High power diode-side-pumped 1 112-nm Nd:YAG laser based on master-oscillator power-amplifier system

We demonstrate a high power high beam quality diode-pumped 1 112-nm Nd：YAG master-oscillator power-amplifier （MOPA） laser system. To increase the extraction efficiency and output power, a four-pass amplifier scheme is employed. Finally, the injected laser output power is amplified from 26 to 64 W with beam quality factor M2=2.85. Furthermore, a theoretical model that takes the temporal overlap inversion number dynamics into account is employed to analyze the performance of the MOPA laser system, and a good agreement with the experimental data is obtained.     

400 Hz高光束质量高功率短脉冲激光器

研制了大能量高光束质量短脉冲激光器,系统采用主振荡+预放大器+主放大器2级主振荡功率放大器(MOPA)结构。采用双棒热效应补偿改善光束质量的措施,在重复频率400 Hz时实现单脉冲能量40 mJ、光束质量因子约为1.2的激光输出。激光器放大后实现单路脉冲能量712.5 mJ、脉宽12.4 ns的激光输出,采用球差补偿的方法提高了激光器的光束质量,在最大输出功率下实现了光束质量因子小于2.3,光光效率27.7%。偏振合束后,激光器输出能量大于1.4 J。     

Pulsed solid-state laser system with fiber phase conjugation and 315 W average output power

Solid-state laser sources with high average output power and high beam quality are required for numerous applications in industry and science. To improve the beam quality, stimulated Brillouin scattering (SBS) mirrors based on optical phase conjugation are used to compensate for phase distortions in master oscillator power amplifier (MOPA) systems. SBS phase conjugation in commercially available silica optical fibers facilitates the construction of high-power solid-state laser systems with high beam quality. Here we present a flash lamp-pumped, passively Q-switched Nd:YAP system which delivers an average output power of 315 W with M²=2.6 at a wavelength of 1.08 μm. Received: 11 July 2001 / Revised version: 28 September 2001 / Published online: 23 November 2001     

Sub-picosecond pulses at 100 W average power from a Yb:YLF chirped-pulse amplification system

We present a high-repetition-frequency, diode-pumped, and chirped-pulse amplification system operating at 106 W average output power with excellent beam quality (M(2)=1.3), based on cryogenically cooled Yb:YLF. 1 nJ seed pulses, derived from a mode-locked Ti:sapphire laser, are first amplified to 1 mJ pulse energy at 10 kHz repetition frequency in a regenerative amplifier. The second-stage, multipass amplifier increases the pulse energy to 10.6 mJ, resulting in a spectral width of 2.2 nm. The pulses are compressed to 865 fs in duration, which is 1.26 times the transform limit.     

120 W high repetition rate Nd:YVO<Subscript>4</Subscript> MOPA laser with a Nd:YAG cavity-dumped seed laser

A master oscillator power amplifier (MOPA) system in which the output from an end-pumped Nd:YAG oscillator cavity dumped at 500 kHz is scaled up by a four-stage Nd:YVO₄ amplifier is reported. Decrease in extraction efficiency of the amplifier chain with crystals different from that in the oscillator was analyzed. With the 5.4 W seed output, 118 W of power was extracted from the amplifier chain at the pump power of 345 W, with an extraction efficiency of 34.2% and an overall optical–optical efficiency of 30.9% for the MOPA system. The beam quality factors were measured as M _x ²=1.45 and M _y ²=1.59 in two orthogonal directions, respectively.     

100-TW sub-20-fs Ti:sapphire laser system operating at a 10-Hz repetition rate

We developed a compact three-stage Ti:sapphire amplifier laser system that produced peak power in excess of 100 TW for a pulse duration of less than 19 fs and an average power of 19 W at a 10-Hz repetition rate. A final 40-mm-diameter Ti:sapphire amplifier is pumped by a Nd:YAG master-oscillator-power-amplifier system that produces ~7-J output of 532-nm radiation. The spatial beam quality is approximately 2 times diffraction limited for the full amplified compressed output pulse. With f/3 optics, this system should therefore be capable of producing a focused intensity of ~3x10(20) W/cm(2) .     

高功率全光纤结构主振荡功率放大器中模式不稳定现象的实验研究

模式不稳定指高功率光纤激光随着输出功率提升发生的模式突变,会导致光束质量下降,限制了衍射极限光束质量光纤激光输出功率的提升,本文研究了全光纤结构主振荡功率放大器中的模式不稳定现象,结果表明,全光纤结构主振荡功率放大器中的模式不稳定现象会导致放大器斜率效率下降;理论计算表明,对于20/400阶跃折射率大模场双包层掺镱光纤,注入种子功率在百瓦左右时,模式不稳定发生的阈值功率在1kW左右:热效应是模式不稳定现象发生的根源。     

12-fs pulses from a continuous-wave-pumped 200-nJ Ti:sapphire amplifier at a variable repetition rate as high as 4 MHz

We demonstrate a novel compact femtosecond Ti:sapphire laser system operating at repetition rates from 10 kHz to 4 MHz. The scheme is based on the combination of a broadband cavity-dumped oscillator and a double-pass Ti:sapphire amplifier pumped by a low-noise cw solid-state laser. Amplified pulses with an extremely smooth spectrum, a duration of only 12 fs, and less than 0.25% rms fluctuation are generated in a beam with M2 < 1.2. A maximum pulse energy of 210 nJ and an average output power of as much as 720 mW are achieved. This output energy is sufficient to generate a stable continuum in a sapphire disk.     

LD侧泵浦Nd：YAG板条双程功率放大器初步研究

 对二极管激光侧泵浦Nd：YAG板条双程功率放大器进行了初步的研究,给出了激光器的数值模拟结果,建立了二极管侧面泵浦Nd:YAG板条激光主振荡-多程放大(MOPA)系统;在100Hz重复频率时,实验获得单脉冲能量为51.9mJ的输出,光束质量M ²小于2,脉冲能量起伏小于2%, 实验结果与数值计算结果相符合。     

全光纤结构高功率主振荡功率放大型单频光纤激光器

研制了一台全光纤结构主振荡功率放大型掺镱单频光纤激光器。该光纤激光器包括种子激光器和级联放大器两部分。种子激光器是自行搭建的环形腔结构的单频窄线宽光纤激光器。在976 nm半导体激光器泵浦下,能够输出线宽为10 MHz量级、波长为1 079.88 nm的单频光,激光功率为10.02 W,光-光转化效率为58.9%,斜率效率为65.3%。     

High power Yb-fiber laser amplifier based on nonlinear chirped-pulse amplification at a repetition rate of 1 MHz

We report a high power fiber amplifier based on nonlinear chirped-pulse amplification(NCPA). To manage the nonlinearity,pulse shaping is introduced by self-phase modulation in the fiber stretcher with the help of spectral filtering. The third-order dispersion is compensated for by the nonlinear phase shift in the NCPA. With optimization, the system can output 382 fs pulse duration with 20 W average power at 1 MHz repetition rate. The long-term average power fluctuation is measured to be0.5% in 24 h, and the beam quality factor(M~2) is 1.25.     

1 mJ, 500 kHz Nd:YAG/Nd:YVO<Subscript>4</Subscript> MOPA laser with a Nd:YAG cavity-dumping seed laser

We report a high-repetition-rate, high-pulse-energy master oscillator power amplifier (MOPA) laser system, in which the seed laser from the Nd:YAG rod-based oscillator cavity dumped at 500 kHz, was scaled up consecutively by a four-stage Nd:YVO₄ preamplifier and a two-stage Nd:YAG zigzag slab main amplifier. The laser pulsed output with the average power of 510 W was achieved, with the efficiency extraction of 26.6% at the main amplifier stage and the single-pulse energy of 1.02 mJ.     

kW级全光纤激光器理论与实验研究

基于主振荡功率放大结构设计了kW级全光纤激光器,对激光器的功率分布及输出、弯曲选模以及冷却条件下增益光纤的热分布进行了数值模拟分析。搭建了所设计的全光纤激光器,在注入总泵浦功率1436W时,实验获得了1060W高功率连续激光输出,光光转换效率73.8%,光束质量因子小于1.6。初步分析了导致激光器实验输出与理论设计二者偏差的原因。     

96.2 W all-fiberized nanosecond single-frequency fiber MOPA

We report experimental results on a 96.2 W all-fiberized nanosecond single-frequency masteroscillator power amplifier (MOPA) laser working at 1064 nm. An external modulation fiber laser with average power of 0.5 mW and line width of 20 kHz is used as the seed source. Amplifying the seed laser in four stages, a single-frequency laser with pulse duration of 10 ns and peak power of 816.7 W is obtained. The average output power is up to 96.2 W. Further power-scaling of this MOPA structure can be realized since our experiment is only pump-power limited.     

High-energy Ho:LLF MOPA laser system using a top-hat pump profile for the amplifier stage

Numerical simulations show the advantage of using a top-hat intensity profile pumping the amplifier stage in an Ho:LuLiF₄ (Ho:LLF) master oscillator power amplifier (MOPA) configuration over a Gaussian pump profile: higher pulse energies could be generated simultaneously with reduced peak fluence in Q-switched operation. In the experimental implementation, the top-hat beam was realized with a coherent beam transformation of the non-absorbed pump beam transmitted by the oscillator to pump the amplifier stage. The Ho:LLF MOPA produced 103.6 mJ at a repetition rate of 100 Hz with a pulse duration of 30 ns at a wavelength of 2053 nm, which corresponds to an optical-to-optical efficiency of 12.9 %. The beam quality was nearly diffraction limited (M ² = 1.03).     

1μm全光纤MOPA结构激光器输出特性研究

主振荡功率放大（main oscillation power amplification, MOPA）结构由于其光束质量良好和参数可调的优点,已成为高功率光纤激光器的主流设计之一。为了改善高功率掺镱光纤激光器（ytterbium-doped fiber laser, YDFL）的输出性能,提高系统的光-光转换效率,文中报道了一台基于915 nm泵浦激光器和双包层掺镱光纤（ytterbium-doped fiber, YDF）的MOPA结构全光纤高功率激光器。该高功率光纤激光器由电调制激光二极管（laser diode, LD）泵浦的种子激光器和掺镱光纤放大器（ytterbium-doped fiber amplifier, YDFA）组成。连续光（continuous wave, CW）工作模式下,激光种子源经过YDFA后,实现了中心波长为1 069.96 nm的激光输出,最大平均输出功率可达945.9 W,MOPA激光器整机的斜率效率高达74.12%,具有良好的稳健性。该研究方案对研制高功率MOPA光纤激光器具有参考意义。     

基于简单MOPA结构实现3.08 kW全光纤窄线宽线偏振激光输出

基于简单的主振荡功率放大结构,演示了一种高功率窄线宽线性偏振全光纤激光器,其最大输出功率为3.08 kW,3 dB线宽为0.2 nm。在整个功率缩放过程中,偏振消光比约为94%,光束质量M 2约为1.4。这是国内外首次实现3 kW全保偏光纤激光输出,与基于相位调制的窄线宽激光器相比,该激光器可实现近似的线宽,同时具有受激布里渊散射阈值高、系统结构简单、成本低等特点。     

QCW diode-pumped 654 W AO Q-switched Nd:YAG rod oscillator-amplifier laser

A diode laser-pumped acoustic-optic Q-switched Nd:YAG master-oscillator power amplifier laser is presented. The laser is quasi continuously pumped at 1.1 kHz with a pulse width of 172 μs, and the ultrasonic frequency of the AO Q-switcher is set at a higher value (53 kHz). The master oscillator is designed as a thermally near-unstable-resonator, which presents an average output power of 48 W with a beam quality value of M² = 1.41 and a Q-switching pulse duration of 121 ns. The maximum average power of the MOPA system is 654 W, and the beam quality is M² = 6.     

30 W output of short pulse duration nanosecond green laser generated by a hybrid fiber-bulk MOPA system

We reported a 30 W average output power 532 nm green laser with 5 ns pulsed duration working at 80–100 kHz generated by a hybrid MOPA system. The hybrid MOPA system consisted of a fiber amplifier and two solid-state amplifiers producing 77 W 1064 nm at pulse repetition rates of 80–100 kHz. The IR-to-green optical conversion efficiency was 44.7% at the working point of 100 kHz. The beam quality of green laser was measured better than M ² < 1.6 in both orthogonal directions. Nanosecond 532 nm lasers with short pulsed duration could be practicable in silicon-based material processing in the Photovoltaic industry.     

InGaAs diode laser system generating pulses of 580 fs duration and 366 W peak power

This paper reports the generation of fs light pulses by a passively mode-locked InGaAs master oscillator power amplifier (MOPA) system. The laser system generates chirped pulses with 6.2 ps duration, a center wavelength of 922 nm and 4 GHz repetition rate. Pulse compression by an external grating compressor reduces the pulse duration to 580 fs. The average power of the compressed pulses of 851 mW corresponds to a peak power of 366 W.