Proton-exchanged optical waveguides fabricated by glutaric acid

In this paper, we first report that a new proton source, glutaric acid, has been used to fabricate optical waveguides in Z-cut lithium niobate crystals. The relationship was experimentally established between proton-exchanged (PE) waveguide parameters and fabrication conditions. It is shown that this new organic acid can be used to obtain deep PE waveguides in fast diffusion speed (0.275 μm²/h at 221°C) and with low loss (0.2 dB/cm). It provides an alternative approach for fabricating PE waveguides in lithium niobate substrate.     

Synthesis and Raman analysis of 1D-ZnO nanostructure via vapor phase growth

1D-nanostructural zinc oxide (ZnO) with different shapes have been synthesized on p-type Si(1 0 0) and glass substrates via vapor phase growth by heating pure zinc powder at temperatures between 480 and 570 °C. The different ZnO nanostructures depend on the substrates and the growth temperatures. Scanning electron microscopy and X-ray diffraction revealed that a well-aligned nanowires array, which are vertical to the substrate of Si(1 0 0) with 18 sides on their heads, but six sides on their stems, has been formed at 480 °C. Raman study on the ZnO nanostructures shows that the coupling strength between electron and phonon determined by the ratio of the second- to the first-order Raman scattering cross-sections declines with decreasing diameter of the nanowires. However, a little changes of the coupling strength in terms of the width of the nanobelts have been observed.     

The Novel Y-Branch With Two Reflectors

A novel Y-branch waveguide with two reflectors is proposed. The normalized transmitted power for the branching angle of 50°is greater than 70%, which is higher than conventional Y-branch with such wide angle.     

Comparative investigation of up-conversion luminescence in Tm/Yb-codoped germanate-niobic and germanium-bismuth glasses: effect of phonon density on up-conversion emission

Tm³⁺/Yb³⁺-codoped germanate-niobic (GN) and germanium-bismuth (GB) glasses have been synthesized by conventional melting and quenching method. Intense blue and weak red emissions centered at 477 and 650 nm, corresponding to the transitions ¹G₄→³H₆ and ¹G₄→³H₄, respectively, were observed at room temperature. The possible up-conversion mechanisms are discussed and estimated. GN glass showed a weaker up-conversion emission than GB glass, which is inconsistent with the prediction from the difference of maximum phonon energy between GN and GB glasses. In this paper, Raman spectroscopy was employed to investigate the origin of the difference in up-conversion luminescence in the two glasses. Compared with phonon side-band spectroscopy, Raman spectroscopy extracts more information including both phonon energy and phonon density. For the first time, our results reveal that, besides the maximum phonon energy, the phonon density of host glasses is also an important factor in determining the up-conversion efficiency.     

离子注入诱导量子阱界面混合效应的光致荧光谱研究

采用多元芯片方法获得了一系列不同离子注入剂量的GaAsAlGaAs非对称耦合量子阱单元,通过光致荧光谱测量,研究了单纯的离子注入导致的界面混合效应.荧光光谱行为与有效质量理论计算研究表明,Al原子在异质结界面的扩散在离子注入过程中已基本完成,而热退火作用主要是去除无辐射复合中心. 关键词： 量子阱 离子注入 光致荧光谱 界面混合     

SO_4~(2)/ZrO_2-SiO_2超强酸催化剂研究(Ⅲ)——酸性及比表面积(英文)

系统地研究了SO2 - 4/ZrO2 _SiO2 催化剂的酸性和比表面积 ,采用吸附吡啶的红外光谱法、BET法以及指示剂法考察了催化剂的组成、温度以及其他处理条件对催化剂酸强度以及催化剂比表面积的影响 .实验结果表明 :在硅锆比小于 10时 ,SO2 - 4/ZrO2 _SiO2 催化剂的比表面积随催化剂中硅锆比的增高而增大 ;在硅锆比为 10左右时 ,比表面积可高达 4 40m2 / g ,数倍于SO2 - 4/ZrO2 催化剂的比表面积 .在相同处理条件下 ,SO2 - 4/ZrO2 _SiO2 催化剂的酸强度低于SO2 - 4/ZrO2 的酸强度 .吸附吡啶的红外光谱证明该催化剂的表面酸点多为Lewis酸点     

Activity coefficients for NaBr in aqueous ternary solutions with sodium propionate and butyrate from EMF measurements

The activity coefficients of NaBr in the NaBr–NaPropionate–H₂O and NaBr–NaButyrate–H₂O systems were determined from EMF measurements at constant total ionic strength of 0.1 0.5 1.0 1.5 2.0 and 2.5 mol-kg^–1 and at 25° C. The activity coefficients were fitted using Scatchard, Pitzer and Lim equations. Finally the excess Gibbs free energy of these mixtures were also calculated.     

单模光纤中皮秒啁啾脉冲压缩

对单模光纤正群速色散区秒啁啾脉冲的非线性传进行了近似的解析分析和定量的数值计算。结果表明，负啁啾脉冲在传输过程中能得到有效压缩。压缩比与脉冲初始峰值功率和初始啁啾程度有关。初始峰值功率一定的脉冲，其压缩比随初始啁啾程度的增大面大，初始啁啾程度一定的脉冲，压缩比随初始峰值功率的增大而减小，表明自相位调制效应导致脉冲压缩效果变差。计算结果还表明，在脉冲时域宽度得到压缩的同时，光谱宽度也能得到同步压缩。     

广西农业科研院所科技开发现状、问题和对策研究

全面系统总结分析了广西农业科研院所科技开发现状，归纳出五大主要技术开发类型和目前科技开发存在的７个主要问题；提出了广西农业科研院所科技开发的十大措施与对策．     

确定事件视界的新公式

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