We report a diode-pumped rod-type Yb:YAG laser amplifier operating at 1 kHz.Cryogenic cooling method was adopted to make the Yb:YAG crystal work with four-level behavior.A single-frequency fiber laser acts as the seed...We report a diode-pumped rod-type Yb:YAG laser amplifier operating at 1 kHz.Cryogenic cooling method was adopted to make the Yb:YAG crystal work with four-level behavior.A single-frequency fiber laser acts as the seed in an actively Q-switched Yb:YAG oscillator.The resonator delivers 5.75-mJ pulses at 1 kHz with a pulse duration of approximately 40 ns.The pulses were amplified to 61 mJ in a four-pass rod-type Yb:YAG amplifier with optical-to-optical efficiency of 24%in the main amplifier.The M^(2)parameter of the output laser is<1.4.展开更多
A high-power CW Yb:YAG slab laser amplifier with no adaptive optics correction has been experimentally established.At room temperature,the amplifier emits a power of 22 kW with an average beam quality(β)of less than ...A high-power CW Yb:YAG slab laser amplifier with no adaptive optics correction has been experimentally established.At room temperature,the amplifier emits a power of 22 kW with an average beam quality(β)of less than 3 in 0.5 min.To our knowledge,this is the brightest slab laser without closed-loop adaptive optics demonstrated to date.In addition,an extracted power of 17 kW with an optical extraction efficiency of 33%,corresponding to a residual optical path difference of less than 0.5μm,is achieved with the single Yb:YAG slab gain module.The slab gain module has the potential to be scalable to higher powers while maintaining good beam quality.This makes a high-power solid-state laser system simpler and more robust.展开更多
A high efficiency compact Yb:KGW regenerative amplifier using an all-fiber laser seed source was comprehensively studied.With thermal lensing effect compensated by the cavity design,the compressed pulses with energy o...A high efficiency compact Yb:KGW regenerative amplifier using an all-fiber laser seed source was comprehensively studied.With thermal lensing effect compensated by the cavity design,the compressed pulses with energy of 1 mJ at 1 kHz and 0.4 mJ at 10 kHz in sub-400-fs pulse duration using chirped fiber Bragg grating(CFBG)stretcher were demonstrated.A modified Frantz-Nodvik equation was developed to emulate the dynamic behavior of the regenerative amplifier.The simulation results were in good agreement with the experiment.Numerical simulations and experimental results show that the scheme can be scalable to higher energy of multi-mJ,sub-300 fs pulses.展开更多
A high power Nd:YAG end-pumped slab amplifier chain with a Nd:YVO_4 innoslab laser as the master oscillator is demonstrated. A chain output power of 5210W with beam quality of 4 times the diffraction limit is achieved...A high power Nd:YAG end-pumped slab amplifier chain with a Nd:YVO_4 innoslab laser as the master oscillator is demonstrated. A chain output power of 5210W with beam quality of 4 times the diffraction limit is achieved by double-passing the first amplifier stage and single-passing the second stage with an optical efficiency of 29% while working at a frequency of 1 kHz and pulse width of 200μs.展开更多
<div style="text-align:justify;"> A new planar waveguide laser was demonstrated. The output energy of 400 mW was achieved by a single waveguide laser;the slope efficiency was 61%. The single waveguide ...<div style="text-align:justify;"> A new planar waveguide laser was demonstrated. The output energy of 400 mW was achieved by a single waveguide laser;the slope efficiency was 61%. The single waveguide laser can expand to waveguide laser group and waveguide laser array to produce higher energy. </div>展开更多
This paper presents an investigation of specific optical fiber core mode leakage behavior that occurs in high-power double-clad fiber lasers as a result of thermally-induced refractive index variations. A model of the...This paper presents an investigation of specific optical fiber core mode leakage behavior that occurs in high-power double-clad fiber lasers as a result of thermally-induced refractive index variations. A model of the power transfer between the core modes and the cladding modes during thermally-induced refractive index variations is established based on the mode coupling theory. The results of numerical simulations based on actual laser parameters are presented. Experimental measurements were also carried out, the results showed good agreement with the corresponding simulation results.展开更多
An ultrafast fiber laser system comprising two coherently combined amplifier channels is reported.Within this system,each channel incorporates a rod-type fiber power amplifier,with individual operations reaching appro...An ultrafast fiber laser system comprising two coherently combined amplifier channels is reported.Within this system,each channel incorporates a rod-type fiber power amplifier,with individual operations reaching approximately 233 W.The active-locking of these coherently combined channels,followed by compression using gratings,yields an output with a pulse energy of 504μJ and an average power of 403 W.Exceptional stability is maintained,with a 0.3%root mean square(RMS)deviation and a beam quality factor M^(2)<1.2.Notably,precise dispersion management of the front-end seed light effectively compensates for the accumulated high-order dispersion in subsequent amplification stages.This strategic approach results in a significant reduction in the final output pulse duration for the coherently combined laser beam,reducing it from 488 to 260 fs after the gratings compressor,while concurrently enhancing the energy of the primary peak from 65%to 92%.展开更多
We propose a novel model to explain the physical process of the thermally induced core laser leakage(TICLL) effect in a high power co-pumped ytterbium doped fiber(YDF) amplifier. This model considers the thermally ind...We propose a novel model to explain the physical process of the thermally induced core laser leakage(TICLL) effect in a high power co-pumped ytterbium doped fiber(YDF) amplifier. This model considers the thermally induced mode bending loss decrease and the thermally induced mode instability(TMI) in the coiled YDF, and is further used to reproduce the TICLL effect in the high power co-pumped step-index 20/400 fiber amplifier. Besides, the TICLL effect in the copumping scheme and counter-pumping scheme is compared. The result proves that the TICLL effect is caused by the combined effect of the thermally induced mode bending loss decrease and the TMI, and could be mitigated by adopting the counter-pumping scheme. To our best knowledge, this is the first theoretical explanation of the TICLL effect in high power fiber amplifier.展开更多
To obtain short pulse width and high peak power laser, a 7 kHz sub-nanosecond microchip laser amplified by a grazing incidence double pass slab amplifier is experimentally demonstrated in this Letter. We use a compact...To obtain short pulse width and high peak power laser, a 7 kHz sub-nanosecond microchip laser amplified by a grazing incidence double pass slab amplifier is experimentally demonstrated in this Letter. We use a compact side-pumped Nd∶YVO4 bounce amplifier with grazing incidence beam for achieving high gains and power extraction. Laser output power of 7.37 W at 7 kHz, 1.2 MW pulse peak power with 877 ps duration and 1.05 mJ energy, 25 pm spectral width, and near diffraction limited mode beam quality are achieved, and the optical-to-optical efficiency is 18%. The laser is packaged in a volume of 356 mm × 226 mm × 84 mm and may be used for applications such as laser altimeters and ladar systems.展开更多
We report femtosecond pulse generation in an amplifier similariton oscillator and a prechirped fiber amplifier system. The final output power is 1.4W, and the fundamental repetition rate is 19.1 MHz after a single sta...We report femtosecond pulse generation in an amplifier similariton oscillator and a prechirped fiber amplifier system. The final output power is 1.4W, and the fundamental repetition rate is 19.1 MHz after a single state fiber amplifier. The pulsewidth is 109 fs.展开更多
We have been experimentally demonstrated an active control technique of dynamic gain-clamped spectra for theerbium-doped fiber amplifiers (EDFA's) by a backward-injected Fabry-Perot (F-P) laser into this EDFA. In ...We have been experimentally demonstrated an active control technique of dynamic gain-clamped spectra for theerbium-doped fiber amplifiers (EDFA's) by a backward-injected Fabry-Perot (F-P) laser into this EDFA. In addition, employing a short length erbium-doped fiber (EDF) that not cause any gain saturation for preamplification in front of this amplifier module, it can reduce the noise figure degradation and simultaneously achieve gain variation from 11.1 dB to 0.5 dB for 10 dB input power level change.展开更多
In this paper,an all-fiberized and narrow-linewidth 5 kW power-level fiber amplifier is presented.The laser is achieved based on the master oscillator power amplification configuration,in which the phase-modulated sin...In this paper,an all-fiberized and narrow-linewidth 5 kW power-level fiber amplifier is presented.The laser is achieved based on the master oscillator power amplification configuration,in which the phase-modulated single-frequency laser is applied as the seed laser and a bidirectional pumping configuration is applied in the power amplifier.The stimulated Brillouin scattering,stimulated Raman scattering,and transverse mode instability effects are all effectively suppressed in the experiment.Consequently,the output power is scaled up to 4.92 kW with a slope efficiency of as high as approximately 80%.The 3-dB spectral width is about 0.59 nm,and the beam quality is measured to be M^(2)~1.22 at maximum output power.Furthermore,we have also conducted a detailed spectral analysis on the spectral width of the signal laser,which reveals that the spectral wing broadening phenomenon could lead to the obvious decrease of the spectral purity at certain output power.Overall,this work could provide a reference for obtaining and optimizing high-power narrow-linewidth fiber lasers.展开更多
High-power fiber lasers have experienced a dramatic development over the last decade.Further increasing the output power needs an upscaling of the fiber mode area,while maintaining a single-mode output.Here,we propose...High-power fiber lasers have experienced a dramatic development over the last decade.Further increasing the output power needs an upscaling of the fiber mode area,while maintaining a single-mode output.Here,we propose an all-solid anti-resonant fiber(ARF)structure,which ensures single-mode operation in broadband by resonantly coupling higherorder modes into the cladding.A series of fibers with core sizes ranging from 40 to 100µm are proposed exhibiting maximum mode area exceeding 5000µm2.Numerical simulations show this resonant coupling scheme provides a higher-order mode(mainly TE01,TM01,and HE21)suppression ratio of more than 20 dB,while keeping the fundamental mode loss lower than 1 dB/m.The proposed structure also exhibits high tolerance for core index depression.展开更多
Compared with traditional uniform fibers, tapered fiber has numerous unique advantages, such as larger mode area,higher pump absorption, suppression to nonlinear effects, and maintaining good beam quality. In this man...Compared with traditional uniform fibers, tapered fiber has numerous unique advantages, such as larger mode area,higher pump absorption, suppression to nonlinear effects, and maintaining good beam quality. In this manuscript, we have constructed an all-fiberized fiber amplifier which is based on a piece of ytterbium-doped tapered double-clad fiber(T-DCF). The fiber amplifier is operated under continuous wave(CW) regime at 1080 nm wavelength. The M2 factor of the amplifier at 1.39 k W output power is ～1.8. The maximum output power of the system reached 1.47 k W, which, to the best of our knowledge, is the highest output power of long tapered fiber based fiber laser system. Our result successfully verifies the potential of power scalability and all-fiberized capability of long tapered fiber, and the performance of our system can be further enhanced by fiber design optimization.展开更多
In this paper,we report the recent progress on the 1 PW/0.1 Hz laser beamline of Shanghai Superintense Ultrafast Laser Facility(SULF).The SULF-1 PW laser beamline is based on the double chirped pulse amplification(CPA...In this paper,we report the recent progress on the 1 PW/0.1 Hz laser beamline of Shanghai Superintense Ultrafast Laser Facility(SULF).The SULF-1 PW laser beamline is based on the double chirped pulse amplification(CPA)scheme,which can generate laser pulses of 50.8 J at 0.1 Hz after the final amplifier;the shot-to-shot energy fluctuation of the amplified pulse is as low as 1.2%(std).After compression,the pulse duration of 29.6 fs is achieved,which can support a maximal peak power of 1 PW.The contrast ratio at-80 ps before main pulse is measured to be 2.5×10^-11.The focused peak intensity is improved by optimizing the angular dispersion in the grating compressor.The maximal focused peak intensity can reach 2.7×10^19W/cm2 even with an f/26.5 off-axis parabolic mirror.The horizontal and vertical angular pointing fluctuations in 1 h are measured to be 1.89 and 2.45μrad,respectively.The moderate repetition rate and the good stability are desirable characteristics for lasermatter interactions.The SULF-1 PW laser beamline is now in the phase of commissioning,and preliminary experiments of particle acceleration and secondary radiation under 300–400 TW/0.1 Hz laser condition have been implemented.The progress on the experiments and the daily stable operation of the laser demonstrate the availability of the SULF-1 PW beamline.展开更多
Recent results in the development of diode-driven high energy, high repetition rate, picosecond lasers, including the demonstration of a cryogenic Yb:YAG active mirror amplifier that produces 1.5 J pulses at 500 Hz re...Recent results in the development of diode-driven high energy, high repetition rate, picosecond lasers, including the demonstration of a cryogenic Yb:YAG active mirror amplifier that produces 1.5 J pulses at 500 Hz repetition rate(0.75 kW average power) are reviewed. These pulses are compressed resulting in the generation of ~5 ps duration,1 J pulses with 0.5 kW average power. A full characterization of this high power cryogenic amplifier, including atwavelength interferometry of the active region under >1 kW average power pump conditions, is presented. An initial demonstration of operation at 1 kW average power(1 J, 1 k Hz) is reported.展开更多
Optical damages, which severely degrade the output energy performance of Nd:glass regenerative amplifiers, are discussed in detail in this paper. By a series of experiments, it has been confirmed that these damages re...Optical damages, which severely degrade the output energy performance of Nd:glass regenerative amplifiers, are discussed in detail in this paper. By a series of experiments, it has been confirmed that these damages result from laser-induced contamination. Based on this work, several improvements are made to boost output energy performance of the regenerative amplifier. The output energy of the regenerative amplifier after improvements declines 4% after 1000 h of operation, much less than it used to, 60% after 560 h of operation.展开更多
We address the power scaling issue in end-pumped laser rod amplifiers by studying,experimentally and numerically,the magnitude of thermal lensing in a high-energy diode-pumped Yb:YAG crystal.The spatio-temporal temper...We address the power scaling issue in end-pumped laser rod amplifiers by studying,experimentally and numerically,the magnitude of thermal lensing in a high-energy diode-pumped Yb:YAG crystal.The spatio-temporal temperature profile of the gain medium and the focal length of the induced thermal lens are determined numerically.The influence of the repetition rate and pumping power on the temperature distribution is analyzed.Experimental measurements covered repetition rates between 1 and 10 Hz and up to 4 kW pumping power.展开更多
We demonstrate a laser diode end-pumped helium gas-cooled multislab Nd:glass laser amplifier. The design and thermal management of the proposed laser amplifier are discussed. The thermally induced wavefront aberration...We demonstrate a laser diode end-pumped helium gas-cooled multislab Nd:glass laser amplifier. The design and thermal management of the proposed laser amplifier are discussed. The thermally induced wavefront aberration of the slabs was also measured and compared with simulation results. A small-signal single-pass longitudinal gain of 1.8 was measured with a pump energy of 7.3 J. With an injected seed energy of 0.6 m J, the output energy from the amplifier reached 0.5 J at 0.2 Hz and 0.43 J at 0.5 Hz in a multipass extraction geometry, thus demonstrating the feasibility of diode-pumped,high-energy lasers with direct gas cooling.展开更多
Rare earth-doped fibres are a diode-pumped,solid-state laser architecture that is highly scalable in average power.The performance of pulsed fibre laser systems is restricted due to nonlinear effects.Hence,fibre desig...Rare earth-doped fibres are a diode-pumped,solid-state laser architecture that is highly scalable in average power.The performance of pulsed fibre laser systems is restricted due to nonlinear effects.Hence,fibre designs that allow for very large mode areas at high average powers with diffraction-limited beam quality are of enormous interest.Ytterbium-doped,rod-type,large-pitch fibres(LPF)enable extreme fibre dimensions,i.e.,effective single-mode fibres with mode sizes exceeding 100 times the wavelength of the guided radiation,by exploiting the novel concept of delocalisation of higher-order transverse modes.The non-resonant nature of the operating principle makes LPF suitable for high power extraction.This design allows for an unparalleled level of performance in pulsed fibre lasers.展开更多
基金Project supported by the National National Science Foundation of China(Grant Nos.12004262 and 62005184)the Natural Science Foundation of Top Talent of SZTU(Grant No.202024555101039)。
文摘We report a diode-pumped rod-type Yb:YAG laser amplifier operating at 1 kHz.Cryogenic cooling method was adopted to make the Yb:YAG crystal work with four-level behavior.A single-frequency fiber laser acts as the seed in an actively Q-switched Yb:YAG oscillator.The resonator delivers 5.75-mJ pulses at 1 kHz with a pulse duration of approximately 40 ns.The pulses were amplified to 61 mJ in a four-pass rod-type Yb:YAG amplifier with optical-to-optical efficiency of 24%in the main amplifier.The M^(2)parameter of the output laser is<1.4.
基金supported by the Joint Fund of the National Natural Science Foundation of China and the China Academy of Engineering Physics(No.U1830132)the National Natural Science Foundation of China(No.62105313)。
文摘A high-power CW Yb:YAG slab laser amplifier with no adaptive optics correction has been experimentally established.At room temperature,the amplifier emits a power of 22 kW with an average beam quality(β)of less than 3 in 0.5 min.To our knowledge,this is the brightest slab laser without closed-loop adaptive optics demonstrated to date.In addition,an extracted power of 17 kW with an optical extraction efficiency of 33%,corresponding to a residual optical path difference of less than 0.5μm,is achieved with the single Yb:YAG slab gain module.The slab gain module has the potential to be scalable to higher powers while maintaining good beam quality.This makes a high-power solid-state laser system simpler and more robust.
基金Project supported by Major Program of the National Natural Science Foundation of China (Grant No. 12034020)the National Natural Science Foundation of China (Grant No. 61805274)+1 种基金the National Key R&D Program of China (Grant No. 2018YFB1107201)the Synergic Extreme Condition User Facility
文摘A high efficiency compact Yb:KGW regenerative amplifier using an all-fiber laser seed source was comprehensively studied.With thermal lensing effect compensated by the cavity design,the compressed pulses with energy of 1 mJ at 1 kHz and 0.4 mJ at 10 kHz in sub-400-fs pulse duration using chirped fiber Bragg grating(CFBG)stretcher were demonstrated.A modified Frantz-Nodvik equation was developed to emulate the dynamic behavior of the regenerative amplifier.The simulation results were in good agreement with the experiment.Numerical simulations and experimental results show that the scheme can be scalable to higher energy of multi-mJ,sub-300 fs pulses.
文摘A high power Nd:YAG end-pumped slab amplifier chain with a Nd:YVO_4 innoslab laser as the master oscillator is demonstrated. A chain output power of 5210W with beam quality of 4 times the diffraction limit is achieved by double-passing the first amplifier stage and single-passing the second stage with an optical efficiency of 29% while working at a frequency of 1 kHz and pulse width of 200μs.
文摘<div style="text-align:justify;"> A new planar waveguide laser was demonstrated. The output energy of 400 mW was achieved by a single waveguide laser;the slope efficiency was 61%. The single waveguide laser can expand to waveguide laser group and waveguide laser array to produce higher energy. </div>
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61307057 and 61675114)
文摘This paper presents an investigation of specific optical fiber core mode leakage behavior that occurs in high-power double-clad fiber lasers as a result of thermally-induced refractive index variations. A model of the power transfer between the core modes and the cladding modes during thermally-induced refractive index variations is established based on the mode coupling theory. The results of numerical simulations based on actual laser parameters are presented. Experimental measurements were also carried out, the results showed good agreement with the corresponding simulation results.
基金supported by the National Natural Science Foundation of China(NSFC)(Grant Nos.9215010612021004,and 11934006)the Innovation Project of Optics Valley Laboratory(No.OVL2021ZD001),the Major Program(JD)of Hubei Province(No.203BAA015)the Cross Research Support Program of Huazhong University of Science and Technology(No.2023JCYJ041).
文摘An ultrafast fiber laser system comprising two coherently combined amplifier channels is reported.Within this system,each channel incorporates a rod-type fiber power amplifier,with individual operations reaching approximately 233 W.The active-locking of these coherently combined channels,followed by compression using gratings,yields an output with a pulse energy of 504μJ and an average power of 403 W.Exceptional stability is maintained,with a 0.3%root mean square(RMS)deviation and a beam quality factor M^(2)<1.2.Notably,precise dispersion management of the front-end seed light effectively compensates for the accumulated high-order dispersion in subsequent amplification stages.This strategic approach results in a significant reduction in the final output pulse duration for the coherently combined laser beam,reducing it from 488 to 260 fs after the gratings compressor,while concurrently enhancing the energy of the primary peak from 65%to 92%.
基金the support of National Natural Science Foundation of China(NSFC)(No.61605246)
文摘We propose a novel model to explain the physical process of the thermally induced core laser leakage(TICLL) effect in a high power co-pumped ytterbium doped fiber(YDF) amplifier. This model considers the thermally induced mode bending loss decrease and the thermally induced mode instability(TMI) in the coiled YDF, and is further used to reproduce the TICLL effect in the high power co-pumped step-index 20/400 fiber amplifier. Besides, the TICLL effect in the copumping scheme and counter-pumping scheme is compared. The result proves that the TICLL effect is caused by the combined effect of the thermally induced mode bending loss decrease and the TMI, and could be mitigated by adopting the counter-pumping scheme. To our best knowledge, this is the first theoretical explanation of the TICLL effect in high power fiber amplifier.
基金supported by the National Natural Science Foundation of China(NSFC)(No.61705268)the NationalScience and Technology Major Project(No.2014ZX01005-101-003)the Innovation Project of Army Engineering University(No.JX2019-01)。
文摘To obtain short pulse width and high peak power laser, a 7 kHz sub-nanosecond microchip laser amplified by a grazing incidence double pass slab amplifier is experimentally demonstrated in this Letter. We use a compact side-pumped Nd∶YVO4 bounce amplifier with grazing incidence beam for achieving high gains and power extraction. Laser output power of 7.37 W at 7 kHz, 1.2 MW pulse peak power with 877 ps duration and 1.05 mJ energy, 25 pm spectral width, and near diffraction limited mode beam quality are achieved, and the optical-to-optical efficiency is 18%. The laser is packaged in a volume of 356 mm × 226 mm × 84 mm and may be used for applications such as laser altimeters and ladar systems.
基金supported by the Ministry of Science and Technology Support Program (2012BAI08B05)the international cooperation program (2011DFA33130)
文摘We report femtosecond pulse generation in an amplifier similariton oscillator and a prechirped fiber amplifier system. The final output power is 1.4W, and the fundamental repetition rate is 19.1 MHz after a single state fiber amplifier. The pulsewidth is 109 fs.
文摘We have been experimentally demonstrated an active control technique of dynamic gain-clamped spectra for theerbium-doped fiber amplifiers (EDFA's) by a backward-injected Fabry-Perot (F-P) laser into this EDFA. In addition, employing a short length erbium-doped fiber (EDF) that not cause any gain saturation for preamplification in front of this amplifier module, it can reduce the noise figure degradation and simultaneously achieve gain variation from 11.1 dB to 0.5 dB for 10 dB input power level change.
基金supported by the Guangdong Key Research and Development Program(No.2018B090904001)the National Natural Science Foundations of China(Nos.62005313 and 61705264)+1 种基金the Innovative Research Team in Natural Science Foundation of Hunan Province(No.2019JJ10005)the Hunan Provincial Innovation Construct Project(No.2019RS3017)。
文摘In this paper,an all-fiberized and narrow-linewidth 5 kW power-level fiber amplifier is presented.The laser is achieved based on the master oscillator power amplification configuration,in which the phase-modulated single-frequency laser is applied as the seed laser and a bidirectional pumping configuration is applied in the power amplifier.The stimulated Brillouin scattering,stimulated Raman scattering,and transverse mode instability effects are all effectively suppressed in the experiment.Consequently,the output power is scaled up to 4.92 kW with a slope efficiency of as high as approximately 80%.The 3-dB spectral width is about 0.59 nm,and the beam quality is measured to be M^(2)~1.22 at maximum output power.Furthermore,we have also conducted a detailed spectral analysis on the spectral width of the signal laser,which reveals that the spectral wing broadening phenomenon could lead to the obvious decrease of the spectral purity at certain output power.Overall,this work could provide a reference for obtaining and optimizing high-power narrow-linewidth fiber lasers.
基金the National Research and Development Program of China(No.2017YFB0405200)National Natural Science Foundation of China(Nos.61675011,61827820,61527822,and 61535009)+2 种基金Beijing Nova Program(No.Z181100006218097)Research Program of Beijing Municipal Education Commission(No.KZ201810005003)State Key Laboratory of Advanced Optical Communication Systems and Networks,China.
文摘High-power fiber lasers have experienced a dramatic development over the last decade.Further increasing the output power needs an upscaling of the fiber mode area,while maintaining a single-mode output.Here,we propose an all-solid anti-resonant fiber(ARF)structure,which ensures single-mode operation in broadband by resonantly coupling higherorder modes into the cladding.A series of fibers with core sizes ranging from 40 to 100µm are proposed exhibiting maximum mode area exceeding 5000µm2.Numerical simulations show this resonant coupling scheme provides a higher-order mode(mainly TE01,TM01,and HE21)suppression ratio of more than 20 dB,while keeping the fundamental mode loss lower than 1 dB/m.The proposed structure also exhibits high tolerance for core index depression.
基金supported by the National Natural Science Foundation of China(No.61505260)the National Key Research and Development Program of China(No.2016YFB0402204)
文摘Compared with traditional uniform fibers, tapered fiber has numerous unique advantages, such as larger mode area,higher pump absorption, suppression to nonlinear effects, and maintaining good beam quality. In this manuscript, we have constructed an all-fiberized fiber amplifier which is based on a piece of ytterbium-doped tapered double-clad fiber(T-DCF). The fiber amplifier is operated under continuous wave(CW) regime at 1080 nm wavelength. The M2 factor of the amplifier at 1.39 k W output power is ～1.8. The maximum output power of the system reached 1.47 k W, which, to the best of our knowledge, is the highest output power of long tapered fiber based fiber laser system. Our result successfully verifies the potential of power scalability and all-fiberized capability of long tapered fiber, and the performance of our system can be further enhanced by fiber design optimization.
基金the support from the electronacceleration team led by Wentao Wang,Rong Qithe proton-acceleration team led by Hui Zhang+4 种基金supported by the National Natural Science Foundation of China(Nos.11127901,61521093 and 61505234)International S&T Cooperation Program of China(No.2016YFE 0119300)Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB160301)Technology Commission of Shanghai Municipality(No.2017SHZDZX02)Youth Innovation Promotion Association of the Chinese Academy of Sciences。
文摘In this paper,we report the recent progress on the 1 PW/0.1 Hz laser beamline of Shanghai Superintense Ultrafast Laser Facility(SULF).The SULF-1 PW laser beamline is based on the double chirped pulse amplification(CPA)scheme,which can generate laser pulses of 50.8 J at 0.1 Hz after the final amplifier;the shot-to-shot energy fluctuation of the amplified pulse is as low as 1.2%(std).After compression,the pulse duration of 29.6 fs is achieved,which can support a maximal peak power of 1 PW.The contrast ratio at-80 ps before main pulse is measured to be 2.5×10^-11.The focused peak intensity is improved by optimizing the angular dispersion in the grating compressor.The maximal focused peak intensity can reach 2.7×10^19W/cm2 even with an f/26.5 off-axis parabolic mirror.The horizontal and vertical angular pointing fluctuations in 1 h are measured to be 1.89 and 2.45μrad,respectively.The moderate repetition rate and the good stability are desirable characteristics for lasermatter interactions.The SULF-1 PW laser beamline is now in the phase of commissioning,and preliminary experiments of particle acceleration and secondary radiation under 300–400 TW/0.1 Hz laser condition have been implemented.The progress on the experiments and the daily stable operation of the laser demonstrate the availability of the SULF-1 PW beamline.
基金supported by the U.S. Department of Energy Accelerator Stewardship programme, Office of High Energy Physics, Office of Science under award DE-SC0016136support by the U.S. Department of Energy, Office of Science SBIR programme under award DE-SC0011375
文摘Recent results in the development of diode-driven high energy, high repetition rate, picosecond lasers, including the demonstration of a cryogenic Yb:YAG active mirror amplifier that produces 1.5 J pulses at 500 Hz repetition rate(0.75 kW average power) are reviewed. These pulses are compressed resulting in the generation of ~5 ps duration,1 J pulses with 0.5 kW average power. A full characterization of this high power cryogenic amplifier, including atwavelength interferometry of the active region under >1 kW average power pump conditions, is presented. An initial demonstration of operation at 1 kW average power(1 J, 1 k Hz) is reported.
基金supported by National Natural Science Foundation of China under Grant No.61405211
文摘Optical damages, which severely degrade the output energy performance of Nd:glass regenerative amplifiers, are discussed in detail in this paper. By a series of experiments, it has been confirmed that these damages result from laser-induced contamination. Based on this work, several improvements are made to boost output energy performance of the regenerative amplifier. The output energy of the regenerative amplifier after improvements declines 4% after 1000 h of operation, much less than it used to, 60% after 560 h of operation.
基金This work is partially supported by the Fundacao para a Ciencia e a Tecnologia(grant agreement No.PD/BD/135222/2017)has been carried out within the framework of Laserlab-Portugal(National Roadmap of Research Infrastructures,22124)the European Union Horizon 2020 research and innovation program under grant agreement No.654148 Laserlab-Europe.
文摘We address the power scaling issue in end-pumped laser rod amplifiers by studying,experimentally and numerically,the magnitude of thermal lensing in a high-energy diode-pumped Yb:YAG crystal.The spatio-temporal temperature profile of the gain medium and the focal length of the induced thermal lens are determined numerically.The influence of the repetition rate and pumping power on the temperature distribution is analyzed.Experimental measurements covered repetition rates between 1 and 10 Hz and up to 4 kW pumping power.
基金supported by the Shanghai Science and Technology Foundation for Young Scholars(Grant No.17YF1429600)the National Natural Science Foundation of China(Grant No.61705242)
文摘We demonstrate a laser diode end-pumped helium gas-cooled multislab Nd:glass laser amplifier. The design and thermal management of the proposed laser amplifier are discussed. The thermally induced wavefront aberration of the slabs was also measured and compared with simulation results. A small-signal single-pass longitudinal gain of 1.8 was measured with a pump energy of 7.3 J. With an injected seed energy of 0.6 m J, the output energy from the amplifier reached 0.5 J at 0.2 Hz and 0.43 J at 0.5 Hz in a multipass extraction geometry, thus demonstrating the feasibility of diode-pumped,high-energy lasers with direct gas cooling.
基金The research leading to these results received funding from the European Research Council under the European Union’s Seventh Framework Programme(FP7/2007-2013)/ERC Grant Agreement No.[240460]the Thuringian Ministry of Education,Science and Culture under contract PE203-2-1(MOFA)and contract B514-10061(Green Photonics).FJ acknowledges financial support from the Abbe School of Photonics.
文摘Rare earth-doped fibres are a diode-pumped,solid-state laser architecture that is highly scalable in average power.The performance of pulsed fibre laser systems is restricted due to nonlinear effects.Hence,fibre designs that allow for very large mode areas at high average powers with diffraction-limited beam quality are of enormous interest.Ytterbium-doped,rod-type,large-pitch fibres(LPF)enable extreme fibre dimensions,i.e.,effective single-mode fibres with mode sizes exceeding 100 times the wavelength of the guided radiation,by exploiting the novel concept of delocalisation of higher-order transverse modes.The non-resonant nature of the operating principle makes LPF suitable for high power extraction.This design allows for an unparalleled level of performance in pulsed fibre lasers.
