Multidimensional influences of indium composition in barrier layers on GaN-based blue laser diodes(LDs)are discussed from both material quality and device physics perspectives.LDs with higher indium content in the bar...Multidimensional influences of indium composition in barrier layers on GaN-based blue laser diodes(LDs)are discussed from both material quality and device physics perspectives.LDs with higher indium content in the barriers demonstrate a notably lower threshold current and shorter lasing wavelength compared to those with lower indium content.Our experiments reveal that higher indium content in the barrier layers can partially reduce indium composition in the quantum wells,a novel discovery.Employing higher indium content barrier layers leads to improved luminescence properties of the MQW region.Detailed analysis reveals that this improvement can be attributed to better homogeneity in the indium composition of the well layers along the epitaxy direction.InGaN barrier layers suppress the lattice mismatch between barrier and well layers,thus mitigating the indium content pulling effect in the well layers.In supplement to experimental analysis,theoretical computations are performed,showing that InGaN barrier structures can effectively enhance carrier recombination efficiency and optical confinement of LD structure,thus improving the output efficiency of GaN-based blue LDs.Combining these theoretical insights with our experimental data,we propose that higher indium content barriers effectively enhance carrier recombination efficiency and indium content homogeneity in quantum well layers,thereby improving the output performance of GaN-based blue LDs.展开更多
Diode end-pumped solid-state lasers have the potential to yield high quality laser beams with high efficiency for laser range finding and warning receiver applications as well as day and night military laser designati...Diode end-pumped solid-state lasers have the potential to yield high quality laser beams with high efficiency for laser range finding and warning receiver applications as well as day and night military laser designation systems. In this paper we presents theoretical calculations using Advanced Dynamics Professional LASCAD software and experimental studies for a high power pigtailed fiber diode laser module of 8 W operating at 808 nm with a specially designed high efficiency cooling system, end pumped high-efficiency Nd:YVO4 laser of 3 × 3 × 10 mm rod and overall cavity length of 44 mm. To the best of our knowledge a self Q-switching effects was generated in Nd:YVO4 laser by changing the cavity dimensions and the position of the intracavity KTP crystal at certain regime of operation for the first time, in which the cavity length is reduced to be 30 mm and the distance between Nd:YVO4 rod and KTP crystal is only 1mm. Self Q-switched laser pulse at 532 nm with high peak power of 96 W, pulse width of 88 ns at FWHM and repetition rate of 400 kHz was achieved. Experimental studies of a passive Q-switched Nd:YVO4 laser using Cr:YAG crystal with three different transmissions of 30%, 40% and 70% were investigated. Passive Q-switched laser pulse at 1064 nm and narrow line width of less than 1.5 nm with highest peak power of nearly 18 kW, short pulse width of less than 4 ns at FWHM and higher repetition rate of 45 kHz using Cr:YAG with transmission of 30% was achieved for the first time.展开更多
In this work,we reported the room-temperature continuous-wave operation of 6.0 W GaN-based blue laser diode(LD),and its stimulated emission wavelength is around 442 nm.The GaN-based high power blue LD is grown on a c-...In this work,we reported the room-temperature continuous-wave operation of 6.0 W GaN-based blue laser diode(LD),and its stimulated emission wavelength is around 442 nm.The GaN-based high power blue LD is grown on a c-plane GaN substrate by metal organic chemical vapor deposition(MOCVD),and the width and length of the ridge waveguide structure are 30 and 1200μm,respectively.The threshold current is about 400 mA,and corresponding threshold current density is 1.1 kA/cm2.展开更多
The 975 nm multimode diode lasers with high-order surface Bragg diffraction gratings have been simulated and calcu-lated using the 2D finite difference time domain(FDTD)algorithm and the scattering matrix method(SMM)....The 975 nm multimode diode lasers with high-order surface Bragg diffraction gratings have been simulated and calcu-lated using the 2D finite difference time domain(FDTD)algorithm and the scattering matrix method(SMM).The periods and etch depth of the grating parameters have been optimized.A board area laser diode(BA-LD)with high-order diffraction grat-ings has been designed and fabricated.At output powers up to 10.5 W,the measured spectral width of full width at half maxi-mum(FWHM)is less than 0.5 nm.The results demonstrate that the designed high-order surface gratings can effectively nar-row the spectral width of multimode semiconductor lasers at high output power.展开更多
High-resolution atomic-beam laser spectroscopy has been performed to study Stark effect of Ba atom. Stark spectra have been observed at various electric fields for Ba highly excited states. The scalar polarizability o...High-resolution atomic-beam laser spectroscopy has been performed to study Stark effect of Ba atom. Stark spectra have been observed at various electric fields for Ba highly excited states. The scalar polarizability of the transition from 6s5d3D2 to 5d6p3F3 at 728.0 nm and the tensor polarizability of the 3F3 level have been determined for the first time, to be αs = -89.8 (12) kHz/(kV/cm)2 and αt = -133.7 (20) kHz/(kV/cm)2, respectively.展开更多
Catastrophic degradation of high power laser diodes is due to the generation of extended defects inside the active parts of the laser structure during the laser operation.The mechanism driving the degradation is stron...Catastrophic degradation of high power laser diodes is due to the generation of extended defects inside the active parts of the laser structure during the laser operation.The mechanism driving the degradation is strongly related to the existence of localized thermal stresses generated during the laser operation.These thermal stresses can overcome the yield strength of the materials forming the active part of the laser diode.Different factors contribute to reduce the laser power threshold for degradation.Among them the thermal transport across the laser structure constitutes a critical issue for the reliability of the device.展开更多
During the last year the high power laser diodes jumped over the 1 kW level of CW power for a stack, and the commercial 1 cm bars reached 100 W output optical power at the standard wavelengths around 800 nm and 980 nm...During the last year the high power laser diodes jumped over the 1 kW level of CW power for a stack, and the commercial 1 cm bars reached 100 W output optical power at the standard wavelengths around 800 nm and 980 nm. The prices are reaching the industry acceptable levels. All Nd∶YAG and fiber industrial lasers manufacturers have developed kW prototypes. Those achievements have set new requirements for the power supplies manufactuers-high and stable output current, and possibilities for fast control of the driving current, keeping safe the expensive laser diode. The fast switching frequencies also allow long range free space communications and optical range finding. The high frequencies allow the design of a 3D laser radar with high resolution and other military applications. The prospects for direct laser diode micro machining are also attractive.展开更多
Femtosecond oscillators with gigahertz(GHz)repetition rate are appealing sources for spectroscopic applications benefiting from the individually accessible and high-power comb line.The mode mismatch between the potent...Femtosecond oscillators with gigahertz(GHz)repetition rate are appealing sources for spectroscopic applications benefiting from the individually accessible and high-power comb line.The mode mismatch between the potent pump laser diode(LD)and the incredibly small laser cavity,however,limits the average output power of existing GHz Kerrlens mode-locked(KLM)oscillators to tens of milliwatts.Here,we present a novel method that solves the difficulty and permits high average power LD-pumped KLM oscillators at GHz repetition rate.We propose a numerical simulation method to guide the realization of Kerr-lens mode-locking and comprehend the dynamics of the Kerr-lens mode-locking process.As a proof-of-principle demonstration,an LD-pumped Yb:KGW oscillator with up to 6.17-W average power and184-fs pulse duration at 1.6-GHz repetition rate is conducted.The simulation had a good agreement with the experimental results.The cost-effective,compact and powerful laser source opens up new possibilities for research and industrial applications.展开更多
Operation of 808-nm laser diode pumping at elevated temperature is crucial to many applications. Reliable operation at high power is limited by high thermal load and low catastrophic optical mirror damage (COMD) thres...Operation of 808-nm laser diode pumping at elevated temperature is crucial to many applications. Reliable operation at high power is limited by high thermal load and low catastrophic optical mirror damage (COMD) threshold at elevated temperature range. We demonstrated high efficiency and high power operation at elevated temperature with high COMD power. These results were achieved through device design optimization such as growth conditions, doping profile, and materials composition of the quantum-well and other layers. Electrical-to-optical efficiency as high as 62% was obtained through lowered threshold current, lowered series resistance and increased slope efficiency. The performance of single broad-area laser diodes scales to that of high power single bars on water-cooled copper micro-channel heatsinks or conductively-cooled CS heatsinks. No reduction in bar performance or significant spectral broadening is seen when these micro-channel coolers are assembled into 6-bar and 18-bar CW stacks for the highest power levels.展开更多
We demonstrate a high power continuous-wave （CW） and acoustic-optically （AO） Q-switched 1314-nm laser with a diode-side-pumped Nd：YLF module. A maximum CW output power of 21.6 W is obtained with a diode pump powe...We demonstrate a high power continuous-wave （CW） and acoustic-optically （AO） Q-switched 1314-nm laser with a diode-side-pumped Nd：YLF module. A maximum CW output power of 21.6 W is obtained with a diode pump power of 180 W, corresponding to an optical-to-optical conversion efficiency of 12.0% and a slope efficiency of 16.1%. In the Q-switching operation, a highest pulse energy of 3.8 mJ is obtained at a pulse repetition rate of 1 kHz. The shortest pulse width and maximum single peak power are 101.9 ns and 37.3 kW, respectively.展开更多
We demonstrate a high-power blue diode laser operated at 447 nm combining laser diodes using an optical fiber bundle. As many as 127 diode lasers at 447 nm were coupled into 400 μm/0.22 NA fibers using an aspherical ...We demonstrate a high-power blue diode laser operated at 447 nm combining laser diodes using an optical fiber bundle. As many as 127 diode lasers at 447 nm were coupled into 400 μm/0.22 NA fibers using an aspherical lens group with different focus lengths. The bare fibers were mechanically bundled through high temperature ultraviolet adhesive after the coatings of the 127 fibers were stripped. The diameter of the fiber bundle was 6 mm. The total output power of such a bundle was 152 W with electro-optical conversion efficiency of 27.56%and the RMS power instability was less than ±1% within 3 h.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
In order to improve the output power and increase the lifetime of laser diodes,expansion-matched submounts were investigated by finite element analysis.The submount was designed as sandwiched structure.By varying the ...In order to improve the output power and increase the lifetime of laser diodes,expansion-matched submounts were investigated by finite element analysis.The submount was designed as sandwiched structure.By varying the vertical structure and material of the middle layer,the thermal expansion behavior on the mounting surface was simulated to obtain the expansion-matched design.In addition,the thermal performance of laser diodes packaged by different submounts was compared.The numerical results showed that,changing the thickness ratio of surface copper to middle layer will lead the stress and junction temperature to the opposite direction.Thus compromise needs to be made in the design of the vertical structure.In addition,the silicon carbide（SiC） is the most promising material candidate for the middle layer among the materials discussed in this paper.The simulated results were aimed at providing guidance for the optimal design of sandwich-structure submounts.展开更多
The thermal characteristics of high-power AlGaAs/GaAs laser diodes（LDs） at high current（2-10 A）are studied with electrical transient method.The temperature rise increases linearly with the current.The thermal resi...The thermal characteristics of high-power AlGaAs/GaAs laser diodes（LDs） at high current（2-10 A）are studied with electrical transient method.The temperature rise increases linearly with the current.The thermal resistance of chip is the largest proportion of total thermal resistance.By increasing the width of the chip from 500 to 800 fim,the temperature rise and thermal resistance decrease by 8.5%and 8.8%,respectively.展开更多
In this paper, the research work of twodimensional beam shaping and homogenization of high power laser diode (LD) stack by a rectangular waveguide is presented. Both the theoretical simulation and experiment results h...In this paper, the research work of twodimensional beam shaping and homogenization of high power laser diode (LD) stack by a rectangular waveguide is presented. Both the theoretical simulation and experiment results have shown that the diode stack beam can be shaped into a uniform square spot with a dimension of 10 mm×10 mm and the non-uniformity less than 5% along both directions of slow axis and fast axis, the shaped beam has a uniform pumping depth over 10 mm, which is well to be used for a rectangular laser medium end pumping.展开更多
We demonstrate a diode-pumped femtosecond Yb:CaGdAlO_(4)(Yb:CALGO)laser with a semiconductor saturable absorber mirror(SESAM)for stable mode-locking operation.A perfect beam profile is measured under 10 W output power...We demonstrate a diode-pumped femtosecond Yb:CaGdAlO_(4)(Yb:CALGO)laser with a semiconductor saturable absorber mirror(SESAM)for stable mode-locking operation.A perfect beam profile is measured under 10 W output power with M_(x)^(2)=1.017 and M_(y)^(2)=1.016 in the horizontal and vertical directions,respectively.At the repetition rate of 71.66 MHz,the optical pulse duration is 247 fs and the pulse energy is 140 nJ at the central wavelength of 1041 nm,corresponding to a peak power of 0.56 MW.In addition,we also generate continuous wave(CW)power of more than 15 W with TEM00 mode,corresponding to an optical-to-optical efficiency of 44.1%.展开更多
A high power cryogenic cooling Tin-doped （2%） GdVO4 laser double-end-pumped by fiber-coupled-diode： with the center wavelength of 804.5 nm at 21 ℃ is reported. The highest continuous-wave （CW） power of 2.35 W at...A high power cryogenic cooling Tin-doped （2%） GdVO4 laser double-end-pumped by fiber-coupled-diode： with the center wavelength of 804.5 nm at 21 ℃ is reported. The highest continuous-wave （CW） power of 2.35 W at 1903 nm is attained at pump power of 24 W. The slope efficiency is 12.5% and the tt, reshoht is 3.2 W. Single- and double-end-pumped types are investigated.展开更多
In this review paper, we introduce a self-phase controlled stimulated Brillouin scattering phase conjugate mirror(SCSBS-PCM) and the Kumgang laser. The SC-SBS-PCM was proposed and demonstrated its success at the acade...In this review paper, we introduce a self-phase controlled stimulated Brillouin scattering phase conjugate mirror(SCSBS-PCM) and the Kumgang laser. The SC-SBS-PCM was proposed and demonstrated its success at the academic low power level, ~100 mJ@10 Hz. The Kumgang laser is under development to verify whether the SC-SBS-PCM is operable at the k W level. It is a 4 kW beam combination laser combining four 1 k W beams using the SC-SBS-PCM. If the Kumgang laser functions successfully, it will be the most important step towards a Dream laser, a hypothetical laser with unlimited power and a high repetition rate.展开更多
基金Project supported by Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.2023124)the National Key Research and Development Program of China(Grant No.2022YFB3608100)+3 种基金Key Research and Development Program of Jiangsu Province(Grant No.BE2021008-1)Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering(Grant No.2022SXTD016)the National Natural Science Foundation of China(Grant Nos.62274157,61904172,62127807,62234011,61974162,62034008,62074142,62074140,and 62250038)Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB43030101)。
文摘Multidimensional influences of indium composition in barrier layers on GaN-based blue laser diodes(LDs)are discussed from both material quality and device physics perspectives.LDs with higher indium content in the barriers demonstrate a notably lower threshold current and shorter lasing wavelength compared to those with lower indium content.Our experiments reveal that higher indium content in the barrier layers can partially reduce indium composition in the quantum wells,a novel discovery.Employing higher indium content barrier layers leads to improved luminescence properties of the MQW region.Detailed analysis reveals that this improvement can be attributed to better homogeneity in the indium composition of the well layers along the epitaxy direction.InGaN barrier layers suppress the lattice mismatch between barrier and well layers,thus mitigating the indium content pulling effect in the well layers.In supplement to experimental analysis,theoretical computations are performed,showing that InGaN barrier structures can effectively enhance carrier recombination efficiency and optical confinement of LD structure,thus improving the output efficiency of GaN-based blue LDs.Combining these theoretical insights with our experimental data,we propose that higher indium content barriers effectively enhance carrier recombination efficiency and indium content homogeneity in quantum well layers,thereby improving the output performance of GaN-based blue LDs.
文摘Diode end-pumped solid-state lasers have the potential to yield high quality laser beams with high efficiency for laser range finding and warning receiver applications as well as day and night military laser designation systems. In this paper we presents theoretical calculations using Advanced Dynamics Professional LASCAD software and experimental studies for a high power pigtailed fiber diode laser module of 8 W operating at 808 nm with a specially designed high efficiency cooling system, end pumped high-efficiency Nd:YVO4 laser of 3 × 3 × 10 mm rod and overall cavity length of 44 mm. To the best of our knowledge a self Q-switching effects was generated in Nd:YVO4 laser by changing the cavity dimensions and the position of the intracavity KTP crystal at certain regime of operation for the first time, in which the cavity length is reduced to be 30 mm and the distance between Nd:YVO4 rod and KTP crystal is only 1mm. Self Q-switched laser pulse at 532 nm with high peak power of 96 W, pulse width of 88 ns at FWHM and repetition rate of 400 kHz was achieved. Experimental studies of a passive Q-switched Nd:YVO4 laser using Cr:YAG crystal with three different transmissions of 30%, 40% and 70% were investigated. Passive Q-switched laser pulse at 1064 nm and narrow line width of less than 1.5 nm with highest peak power of nearly 18 kW, short pulse width of less than 4 ns at FWHM and higher repetition rate of 45 kHz using Cr:YAG with transmission of 30% was achieved for the first time.
基金This work was supported by the National Key R&D Program of China(Grant Nos.2018YFB0406903,2017YFB0405001,2016YFB0400803 and 2016YFB0401801)the Science Challenge Project(Grant No.TZ2016003)+5 种基金the National Natural Science Foundation of China(Grant Nos.62034008,62074142,62074140,61974162,61904172,and 61874175)the Youth Innovation Promotion Association of Chinese Academy of Sciences(Grant No.2019115)Beijing Nova Program(Grant No.202093)Beijing Municipal Science and Technology Project(Grant No.Z161100002116037)Jiangsu Institute of Advanced Semiconductors(IASEMI 2020-CRP-02)Young Elite Scientists Sponsorship Program by CAST.
文摘In this work,we reported the room-temperature continuous-wave operation of 6.0 W GaN-based blue laser diode(LD),and its stimulated emission wavelength is around 442 nm.The GaN-based high power blue LD is grown on a c-plane GaN substrate by metal organic chemical vapor deposition(MOCVD),and the width and length of the ridge waveguide structure are 30 and 1200μm,respectively.The threshold current is about 400 mA,and corresponding threshold current density is 1.1 kA/cm2.
基金supported by the National Key R&D Program of China,No.2022YFB4601201.
文摘The 975 nm multimode diode lasers with high-order surface Bragg diffraction gratings have been simulated and calcu-lated using the 2D finite difference time domain(FDTD)algorithm and the scattering matrix method(SMM).The periods and etch depth of the grating parameters have been optimized.A board area laser diode(BA-LD)with high-order diffraction grat-ings has been designed and fabricated.At output powers up to 10.5 W,the measured spectral width of full width at half maxi-mum(FWHM)is less than 0.5 nm.The results demonstrate that the designed high-order surface gratings can effectively nar-row the spectral width of multimode semiconductor lasers at high output power.
文摘High-resolution atomic-beam laser spectroscopy has been performed to study Stark effect of Ba atom. Stark spectra have been observed at various electric fields for Ba highly excited states. The scalar polarizability of the transition from 6s5d3D2 to 5d6p3F3 at 728.0 nm and the tensor polarizability of the 3F3 level have been determined for the first time, to be αs = -89.8 (12) kHz/(kV/cm)2 and αt = -133.7 (20) kHz/(kV/cm)2, respectively.
基金funded by the Spanish Government(MAT-2010-20441-C02)
文摘Catastrophic degradation of high power laser diodes is due to the generation of extended defects inside the active parts of the laser structure during the laser operation.The mechanism driving the degradation is strongly related to the existence of localized thermal stresses generated during the laser operation.These thermal stresses can overcome the yield strength of the materials forming the active part of the laser diode.Different factors contribute to reduce the laser power threshold for degradation.Among them the thermal transport across the laser structure constitutes a critical issue for the reliability of the device.
文摘During the last year the high power laser diodes jumped over the 1 kW level of CW power for a stack, and the commercial 1 cm bars reached 100 W output optical power at the standard wavelengths around 800 nm and 980 nm. The prices are reaching the industry acceptable levels. All Nd∶YAG and fiber industrial lasers manufacturers have developed kW prototypes. Those achievements have set new requirements for the power supplies manufactuers-high and stable output current, and possibilities for fast control of the driving current, keeping safe the expensive laser diode. The fast switching frequencies also allow long range free space communications and optical range finding. The high frequencies allow the design of a 3D laser radar with high resolution and other military applications. The prospects for direct laser diode micro machining are also attractive.
基金supported by the National Key Research and Development Program of China(No.2022YFA1604202)National Natural Science Foundation of China(No.62105253)+1 种基金Natural Science Foundation of Shaanxi Province,China(No.2023-JC-YB-485)Shaanxi University of Technology(No.SLGRC202419)。
文摘Femtosecond oscillators with gigahertz(GHz)repetition rate are appealing sources for spectroscopic applications benefiting from the individually accessible and high-power comb line.The mode mismatch between the potent pump laser diode(LD)and the incredibly small laser cavity,however,limits the average output power of existing GHz Kerrlens mode-locked(KLM)oscillators to tens of milliwatts.Here,we present a novel method that solves the difficulty and permits high average power LD-pumped KLM oscillators at GHz repetition rate.We propose a numerical simulation method to guide the realization of Kerr-lens mode-locking and comprehend the dynamics of the Kerr-lens mode-locking process.As a proof-of-principle demonstration,an LD-pumped Yb:KGW oscillator with up to 6.17-W average power and184-fs pulse duration at 1.6-GHz repetition rate is conducted.The simulation had a good agreement with the experimental results.The cost-effective,compact and powerful laser source opens up new possibilities for research and industrial applications.
文摘Operation of 808-nm laser diode pumping at elevated temperature is crucial to many applications. Reliable operation at high power is limited by high thermal load and low catastrophic optical mirror damage (COMD) threshold at elevated temperature range. We demonstrated high efficiency and high power operation at elevated temperature with high COMD power. These results were achieved through device design optimization such as growth conditions, doping profile, and materials composition of the quantum-well and other layers. Electrical-to-optical efficiency as high as 62% was obtained through lowered threshold current, lowered series resistance and increased slope efficiency. The performance of single broad-area laser diodes scales to that of high power single bars on water-cooled copper micro-channel heatsinks or conductively-cooled CS heatsinks. No reduction in bar performance or significant spectral broadening is seen when these micro-channel coolers are assembled into 6-bar and 18-bar CW stacks for the highest power levels.
基金supported by the National Natural Science Foundation of China(Nos.61275142,91022003,51021062,and 61308042)the China PostdoctoralScience Foundation(No.2013M531594)
文摘We demonstrate a high power continuous-wave （CW） and acoustic-optically （AO） Q-switched 1314-nm laser with a diode-side-pumped Nd：YLF module. A maximum CW output power of 21.6 W is obtained with a diode pump power of 180 W, corresponding to an optical-to-optical conversion efficiency of 12.0% and a slope efficiency of 16.1%. In the Q-switching operation, a highest pulse energy of 3.8 mJ is obtained at a pulse repetition rate of 1 kHz. The shortest pulse width and maximum single peak power are 101.9 ns and 37.3 kW, respectively.
基金Project supported by the Beijing Engineering Technology Research Center of All-Solid-State Lasers Advanced Manufacturing the National High Technology Research and Development Program of China(No.2014AA032607)+1 种基金the National Natural Science Foundation of China(Nos.61404135,61405186,61308032,61308033)the National Key R&D Program of China(Nos.2016YFB0401804,2016YFB0402002)
文摘We demonstrate a high-power blue diode laser operated at 447 nm combining laser diodes using an optical fiber bundle. As many as 127 diode lasers at 447 nm were coupled into 400 μm/0.22 NA fibers using an aspherical lens group with different focus lengths. The bare fibers were mechanically bundled through high temperature ultraviolet adhesive after the coatings of the 127 fibers were stripped. The diameter of the fiber bundle was 6 mm. The total output power of such a bundle was 152 W with electro-optical conversion efficiency of 27.56%and the RMS power instability was less than ±1% within 3 h.
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.
文摘In order to improve the output power and increase the lifetime of laser diodes,expansion-matched submounts were investigated by finite element analysis.The submount was designed as sandwiched structure.By varying the vertical structure and material of the middle layer,the thermal expansion behavior on the mounting surface was simulated to obtain the expansion-matched design.In addition,the thermal performance of laser diodes packaged by different submounts was compared.The numerical results showed that,changing the thickness ratio of surface copper to middle layer will lead the stress and junction temperature to the opposite direction.Thus compromise needs to be made in the design of the vertical structure.In addition,the silicon carbide（SiC） is the most promising material candidate for the middle layer among the materials discussed in this paper.The simulated results were aimed at providing guidance for the optimal design of sandwich-structure submounts.
文摘The thermal characteristics of high-power AlGaAs/GaAs laser diodes（LDs） at high current（2-10 A）are studied with electrical transient method.The temperature rise increases linearly with the current.The thermal resistance of chip is the largest proportion of total thermal resistance.By increasing the width of the chip from 500 to 800 fim,the temperature rise and thermal resistance decrease by 8.5%and 8.8%,respectively.
文摘In this paper, the research work of twodimensional beam shaping and homogenization of high power laser diode (LD) stack by a rectangular waveguide is presented. Both the theoretical simulation and experiment results have shown that the diode stack beam can be shaped into a uniform square spot with a dimension of 10 mm×10 mm and the non-uniformity less than 5% along both directions of slow axis and fast axis, the shaped beam has a uniform pumping depth over 10 mm, which is well to be used for a rectangular laser medium end pumping.
基金the National Key R&D Program of China(No.2018YFB110720)the National Natural Science Foundation of China(Nos.61575217 and 91850209)the Strategic Priority Research Program of CAS(No.XDB16030200).
文摘We demonstrate a diode-pumped femtosecond Yb:CaGdAlO_(4)(Yb:CALGO)laser with a semiconductor saturable absorber mirror(SESAM)for stable mode-locking operation.A perfect beam profile is measured under 10 W output power with M_(x)^(2)=1.017 and M_(y)^(2)=1.016 in the horizontal and vertical directions,respectively.At the repetition rate of 71.66 MHz,the optical pulse duration is 247 fs and the pulse energy is 140 nJ at the central wavelength of 1041 nm,corresponding to a peak power of 0.56 MW.In addition,we also generate continuous wave(CW)power of more than 15 W with TEM00 mode,corresponding to an optical-to-optical efficiency of 44.1%.
文摘A high power cryogenic cooling Tin-doped （2%） GdVO4 laser double-end-pumped by fiber-coupled-diode： with the center wavelength of 804.5 nm at 21 ℃ is reported. The highest continuous-wave （CW） power of 2.35 W at 1903 nm is attained at pump power of 24 W. The slope efficiency is 12.5% and the tt, reshoht is 3.2 W. Single- and double-end-pumped types are investigated.
基金supported by the ‘Dual Use Technology Program’ at the Agency for Defense Development (ADD) of the Republic of Korea (UM12012RD1)
文摘In this review paper, we introduce a self-phase controlled stimulated Brillouin scattering phase conjugate mirror(SCSBS-PCM) and the Kumgang laser. The SC-SBS-PCM was proposed and demonstrated its success at the academic low power level, ~100 mJ@10 Hz. The Kumgang laser is under development to verify whether the SC-SBS-PCM is operable at the k W level. It is a 4 kW beam combination laser combining four 1 k W beams using the SC-SBS-PCM. If the Kumgang laser functions successfully, it will be the most important step towards a Dream laser, a hypothetical laser with unlimited power and a high repetition rate.
