铋化物发光玻璃中银表面等离激元对铒离子的发光增强作用

局域表面等离激元可以由自由空间的光直接激发,这也是局域表面等离激元的优点所在。研究铋化物发光玻璃中纳米银颗粒的表面等离激元对铒离子发光的增强效应、进一步的提高铋化物发光玻璃中铒离子的发光性能很有意义。首先,测量了(A)Er 3+(0.5%)Ag(0.5%):铋化物发光玻璃与(B)Er 3+(0.5%):铋化物发光玻璃样品的吸收谱,发现(A)Er 3+(0.5%)Ag(0.5%):铋化物发光玻璃在约600.0 nm处有一个较弱的宽的银表面等离激元共振吸收峰。同时发现两者都有典型的铒离子的吸收峰,它们的吸收几乎完全一样:在波峰形状、峰值强度和峰值波长等方面都很相近。测量了(A)Er 3+(0.5%)Ag(0.5%):铋化物发光玻璃和(B)Er 3+(0.5%):铋化物发光玻璃样品的激发谱,发现有位于379.0,406.0,451.0,488.0和520.5 nm的5个550.0 nm可见光的可见激发谱峰,和位于379.0,406.5,451.0,488.5,520.5,544.0,651.5和798.0 nm的8个1531.0 nm红外光的红外激发谱峰,容易指认出依次为Er 3+的4I 15/2→4G 11/2,4I 15/2→2H 9/2,4I 15/2→(4F 3/2,4F 5/2),4I 15/2→4F 7/2,4I 15/2→2H 11/2,4I 15/2→4S 3/2,4I 15/2→4F 9/2和4I 15/2→4I 9/2跃迁的吸收峰,通过测量发现(A)Er 3+(0.5%)Ag(0.5%):铋化物发光玻璃相对于(B)Er 3+(0.5%):铋化物发光玻璃样品的可见和红外激发谱的最大增强依次分别是238%和133%。最后,测量了它们的发光谱,发现有位于534.0,547.5和658.5 nm的三组可见发光峰,容易指认出依次为Er 3+的2H 11/2→4I 15/2,4S 3/2→4I 15/2,4F 9/2→4I 15/2荧光跃迁。还发现红外发光峰位于978.0和1531.0 nm,依次为Er 3+的4I 11/2→4I 15/2和4I 13/2→4I 15/2的荧光跃迁。通过测量发现(A)Er 3+(0.5%)Ag(0.5%):铋化物发光玻璃相对于(B)Er 3+(0.5%):铋化物发光玻璃样品的可见和红外发光谱的最大增强依次分别是215%和138%。对于银表面等离激元增强铒离子发光的机理,认为主要为纳米银颗粒的局域表面等离激元共振,造成金属纳米结构附近产生的局域电场的强度要远大于入射光的电场强度,从而导致了金属纳米结构对入射光产生强烈的吸收和散射,进而导致了荧光的增强;即局域表面等离子体共振局域场的场增强效应。     

高功率激光运转条件下大模场掺镱石英光纤模式特性的仿真研究

在高功率激光运转条件下,掺杂稀土离子的量子亏损和玻璃材料的本征吸收均会造成光纤放大器中增益光纤温度的整体上升与梯度分布。在热平衡状态下,光纤材料的热光效应将会诱导光纤横向折射率的再分布,引发高功率激光运转条件下增益光纤模式特性的改变。为此,利用多物理场有限元建模的数值计算方法对高功率激光运转条件下大模场掺镱石英光纤的热致模式特性展开系统研究,分析总结大模场增益光纤的模式特性在不同激光运转功率、增益光纤设计参数(纤芯直径、数值孔径、热光系数)和光纤弯曲使用条件下的变化规律。结果表明,随着激光运转功率的增加,纤芯和包层之间的温差会变大,从而导致光纤的归一化参数V值增大,最终使模式的传输损耗系数减小,模式在纤芯区域的功率因子增大。     

基于线粒体co I 基因探讨无尾目10个科的分子系统关系

运用PCR技术和相关生物软件，对大头蛙Limnonectes kuhlii和脆皮大头蛙Limnonectes fragilis的线粒体coⅠ基因全序列进行了测定与分析．结合GenBank上已公布的无尾目10个科22个物种的同源序列，以爬行纲楔齿蜥Sphenodon punctatus和密河鳄Alligator mississippiensis为外群，基于核苷酸序列（选取前两位密码子）和氨基酸序列两种数据形式，分别构建NJ树和MP树．结果表明：系统树将无尾目10个科分为两大支，一支为新蛙亚目Neobatrachia的5科15个物种，一支为古蛙亚目Archaeobatrachia的5个科9个物种（其中包括锄足蟾科Pelobatidae和负子蟾科Pipidae），并推测这两个亚目均为单系群．古蛙亚目一支内的盘舌蟾科Discoglossidae与铃蟾科Bombinatoridae亲缘关系较近；新蛙亚目内蟾蜍科Bufonidae与雨蛙科Hylidae，蛙科Ranidae与树蛙科Rhacophoridae两两亲缘关系较近．蛙科中泽陆蛙Fejervarya limnocharis与大头蛙属3个种首先形成姐妹群，表明其较近的亲缘关系，同时推断大头蛙与福建大头蛙Limnonectes fujianensis亲缘关系近于脆皮大头蛙．     

Fe对掺钕磷酸盐激光玻璃激光性能的影响

 在理论分析的基础上,具体讨论了Fe质量分数小于10^-4对1 053 nm处光吸收损耗和Nd³⁺无辐射跃迁几率的影响规律,发现Fe在1 053 nm处的光吸收损耗和Nd³⁺无辐射跃迁能量转移都与Fe质量分数成平方关系增长, Fe对1 053 nm光吸收的影响较大而Fe与Nd³⁺之间的能量转移不足50 Hz。这对生产过程中Fe含量的控制有重要指导意义。     

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.     

Spectroscopic properties of neodymium-doped tellurite glass fiber

Nd~(3+)-doped tellurite glass and a single mode tellurite glass fiber with a core diameter of 8 μm were prepared in this work. The 1.33-μm emission from the ~4F_(3/2)→~4I_(13/2) transition of Nd~(3+) with a spectral bandwidth of 55 nm in tellurite glass fiber is observed. The lifetime of 164 μs of ~4F_(3/2) level and quantum efficiency of about 100% are obtained.     

Amplified spontaneous emission properties of a single mode Er3+-doped tellurite fiber

Spectral characteristics of the amplified spontaneous emission(ASE)from a novel single mode Er3+ doped tellurite fiber with D-type cladding is reported in this letter.When pumped at 980 nm,an ASE source that has nearly a 100-nm flat FWHM bandwidth is obtained with a fiber length of 30-60 cm. Variation of ASE spectra with pump powers and fiber lengths are measured.Output power up to 2.0 mW is obtained with a launched pump power of 660 mW.     

Yb3+掺杂浓度对Er3+/Yb3+共掺SiO2-Al2O3-La2O3玻璃光谱性质的影响

测量了不同Yb3+ 离子掺杂浓度下 ,Er3+ /Yb3+ 共掺SiO2 Al2 O3 La2O3玻璃的吸收光谱、荧光光谱和Yb3+离子2 F5/ 2 的能级寿命 ,应用迈克康伯 (McCumber)理论计算了Er3+ 的受激发射截面σemi,讨论了Yb3+ 离子浓度对其自身吸收性质、Er3+ 离子发光性质 ,以及Yb3+ →Er3+ 能量传递效率 (η)的影响 ,初步探明该基质玻璃中Yb3+ 离子掺杂数浓度的最佳范围为 3 .94× 1 0 2 0 cm- 3至 5 .92× 1 0 2 0 cm- 3,在此掺杂范围内 ,Yb3+ 离子的最大吸收系数为9.8cm- 1 ,Er3+ 的峰值发射截面和Yb3+ →Er3+ 能量传递效率 (η)分别为 0 64× 1 0 - 2 4 m2 和 92 %。     

高能、超短脉冲、可调谐激光器用掺镱氟磷酸盐玻璃研究进展

Yb^3 与其它稀土离子相比有最简单的能级结构，这使它具有一些独特的性质，如避免激发态吸收，消除上转换和浓度猝灭等，因此它是高能输出激光器介质的理想掺杂离子。氟磷玻璃综合了氟化物玻璃和磷酸盐玻璃的优点，可降低磷酸盐的声子能量，改善其易吸湿性；提高氟化物玻璃的物理化学性能等，这使它成为稀土掺杂可调谐光纤激光器的很好的掺杂介质。众多研究表明，Yb^3 掺杂氟磷玻璃是一种很有前途的激光工作物质。本文总结了Yb^3 掺杂氟磷玻璃的特点，性质，结构及存在的问题。     

Spectra and lasing properties of Er~(3+),Yb~(3+):phosphate glasses

The effects of Al_2O_3, Yb_2O_3, Er_2O_3 and OH~- on spectral properties of P_2O_5.Na_2O.SrO.Al_2O_3.Yb_2O_3.Er_2O_3 erbium phosphate glass were studied. 5, 8, and 13 mol% Al_2O_3, 4, 5, 6, 7 and 8 mol% Yb_2O_3 and0.05, 0.2, and 0.4 mol% Er_2O_3 were used. It was found that Al_2O_3 can improve fluorescent lifetime ofEr~(3+)ions, but the integrated absorption cross section of Er~(3+)ions decreases with the increase of Al_2O_3concentration. Evaluating from energy transfer efficiency of Yb~(3+)to Er~(3+)and spectral parameters ofYb~(3+)and Er~(3+),we conclude that 6 mol% Yb_2O_3 and 0.4 mol% Er_2O_3 are needed for LD pumped