激光熔覆大厚度Fe57Co8Ni8Zr10Si4B13非晶表层及其微结构研究

利用激光熔覆制备出１.２ｍｍ厚的Ｆｅ５７Ｃｏ８Ｎｉ８Ｚｒ１０Ｓｉ４Ｂ１３大厚度非晶表层。用ＸＲＤ，ＥＤＳ，ＴＥＭ，ＤＳＣ及硬度仪对获得的非晶表层进行了多种分析，研究了非晶合金表层的微结构与非晶形成能力，初步探讨了大厚度非晶表层的形成机制。

Performance analyses of flowing chemical oxygen-iodine laser

A modified simplified rate-equation model that utilizes the Voigt profile function and another gain saturation model deduced from the kinetic equations are presented for performance analyses of a flowing chemical oxygen-iodine laser. Both models are adapted to both the condition of homogeneous broadening and that of inhomogeneous broadening being of importance and the condition of inhomogeneous broadening being predominant. Effects of temperature and iodine density on the output power and on variations of output power, optical intensity, and saturation intensity with flow distance are presented as well. There are differences between results of two models, but both qualitatively agree with known results.

Code conversion from signed-digit to complement representation based on look-ahead optical logic operations

We present, for the first time to our knowledge, a generalized lookahead logic algorithm for number conversion from signed-digit to complement representation. By properly encoding the signed-digits, all the operations are performed by binary logic, and unified logical expressions can be obtained for conversion from modified-signed-digit (MSD) to 2's complement, trinary signed-digit (TSD) to 3's complement, and quarternary signed-digit (QSD) to 4's complement. For optical implementation, a parallel logical array module using an electron-trapping device is employed and experimental results are shown. This optical module is suitable for implementing complex logic functions in the form of the sum of the product. The algorithm and architecture are compatible with a general-purpose optoelectronic computing system. (C) 2001 Society of Photo-Optical Instrumentation Engineers.

1.55-mu m InGaAs/InGaAlAs MQW vertical-cavity surface-emitting lasers with InGaAlAs/InP distributed Bragg reflectors

High-performance InGaAs/InGaAlAs multiple-quantum-well vertical-cavity surface-emitting lasers (VCSELs) with lnGaAlAs/InP distributed Bragg reflectors are proposed for operation at the wavelength of 1.55 mum. The lasers have good heat diffusion characteristic, large index contrast in DBRs, and weak temperature sensitivity. They could be fabricated either by metal-organic chemical vapor deposition (MOCVD) or by molecular beam epitaxy (MBE) growth. The laser light-current characteristics indicate that a suitable reflectivity of the DBR on the light output side in a laser makes its output power increase greatly and its lasing threshold current reduce significantly, and that a small VCSEL could output the power around its maximum for the output mirror at the reflectivity varying in a broader range than a large VCSEL does. (C) 2004 Elsevier Ltd. All rights reserved.

基于光弹调制技术的波片相位延迟量测量方法

提出了一种基于光弹调制技术的波片相位延迟量测量方法，利用米勒矩阵对其进行了理论推导和误差分析。测量光路包括激光器、起偏器、光弹调制器、被测波片、检偏器和光电探测器，利用探测信号的归一化基频分量和二次谐波分量精确计算出被测波片的相位延迟量。该方法能测量紫外到红外光谱范围内任意相位延迟量的波片，误差分析表明其误差小于0．05°。实验验证了该测量方法的有效性，波片相位延迟量的重复测量精度为0．0048°．

网络的发展对光盘应用的影响

一、引言21世纪是数字化和多媒体化的信息时代,随着社会和经济的发展,特别是IT产业的快速发展,全球信息每年以指数方式上升。最近IDC的研究报告指出,2006年,全球的信息量为1610亿GB;到2010年,全球数字信息量预计为9880亿GB。中国的数字信息总量,也将从2006年的127.1亿GB增加到900.5亿GB,占全球信息总量的9.1%。同时,根据国家信息产业部的年度

Far-field intensity distribution of a beam generated by a resonator with a phase-unifying mirror

The far-field intensity distribution (FFID) of a beam generated by a phase-unifying mirror resonator was investigated based on scalar diffraction theory. Attention was paid to the parameters, such as obscuration ratio and reflectivity of the phase-unifying mirror, that determine the FFID. All analyses were limited to the TEM00 fundamental mode. (c) 2005 Optical Society of America.

两种后处理方法对HfO2薄膜性能的影响

利用电子束蒸发和光电极值监控技术制备了氧化铪薄膜，并分别用两种后处理方法（空气中退火和氧等离子体轰击）对样品进行了处理．然后，对样品的透过率、吸收和抗激光损伤阈值进行了测试分析．实验结果表明，两种后处理方法都能不同程度地降低了氧化铪薄膜的吸收损耗、提高了抗激光损伤阈值．实验结果还表明，氧等离子体轰击的后处理效果明显优于热退火，样品的吸收平均值在氧等离子体后处理前后分别为34．8ppm和9．0ppm，而基频（1 064nm）激光损伤阈值分别为10．0J／cm^2和21．4J／cm^2．

Design of high-efficiency diffraction gratings based on rigorous coupled-wave analysis for 800nm wavelength

We report on the design of a high diffraction efficiency multi-layer dielectric grating with wide incident angle and broad bandwidth for 800 nm. The optimized grating can achieve > 95% diffraction efficiency in the first order at an incident angle of 5 degrees from Littrow and a wavelength from 770nm to 830 nm, with peak diffraction efficiency of > 99.5% at 800 nm. The electric field distribution of the optimized multi-layer dielectric grating within the gratings ridge is 1.3 times enhancement of the incidence light, which presents potential high laser resistance ability. Because of its high-efficiency, wide incident, broad bandwidth and potential high resistance ability, the multi-layer dielectric grating should have practical application in Ti:sapphire laser systems.

兴山龙门河地区的植物群落与物种多样性研究

龙门河地区地处湖北省的西部，神农架的南坡，处于中亚热带向北亚热带过渡的地带。对其植物与植物群落的研究得到如下结果： 龙门河地区共有维管植物160科724属1737种，其中种了植物140科692属共1686种。其植物区系有显著的温带性，温带分布属共380属，占总属数的54.9%，这可能和该地区的地理位置，海拔及人为活动的影响有关，该地区的植物区系还具有古老性，特有属丰富特点，且有较多的珍稀濒危植物分布。 龙门河地区的植被共划分三个自然植被型共16个群系。在高海拔地区保存有较原始的落叶阔叶林，低海拔地区多为人为破坏后的次生类型。这些植被类型随环境条件的变化呈现较有规律的分布，依照其垂直分布的情况，可以将该地区植被划为三个带，即常绿阔叶林带低于海拔900(-1300)m;常绿落叶阔叶混交林位于海拔900(-1300)-600m之间;落叶阔叶林带在海拔1600(-1300)-2200m之间，无针叶林带在龙门河地区分布。应用TWINSPAN和DCA程序对各调查样地进行数量分类和排序结果说明，植物群落的分布与环境因子明显相关，但排序轴不能用海拔等单个的因子来解释。对各群落乔木层的Gleason丰富度指数，Shannon-Wiener指数及Pielou均匀度指数对比后发现，各种指数在不同的群落之间及不同海拔高度上没有明显的规律，这可能是由于人类活动混淆了群落成分及结构的结果。 锐齿槲栎林是神农架地区一种重要的落叶阔叶林，其分布广泛，保存较好。通过对锐齿槲栎种群大小结构的研究发现，中等大小的锐齿槲栎个体数量较多，幼苗与幼树的数量在不同样地间变化很大，其大小结构分布图中多有一定程度的缺失。锐齿槲栎种群多呈现聚集分布，不同的尺度下其聚集程序不同。在大多数尺度下，幼苗幼树的聚集程度比相同尺度下成体的聚集程序高。幼苗更新是锐齿槲栎更新的一种主要形式，其幼苗的出现与林窗的形成有密切的关系。在锐齿槲栎幼苗成长为幼树的过程中，同于种内与种间竞争的影响。导致了许多幼树的死亡。正是由于林窗形成等干扰因素的影响才使锐齿槲栎幼树得以进入群落上层。