LD抽运的Nd：YLF／Cr^4＋：YAG被动调Q激光器

报道了激光二极管（LD）抽运的Nd：YLF激光器，采用平凹腔结构，分别用两片Cr^4＋：YAG可饱和吸收晶体，实现了被动调Q，输出激光波长为1053nm。采用厚度为0．5mm小信号透过率为90％的Cr^4＋ YAG，在泵浦功率最大为17W时，输出脉冲宽度为60．6ns，平均功率为1．5W，重复频率为9．5kHz，单脉冲能量为157．9mJ；采用厚度为0．55mm小信号透过率为95％的Cr^4＋ YAG，在泵浦功率最大为17W时，输出脉冲宽度为68．6ns，平均功率为1．35W，重复频率为14kHz，单脉冲

Ultrabroad infrared luminescences from Bi-doped alkaline earth metal germanate glasses

We report on ultrabroad infrared (IR) luminescences covering the 1000-1700-nm wavelength region, from Bi-doped 75GeO(2) 20RO-5Al(2)O(3) 1B(2)O(3) (R = Sr, Ca, and Mg) glasses. The full width at half-maximum of the IR luminescences excited at 980 nm increases (315 -> 440 -> 510 nm) with the change of alkaline earth metal (Mg2+ -> Ca2+ -> Sr2+). The fluorescence lifetime of the glass samples is 1725, 157, and 264 mu s when R is Sr, Ca, and Mg, respectively. These materials may be promising candidates for broad-band fiber amplifiers and tunable laser resources.

Surface morphology and properties of zirconia thin films prepared at different deposition rates

ZrO2 thin films were prepared on BK7 glass substrates by electron beam evaporation deposition method. The influence of deposition rate varying from 1.2 to 6.3 nm s(-1) on surface morphology and other properties of ZrO2 films were examined. With increasing deposition rate, the surface defect density increased. The decrease in half width at full maximum in X-ray diffraction pattern with deposition rate indicates an increase in crystal dimension with increasing deposition rate. Electron beam deposited ZrO2 films are known to be inhomogeneous. From the change of the peak transmittance value, it can be deduced that the inhomogeneity of ZrO2 films strengthened gradually with increasing deposition rate. The type of surface defects changed from nodules to craters when the deposition rate was high enough.

High-reflectance 193 nm Al2O3/MgF2 mirrors

Thin-film single layers of Al2O3 and MgF2 were deposited upon super polished fused-silica by electron-beam evaporation. The subsequent optical constants n and k were reported for the spectral range of 180-230 nm. High-reflectance dense multilayer coatings for 193 nm were designed on the basis of the evaluated optical constants and produced. The spectra of the reflectance of HR coatings were compared to the theoretical calculations. HR mirrors of 27 layers with a reflectance of more than 98% were reported. (c) 2004 Elsevier B.V. All rights reserved.

南亚热带森林生态系统中土壤微生物与氮素循环的研究

该成果的主要的研究结果有：１.南亚热带森林土壤微生物的分解作用明显，促进了养分循环，凋落物年分解释放的氮约为植物生长需氮量的70%，生物循环是本地带最重要的营养循环机制之一；２.土壤微生物与土壤氮素关系密切并有一定的规律性；３.土壤微生物营养库，在调节植物营养方面有重要作用；４.报道了１０多种新的豆科固氮植物资源及南亚热带森林中主要豆科植物固氮种类；５.豆科植物人工森林生态系统的固氮量为8.7---157 kg.ha-1.a-1 ，豆科固氮可成为森林重要氮源；６.固氮促进了植物对磷、钾元素的吸收和积累，固氮带动了其他营养元素的循环；７.磷素的植物体内再吸收利用率为62.5%，其量为生长需磷量的80％，对贫磷土壤的植物生长有重要意义；８.以多方面实测数据建立的氮循环模型，该成果填补了南亚热带森林生态系统氮素循环研究的空白。对森林生态系统和环境保护的理论研究和应用方面均有重要意义，可供科研、教学、环保及林业部门作参考。