用多级衍射全息光栅实现2-D自由空间光学互连网络

用Mach-Zehnder干涉仪分两步记录制作了具有多级衍射的全息光栅.利用其多级衍射效应,实现了一点到多点的光学互连.再将两个1-D光栅正交密接实现2-D自由空间光学互连网络.结果表明该方法是可行的,且结构简单、操作容易.     

用作光学蝶互边网络的全息互连光栅的研究

提出了利用平面倾斜条纹透射体全息光栅等光强的０级和１级衍射光实现蝶互连网络中的直连和交连。在红敏光致聚合物干版上面制备出了这种光栅互连器件，并给出了这种器件的设计原理和制备方法。     

用作光学蝶互连网络的全息互连光栅的研究

提出利用平面倾斜条纹（Ｓｌａｎｔｅｄ－ｆｒｉｎｇｅ）透射体全息光栅等光强的０级和１级衍射光实现蝶互连网络中的直连和交连。在红敏光致聚合物干版上制备出了这种光栅互连器件，并给出了这种器件的设计原理和制备方法     

64×64全交叉互连函数的光学实现

光互连全交叉网络在巨型计算机和光子交换网络系统等领域具有十分重要的潜在应用。本文在自行设计研制成功棱镜光栅和６５×６５大列阵Ｄａｍｍａｎｎ光栅的基础上，运用自由空间光学互连技术实现了６４×６４全交叉网络的互连函数。采用互连矩阵对输出图样进行了计算，结果与实验吻合。     

多光束全息互连元件效率的理论分析

多光束全息互连元件往往需要大量的耦合波方程才能描述。本文通过分析记录时生成的互调制光栅的性质及其对衍射的影响,对问题进行适当的简化。通过解不同条件下的耦合波方程、分别给出了多光束全息图在各种不同情况下的衍射效率的近似解析表达式,展示了衍射效率与各实验参量之间的关系。为进一步研究多光束全息互连元件的性质、比较各种条件下的效率以及各参量对总体效率的影响,提供了方便。     

基于双光栅的马赫-曾德尔干涉仪的初步研制

设计和初步制备了基于双光栅的等臂和不等臂马赫-曾德尔干涉仪,两个衍射光栅分别用作光束分裂器和光束复合器.来自激光器的平行光束透过第一光栅后产生多柬衍射光,等臂干涉仪使用两个平面反射镜反射两束对称衍射光至第二光栅的同一位置并产生完全重合的衍射条纹,即每束衍射光包含两个成分.利用光探测器监测任一束重合的衍射光束,该光束两成分之间的相位差随时间的变化就能够被准确测定.而不等臂干涉仪仅使用一个反射镜反射某一束衍射光并使之与零级光束透过第二光栅后产生完全重合的衍射条纹.通过使用一个厚度为50μm的玻璃片来改变相位差,对不等臂干涉仪的干涉效果进行了测试,得到了与理论值相符的实验结果.     

基于全内反射的重铬酸明胶全息光互连器件的研究

研究了利用重铬酸明胶制备的基于全内反射的全息光互连器件，实现了兰光记录，近红外光再现，计算出记录光束的入射角与再现光束的偏转角间的关系曲线以及记录光束的入射角与波长比的关系曲线，器件衍射效率达６０％。     

光互连模块中偶数大点阵64×64位相计算全息光栅的简化设计和分析

采用简化的综合设计方法，对偶数大点阵位相计算全息光栅进行了优化设计和分析，实验上研制出用于光互连模块的６４×６４大点阵位相计算全息光栅分束器，优化设计一维衍射效率为８０．１％，光强不均匀性小于０．３％。     

超短脉冲激光光束被局域体全息光栅衍射的性质分析

利用二维耦合波理论,分析了超短脉冲激光光束被完全重叠型的局域体全息光栅衍射的时空变化性质,给出了衍射和透射脉冲激光光束沿光栅出射边界的强度时空分布。以LiNbO3晶体为例,数值研究了衍射光脉冲强度沿光栅出射边界的分布和脉冲波形的变化及光栅的总衍射效率受光栅二维尺寸、入射角度、光栅折射率调制度及入射脉冲的脉冲时域半峰全宽等条件的影响而变化的情况。与一维体全息光栅对超短脉冲激光光束衍射的性质,及此光栅对连续光衍射的性质作比较,给出了合理选择光栅参量及入射条件以在光栅出射边界上得到总衍射效率较大且分布较均匀的衍射光脉冲的方法。     

楔块调整式Talbot干涉仪改变写入Bragg波长的调谐误差

在楔块调整式Talbot干涉仪中,光纤Bragg光栅的写入区为直接由相位模板衍射的±1级衍射光束形成的干涉条纹的近场干涉区,和由±1级衍射光束经两平面镜反射后形成的可调谐写入Bragg波长的干涉条纹的远场干涉区。在改变写入光纤光栅Bragg波长的过程中,光纤光栅的Bragg波长是由平面镜的交叉角决定的,而且,影响调谐精度的三种主要因素被控制在光纤光栅生产允许的范围内,即推动机构的位移误差系数Cd为～-0.08nm/μm,楔块的倾斜误差系数Cα为-0.15～0.23nm/(′),和转动机构的传动角误差系数Cβ为～-0.08nm/(′)。     

The single diffractive component in hadron-hadron collisions within the two-component Dual Parton model

The single diffractive component in hadronhadron interactions is studied in the two-component Dual Parton Model. We distinguish high mass single diffraction represented by a triple-Pomeron exchange and low mass single diffraction described via a two channel eikonal method. The calculated single diffractive cross sections, and the distributions agree quite well with data from collider and fixed target experiments. The fit of the model parameters to cross section data gives a extrapolation of the total, elastic, and single diffractive cross sections to supercollider energies which depends on the parton structure functions used for the minijet component.     

Diffractive meson production from virtual photons with odd charge-parity exchange

We calculate the cross section of diffractive charge-parity neutral meson production in virtual photon proton collision at high energies. Due to the opposite -parities of photon and meson () this process probes the -channel odderon exchange which is described here as noninteracting three–gluon exchange. Estimates for the cross section of inelastic diffractive process are presented. The total cross section of diffractive meson photoproduction is found to be 47 pb. The cross sections for the diffractive production of light mesons () in collisions are of the same order if the photon virtuality is . Received: 30 July 1997     

Diffractive jet production in deep-inelastic e^+p collisions at HERA

A measurement is presented of dijet and 3-jet cross sections in low- diffractive deep-inelastic scattering interactions of the type , where the system X is separated by a large rapidity gap from a low-mass baryonic system Y. Data taken with the H1 detector at HERA, corresponding to an integrated luminosity of 18.0 pb, are used to measure hadron level single and double differential cross sections for and . The energy flow not attributed to jets is also investigated. The measurements are consistent with a factorising diffractive exchange with trajectory intercept close to 1.2 and tightly constrain the dominating diffractive gluon distribution. Viewed in terms of the diffractive scattering of partonic fluctuations of the photon, the data require the dominance of over states. Soft colour neutralisation models in their present form cannot simultaneously reproduce the shapes and the normalisations of the differential cross sections. Models based on 2-gluon exchange are able to reproduce the shapes of the cross sections at low values. Received: 21 December 2000 / Published online: 6 April 2001     

Tests of QCD factorisation in the diffractive production of dijets in deep-inelastic scattering and photoproduction at HERA

Measurements are presented of differential dijet cross sections in diffractive photoproduction (Q²<0.01 GeV²) and deep-inelastic scattering processes (DIS, 4<Q²<80 GeV²). The event topology is given by ep→eXY, in which the system X, containing at least two jets, is separated from a leading low-mass baryonic system Y by a large rapidity gap. The dijet cross sections are compared with NLO QCD predictions based on diffractive parton densities previously obtained from a QCD analysis of inclusive diffractive DIS cross sections by H1. In DIS, the dijet data are well described, supporting the validity of QCD factorisation. The diffractive DIS dijet data are more sensitive to the diffractive gluon density at high fractional parton momentum than the measurements of inclusive diffractive DIS. In photoproduction, the predicted dijet cross section has to be multiplied by a factor of approximately 0.5 for both direct and resolved photon interactions to describe the measurements. The ratio of measured dijet cross section to NLO prediction in photoproduction is a factor 0.5±0.1 smaller than the same ratio in DIS. This suppression is the first clear observation of QCD hard scattering factorisation breaking at HERA. The measurements are also compared to the two soft colour neutralisation models SCI and GAL. The SCI model describes diffractive dijet production in DIS but not in photoproduction. The GAL model fails in both kinematic regions.     

Diffractive open charm production in deep-inelastic scattering and photoproduction at HERA

Measurements are presented of diffractive open charm production at HERA. The event topology is given by ep→eXY where the system X contains at least one charmed hadron and is well separated by a large rapidity gap from a leading low-mass proton remnant system Y. Two analysis techniques are used for the cross section measurements. In the first, the charm quark is tagged by the reconstruction of a D^*±(2010) meson. This technique is used in deep-inelastic scattering (DIS) and photoproduction (γp). In the second, a method based on the displacement of tracks from the primary vertex is used to measure the open charm contribution to the inclusive diffractive cross section in DIS. The measurements are compared with next-to-leading order QCD predictions based on diffractive parton density functions previously obtained from a QCD analysis of the inclusive diffractive cross section at H1. A good agreement is observed in the full kinematic regime, which supports the validity of QCD factorization for open charm production in diffractive DIS and γp.     

Single diffractive hadron-nucleus interactions within the dual parton model

Single diffractive hadron-nucleus interactions are studied within the framework of the dual parton model. Introducing a diffractive component into the Monte-Carlo event generator DTUNUC we investigate particle production and the dependence of the diffractive cross section on the atomic number of the target nucleus. A comparison of the numerical results with recent experimental data is presented. We furthermore introduce hadronic cross section fluctuations and discuss their influence on diffractive proton-nucleus cross sections.     

Universal function of the diffractive process in color dipole picture

In this study, we obtain the universal function corresponding to the diffractive process and show that the cross section exhibits geometrical scaling. It is observed that diffractive theory according to the color dipole approach at small-x is a convenient framework that reveals the color transparency and saturation phenomena. We also calculate the contribution of heavy quark production in the diffractive cross section at high energy that is determined by the small size dipole configuration. The ratio of the diffractive cross section to the total cross section in electronproton collision is the other important quantity that is computed in this work.     

Diffractive heavy flavour production at the Tevatron and the LHC

We give predictions for diffractive heavy flavour production at the Tevatron and the LHC in leading-order approximation. In the framework of these studies we use three different models for the partonic structure of the Pomeron recently proposed by Stirling and Kunszt. These Pomeron models are, despite being fitted to the same diffractive deep inelastic HERA data, very different in their parton content and taken together provide a powerful tool to probe the structure of the Pomeron. All models satisfy GLAP evolution and show a significant Q₂ dependence. We give numerical predictions for single as well as double diffractive cross sections assuming a Donnachie-Landshoff-type Pomeron flux factor.     

Isoscalar diffractive photoproduction: A source of gluonium

Data on diffractive photoproduction of isoscalar states appear to be anomalously large in a number of channels. Isoscalar diffractive photoproduction is studied in a model in which the pomeron is approximated by two gluons, and in which gluon intermediate states are allowed in the pomeron-meson interaction. It is shown that the model allows a resolution of the long-standing problem of the small (in vector meson dominance terms) diffractive θ photoproduction cross section. This sets the scale for the calculation, and it is then demonstrated that the model can explain the large isoscalar cross section if it is due primarily to the diffractive photoproduction of a system of gluons.