High-power diode-pumped Yb-doped fiber laser at 1150 nm

A model of steady-state rate equations including amplified spontaneous emission for long-wavelength Yb doped fiber laser is set up, which provides design principle for a practical laser system. We demonstrate a diode-pumped all-fiber Yb-doped fiber laser at 1150 nm with an output power of 33.6 W, the optical efficiency is 60%.     

High-power tunable Er,Yb ribbon fiber laser

A high-power Er,Yb double-clad ribbon fiber laser pumped by a 9-diode-bar pump module is reported. The laser yielded 102 W of continuous-wave output at 1566 nm for a launched pump power of 244 W, corresponding to a slope efficiency of ~ 44% with respect to launched pump power. Tunable operation was achieved using a simple external feedback cavity with a diffraction grating and the operating wavelength could be tuned from 1533 nm to 1567 nm. Temperature distribution in the ribbon fiber geometry and prospects of power scaling will be discussed.     

High-power all-normal-dispersion femtosecond pulse generation from a Yb-doped large-mode-area microstructure fiber laser

We report on an all-normal-dispersion mode-locked fiber laser based on a large-mode-area Yb-doped microstructure fiber and using a high nonlinear modulation depth semiconductor saturable absorber mirror. The laser delivers 3.3 W of average output power with positively chirped 5.5 ps pulses at a center wavelength of 1033 nm. The pulse repetition rate is 46.4 MHz, which results in an energy per pulse of 71 nJ. These pulses are extracavity dechirped down to 516 fs by using bulk gratings. The average power of the dechirped pulses is 2.3 W, which corresponds to a peak power of more than 96 kW.     

High-power superfluorescent source with a side-pumped Yb-doped double-cladding fiber

A compact supe uorescent source based on an Yb-doped double-cladding fiber amplifier is described. The packaged amplifier is pumped at 975 nm by side-coupling emission from a 2.0-W broad-stripe laser diode through an imbedded V groove. The fiber source generates 485 mW of broadband emission centered at 1055 nm with a 41-nm FWHM flat power spectrum.     

High-power photonic-bandgap fiber laser

An original architecture of an active fiber allowing a nearly diffraction-limited beam to be produced is demonstrated. The active medium is a double-clad large-mode-area photonic-bandgap fiber consisting of a 10,000 ppm by weight Yb(3+)-doped core surrounded by an alternation of high- and low-index layers constituting a cylindrical photonic crystal. The periodic cladding allows the robust propagation of a approximately 200 microm(2) fundamental mode and efficiently discriminates against the high-order modes. The M(2) parameter was measured to be 1.17. A high-power cw laser was built exhibiting 80% slope efficiency above threshold. The robust propagation allows the fiber to be tightly bent. Weak incidence on the slope efficiency was observed with wounding radii as small as 6 cm.     

国产30/600μm掺镱光纤实现4.1kW激光输出

采用化学气相沉积结合气相/液相复合掺杂方式制备30/600 μm掺镱双包层光纤,石英纤芯中的掺杂组分为Yb₂O₃, Al₂O₃,P₂O₅。基于976 nm发光二极管反向抽运方式,构建全光纤化的主控振荡器功率放大器结构对增益光纤进行测试。实验中,种子源功率为189 W,当泵浦总功率为4747 W时,激光输出功率为4120 W,放大级光光效率为85%,3 dB带宽为1.6 nm。激光器连续工作1 h,激光功率稳定在4100 W,未发生明显的功率衰退现象。     

Multi-coupler side-pumped Yb-doped double-clad fiber laser

The side-coupler of angle polished method, using angle-polished multimode fiber and optical adhesive, is used to efficiently pump an Yb-doped double-clad fiber laser. The maximum coupling efficiency of 78.6% is achieved by the side-coupler for a multimode fiber with a circular core of 200 μm and a double-clad fiber with a 350/400 μm D-shaped inner cladding. While laser diodes (LDs) with three side-couplers are simultaneously used as pump sources, maximum output power of 1.38 W and slope efficiency of 48.9% are demonstrated in the fiber laser system.     

国产有源光纤成功实现6 kW激光输出

光纤激光是继气体激光、化学激光和固体激光之后的新一代激光技术,是近年来世界各国科学研究的热点领域。制约光纤激光功率提升的主要技术瓶颈是系统集成技术和光纤材料制备技术。目前,我国科研工作者成功掌握了千瓦级光纤激光系统集成技术并实现了产业化,但是所用的光纤激光材料与核心器件还严重依赖进口。相较于比较成熟的系统集成技术,我国光纤激光材料的科学研究和产业化进程相对滞后,尚无法提供成熟稳定的有源光纤产品。 2016年6月,中国工程物理研究院激光聚变研究中心的研究人员经过近三年科研攻关,成功研发了30/900规格（纤芯30 m/包层900 m）镱掺杂铝磷硅（Yb-APS）三元体系激光光纤并实现了6.03 kW最高功率输出,在5 kW功率水平下可长期稳定工作。光纤激光材料综合测试平台采用了传统的1+1型MOPA放大结构（即信号种子源与一级主放）：信号光种子源的功率为40 W,光束质量M2=1.1;第二级MOPA放大级使用的976 nm LD泵浦光总功率9.95 kW,经过CPS功率剥离器激光净化处理后,最终安全地实现了6.03 kW最大功率输出。如图1所示,最高输出功率时斜率效率为61.25%,源于1∶30的芯包比和20 m以上的光纤使用长度;激光输出光谱中心波长1080 nm,3 dB带宽为1.89 nm,受激拉曼抑制比＞15 dB;5 kW稳定工作时,光束质量M2=2.38,未发现光子暗化效应。中物院激光聚变研究中心所研制的镱掺杂铝磷硅三元体系有源光纤(30/900 Yb-APS fiber)成功实现了6.03 kW激光输出,是我国高功率光纤激光材料研究领域的重要进步,为制备低损耗、高掺杂、高吸收、高增益、无光子暗化效应的商业激光光纤产品奠定了坚实的技术基础。     

高功率窄线宽光纤激光技术

以波长拓展为主线介绍了单频光纤振荡器的研究进展,以功率提升为主线介绍了单频连续光纤放大器的发展现状,以产生窄线宽种子源的方法为依据总结了1 μm波段高功率窄线宽连续光纤激光器的国内外研究成果。分析当前高功率单频光纤激光器和高功率窄线宽光纤激光器的发展趋势和面临的主要挑战,梳理并讨论高功率窄线宽光纤激光的关键技术,并基于当前高功率窄线宽光纤激光器的发展现状介绍其在各领域的应用价值。     

Output power improvement in an Yb-doped fiber laser with an additional unpumped Yb-doped fiber

Master oscillator power amplifier (MOPA) technology has been widely used in high-power or ultrashort-pulse fiber laser systems because the shape of the laser pulse can be easily adjusted. Usually, the first amplification stage of a 1064 nm fiber laser uses the core-pumped Yb-doped fiber amplifier (YDFA); however, the gain or output power is limited owing to the strong amplifier spontaneous emission (ASE) in the 1030 nm band. This paper presents the improved output power in an YDFA by inserting an additional unpumped Yb-doped fiber, which absorbs the lost backward ASE emitted from the pump end. We achieved an output power increase of more than 10% in a low-power signal, and the increase in output power decreased as the signal power increased. Moreover, the insertion of an additional unpumped Yb-doped fiber restricted the unwanted 1030 nm lasing in a low-power signal.     

Self-organization in a multicore fiber laser array

We explain an observed spontaneous transition to the high-brightness, in-phase array state of a seven-core ytterbium-doped fiber laser array [IEEE Photonics Technol. Lett. 13, 439 (2001)]. The responsible mechanism is nonlinear refraction, and either in-phase or antiphase array modes can be selected by control of pump intensity. The phenomenon appears to be robust and scalable.     

Ultrawide tunable Er soliton fiber laser amplified in Yb-doped fiber

A Raman-shifted and frequency-doubled high-power Er-fiber soliton laser for seeding an efficient high-power Yb fiber femtosecond amplifier is demonstrated. The Raman-shifted and frequency-doubled Er-soliton laser is tunable from 1.00 to 1.070microm and produces bandwidth-limited 24-pJ pulses at a repetition rate of 50 MHz with a FWHM pulse width of 170 fs at 1.040microm . The Yb(3+) amplifier has a slope efficiency of 52% and generates 3-ps linearly chirped pulses with an average power of 0.8 W at 1.05microm . After pulse compression, 74-fs bandwidth-limited pulses with an average power of 0.4 W and a pulse energy of 8 nJ are generated.     

High-power diode-cladding-pumped Tm-doped silica fiber laser

The operation of a diode-pumped Tm-doped silica fiber laser that uses the cladding-pumping arrangement to produce high-power cw output at wavelengths near 2 microm is reported. We obtained a maximum output power of 5.4 W at a slope efficiency of 31% with respect to the launched pump power at a total optical-to-optical efficiency of 22%. The fiber-laser output wavelength was tuned between 1.880 and 2.033 microm by adjustment of the fiber length, with >4W of power obtainable from 1.94 to 2.01 microm. Self-pulsations detected in the output from the double-clad fiber laser may indicate the presence of ion-clustering effects.     

High-power linearly-polarized tunable Raman fiber laser

In this study, we demonstrate an all-fiber high-power linearly-polarized tunable Raman fiber laser system. An inhouse high-power tunable fiber laser was employed as the pump source. A fiber loop mirror(FLM) serving as a high reflectivity mirror and a flat-cut endface serving as an output coupler were adopted to provide broadband feedback. A piece of 59-m commercial passive fiber was used as the Raman gain medium. The Raman laser had a 27.6 nm tuning range from1112 nm to 1139.6 nm and a maximum output power of 125.3 W, which corresponds to a conversion efficiency of 79.4%.The polarization extinction ratio(PER) at all operational wavelengths was measured to be over 21 d B. To the best of our knowledge, this is the first report on a hundred-watt level linearly-polarized tunable Raman fiber laser.     

High-power continuous-wave cladding-pumped Raman fiber laser

We demonstrate a high-power single-mode cladding-pumped Raman fiber laser. The Raman fiber laser consists of a 1.2 km long germanium-doped double-clad fiber in a linear cavity, which is spliced to a single-mode fiber. The laser is end pumped by a multimode erbium-ytterbium-doped fiber, which is coupled to the inner cladding of the Raman fiber. The embedded core was designed to be single mode at the Raman Stokes wavelength, and up to 10 W of power was obtained at 1660 nm from the single-mode fiber end. The laser has a slope efficiency of 67% and a threshold of 6.5 W.     

多芯光纤激光器中共相位模式功率的提高

 以七芯光纤激光器为例,提出一种提高多芯光纤激光器总输出光功率中共相位模式所占比例的方法,即把多芯光纤激光器作为种子光源,输出信号光再经过多芯光纤放大器进行放大。基于速率方程组对激光器和放大器中的模式竞争进行了数值分析。计算表明：激光器输出端与放大器输入端之间距离存在一个最佳值,以使得放大器输出信号中低阶模式功率占总输出功率的比例最低,可以下降到小于1%。研究表明：级联放大系统可以有效增强共相位模式同时抑制低阶模式,比传统的塔耳博特腔激光器具有更好的光束质量。     

全正色散多波长被动锁模耗散孤子掺镱光纤激光器

报道了一种带有周期性双折射光纤滤波器的全正色散多波长被动锁模耗散孤子掺镱光纤激光器. 通过数值模拟发现加入滤波器后激光器能输出多波长耗散孤子脉冲, 调节滤波器带宽大小可以得到不同波长个数和波长间隔的多波长锁模耗散孤子脉冲. 在激光器产生的四波长和五波长耗散孤子脉冲中观察到了耗散孤子分子, 并且通过调节滤波器参数和饱和功率可以改变多波长脉冲中耗散孤子分子的个数和波长. 这是在被动锁模光纤激光器中首次实现包含有耗散孤子分子的多波长脉冲. 另外还在实验上实现了全正色散双波长被动锁模耗散孤子的产生. 关键词： 全正色散 耗散孤子 多波长脉冲 孤子分子     

11-mJ pulse energy wideband Yb-doped fiber laser

We report a wide bandwidth (Δλ=8 nm) optical pulsed MOPA (master oscillator power amplifier) source emitting 11.23 mJ pulses (1.25 MW peak power) in the wavelength centered at (λ=1064 nm). Pulse duration and repetition rate were 9 ns and from 10 Hz to 100 Hz, respectively. In order to suppress amplified spontaneous emission (ASE), multi-stage pulse pump technology is applied. And the large core diameter (90 μm) and wide bandwidth ensures the high peak power and energy output.     

Widely tunable Yb-doped laser with all fiber structure

In this paper, an all fiber Yb³⁺-doped fiber ring laser with large tuning range has been reported. A 976 nm laser diode (LD) pumped laser is used as the pump source and high concentration Yb³⁺-doped fiber is adopted as gain medium. Adjusting the polarization controller (PC), a widely tunable range of 20 nm from 1030 to 1050 nm is obtained. The spectral linewidth of the pulse is less than 0.2 nm. Comparing with other fiber laser structures, the fiber laser with an all-fiber structure has higher efficiency and better stability. The laser also has very stable and flat output within the whole tuning range.     

Efficient skew-angle cladding-pumped tunable narrow-linewidth Yb-doped fiber laser

A skew-angle cladding-pumped tunable Yb-doped fiber laser is presented. The laser was tunable over more than 30 nm, from 1022 to 1055 nm, by employing a volume Bragg grating in a retroreflector configuration as one of the cavity delimiters. Output powers in excess of 4.3 W were recorded with a spectral bandwidth of 5 GHz and an M(2) value below 1.3 over the whole tuning range.