Tm3+ ,Yb3+共掺微晶玻璃蓝色上转换荧光的温度特性

制备了Tm³⁺,Yb³⁺共掺氟氧化物微晶玻璃, 在980 nm二极管激光器泵浦下研究了其上转换发光。发现将前驱玻璃进行热处理后,源于Tm³⁺的¹G₄能级到基态³H₆跃迁所产生的蓝色上转换荧光在463 nm和476 nm出现明显劈裂。在此基础上分析了该劈裂蓝色上转换荧光在303~623 K范围内的温度特性。结果表明:Tm³⁺,Yb³⁺共掺氟氧化物微晶玻璃蓝色上转换荧光可应用于光学测温,其测温最大灵敏度为4.2×10^-4 K^-1,相应温度为352 K。     

NaYF4∶Eu3+, Tm3+, Yb3+材料中Stokes和反Stokes发光研究

合成了Eu3+,Tm3+和Yb3+掺杂的NaYF₄材料。360 nm光激发呈蓝色发光,峰值位于452 nm,对应Tm3+的1D₂→3F₄跃迁;395 nm光激发呈橙色发光,峰值位于591 nm,对应Eu3+的5D₀→7F₁跃迁;409 nm光激发呈红色发光,峰值位于613 nm,对应Eu3+的5D₀→7F₂跃迁;980 nm光激发呈蓝色和红色发光,发光峰位于474和646 nm。蓝光来源Tm3+的1G₄ →3H₆跃迁,红光来源Tm3+的1G₄→3F₄跃迁。在双对数曲线中,蓝光474 nm和红光646 nm的斜率分别为2.1和2.4,在980 nm光激发下,蓝光和红光发射都是双光子过程。还研究了材料的吸收光谱,并利用X射线衍射,扫描电镜测试了材料的物相结构和微观形貌。结果表明：NaYF₄∶Eu3+, Tm3+, Yb3+材料具有较规则的六方相结构,结晶良好。     

The Study on the Interaction between Tm3+ and Tb3+ Rare Earth Ions in YVO4 Crystal

In this paper the measurement result of transmission spectrum of Tb,Tm∶YVO4 is presented. The intensity Ωt, the probabilities of radiating transition, non-radiating transition, the cross-relaxation and the lifetimes of Tm3+ ions at 3H4 and 3F4 levels are calculated. The results show that when the concentration of Tm3+ ions >1.2 at.-%, the fluorescent lifetime of upper level 3H4 is shorter than that of lower level 3F4 due to the interaction between Tm3+ and Tb3+ ions, thus the lasing self-termination at ～1.5 μm can be eliminated.     

Tm∶YVO4晶体中Tm3+的发光研究

测量了Tm∶YVO4 晶体的吸收光谱 ,以 34 6nm、36 3nm(1D2 )、475nm(1G4 )、6 98nm (3 F2 ,3 F3 )和 80 1nm(3 H4 )光激发时的发射光谱 ,以及位于 45 4nm (1D2 → 3 F4 )、475nm (1G4 → 3 H6)、6 46nm (1G4 → 3 F4 )、80 6nm(3 H4 →3 H6)的荧光谱线的激发光谱 ,对测量的结果进行了详细分析 ,解释了离子能级间的跃迁过程。提出了Tm∶YVO4 晶体基质与Tm3 + 之间的能量交换的概念和新的跃迁通道 ,证实了存在1D2 +3 H6→1G4 +3 F4 以及1G4 +3 H6→3 H4 +3 H5的能量传递过程 ,还可能存在交叉弛豫过程 1G4 +3 H6→3 F2 +3 F4 。这些过程使得Tm∶YVO4 晶体难以实现1D2 能级上转换发光 (4 5 4nm左右 ) ,但 475nm的上转换发光 (1G4 →3 H6)较强 ,3 F4 能级是潜在红外激光发射能级。     

Tm(0.1)Yb(10.9)氟氧化物玻璃的直接上转换敏化发光

本文首次研究了Tm(0.1)Yb(10.9)氟氧化物玻璃在966nm半导体激光激发下的直接上转换敏化发光现象。测量发现存在很强的^1G4→^3H6的474nm三光子和较弱的^1D2→^3H6的362nm,^1D2→^3F4的452nm,^1G4→^3F4的650nm三光子以及^3F3→^3H6的681nm二光子上转换发光。并对他们的上转换机理做了简要的讨论分析。     

大尺寸掺钕和掺铥铝酸钇晶体的生长和退火技术

通过分析铝酸钇(YAP)晶体产生孪晶、开裂、色心和弥散性散射的原因,探讨了克服这些缺陷和问题的技术途径.采用提拉法生长了b轴方向的掺钕和掺铥铝酸钇(Nd:YAP和Tm:YAP)晶体,通过温场系统、生长工艺参数和切割工艺的优化,克服了晶体开裂的问题,晶体直径达到46mm;通过真空退火工艺,既显著减轻了紫外和可见区的色心吸收,又减小了晶体的应力,有助于克服晶体在加工过程中的开裂问题.晶体生长实验和晶体的显微观察表明:YAP晶体中的弥散状散射很可能同熔体中组分的均匀性有关,通过增大晶体的直径,增强强迫对流有助于减轻晶体中的弥散状散射.高质量b轴Nd:YAP和a轴Tm:YAP晶体已分别实现二极管泵浦大于140W的1.079μm和大于10W的1.99μm激光输出.     

Judd--Ofelt analysis of spectra and experimental evaluation of laser performance of Tm3+ doped Lu2SiO5 crystal

This paper reports that the Tm^3＋：Lu2SiO5 （Tm：LSO） crystal is grown by Czochralski technique. The roomtemperature absorption spectra of Tm：LSO crystal are measured on a b-cut sample with 4 at.% thulium. According to the obtained Judd-Ofelt intensity parameters Ω2=9.3155×10^-20 cm^2, Ω4=8.4103×10^-20 cm^2, Ω6=1.5908×10^-20 cm^2, the fluorescence lifetime is calculated to be 2.03 ms for ^3F4 → ^3H6 transition, and the integrated emission cross section is 5.81×10^-18 cm^2. Room-temperature laser action near 2μm under diode pumping is experimentally evaluated in Tm：LSO. An optical-optical conversion efficiency of 9.1% and a slope efficiency of 16.2% are obtained with continuouswave maximum output power of 0.67 W. The emission wavelengths of Tm：LSO laser are centred around 2.06μm with spectral bandwidth of -13.6 nm.     

应用于2.1μm激光的Tm~(3+)/Ho~(3+)共掺氟碲酸盐微结构光纤研究

采用棒管法制备了低羟基含量的Tm~(3+)/Ho~(3+)共掺氟碲酸盐微结构光纤。当使用波长为1 560 nm的激光器泵浦Tm~(3+)/Ho~(3+)共掺光纤时,处于Tm~(3+)基态3H6的电子被激发至3F4能级,进一步通过Tm~(3+)和Ho~(3+)间的能量传递过程3F4→3H6(Tm~(3+)):5I8→5I7(Ho~(3+))(能量失配为745 cm-1)布居Ho~(3+)的5I7能级,5I7能级上的电子向5I8能级跃迁发射出2.1μm的光。使用1 560 nm光纤激光器作为泵浦源,18 cm长的Tm~(3+)/Ho~(3+)氟碲酸盐微结构光纤作为增益介质,获得了波长为2 063 nm的激光输出。所得激光的斜率效率为12.9%,激光阈值为163 m W,未饱和的最大输出功率为40 m W。研究结果表明,Tm~(3+)/Ho~(3+)共掺氟碲酸盐微结构光纤可用于制作2.1μm光纤激光器。     

Sol-gel preparation and characterization of CoFe2O4-SiO2 nanocomposites

Magnetic nanocomposites formed by cobalt ferrite particles dispersed in a silica matrix were prepared by a sol-gel process. The effects of the thermal treatment temperature and the salt concentration on the structural and magnetic properties of the composites were investigated. By controlling these parameters, CoFe₂O₄/SiO₂ nanocomposites with different crystallite size and magnetic properties were obtained. By increasing the annealing temperature and salt concentration, composites with a progressive increase in the coercive field and of the density of magnetization were produced. In particular, a nanocomposite, with a Fe/Si molar concentration of 21%, obtained by drying the gel at 150 °C and further annealing at 800 °C, has a coercivity of 2000 Oe, which is more than twice higher than the coercivity of bulk cobalt ferrite.     

能量传递上转换对Tm，Ho：YLF调Q激光器上能级寿命的影响

根据激光二极管纵向抽运Tm,Ho：YLF激光器的能级跃迁和能量传递过程，在考虑能量传递上转换(ETU)的情况下，建立了Tm,Ho：YLF主动调Q激光器的准三能级速率方程，得出了激光单脉冲能量的解析表达式.在理论上指出，能量传递上转换不但减小了输出单脉冲能量，而且严重减小了激光上能级寿命.实验上给出了在固定抽运功率下，单脉冲能量随重复频率的变化关系，验证了理论所指出的能量传递上转换减小了激光上能级寿命. 关键词： 二极管抽运 Tm Ho：YLF晶体 能量传递上转换 速率方程