有机-无机复合ZrO2-SiO2平面光波导

采用溶胶-凝胶法合成ZrO2-SiO2有机一无机复合光波导材料,通过改变其中ZrO2的含量来调节材料的折射率,使材料分别适用于平面光波导的导光层(ng≈1．497)和衬底层、包层(mb=nc≈1．479)。采用旋转涂膜工艺和相应的热处理,在单晶硅基片上制备衬底层、导光层和包层等薄膜,其中导光层介质因具有感光性而可通过紫外光刻来制备光路图案。所得有机一无机复合ZrO2-SiO2板型平面光波导(衬底层 导光层),用棱镜耦合截断法测试其光损耗在632．8nm波长处约为0．8dB／cm。对板型平面波导的导光层薄膜进行紫外光刻和异丙醇淋洗,制备出脊状光波导通道,在覆盖包层后,即获得埋层沟道式平面光波导。采用端耦合截断法测试了埋层沟道式平面光波导的光损耗(小于0．1dB／cm),并观察了其近场图像以及导光材料在近红外窗口的吸收光谱。     

多层介质波导的一种新方法及其在非均匀介质平面光波导中的应用

本文提出求解多层介质平面光波导的一个简单而直接的方法。将其应用于非均匀平面光波导,可以求解任意折射率分布和TM模问题。以抛物线型和指数型分布为例,说明只要分层数目足够多,本文介绍的方法可以达到任意精度。     

用转移矩阵法研究LNN型非线性平面光波导

用转移矩阵法数值分析了芯区和衬底为非线性介质、覆盖层为线性介质结构平面光波导的传播特性,包括TM的模场分布和功率与有效折射率之间关系的分析.解析地表达了模式本征方程和功率分布,对非线性介质中电场强度与介质非线性系数的关系进行了研究.计算结果表明,TM的模场分布和功率与有效折射率及介质的非线性系数有关.     

PPQ共轭有机聚合物平面光波导的非线性传输特性的实验研究

从实验上研究了聚苯基喹恶啉（ＰＰＱ）共轭有机物平面光波导中的飞秒光脉冲的非线性传输特性，难过研究其光波导中由于自相位调制效应而导致的光谱展宽，得到了ＰＰＱ的非线性折射率，同时表明ＰＰＱ共轭有机物平面光波导中具较大的非线性效应，有可能制作较理想的全光器件。     

对称平面单轴晶体金属波导的模式场(1)

由于平面各向异性介质金属波导的重要应用,本文讨论了光在对称平面单轴晶体金属波导(波导层是单轴晶体,两个波导界面均为金属)内的传输特性.对于晶体光轴位于波导界面法方向与传输方向构成的平面内的特殊波导结构,利用麦克斯韦方程组并结合单轴晶体的性质,精确解出了波导模式场.结果表明:1)此种特殊结构波导内存在横电波(TE)和横磁波(TM);2)TM波的坡印廷矢量与波矢方向不在一条直线上;3)波导层为负单轴晶体时波导主模是TE波主模,而波导层为正单轴晶体时波导主模是TM波主模.     

多量子阱光波导中非线性TM波的有限元解

本文用有限元法分析了任意非线性介质的多量子阱(MQW)光波导中传输与总光功率有关的TM波性质。用简单的迭代过程得到目洽解。给出了MQW波导具有不同非线性机理时,非线性TM波的色散关系、磁场(Hx)以及二个电场(Ey和Ez)的分布。结果表明:分子取向机理的光波导对非线性TM模存在不同的功率限制作用。     

非中心对称介质构成的光波导中的孤子传输

众所周知,由非线性Schr?dinger方程描述的光学孤子可以在光纤(由中心对称介质构成的光波导)中稳定传输。本文在理论上证明,在强色散的条件下,非中心对称介质构成的光波导中(比如薄膜波导,晶体光纤等),同样可传输这种光学孤子。由于定义了等效折射率系数,本文的结果还可用来讨论此类波导中与非线性折射率相关的其他非线性光学效应,比如自相位调制效应等。 关键词：     

非线性介质的表面等离子体波导设计和优化

设计了一种基于非线性介质Si-NC/SiO2的混合表面等离子体波导,利用有限元方法定量分析了这种波导所支持基模的能流密度分布、有效折射率、传播长度和有效面积与几何结构参数以及非线性介质的依赖关系.分析结果表明,光场主要被限制在非线性区域,通过调节非线性层的厚度以及非线性比例因子,可以实现模式的有效折射率和传播长度等传输特性参数的调节.固定非线性介质比例因子,有效折射率和传播距离随非线性层厚度增加而增大;固定波导尺寸,有效折射率随比例因子增大而增大,传播距离和有效面积较小.最后,根据分析结果对非线性效应进行优化,优化后波导最优结构尺寸为波导宽度为250nm,非线性材料层厚度为100nm,硅层厚度为150nm.     

金属包层渐变折射率介质光波导的传输特性与损耗

用金属包层介质光波导损耗的微扰理论及藉助多层近似法用递推公式分析渐变折射率波导传播常数的方法,对几种类型的金属包层渐变折射率介质光波导的传输特性与损耗进行分析和讨论,得到了与精确数值计算结果相吻合的结果.     

集成光学 集成光学、波导理论

TN2522006010411SiO2平面光波导的PECVD制备和膜层特性研究=PECVD deposition of silica plane waveguides and the fil mproperties[刊,中]/陈思乡(武汉理工大学机电工程学院.湖北,武汉(430070)),江征风…∥光通信研究.—2005(5).—68-70研究了等离子体增强化学汽相沉积(PECVD)的光波导膜层的光学特性,论述了沉积工艺参量和退火处理对膜层性能的影响。优化工艺获得了高质量的波导膜层,成功设计制作了在1550nm中心波长损耗低于0.1dB/cm的平面光波导和阵列波导光栅(AWG)器件。图7表1参4(于晓光)TN25220060104125层非线性平板波导T…     

Core ionization potentials in carbon monoxide

Conflicting values have been reported for the core ionization potentials in carbon monoxide. We have remeasured these and find 296.24 ± 0.03 for the carbon 1s ionization potential and 542.57 ? 0.03 for oxygen 1s. The carbon value is close to previously reported values; that for oxygen is higher by ～ 0.5 eV. These results are compared with ionization potentials calculated from molecular orbital theory. The value predicted by near-Hartree-Fock calculations for oxygen is too low by ～ 1eV and that for carbon is too high by ～ 0.5 eV.     

铝锂合金样品的前处理及其Ag和Li的光谱分析

针对铝锂合金样品检测其Ag和Li,采用等离子体原子发射光谱法(ICP-OES)同时测定Ag和Li,火焰原子吸收光谱法(FAAS)分别测定Ag和Li,单宁酸分光光度法(VS)测Ag,对不同的光谱测定方法进行了比较,证明了ICP-OES检测铝锂合金中的Ag和Li具有较高的抗干扰性。对比了三种不同的样品消解方法,确定了FAAS测Li采用王水溶样最佳,ICP-OES,FAAS和VS测Ag采用HCl+H₂O₂体系溶样准确度更高。详细讨论了样品中共存元素Al, Mg, Zr, Ti, Cu的干扰及消除方法。用氨水沉淀消除共存元素Al,Ti,Zr,8-羟基喹啉沉淀分离Mg和Cu的方法消除原子吸收光度法测Ag的干扰;采用磷酸盐沉淀分离Ti而消除原子吸收光度法测Li的干扰;采用与原子吸收光度法测银相同的消除干扰方法,消除上述离子干扰,滤去干扰沉淀后,用硝酸赶盐酸解蔽Ag+离子,同时分解消除8-羟基喹啉的颜色,以消除分光光度法测银的干扰。对比消除干扰前后的结果发现准确度显著提高,证明消除干扰的方法切实有效。将选择的最佳消解体系和干扰消除方法应用于铝锂合金样品的测定,ICP-OES测Li和Ag回收率分别在100.39%～103.01%和100.42%～103.73%之间,FAAS测Li和Ag 回收率分别在95.91% ～99.98%和98.04%～103.67%之间,分光光度法测Ag回收率在98.00%～101.00%之间,测定结果满足分析要求。     

A New Coherent States Approach to Semiclassics Which Gives Scott’s Correction

We introduce a new semiclassical calculus by generalizing the standard coherent states. This is applied to the semiclassical expansion for the sum of negative eigenvalues of Schrödinger operators which leads to a new proof of the Scott correction for non-relativistic molecules.Work partially supported by an EU TMR grant, by a grant from the Danish research council, and by MaPhySto – Centre for Mathematical Physics and Stochastics, funded by a grant from The Danish National Research Foundation. ©2003 by the authors. This article may be reproduced in its entirety for non-commercial purposes.     

机械合金化致二元过渡金属非晶态合金形成规律的探讨

运用Ｍｉｅｄｅｍａ参数和尺寸因子Ｒ分别构成Ｍｉｅｄｅｍａ参数坐标和三维化学坐标成功地研究机械合金化二元过渡金属非晶合金的形成规律。基于实验事实所确定的机械合金化二元非晶的形成条件分别是见原文，以上两判据区分机械合金化非晶态合金形成与否的准确度分别为８０％和８８％。从微观原子的相互作用以及固态反应非晶化热力学和动力学的角度分析了以上参数在描述机械合金化二元过渡族合金体系非晶形成规律的内在物理涵义以及与固态反应非晶化实现所需条件的联系。 关键词：     

Application of ESPI-method for strain analysis in thin wall cylinders

The Centre for Industrial and Engineering Optics, DIT, Ireland, have recently developed and applied new optical techniques for the measurement of mechanical strain, one of which was based on electronic speckle pattern interferometry (ESPI). The accuracy of this optical technique when used on flat surfaces is well established. In this research the technique is tested on curved surfaces, and results are compared with the theoretical hoop strain as predicted by the bi-axial strain equation modified for the thin cylinder, and by those obtained by electrical resistance strain gauge (ERSG) undoubtedly the principal method of measuring mechanical strain. For testing procedures, a special unit was designed and produced for holding and loading the thin cylinder. Also the basic equation for hoop strain by ESPI for flat surfaces was modified for applications on curved surfaces.Thin cylinder hoop strain obtained by ESPI and calculated by a modified equation show remarkably good correlation to the predicted theoretical value as well as to the results obtained by ERSG. Since the ESPI theory was originally developed for use on flat surfaces, there are reasonable grounds for further investigating this relationship especially where curved surfaces are involved.     

Spin squeezing in the presence of dissipation

The transfer of spin between photons and localized atomic levels, for a chain of two-level atoms, is studied. The Hamiltonian of the system is modelled by a radiation term and by atom-atom and radiation-atom interactions. Effects due to dissipation are accounted for by atom-photon exchange-interactions of complex strength. It is found that the spin-squeezing is suppressed by dissipation. Calculations are performed for arrays of Rb atoms excited by a GaAlAs laser.     

Two-dimensional phased arrays for application in surgery: Scanning by several focuses

Numerical simulation and comparative analysis of acoustic fields formed by two-dimensional phased arrays designed for ultrasonic surgery are conducted for the case of scanning by several focuses (in particular, by nine focuses arranged in a line and also by an array of nine focuses forming a 3×3 square grid). Calculations are performed for arrays with elements positioned at the surface both regularly (in square, ring, or hexagonal patterns) and randomly. Criteria for evaluating the “quality” of the intensity distributions in the field formed by the array in the case of scanning by several focuses are proposed. The quality of the intensity distributions for arrays containing 255 and 256 elements 5 mm in diameter arranged in regular patterns on the array’s surface (in square, ring, or hexagonal patterns) is inferior to that for arrays containing 256 randomly positioned elements. Among the regular arrays, the highest quality of intensity distributions is obtained for ring arrays, and the lowest quality is obtained for arrays with elements arranged in square or hexagonal patterns. The irregularity in the element positioning the array’s surface improves the quality of intensity distributions by reducing the secondary intensity peaks in the field formed by the array and, primarily, in the focal plane.     

Anlage zur Kernpolarisation mittels polarisierter Neutronen

An experimental set-up to be used for nuclear polarisation by means of the absorption of thermal polarized neutrons is described. The set-up consists essentially of a double spectrometer arrangement for polarized neutrons in connection with an arrangement for the detection of the nuclear polarisation by means of the anisotropic β-decay. The described method is especially useful for short-living isotopes which cannot be polarized by other methods.     

Intensity distribution and coherence property for the broadband Gaussian Schell-model array beams in free space

The intensity distribution and the equal-time complex degree of coherence for the broadband Gaussian Schell-model array beams with different bandwidth propagating in free space are analyzed by the numerical calculation. Results show that the intensity distribution for the broadband Gaussian Schell-model array beams by uncorrelated superposition is rarely affected by the bandwidth; the intensity distribution in the far field for the broadband Gaussian Schell-model array beams by correlated superposition is affected by the bandwidth more obviously than that in the near field. With the increasing of the propagation distance, differences in the equal-time complex degree of coherence for the broadband Gaussian Schell-model array beams with different bandwidth become prominent.     

Convergence of the Godunov scheme for a simplified one-dimensional hydrodynamic model for semiconductor devices

Convergence of approximate solutions derived by the Godunov scheme for a simplified one-dimensional hydrodynamic model for semiconductor devices is established by using the compensated compactness method. A global existence theorem is shown; and a numerical method for the computation of the physical global solution of this model is provided by this approach.