Cooperative downconversion in GdAl3(BO3)(4): RE3+,Yb3+ (RE=Pr, Tb, and Tm)

An efficient near-infrared (NIR) quantum cutting (QC) in GdAl3(BO3)(4):RE3+,Yb3+ (RE=Pr, Tb, and Tm) phosphors has been demonstrated, which involves the conversion of the visible photon into the NIR emission with an optimal quantum efficiency approaching 200%, by exploring the cooperative downconversion mechanism from RE3+ (RE=Pr, Tb, and Tm) excitons to the two activator ions, Yb3+. The development of NIR QC phosphors could open up a new approach in achieving high efficiency silicon-based solar cells by means of downconversion in the visible part of the solar spectrum to similar to 1000 nm photons with a twofold increase in the photon number. (c) 2007 American Institute of Physics.

Tm^3＋-Yb^3＋共掺氧氟硅酸盐玻璃热学性能和上转换发光特性研究

稀土掺杂氧氟玻璃是一种优良的上转换发光材料，制备了组分为35SiO2—15AlO1.5-（45-x）PbF2-xCdF2—0．1TmF3—1．5YbF3（x=0，10，20，30）的氧氟硅酸盐玻璃，系统研究了CdF2含量对其热学性能和光学性能的影响。研究表明用CdF2部分替代PbF，可以提高玻璃的热稳定性、使紫外吸收截至边向短波方向移动；随着CdF2含量的增加，开始Tm^3＋蓝光和红光上转换发光增强缓慢，而后迅速增强．而近红外上转换发射先显著增强后增强放缓；由于蓝光和近红外发光强度远大于红光发光强度，所以

980 nm 抽运下Yb-Tm-Ho 三掺氟磷酸盐玻璃的2 μm 荧光性质

The thermal stability, 2 μm fluorescence properties and energy transfer mechanism in Ho³⁺ doped fluorophosphate glass sensitized by Yb³⁺ and Tm³⁺ were investigated. The characteristic temperatures, absorption spectrum and fluorescence spectrum of the glass sample were measured. ΔT calculated from the characteristic temperatures shows that the thermal stability of fluorophosphate glass is better than fluoride glass. According to the absorption spectrum, several spectroscopic parameters of the glass sample, such as Judd-Ofelt parameters and spontaneous transition probability were calculated and compared with other glass hosts. The largest spontaneous transition probability for Ho³⁺:⁵ I7&rarr⁵I8 transition in fluorophosphate glass which is 78.48 s^-1 indicates that fluorophosphate glass is an appropriate base glass to achieve 2 m fluorescence. From the fluorescence spectrum of the glass sample, the extremely strong 2.0 μm fluorescence intensity is observed, which is higher than the intensity of 1.8 μm fluorescence, showing that Ho³⁺ ions sensitized by Yb³⁺ and Tm³⁺ is efficient. Meanwhile, the absorption sections and emission sections of Yb³⁺, Tm³⁺ and Ho³⁺ were calculated and the pumping scheme and energy transfer mechanism among Yb³⁺, Tm³⁺ and Ho³⁺ are discussed. The study indicates that Yb-Tm-Ho tri-doped fluorophosphate glass is a significant sensitization glass system under 980 nm excitation for 2 μm applications.

铒玻璃在1．54μm实现1 Hz下3 J和5 Hz下0．6 J的激光输出

近年来,随着激光告警、激光指示、风速测量、激光雷达尤其是激光美容等方面的需求逐渐增加,要求掺铒激光玻璃能够实现比以往更高重复频率以及更大能量的激光输出,其中对脉冲能量的要求达1～10 J。

Structural and up-conversion luminescence properties in Tm (3+)/Yb3+-codoped heavy metal oxide-halide glasses

Tm3+/Yb3+-codoped heavy metal oxide-halide glasses have been synthesized by conventional melting and quenching method. Structural properties were obtained based on the Raman spectra, indicating that halide ion has an important influence on the phonon density and maximum phonon energy of host glasses. Intense blue and weak red emissions centered at 477 and 650 nm, corresponding to the transitions (1)G(4) -> H-3(6) and (1)G(4) -> H-3(4), respectively, were observed at room temperature. The possible up-conversion mechanisms are discussed and estimated. With increasing halide content, the up-conversion luminescence intensity and blue luminescence lifetimes of Tm3+ ion increase notably. Our results show that with the substitution of halide ion for oxygen ion, the decrease of phonon density and maximum phonon energy of host glasses both contribute to the enhanced up-conversion emissions. (c) 2005 Elsevier B.V. All rights reserved.

Broadband near-infrared emission in Er3+-Tm3+ codoped chalcohalide glasses

The near-IR emission spectra of Er3+-Tm3+ codoped 70GeS(2)-20In(2)S(3)-10CsI chalcohalide glasses were studied with an 808 nm laser as an excitation source. A broad emission extending from 1.35 to 1.7 mu m with a FWHM of similar to 160 nm was recorded in a 0.1 mol.% Er2S3, 0.5 mol.% Tm2S3 codoped chalcohalide glass. The fluorescence decay curves of glasses were measured by monitoring the emissions of Tm3+ at 1460 nm and Er3+ at 1540 nm, and the lifetimes were obtained from the first-order exponential fit. The luminescence mechanism and the possible energy-transfer processes are discussed with respect to the energy-level diagram of Er3+ and Tm3+ ions. (C) 2008 Optical Society of America

Cooperative downconversion in Yb3+-RE3+ (RE = Tm or Pr) codoped lanthanum borogermanate glasses

We report on cooperative downconversion in Yb3+-RE3+ (RE = Tm or Pr) codoped lanthanum borogermanate glasses (LBG), which are capable of splitting a visible photon absorbed by Tm3+ or Pr3+ ions into two near-infrared photons. The results indicate that Pr3+-Yb3+ is a more efficient ion couple than Tm3+-Yb3+ in terms of cooperative downconversion. We have obtained a highest quantum yield of 165% and 138% for Pr3+-Yb3+ and Tm3+-Yb3+ codoped LBG glasses under 468 nm excitation, respectively. However, ultraviolet light excitation to the charge transfer band of Yb3+ does not result in quantum splitting as rapid relaxation from the charge transfer band to 4f(13) levels of Yb3+ dominates. (C) 2008 Optical Society of America

室温下连续波运行Tm:YAP泵浦的Ho:YAG激光器

我们报道了一种以二极管泵浦的 1.94 μm Tm:YAP激光器为泵浦源，常温下在2.1 μm连续运行的Ho:YAG激光器。最大输出功率1.5 W，相应斜率效率为17.9%，二极管到的转换效率为5.6%。

提拉法Tm：YAG晶体的生长缺陷研究

采用提拉法(CZ)生长了质量优异的Tm：YAG晶体．部分晶片在1000℃的空气气氛中退火25h．借助光学显微镜、扫描电子显微镜(SEM)，结合化学腐蚀法，对Tm：YAG晶体退火前后(111)面的缺陷特征进行了研究．Tm：YAG晶体(111)面的位错腐蚀坑呈三角形．在偏光显微镜下观察了退火前后Tm：YAG晶体(111)面的应力双折射．同时应用高分辨X射线衍射法测定了晶体的完整性．实验结果表明，长时间空气气氛下高温退火有效降低了晶体中总的位错密度，提高了晶体质量．