90 GW peak power few-cycle mid-infrared pulses from an optical parametric amplifier

We demonstrate a compact 20 Hz repetition-rate mid-IR OPCPA system operating at a central wavelength of 3900 nm with the tail-to-tail spectrum extending over 600 nm and delivering 8 mJ pulses that are compressed to 83 fs (<7 optical cycles). Because of the long optical period (～13 fs) and a high peak power, the system opens a range of unprecedented opportunities for tabletop ultrafast science and is particularly attractive as a driver for a highly efficient generation of ultrafast coherent x-ray continua for biomolecular and element specific imaging.     

128 W单频线偏振光纤放大器特性研究

高功率单频激光在激光雷达、光谱学、精密测量等领域具有广阔的应用前景.采用中心波长为1064 nm、光谱线宽为20 kHz、偏振消光比（PER）高于20 dB的单频线偏振分布式反馈光纤激光器做种子源（尾纤输出功率约为10 mW）,利用种子注入主振荡功率光纤放大技术,通过两级级联放大实现了128 W高功率单频、线偏振、近衍射极限单模连续激光输出.主放大器光-光效率达到83%,PER高于12 dB.采用分段温控技术有效地提高了光纤中的受激布里渊散射（SBS）阈值,实验中未观察到明显的放大自发辐射和SBS现象,进 关键词： 掺Yb光纤放大器 主振荡功率光纤放大 单频 线偏振     

High power single-frequency continuous-wave Nd:YVO4 master-oscillator power amplifier

We report a highly-efficient, high-power, single-frequency Nd:YVO₄ master-oscillator power-amplifier with near-diffraction-limited output beam quality. A diode-pumped Nd:YVO₄ ring laser incorporating a passive method for suppressing axial-mode-hopping was employed as the master-oscillator, and was amplified by a three-stage diode-end-pumped Nd:YVO₄ amplifier, yielding 79 W of output with an extraction efficiency of 29%. The overall power gain was 15 dB for an input power from the master-oscillator of 2.4 W, and the M² parameter was less than 1.5 at the maximum power. The prospects for a further increase of power and brightness via this approach are considered. PACS 42.55.Xi; 42.60.Da; 42.60.Jf     

100-W single-frequency master-oscillator fiber power amplifier

We report the efficient generation of 100-W single-frequency radiation with diffraction-limited beam quality at the 1064-nm wavelength by use of a master-oscillator fiber power-amplifier system, consisting of a diode-pumped monolithic nonplanar ring laser as the master oscillator and an Yb-doped large-mode-area fiber as the power amplifier. The emission spectrum, the intensity noise behavior, and further power-scaling possibilities to the >200-W level, which are determined by the threshold of stimulated Brillouin scattering in the fiber amplifier, are discussed.     

23W peak power picosecond pulses from a single-stage all-semiconductor master oscillator power amplifier

Using a single-stage all-semiconductor master oscillator-power amplifier, we generate narrow-band laser pulses of 23?W peak power at 1063?nm wavelength. These pulses of 40?ps length FWHM have a variable repetition rate and pulse energies around 2?nJ, which exceeds previous realizations and makes them ideally suited for second harmonic generation. With a spectral filter, an extinction ratio above 36?dB could be achieved at nearly 10?W peak power. We use a novel spectral method to reliably determine pulse energies independently of the background level.     

Generation of megawatt peak power picosecond pulses from a divided-pulse fiber amplifier

Control of nonlinearity is a challenge in fiber amplifiers designed to generate pulses of a few picoseconds duration, and as a result, picosecond fiber amplifiers have failed to reach peak power of 1MW. Divided-pulse amplification, combined with the use of circular polarization, allows the generation of 2.2?ps pulses with energy as high as 2.5?μJ and peak power of 1?MW.     

High-peak power multi-wavelength picosecond pulses generated from a BaWO4 Raman-seeded optical parametric amplifier

We report the generation of high-peak power multi-wavelength picosecond laser pulses using optical parametric amplification (OPA) in BBO seeded with pulses generated in a 5-mm length BaWO₄ crystal by stimulated Raman scattering of 18-ps laser pulses at 532 nm. The maximum output energy of the amplified first-Stokes component at 559.7 nm was about 1.76 mJ. The corresponding maximum peak power, pulse duration and spectral line width were measured to be 117.3 MW, 15 ps and 18.0 cm⁻¹, respectively. The multi-wavelength picosecond laser pulses were in the visible and near infrared ranges. Using this Raman-seeded OPA technique, the beam quality of the stimulated Raman scattering pulses can be improved.     

7.3-W single-frequency master-oscillator fiber power amplifier with China-made double-clad fiber

A narrow-linewidth master-oscillator fiber power amplifier system was presented, in which an ultrastable,continuous-wave, single-frequency laser was adopted as the master oscillator and a China-made Yb-doped large-mode-area fiber was used as the power amplifier medium. The system generates single-frequency radiation up to 7.3 W at 1064-nm wavelength with 39% slope efficiency and 26% optical-optical power conversion efficiency. The spectral characteristics as well as the suppression of amplified spontaneous emission were discussed in detail.     

kW级主振荡功率放大光纤激光器输出特性

分析了kW级光纤激光器实现单模激光输出的模式控制方式。采用主振荡功率放大方式,实现了工作波长1.08 m、最大输出功率1.05 kW的全光纤单模激光输出。对激光光谱和光束质量随激光功率的变化等输出特性进行了研究,结果表明:随着激光功率的增大中心波长和光束质量无变化,但谱宽逐渐展宽。分析了激光光谱展宽的原因,认为随着激光功率的增大,光栅纤芯的折射率变化增大,引起本振级的谱宽展宽,而本振级因谱宽展宽引入的噪声在放大级被放大,再加上放大级本身引入的自发辐射,共同造成放大级的谱宽展宽。对光束质量变差的原因进行了分析,认为光纤弯曲导致原先在纤芯中传输的激光部分被泄露到包层中,从而使光束质量变差。     

Single-frequency master-oscillator fiber power amplifier system emitting 20 W of power

We report a master-oscillator fiber power-amplifier system consisting of a diode-pumped monolithic nonplanar ring laser as the master oscillator and a Yb-doped large-mode-area double-clad fiber as the power amplifier. The system emits up to 20.1 W of single-frequency radiation at a wavelength of 1064 nm with diffraction-limited beam quality (M(2)相似文献   

kW级主振荡功率放大光纤激光器输出特性

分析了kW级光纤激光器实现单模激光输出的模式控制方式。采用主振荡功率放大方式,实现了工作波长1.08 m、最大输出功率1.05 kW的全光纤单模激光输出。对激光光谱和光束质量随激光功率的变化等输出特性进行了研究,结果表明：随着激光功率的增大中心波长和光束质量无变化,但谱宽逐渐展宽。分析了激光光谱展宽的原因,认为随着激光功率的增大,光栅纤芯的折射率变化增大,引起本振级的谱宽展宽,而本振级因谱宽展宽引入的噪声在放大级被放大,再加上放大级本身引入的自发辐射,共同造成放大级的谱宽展宽。对光束质量变差的原因进行了分析,认为光纤弯曲导致原先在纤芯中传输的激光部分被泄露到包层中,从而使光束质量变差。     

High-power top-hat pulses from a Yb master oscillator power amplifier for efficient optical parametric amplifier pumping

We demonstrate shaping of high-energy broadband Yb amplifier pulses for the generation of a (sub)picosecond top-hat temporal pulse profile that significantly improves pumping efficiency of an optical parametric amplifier (OPA). Phase-only modulation is applied by an acousto-optic programmable dispersion filter. This simple scheme is scalable to a high average power due to a relatively broad bandwidth of the Yb:CaF(2) gain medium used in the amplifier that supports a sub-150-fs transform-limited pulse duration. Additionally we show that OPA seeding with supercontinuum remains possible because top-hat-shaped pulses passed through a glass block recompress to ≈200 fs with minimum satellite production.     

高功率,高重复率飞秒光脉冲放大器

利用铜蒸气激光器泵浦碰撞锁模染料激光放大器,获得2.4μJ,70 fs低色散光脉冲,脉冲重复率为5kHz.     

Double-pass copper-vapor laser amplifier with a high peak power

New findings concerning a double-pass amplifier of original design allowing for a significant increase in the peak power of laser pulses without changing the lasing mean power and pump power are presented. A peak power of 305 kW is demonstrated at a lasing mean power of about 25 W. The physics of such an amplifier and prospects for its application are discussed.     

High power terahertz pulses generated in intense laser-plasma interactions

Terahertz (THz) radiation has attracted much attention due to its wide potential applications. Though radiation can be generated with various ways, it is still a big challenge to obtain strong tabletop sources. Plasma, with the advantage of no damage limit, is a promising medium to generate strong THz radiation. This review reports recent advances on strong THz radiation generation from low-density gases and high-density solid targets at different laser intensities.     

高峰值功率大模场全光纤脉冲放大器

报道了一种由纤芯直径分别为15μm和25μm的大模场光纤组成的全光纤脉冲放大器模块.当注入脉冲宽度为10 ns,重复频率为1 Hz.光谱宽度为0.3 nm,脉冲能量为80 nJ的激光脉冲时,经过两级放大输出的激光脉冲峰值功率为30 kW,单脉冲能量为300μJ.此外,实验研究了该放大器模块输出的时间特性.研究发现:由于受激布里渊散射(SBS)效应,限制了单纵模光纤激光在光纤中的高能量放大,采用宽带激光脉冲可以有效地抑制SBS效应,提高光纤放大器的SBS阈值.     

1.57 MW peak power pulses generated by a diode-pumped Q-switched Nd:LuAG ceramic laser

The pulse characteristics of a laser diode dual-end-pumped electro-optic Q-switched Nd:LuAG ceramic laser at various repetition rates are presented. The largest output pulse energy of 11 mJ is realized at the repetition rate of 100 Hz with pump energy of 84.3 mJ, and the slope efficiency in respect to pump pulse energy is 18.6%. The single pulse peak power reaches up to 1.57 MW. Using Nd:LuAG ceramic as the amplification medium seeded by an Nd:YAG laser of 5.2 mJ, a 10.3 mJ amplified pulse is obtained with pump pulse energy of 42.8 mJ, corresponding to an extraction efficiency of 11.9%.     

高峰值功率大模场全光纤脉冲放大器

报道了一种由纤芯直径分别为15 μm和25 μm的大模场光纤组成的全光纤脉冲放大器模块。当注入脉冲宽度为10 ns,重复频率为1 Hz,光谱宽度为0.3 nm,脉冲能量为80 nJ的激光脉冲时,经过两级放大输出的激光脉冲峰值功率为30 kW,单脉冲能量为300 μJ。此外,实验研究了该放大器模块输出的时间特性。研究发现：由于受激布里渊散射（SBS）效应,限制了单纵模光纤激光在光纤中的高能量放大,采用宽带激光脉冲可以有效地抑制SBS效应,提高光纤放大器的SBS阈值。     

Nd:YAG master-oscillator power amplifier with a rhodium-doped BaTiO(3) self-pumped phase-conjugate mirror

We investigate Nd:YAG master-oscillator power amplifier arrangements with an infrared-sensitive rhodium-doped BaTiO(3) photorefractive phase-conjugate mirror. In these setups the phase-conjugate mirror is simple to implement, compact, passive, and completely self-contained. We demonstrate a reasonable extraction efficiency (~50%), response times in the range of several minutes with our experimental conditions and an excellent ability of the phase-conjugate mirror to compensate for severe phase aberrations.     

Stable rectangular pulses supported by a quantum dot optical amplifier

We predict the formation of a stable solitary rectangular pulse in semiconductor quantum dot media. The formation of such a pulse occurs when a quantum dot system is pumped in a way, where the s shell excitation exhibits gain while the p shell absorbs. We provide formulas to describe the rectangular pulse by the systems material parameters. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)