272 W quasi-single-mode picosecond pulse laser of ytterbium-doped large-mode-area photonic crystal fiber

A large-mode-area(LMA) ytterbium-doped photonic crystal fiber(PCF) with core NA of 0.034 and core diameter of 50 μm was made by the stack-and-draw technique. The core is formed by Yb~(3+)/Al~(3+)/F-/P~(5+) co-doped silica glass containing 0.09 mol% Yb_2O_3 with an absorption coefficient at 976 nm up to 3.2 d B/m. The core glass with homogeneous distribution of Yb~(3+) ions and refractive index difference of 4 × 10~(-4) compared with pure silica was prepared by the sol-gel method and heat homogenization at 2000°C. Laser power amplification of this LMA PCF was studied using a seed source of 21 ps pulse duration and 48.7 MHz repetition rate at 1030 nm wavelength. With pump power of 520 W, a maximum 272 W(266 k W peak power) quasi-single-mode laser output with M~2 of 2.2 was achieved in a 4.7 m fiber length bent at a diameter of 47 cm with slope efficiency of 52%, and no obvious mode instability, stimulated Raman scattering, or thermal damage on the end facet of the fiber were observed.     

掺钕磷酸盐玻璃的小信号增益性能

测试了应用于神光Ⅱ系列装置93片N31型钕玻璃的小信号增益系数。结果表明,Nd2O3质量分数为2.2%的钕玻璃平均小信号增益系数为0.0387 cm-1,Nd2O3质量分数为3.0%的钕玻璃平均小信号增益系数为0.0416 cm-1,两种浓度的钕玻璃不同样品间小信号增益系数的起伏范围分别为0.86%和0.76%。根据所测定的增益值,表明N31型钕玻璃的增益起伏符合神光Ⅱ系列装置要求,为实现该装置中每一路增益性能的平衡提供了有力保障,也为今后对更大尺寸钕玻璃增益性质的控制提供了经验。     

掺镱PCF的端面处理工艺及激光性能研究（特邀）

基于自制的掺镱大模场光子晶体光纤,探索出一种高效快速的光子晶体光纤端面处理工艺。使用二氧化碳激光熔接机对光子晶体光纤进行旋转加热处理,并配合大口径光纤切割刀对塌缩区域进行切割。通过对比光纤在不同激光加热功率和加热时间下的塌缩效果,确定了最佳的加热功率和时间。对端面处理后的光纤进行激光震荡实验,测试光纤的激光性能,与未进行端面处理时的激光实验结果相比较,端面塌缩处理没有对光纤的激光性能产生较大的影响。通过所述的实验方法,成功得到高质量光子晶体光纤塌缩端面,空气孔塌缩界面齐整,且没有对光纤本身的激光性能产生较大的影响。实验工艺周期短、成功率高,证明利用激光加热塌缩来处理光子晶体光纤端面是一种非常有效的方法,极大地拓展了光子晶体光纤的使用范围,具有很强的实用价值。     

Determination of energy transfer and upconversion constants for Yb~(3+)/Er~(3+) codoped phosphate glass

<正>The energy transfer and cooperation upconversion processes are investigated in Yb~(3+)/Er~(3+) codoped phosphate glass.Based on the measured curves of output power versus incident power,the laser and spectroscopic parameters of the glass are fitted and analyzed.We focus on the resonant energy transfer constant k from Yb~(3+) to Er~(3+) as well as the cooperation upconversion coefficient C_(up) from ~4I_(13/2) of Er~(3+).The fitted k and C_(up) can give almost the same results for different thicknesses of glass disk with the same doping concentrations.The determination of these parameters is helpful for the development of Yb~(3+)/Er~(3+) codoped laser glass.     

激光二极管抽运自主研制铒玻璃实现325 mW连续激光输出

1.54μm波段激光在军事、医疗、通讯等领域有重要应用,而铒玻璃激光器以其能直接获得1.54μm波长激光输出受到广泛关注.中国对铒玻璃激光器进行研究的单位主要有:上海光学精密机械研究所,南开大学和西南技术物理所.对于连续抽运铒玻璃微片激光器,目前中国报道的最大输出功率低于100 mW,国际上报道的最大输出功率约350 mW.     

Watt-level Yb-doped silica glass fiber laser with a core made by sol-gel method

A Yb-doped silica glass fiber laser with a core made by sol-gel method is reported. The maximum power of 1.14 W is obtained with a pump power of 5.46 W at a wavelength of 976 nm. The slope efficiency is 34%. The refractive index fluctuation across the core is below 5×10^-4 at a doping level of Yb 0.15 mol%, A203 4.0 mol%, and P2O5 2.0 mol%. High background attenuation of 6 dB/m at 1 053 nm limites the slope efficiency and maximum output power.     

Determination of energy constants for Yb3＋/Er3＋ transfer and upconversion codoped phosphate glass

The energy transfer and cooperation upconversion processes are investigated in Yb3＋/Er3＋ codoped phos- phate glass. Based on the measured curves of output power versus incident power, the laser and spectroscopic parameters of the glass are fitted and analyzed. We focus on the resonant energy transfer constant k from Yb3＋ to Er3＋ as well as the cooperation upconversion coefficient Cup from 4113/2 of Era＋. The fitted k and Cup can give almost the same results for different thicknesses of glass disk with the same dop- ing concentrations. The determination of these parameters is helpful for the development of Yb3＋/Er3＋ codoped laser glass.     

溶胶凝胶法制备Yb3+/Er3+共掺氧化铝材料的光谱性质

为了得到更加有效的掺饵光波导放大器材料,采用改进了激活剂掺入途径的溶胶凝胶方法,制作了不同比例Yb3+Er3+共掺杂的γ相氧化铝粉体材料方法,测量了样品的吸收和光致发射光谱并进行了分析.结果表明,Yb3+离子的掺入能很大地提高样品对980nm左右激发光的吸收效率,Er3+离子1534nm主发射峰的发射强度最大增加了约6.3倍;体系中Yb3+:Er3+的掺杂存在最佳比例,最佳掺杂比例约为6:1;同时X射线衍射法测试表明,最佳的热处理温度为900℃,相同的热处理温度下,Yb3+的掺入能延缓Al2O3由无定形相向γ相转变的过程,这一结果对进一步改善掺饵光波导放大器的特性是有帮助的.