,and SPPs are epitomized in such a simple Gr/2D cGSBT gratings/Au heterostructure,which allows easy realization of an ultrafast mode-locked laser quite stable working at 1550 nm range due to the strong nonlinear optical absorption capability.This approach overcomes the heat and energy loss in metallic gratings or a Gr-based heterostructure,exhibiting great potential for applications in the design and fabrication of photonic devices.
基金Supported by Guangdong Basic and Applied Basic Research Fund,China(2024A1515012429)。
文摘As a representative transition metal dichalcogenides(TMD),NiTe_(2)has an ultra-fast optical response,high carrier mobility,and excellent environmental stability.It has a broad application prospect in the fields of ener-gy,biomedicine,optoelectronic devices,and so on.At present,there have been scant reports on the application of NiTe_(2)in the field of ultrafast photonics.In this work,NiTe_(2)was synthesized by chemical vapor deposition(CVD)and integrated with a tapered optical fiber to achieve mode-locking in an erbium-doped fiber laser(EDFL)and a thu-lium-doped fiber laser(TDFL).The mode-locked EDFL exhibited a pulse width of 678 fs and an output power of 3.92 mW.The pulse width of mode-locked TDFL was estimated to have a pulse width of 694 fs with an output power of 21.64 mW.These results demonstrate that NiTe_(2)is an effective saturable absorber material with potential applica-tions in the field of ultrafast optics.
基金Supported by the National Natural Science Foundation of China under Grant Nos 60225005 and 10227401, the Knowledge Innovation Programme of Chinese Academy of Sciences, and the National Hi-Tech ICF Committee of China.
文摘We realize a stable self-starting passively mode-locking all-solid-state laser by using novel GaAs mirrors as the absorber and output coupler. The GaAs mirror is grown by the technology of metal organic chemical vapour deposition at low temperature. With such an absorber as the output coupler in the laser resonator, laser pulses with duration of 42ps were generated at a repetition rate of 400MHz, corresponding to the average power of 590mW.
基金supported by the National Natural Science Foundation of China(Grant No.92477133)the Guangdong Basic and Applied Basic Research Foundation(Grant No.2025A1515011662)+1 种基金the National Natural Science Foundation of Fujian Province(Grant No.2025J01060)the National Natural Science Foundation of Xiamen(Grant No.3502Z202571016).
文摘Ytterbium(Yb)-based mode-locked fiber lasers have undergone significant development and found widespread applications owing to their high efficiency,compact size,and low cost.However,these lasers typically operate within the 1030 to 1080 nm range,and expanding their operational wavelength is crucial for applications across various fields.We present the direct generation of a mode-locked laser at 1120.06 nm using an all-polarization-maintaining structure,establishing the longest wavelength reported to date for Yb-doped fiber-based mode-locked lasers.A stable picosecond pulse laser at 1120 nm was realized by combining high-concentration Yb-doping and phase-biasing technology within a figure-9 cavity configuration.The laser delivers a pulse duration of 6.20 ps,a spectral width of 0.19 nm centered at 1120.06 nm,and a repetition rate of 21.52 MHz and reaches a maximum output power of 1.39 W via a double-cladding Yb fiber power amplifier in a master oscillator power amplifier configuration.Furthermore,we present a theoretical investigation of the laser performance,with simulation results aligning well with experimental findings.In addition,a 560.06-nm ultrafast yellow-green laser was generated through frequency doubling in a lithium triborate crystal.We present an approach for long-wavelength Yb-doped mode-locked lasers,with the potential to advance the development and application of Yb-based fiber lasers.
基金supported by the National Natural Science Foundation of China(Grant No.61975107)the Natural Science Foundation of Shanghai(Grant Nos.24ZR1422000 and 20ZR1471500),and the“111”Project(Grant No.D20031).
文摘Ultra-narrow bandwidth mode-locked lasers with tunable pulse duration can be versatile light sources for diverse applications.However,the spectral-temporal control of a narrow bandwidth mode-locked laser is challenging due to limited gain and nonlinearity,hindering practical applications of such lasers.We demonstrate a pulse duration widely tunable mode-locked ultra-narrow bandwidth laser using a composite filtering mechanism and a single-wall carbon nanotube.The laser pulse duration can be adjusted from 481 ps to 1.38 ns,which is the widest tuning range achieved in narrow-bandwidth passively mode-locked lasers.When the pulse duration is 1.38 ns,the corresponding spectral width reaches 4 pm(502 MHz).Numerical simulations support the experimental results and show that the evolution of long pulses in the laser cavity behaves similarly to a quasi-continuous wave with a low breathing ratio.We have not only designed a simple and flexible tunable scheme for the dilemma of spectral-temporal control in narrow-bandwidth mode-locked fiber lasers but also provided a unique and idealized light source for various applications that takes into account robust output.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFB4600158)。
文摘We report on a Kerr-lens mode-locked(KLM)femtosecond Yb:CaYAlO_(4)(Yb:CYA)laser operating at a repetition rate of 1.04 GHz,pumped by a single-mode fiber laser.The laser delivers an average output power of 1.37 W with a pulse duration of 109 fs.Potential improvements,including scaling the pump power,increasing the repetition rate,and further reducing the pulse duration,are discussed.This study contributes to the advancement of Watt-level GHz femtosecond laser generation and its applications.
基金Project supported by the National Key R&D Program of China(Grant No.2018YFB0504500)the National Natural Science Foundation of China(Grant Nos.51472162,51672177,and 61475171)the Talent Introduction Research Project of Shanghai Institute of Technology,China(Grant No.YJ 2018-8)
文摘CsPbBr3 nanocrystal is used as the saturable absorber(SA) for mode-locking Tm-doped fiber laser in a ring fiber cavity.The modulation depth, saturable intensity, and non-saturable loss of the fabricated SA are 14.1%, 2.5 MW/cm^2,and 5.9%, respectively.In the mode-locking operation, the mode-locked pulse train has a repetition rate of 16.6 MHz with pulse width of 24.2 ps.The laser wavelength is centered at 1992.9 nm with 3-dB spectrum width of 2.5 nm.The maximum output power is 110 mW with slope efficiency of 7.1%.Our experiment shows that CsPbBr3 nanocrystal can be used as an efficient SA in the 2-μm wavelength region.
基金supported by the National Natural Science Foundation of China(Grant Nos.61378028,61421002,61475030,and 61377042)the National Basic Research Program of China(Grant No.2012CB315701)the New Century Excellent Talents Program in University,China(Grant No.NCET-13-0092)
文摘Passive harmonic mode locking of an erbium-doped fiber laser based on few-layer molybdenum disulfide(MoS2)saturable absorber(SA) is demonstrated. The few-layer MoS2 is prepared by the chemical vapor deposition(CVD) method and then transferred onto the end face of a fiber connector to form a fiber-compatible Mo S2SA. The 20 th harmonic modelocked pulses at 216-MHz repetition rate are stably generated with a pulse duration of 1.42 ps and side-mode suppression ratio(SMSR) of 36.1dB. The results confirm that few-layer MoS2 can serve as an effective SA for mode-locked fiber lasers.
基金Project supported by the National Natural Science Foundation of China(Grant No.12164030)Young Science and Technology Talents of Inner Mongolia,China(Grant No.NJYT22101)+1 种基金the Central Government Guides Local Science,the Technology Development Fund Projects(Grant No.2023ZY0005)the Science and Technology Plan Projects of Inner Mongolia Autonomous Region of China(Grant No.2023KYPT0012)。
文摘In the last few years,research on advanced ultrafast photonic devices has attracted great interest from laser physicists.As a semiconductor material with excellent nonlinear saturation absorption characteristics,Ga As has been used in solidstate and fiber lasers as a mode-locker.However,the pulse widths that have been reported in the searchable published literature are all long and the shortest is tens of picoseconds.Femtosecond pulse widths,desired for a variety of applications,have not yet been reported in Ga As-based pulsed lasers.In this work,we further explore the nonlinear characteristics of Ga As that has been magnetron sputtered onto the surface of a tapered fiber and its application in the generation of femtosecond lasing via effective dispersion optimization and nonlinearity management.With the enhanced interaction between evanescent waves and Ga As nanosheets,mode-locked soliton pulses as short as 830 fs are generated at repetition rates of 4.64 MHz.As far as we know,this is the first time that femtosecond-level pulses have been generated with a Ga As-based saturable absorber.In addition,soliton molecules,including in the dual-pulse state,are also realized under stronger pumping.This work demonstrates that Ga As-based photonic devices have good application prospects in effective polymorphous ultrashort pulsed laser generation.
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Project supported by the National Key Research and Development Program of China(Grant No.2017YFF0106302)the National Natural Science Foundation of China(Grant Nos.61975225 and 61927813)Shanghai International Cooperation Project,China(Grant No.18590780100).
文摘The pulse generation from active mode-locking terahertz quantum cascade laser is studied by Maxwell-Bloch equations.It is shown that longer dephasing time will lead to multiple pulses generation from the laser.The dependence of output field on modulation length and radio-frequency parameters is obtained.In order to achieve short pulse generation,the DC bias should close to threshold value and modulation length should be shorter than 0.256 mm.The output pulse is unstable and the envelope shows many oscillations in the presence of spatial hole burning,resulting destabilization of mode-locking.
基金Project supported by the Innovation Program for Quantum Science and Technology(Grant No.2023ZD0301000)the National Natural Science Foundation of China(Grant Nos.12434018,62475073,1243000542,11621404,11561121003,11727812,61775059,12074122,62405090,62035005,and 11704123)+1 种基金the Natural Science Foundation of Shanghai(Grant No.23ZR1419000)China Postdoctoral Science Foundation(Grant Nos.2023M741188 and 2024T170275)。
文摘Synchronized dual-wavelength mode-locked laser is investigated numerically and experimentally in the normal dispersion regime.A programmable optical processor is introduced to shape the spectral profile and adjust the net dispersion,which is demonstrated be a convenient and reliable approach to generate dual-color solitons.The time-stretch dispersive Fourier transform and frequency-resolved optical grating techniques are utilized to measure the spectral and temporal characteristics of dual-color solitons,respectively.The numerical results are consistent with experimental results.This work may facilitate the development of filter-based mode-locked laser and the understanding of multi-wavelength soliton dynamics.
基金Supported in part by the National Natural Science Foundation of China under Grant No 11074078the Specialized Research Fund for the Doctoral Program of Higher Education under Grant No 20094407110002the Key Program for Scientific and Technological Innovations of Higher Education Institutes in Guangdong Province under Grant No cxzd1011.
文摘A compact,intracavity optical deposition of graphene saturable absorber(SA)for low-threshold passively mode-locked fiber laser is proposed and demonstrated.The optical deposition is implemented in the laser cavity by using a slot collimator.Utilizing the fabricated graphene SA,the fiber laser achieves self-starting,passively mode-locked operation at a low threshold of 32 mW pump power,delivering a 13.1-MHz 2.36-ps pulse train.
基金Shaanxi Province Qin Chuangyuan“Scientist+Engineer”Team Construction Project(2022KXJ-071)2022 Qin Chuangyuan Achievement Transformation Incubation Capacity Improvement Project(2022JH-ZHFHTS-0012)+8 种基金Shaanxi Province Key Research and Development Plan-“Two Chains”Integration Key Project-Qin Chuangyuan General Window Industrial Cluster Project(2023QCY-LL-02)Xixian New Area Science and Technology Plan(2022-YXYJ-003,2022-XXCY-010)2024 Scientific Research Project of Shaanxi National Defense Industry Vocational and Technical College(Gfy24-07)Shaanxi Vocational and Technical Education Association 2024 Vocational Education Teaching Reform Research Topic(2024SZX354)National Natural Science Foundation of China(U24A20115)2024 Shaanxi Provincial Education Department Service Local Special Scientific Research Program Project-Industrialization Cultivation Project(24JC005,24JC063)Shaanxi Province“14th Five-Year Plan”Education Science Plan,2024 Project(SGH24Y3181)National Key Research and Development Program of China(2023YFB4606400)Longmen Laboratory Frontier Exploration Topics Project(LMQYTSKT003)。
文摘A dual-phase synergistic enhancement method was adopted to strengthen the Al-Mn-Mg-Sc-Zr alloy fabricated by laser powder bed fusion(LPBF)by leveraging the unique advantages of Er and TiB_(2).Spherical powders of 0.5wt%Er-1wt%TiB_(2)/Al-Mn-Mg-Sc-Zr nanocomposite were prepared using vacuum homogenization technique,and the density of samples prepared through the LPBF process reached 99.8%.The strengthening and toughening mechanisms of Er-TiB_(2)were investigated.The results show that Al_(3)Er diffraction peaks are detected by X-ray diffraction analysis,and texture strength decreases according to electron backscatter diffraction results.The added Er and TiB_(2)nano-reinforcing phases act as heterogeneous nucleation sites during the LPBF forming process,hindering grain growth and effectively refining the grains.After incorporating the Er-TiB_(2)dual-phase nano-reinforcing phases,the tensile strength and elongation at break of the LPBF-deposited samples reach 550 MPa and 18.7%,which are 13.4%and 26.4%higher than those of the matrix material,respectively.
基金National Natural Science Foundation of China(51504138,51674118,52271177)Hunan Provincial Natural Science Foundation of China(2023JJ50181)Supported by State Key Laboratory of Materials Processing and Die&Mould Technology,Huazhong University of Science and Technology(P2024-022)。
文摘To explore the formation mechanism of anisotropy in Ti-6Al-4V alloy fabricated by selective laser melting(SLM),the compressive mechanical properties,microhardness,microstructure,and crystallographic orientation of the alloy across different planes were investigated.The anisotropy of SLM-fabricated Ti-6Al-4V alloys was analyzed,and the electron backscatter diffraction technique was used to investigate the influence of different grain types and orientations on the stress-strain distribution at various scales.Results reveal that in room-temperature compression tests at a strain rate of 10^(-3) s^(-1),both the compressive yield strength and microhardness vary along the deposition direction,indicating a certain degree of mechanical property anisotropy.The alloy exhibits a columnar microstructure;along the deposition direction,the grains appear equiaxed,and they have internal hexagonal close-packed(hcp)α/α'martensitic structure.α'phase has a preferential orientation approximately along the<0001>direction.Anisotropy arises from the high aspect ratio of columnar grains,along with the weak texture of the microstructure and low symmetry of the hcp crystal structure.
文摘Conventional ignition methods are proving to be ineffective for low-sensitivity energetic materials,highlighting the need to investigate alternative ignition systems,such as laser-based techniques.Over the past decade,lasers have emerged as a promising solution,providing focused energy beams for controllable,efficient,and reliable ignition in the field of energetic materials.This study presents a comparative analysis of two state-of-the-art ignition approaches:direct laser ignition and laser-driven flyer ignition.Experiments were performed using a Neodymium-doped Yttrium Aluminum Garnet(Nd:YAG)laser at different energy beam levels to systematically evaluate ignition onset.In the direct laser ignition test setup,the laser beam was applied directly to the energetic tested material,while laserdriven flyer ignition utilized 40 and 100μm aluminum foils,propelled at velocities ranging from 300 to 1250 m/s.Comparative analysis with the Lawrence and Trott model substantiated the velocity data and provided insight into the ignition mechanisms.Experimental results indicate that the ignition time for the laser-driven flyer method was significantly shorter,with the pyrotechnic composition achieving complete combustion faster compared to direct laser ignition.Moreover,precise ignition thresholds were determined for both methods,providing critical parameters for optimizing ignition systems in energetic materials.This work elucidates the advantages and limitations of each technique while advancing next-generation ignition technology,enhancing the reliability and safety of propulsion systems.
基金supported by the National Natural Science Foundation of China(Grant Nos.11804348,11775056,11975154,12225505,and 12405281)the Science Challenge(Project No.TZ2018005)+2 种基金supported by the Shanghai Pujiang Program(Grant No.23PJ1414600)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB0890203)supported by the Accelerator Technology Helmholtz Infrastructure consortium ATHENA.
文摘The effects of initial spin orientation on the final electron beam polarization in laser wakefield acceleration in a pre-polarized plasma are investigated theoretically and numerically.From the results of variation of the initial spin direction,the spin dynamics of the electron beam are found to depend on the self-injection mechanism.The effects of wakefields and laser fields are studied using test particle dynamics and particle-in-cell simulations based on the Thomas-Bargmann-Michel-Telegdi equation.Compared with transverse injection,longitudinal injection is found to be preferable for obtaining a highly polarized electron beam.
