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.     

百瓦级全光纤结构单频掺铥主振荡功率放大器

报道了平均功率超过百瓦的单频掺铥全光纤结构主振荡功率放大器。使用线宽小于100kHz、中心波长为1.97μm的单频种子源进行级联放大,主放大器的斜率效率为50%。监测放大器的回光功率和光谱,没有发现受激布里渊散射以及其他非线性效应。通过增加泵浦功率,可以获得更高功率的掺铥单频放大输出。     

Efficient generation of 200 mJ nanosecond pulses at 100 Hz repetition rate from a cryogenic cooled Yb:YAG MOPA system

A diode-pumped Master Oscillator Power Amplifier (MOPA) laser system based on cryogenic cooled Yb:YAG has been designed, developed and its output performance characterised. The laser system consists of a fibre oscillator, an active mirror regenerative amplifier and a four pass main amplifier. 2.4 mJ, 10 ns, 100 Hz seed pulses from the fibre oscillator/regenerative amplifier arrangement were amplified up to pulse energies of over 200 mJ by using the four pass main amplifier arrangement. As a further study we have obtained an increased slope efficiency of 40% and an optical-to-optical efficiency of 30% using a pinhole vacuum spatial filter/image relay for laser mode control. With 1.8 mJ input seed pulses, output pulse energies of around 150 mJ were achieved.     

6.1 MW, 10 kHz Side-Pumped Burst-Mode Nd:YAG Laser

We present a compact high-peak-power, high-repetition-rate burst-mode laser from a master-oscillator power amplifier (MOPA) at 1064 nm for laser-based measurement applications. The oscillator is an 808 nm pulsed laser diode side-pumped acousto-optical (A-O) Q-switched Nd:YAG laser at repetition rates ranging from 10–100 kHz, producing a pulse train with a pulse number of 2–25. The maximum output energy of the oscillator is 15.6 mJ at 10 kHz, whereas it is 1.7 mJ at 100 kHz. After twostage amplifiers, a single-pulse energy of 85.2 mJ with a pulse-width of 14.5 ns is achieved at 10 kHz, which produces a peak power of 6.1 MW. At 100 kHz, the total burst energy reaches 220 mJ with a single-pulse energy of 8.8 mJ in the pulse burst laser system.     

输出平均功率大于2W的高功率、包层抽运、超短脉冲铒镱共掺光纤激光器

采用主振荡功率放大的方式，研制成功集宽带波长连续可调谐、带宽内输出功率谱均衡、高重复频率和高功率性能于一体的超短脉冲包层抽运铒镱共掺光纤激光器.将优化主振荡器和功率放大器的腔结构与掺铒光纤的饱和增益特性结合起来，实现了1535nm—1570nm(35nm带宽)的输出功率均衡的波长连续可调谐激光输出，在带宽内激光功率的最大波动仅为0.5dBm；带宽内平均输出功率大于2W、脉冲重复频率大于10GHz、脉冲宽度小于30ps.该激光器具有综合性能指标先进、结构简单、全光纤化、使用方便等优点. 关键词： 光纤激光器 包层抽运 短脉冲 高重复频率     

Theory of Pr:ZBLAN ultraviolet upconversion fiber master oscillator power amplifier

A theoretical study for ultraviolet upconversion fiber master oscillator power amplifier (MOPA) based on the transition from the 4f5d state to the ³H₄ ground state in Pr³⁺:ZBLAN fiber is performed by using steady population rate equations and propagation equations. The variation of the output power with the fiber length of master oscillator and MOPA and the launched pump powers, the dependence of the slope efficiency on the fiber length of master oscillator and MOPA, and the optimum fiber length of MOPA as a function of the launched pump powers, are calculated. Both the output power and the slope efficiency of MOPA are 2-3 times those of the simplex oscillator. It is found that the UV upconversion fiber MOPA system can effectively improve the output power and the slope efficiency of laser.     

Study of gain dynamics and temporal jitter effects in copper vapor laser oscillator-amplifier chain

Effect of temporal jitter on the performance of copper vapor laser (CVL) master oscillator power amplifier (MOPA) chain using Monte-Carlo techniques was studied. The MOPA chain comprised an oscillator and five amplification stages. Amplification of CVL signal in each amplifier stage was modeled using rate equation based optical model. The effect of temporal jitter on the pulse energy stability in CVL MOPA chain was estimated for various jitter values. Our studies show that the pulse energy spread and the pulse energy instability increases with increase in jitter which in turn depends on the gain pulse width and the jitter considered. Pulse to pulse gain variation in CVL MOPA chain was studied along with temporal jitter. The acceptable tolerance limit on temporal jitter is ±4 ns for a pulse energy stability of 5% of CVL MOPA chain.     

26W near diffraction limited Q-switched green laser based on a diode-end-pumped master oscillator power amplifier

An efficient acousto-optically Q-switched extracavity frequency-doubled 532nm laser based on a diode-end-pumped master oscillator power amplifier (MOPA) is demonstrated. With a type I non-critically phase-matched LBO, 26W of average power at 532nm in a near diffraction limited mode at a repetition rate of 30kHz was generated under 43W pump power of 1064nm Nd:YVO_{4} laser, which correspond to a frequency-doubling conversion efficiency of 60%.     

100 W全光纤声光调Q光纤激光器实验研究

 报道了一台全光纤结构主振荡功率放大(MOPA)型掺镱脉冲光纤激光器,以光纤光栅为腔镜,光纤型声光调Q的光纤激光器为种子源,通过两级掺镱双包层光纤放大器实现功率放大。对声光调Q的光纤激光器输出特性进行了研究,比较了不同泵浦波长、不同重复频率对激光输出功率和脉冲宽度的影响,并实现了最短脉冲宽度25 ns、单脉冲能量45 μJ的脉冲激光输出。在重复频率50 kHz时,对脉冲宽度130 ns、平均功率0.6 W的种子光进行放大,得到了平均功率102.5 W、脉冲宽度约240 ns的激光输出。     

High-repetition-rate high-beam-quality 43 W ultraviolet laser with extra-cavity third harmonic generation

High-power, high-repetition-rate extra-cavity third harmonic generation of 355 nm with high beam quality has been developed. The acoustic-optical Q-switched Nd:YVO₄ MOPA laser including 2- and 4-stage amplifiers was used as the IR source. With the extra-cavity frequency conversion of LBO crystals, 30.2 W TEM₀₀-mode 355 nm UV laser was obtained with a 2-stage amplifier MOPA laser, and the optical-to-optical (1064 nm to 355 nm) conversion efficiency was up to 30%. Enhanced 43 W TEM₀₀ UV laser at 60 kHz was achieved with a 4-stage amplifier MOPA IR laser, and pulse duration was 10.7 ns corresponding to the peak power as high as 67 kW, with single pulse energy of 0.72 mJ. The optical–optical efficiencies from IR and diodes to UV were 28% and 10% respectively.     

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.     

天光一号MOPA光学角多路系统的研制

 光学角多路系统是主振功放(MOPA)装置的重要组成部分。它不仅连接着主振荡器、预放大器及主放大器三个KrF激光系统，而且起着压缩激光脉宽的作用。光学角多路能使主振激光脉冲在能量上得到足够的放大，并使泵浦预放、主放激光腔的电子束能量及其脉宽得到充分的利用。介绍了天光一号装置上MOPA光学角多路系统的结构,并结合多年来运行的实践，提出了若干优化措施。     

An Efficient Single-Frequency Yb-Doped All-Fiber MOPA Laser at 1064.3 nm

An efficient narrow-linewidth single-frequency(SF) Yb-doped all-fiber master oscillator power amplifier(MOPA)laser operating at 1064.3 nm is demonstrated experimentally.A ring cavity SF fiber laser is used as the seed source for the MOPA system and the Yb-doped fibers are employed as the gain medium or the saturable absorber.The SF operation is observed to be stable without mode hopping.The highest output power of 266 mW is obtained under the 400 mW pump power with the corresponding slope efficiency of 66.2%.The linewidth of the amplified output laser is approximately 1 kHz and its optical signal-to-noise ratio is over 45 dB.     

Femtosecond diode laser MOPA system at 920 nm based on asymmetric colliding pulse mode-locking

We report on the generation of 267 fs long pulses with a peak power of 661 W emitted by an InGaAs diode laser master-oscillator power-amplifier (MOPA) system with an external grating compressor. The oscillator emits strongly chirped picosecond pulses with several nanometer of bandwidth, which can be amplified without significant phase modulation and are compressed to femtosecond pulses after leaving the amplifier. We used a diode laser module for asymmetric colliding pulse mode-locking and optimized the collision point and the relative intensity of the counter-propagation pulses.     

单频纳秒脉冲全光纤激光器实现300 W平均功率输出

搭建了一台主振荡功率放大（MOPA）结构的单频脉冲全光纤激光器。通过对线宽为 20 kHz 的连续单频激光器进行强度调制,获得了重复频率 10 MHz、脉宽约 8 ns、平均功率约 0.5 mW 的单频脉冲种子激光。采用多级掺镱光纤放大器对脉冲种子激光进行级联放大,获得了平均功率 300.8 W 的高功率激光输出。目前,激光器输出功率仅受限于泵浦功率,有望通过增加泵浦功率进一步提高输出功率。     

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.     

Pulsed ytterbium-doped large mode area double-clad fiber amplifier in MOFPA configuration

A pulsed master oscillator fiber power amplifier working in nanosecond range has been developed. An ytterbium-doped double-clad (large mode area) optical fiber was used as an amplifying medium. Actively Q-switched Nd:YVO laser was used as a seed of light pulses. The system worked at the repetition rate from 10 kHz to 40 kHz. At the amplifier output, pulses of 10.9 kW peak-power were achieved. The laser system worked at the slope efficiency of 30%.     

光纤激光泵浦MgO:PPLN高功率中波红外光参量振荡器

为实现高效率、高功率中波红外激光输出,研制基于MgO:PPLN晶体的中波红外光参量振荡器（OPO）,泵浦源为基于主振荡功率放大（MOPA）结构的线偏振掺Yb光纤激光器（YDFL）。实验结果表明:YDFL可实现最高79.1 W的1064.1 nm脉冲线偏振激光输出;在YDFL泵浦下,通过优化输出镜曲率半径和泵浦光束腰直径,该OPO实现最高9.15 W的3.754 μm脉冲激光输出,光光转换效率为11.57%,重复频率为300 kHz,脉冲宽度约为110 ns。     

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.     

Simultaneous spectrum and coherent combining by active phasing dual two-tone all-fiber MOPA chains

We present a new approach for simultaneous spectral and coherent combining in a master oscillator power amplifier (MOPA) configuration with active phasing. Spectrally combined single-frequency seed lasers are employed as a master oscillator for the all-fiber power amplifier chain, which provides robust performance suppressing of the stimulated Brillouin scattering effect, while coherent combining of spectrally combined amplifiers with active phase control provides stable in-phase combining, despite the strong phase fluctuation. In experiments, two spectrally combined seed MOPA chains are coherently combined with a total output power of 390 W. The power of the main lobe in the closed loop is two times of that value in the open loop, and visibility of more than 75% of the long-exposure interference pattern at the receiving plane is obtained.