大模场面积光纤激光器79．4W单横模输出

abstract {A large-mode-area (LMA) multimode fiber before and after coiling was studied contrastively in the experiment. Single-transverse-mode output was achieved when the fiber laser was coiled around a mandrel of 65 mm radius. After coiling, beam quality factor of the laser dropped from 1.24 to 1.06 and slope efficiency dropped from 64.7% to 54.3%. When the launched pump power was 149 W, the corresponding output power was 94.7 W and 79.4 W, respectively. However, the brightness of the coiled fiber laser was 1.15 times that of the uncoiled. Coiled modal losses of different modes were also calculated for the fiber employed in the experiment. The measured results agree well with the calculated ones.}

掺铒碲钨酸盐玻璃及其平面波导

研制了一种用于宽带波导放大器的掺铒碲钨酸盐激光玻璃材料，对玻璃热稳定性、光谱性质进行了表征，并在其上采用离子交换法制作了平面光波导．掺铒碲钨酸盐玻璃的转变温度Tg和析品开始温度Tx分别为377．1和488．5℃；荧光半高宽为52nm；应用McCumber理论，计算得出Er^3+离子4I13／2→^4I15／2跃迁在峰值波长1532nm的受激发射截面为0．91×10^-20cm^2．不同条件下制作了在632．8nm处多模的平面光波导，通过拟合得到Ag^+离子在300℃的有效扩散系数De为2．82×10^-1

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.

白宝石晶体的高温强度及强化技术研究进展

白宝石高温强度的降低主要是由于c轴方向受到压应力时产生r面双晶所引起的。高温强度的下降导致其抗热震性能降低，从而限制了白宝石晶体作为红外窗口和头罩材料的应用。白宝石晶体的强化主要以消除双晶核以及控制双晶的扩展来实现。本文分析了影响白宝石强度的主要因素，在此基础上对目前白宝石晶体强化的方法进行了总结和分析。