20 W single-mode Yb3+ -doped phosphate fiber laser

We report the demonstration of the first, to our knowledge, cladding-pumped continuous-wave Yb(3+)-doped phosphate-glass fiber laser. Phosphate hosts are of interest because they can be much more heavily doped than silica, and because of the possibility that they may have a higher photodarkening threshold. In an 84.6 cm double-clad fiber doped with 12 wt. % of Yb(2)O(3) and laser-diode pumped at 940 nm, nearly 20 W of single-mode 1.07 microm output power was generated with 60.2 W of absorbed pump power. The measured dependence of the output power on pump power is in excellent agreement with simulations.     

一种基于增益调制技术的全光纤化脉冲Yb光纤激光器

以波长为975 nm的半导体激光器作为泵浦源,周期性地脉冲泵浦一个包含Yb掺杂光纤和光纤光栅对的Yb光纤激光器,实现了基于增益调制技术的全光纤化高功率Yb光纤激光器的稳定脉冲输出.在50 kHz重频下,采用20 W的泵浦功率和2.4 μs的泵浦脉冲宽度,获得了1 060 nm波长脉冲宽度仅100 ns的稳定脉冲激光输出,单脉冲激光能量约为20 μJ.以此作为脉冲激光种子进行功率放大,获得了性能稳定的全光纤结构高功率脉冲激光输出,放大后单脉冲能量超过200 μJ,激光放大器斜率效率达到60%.     

Dual-core ytterbium fiber amplifier for high-power 1060 nm swept source multichannel optical coherence tomography imaging

A novel (to our knowledge) dual-core ytterbium (Yb(3+)) doped fiber, as an optically pumped amplifier, boosts the output power from a 1060 nm swept source laser beyond 250 mW, while providing a wavelength tuning range of 93 nm, for optical coherence tomography (OCT) imaging. The design of the dual-core Yb-doped fiber amplifier and its multiple wavelength optical pumping scheme to optimize output bandwidth are discussed. Use of the dual-core fiber amplifier showed no appreciable degradation to the coherence length of the seed laser. The signal intensity improvement of this amplifier is demonstrated on a multichannel in vivo OCT imaging system at 1060 nm.     

Yb(3+)-ring-doped fiber for high-energy pulse amplification

We report what is to our knowledge the first demonstration of pulse amplification in a cw-pumped fiber in which the doped gain medium has a ring shape surrounding a single-mode core. For a given pump power, ring doping reduces the gain and hence the power lost to amplified spontaneous emission. Thereby, a significantly larger amount of energy can be stored in the amplifier. Using an Yb(3+)-doped fiber pumped by 540 mW of power at 1000 nm, we measured 69 microJ of extracted pulse energy at 1047 nm, the highest value reported to date from a single-mode Yb(3+)-doped fiber. We predict that a fiber cladding pumped by a diode bar can produce pulse energies in excess of 1 mJ.     

光纤光栅选频掺Yb3+双包层光纤激光器

利用相位掩模法，在D形内包层掺Yb3+双包层光纤一端直接写制出Bragg光栅，用作双包层光纤激光器的输出腔镜.试验得到了线宽为0.196nm，波长为1058.2nm，最高输出功率为570mW的稳定激光输出，解决了激光器中模式竞争造成的输出不稳定现象.从速率方程出发，对激光器的输出功率与抽运功率、光栅反射率的关系以及最佳光纤长度进行了理论分析，结果与实验符合很好. 关键词： 双包层光纤光栅 掺Yb3＋双包层光纤激光器 相位掩模 速率方程     

Room-temperature diode-pumped Yb, Na: PbF2 laser

Growth, spectroscopic properties, and laser performance of Yb, Na:PbF(2) crystals have been investigated. With a 2 mol.% Yb(3+)-doped sample we obtained 2.65 W output power at 1045 nm for 7.5 W of incident power at 976 nm. The laser wavelength could be tuned from 1017 to 1078 nm, showing the great potential of Yb, Na:PbF(2) as an amplifier medium for femtosecond pulses.     

Green Er(3+):YLiF(4) upconversion laser at 551nm with Yb(3+) codoping: a novel pumping scheme

We report room-temperature continuous-wave upconversion laser emission on the green transition (4)S(3/2)?(4)I(15/2) in Er(1%), Yb(3%):YLiF(4) at 551nm. Green laser operation was obtained for titanium-sapphire pump wavelengths continuously tunable between 955 and 974.5nm. Codoping with Yb(3+) resulted in a more efficient excitation of the upper laser level by upconversion processes. The maximum green laser output power was 37mW at an incident titanium-sapphire pump power level of 1580mW at 966nm.     

High-power Tm-doped fiber distributed-feedback laser at 1943 nm

We report on high-power operation of a fiber distributed-feedback (DFB) laser fabricated from Tm-doped photosensitive alumino-silicate fiber and in-band pumped by an Er/Yb fiber laser at 1565 nm. The fiber DFB laser yielded up to 875 mW of single-ended output at 1943 nm on two orthogonally polarized modes for 3.5 W of absorbed pump power. Further scaling of the DFB laser output power was achieved with the aid of a simple Tm-doped fiber amplifier stage spliced directly to the DFB fiber without the need of an optical isolator. The maximum output power from the DFB laser and fiber amplifier was >3 W for a combined absorbed pump power of 8.1 W. The influence of thermal loading, owing to quantum defect heating in the Tm-doped core, on the output power and longitudinal mode behavior is discussed, and the prospects for further improvement in performance are considered.     

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.     

Power scaling method for 2-microm diode-cladding-pumped Tm(3+)-doped silica fiber lasers that uses Yb(3+) codoping

Unidirectional dual-wavelength pumping at 805 and 975 nm of a Tm(3+)-doped silica double-clad fiber laser that has been codoped with Yb(3+) is demonstrated. With equal 2-wt. % concentrations of the Tm(3+) and Yb(3+) ions, slope efficiencies of 49% (57%) and 35% (40%) with respect to the launched (absorbed) pump power of the 805- and 975-nm pump wavelengths, respectively, were obtained. Efficient Yb(3+) --> Tm(3+) energy transfer and efficient cross relaxation combined with minimal upconversion losses were thus operating. At the maximum output power of 18 W, the fiber laser operated at a center wavelength of 2050 nm.     

Resonant optical nonlinearity measurement of Yb(3+) / Al(3+) codoped optical fibers by use of a long-period fiber grating pair

A new method of measuring optical nonlinearity for resonant nonlinear optical fibers is proposed. A long-period fiber grating (LPG) pair was used to measure the nonlinear refractive index n(2) of a Yb(3+)/Al (3+) codoped optical fiber, which was spliced between the two LPGs, as the fiber was pumped with a laser diode. The nonlinear refractive index of the Yb(3+)/Al (3+) codoped fiber near 1580 nm depended on the pump power. As the pump power increased, the nonlinear refractive index decreased. At launched pump powers of 2-8 mW, the nonlinear refractive index of the Yb(3+)/Al (3+) codoped fiber near 1580 nm was ~7.5x10(-15)m (2)/W .     

Wavelength tunable high power laser using a double-clad Er:Yb doped fiber

We experimentally demonstrated a stable, wavelength-tunable fiber laser using a polarization-maintaining, double-clad Er:Yb doped fiber amplifier in the cavity. The output wavelength is tunable over the range from 1535 to 1567 nm using a fixed grating and the dichroic mirror placed on a rotational mount; under rotation of the dichroic mirror the tuning ratio of 50 nm/deg was found. We studied the wavelength tuning range dependence on the amplifier fiber length and achieved a maximal output power of 850 mW. This configuration can be Q-switched for high peak power and its narrow bandwidth is suitable for nonlinear optics applications, such as parametric teraherthz generator.     

双包层掺Yb3+光纤环形脉冲激光形成研究

对采用环形腔结构,由偏振敏感的光隔离器构成超短脉冲掺Yb³⁺光纤激光器输出的动力学特性进行了数值模拟.模拟表明:在没有进行色散补偿的掺Yb³⁺光纤环形激光器中,采用非线性偏振旋转的附加脉冲锁模技术,通过改变偏振控制器的方向,可以使激光器工作在不同的区域.实验用976 nm的半导体激光器作为泵浦源,通过调整偏振控制器,实验观测到掺Yb³⁺环形激光器工作在稳态和自脉动状态,其脉动的周期由光纤激光器腔长决定.     

宽带可调谐掺Yb3+双包层光纤激光器的研究

利用闪耀光栅构成可调谐Littrow外腔,对掺Yb³⁺双包层光纤激光器的波长调谐输出进行了实验研究.激光调谐输出波长范围70nm.针对光纤内的双折射效应对激光的输出功率的影响,实验中使用了在线光纤偏振控制器,从而有效地减小了调谐曲线的起伏及其与荧光谱的差别,并得到了窄线宽、线偏振、宽带调谐的激光输出.     

国产光纤实现同带抽运3000W激光输出

同带抽运是目前实现高功率光纤激光器的有效手段.本文基于同带抽运方式,以国产25/250μm掺镱双包层光纤为增益光纤,构建了全光纤化的主控振荡器功率放大器.实验中采用的国产光纤是中国电子科技集团公司第四十六研究所采用化学气相沉积结合气相-液相复合掺杂工艺制备的,其Yb~(3+)离子的分布更均匀,吸收截面更大,吸收系数更高.实验中,在种子光功率为67.8 W、抽运总功率为3511 W的条件下,实现了3079 W的激光输出,斜效率为85.9%,光束质量M~2约为2.14,3dB带宽为1.4nm,这是目前基于国产光纤同带抽运方式实现的最高功率.理论和实验结果表明国产光纤制备技术不断成熟,已经具备承受高功率输出的能力.继续提高抽运功率,优化增益光纤长度,改良散热方式,国产光纤有望实现更高功率的激光输出.     

Two-color fiber amplifier for short-pulse, mid-infrared generation

A short-pulse, two-color Yb:fiber laser system has been developed for mid-infrared generation. To date, 20 microW of average power at a wavelength of approximately 18 microm is generated by difference-frequency mixing 300 mW average power from the two-color Yb:fiber amplifier. The mid-infrared power was not limited by two-photon absorption, allowing it to be scaled by increasing the amplifier power.     

A High Efficiency Yb~(3 )-doped Fiber Ring Cavity Laser with Narrow Line-width

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Er3+-Yb3+共掺磷酸盐玻璃(LGS-L)波导放大器设计

就作者自行研制的Er3 + Yb3 + 共掺磷酸盐玻璃 (LGS L) ,用重叠积分方法进行放大器设计。在Er3 + 、Yb3 + 掺杂浓度分别为 1.5 1× 10 2 6ions/m3 、19.1× 10 2 6ions/m3 的情况下可获得 2 .6dB/cm的增益 ;Er3 + 掺杂浓度为2× 10 2 6ions/m3 时 ,在 4cm的器件上可获得超过 15dB的增益。此外 ,讨论了信号光和抽运光光场强度的横向分布与Er3 + 、Yb3 + 横向掺杂浓度分布之间的重叠对放大器增益的影响 ,放大器的最佳长度 ,以及在 980nm抽运下 ,Yb3 + 、Er3 + 掺杂浓度比对放大器增益的影响。     

Efficient special S-band ytterbium fiber laser emitting at 1012 nm and its application in tandem pumping

We presented the first demonstration of a special S-band Yb-doped fiber laser with a central wavelength of 1012 nm. By pumping common alumosilicate fiber doped with 974 nm laser diode, efficient lasing at 1012 nm was achieved with a maximal output power of 331 mW and 55% power conversion efficiency. We also built a fiber amplifier to validate the feasibility of the 1012 nm laser as the tandem pump source by boosting the 1064 nm C-band laser power up. The slope efficiency of the tandem-pumped fiber amplifier is 63%.     

Yb,Na:PbF(2): a potential new high-power laser material

Yb:PbF(2) and Yb,Na:PbF(2) laser crystals are grown by the Bridgman method. Room-temperature absorption, photoluminescence spectra, and fluorescence lifetimes of Yb(3+) ions in the crystals have been investigated. Experimental results show that Na(+) ions codoping with Yb(3+) as charge compensators can suppress the deoxidization of Yb(3+) to Yb(2+). The result of diode-pumped laser operation of a Yb,Na:PbF(2) single crystal is reported for the first time to the best of our knowledge . With a 1mol.%Yb(3+)-doped sample, we obtained 2.37W output power at 1056nm for 17.9W of incident power at 978nm.