障碍物遮挡下漂移涡旋光束拓扑荷数的测量

复杂环境中漂移扰动和不透明障碍物破坏光振幅和光相位,给拓扑荷数（TC）精准测量带来挑战。分析了两种均匀离轴的多中心涡旋光束和一种随机离轴的漂移涡旋光束经扇形不透明障碍物（SSOO）后的传输情况,提出一种利用单柱透镜测量漂移涡旋光束TC的方法。对比光强法、傅里叶变换法以及相位法在极端条件下对漂移涡旋光束TC测量的结果,发现在以上3种方法失效时,所提方法仍可对输入光束的TC值大小及符号作出准确判断。这种抗光束漂移和抗遮挡的TC测量法对基于涡旋光的光通信和光加密具有重要应用价值。     

几周期余弦-高斯激光脉冲的时间重心

研究了几周期超短余弦-高斯脉冲的时间重心与绝对相位以及与余弦函数参量之间的关系．给出了几周期超短余弦-高斯脉冲时间重心的解析表达式和模拟图形．结果表明，余弦-高斯脉冲的时间重心随着绝对相位的变化而发生漂移，并且脉冲宽度对余弦-高斯脉冲时间重心的漂移量也有一定的影响．余弦函数的参量在一定取值范围内对余弦-高斯脉冲也有较大的影响，它可能导致几周期余弦-高斯脉冲的时间重心有较大的漂移．     

规范理论随机量子化的新方案

在规范理论随机量子化中，运用投影算子和函数δ（ｔ）构成的核，在零初值条件下，当ｔ趋于∞时，可以使之收敛于平衡态，并得到协变规范下的传播子。这样，规范理论和非规范理论的随机量子化方案即统一于只运用核函数。文中分别对麦克斯韦场、Ｃｈｅｒｎ－Ｓｉｍｏｎ场及线性引力理论进行了讨论。另外，还证明了上述形式的核不会对平衡分布产生影响。 关键词：     

光拍频和干涉现象

本文对比了光拍频和光干涉两种现象，强调了它们的同一性。前者是强度随时间相位［（ω１－ω２）ｔ］而变的一种运动形式。后者则是强度随空间相位（光程差引起）而变的．本文并指出，在干涉现象中，全面地辩证地把握两种相位形式，对解决一些科学实际问题是有益的．     

用相位图分析驻波形成

波的核心是相位，驻波的关键是入射波与反射波的相位差，入射波和反射波相位随ｘ、ｔ变化的关系可用相位图（移动的斜线）表示，而相位差仅随ｘ变化，也可用斜线表示，这样即可很方便地确定波节和波腹的位置。     

Kerr效应对非简并双光子J—C模型中光场相位的影响

应用Pegg-Barnett相位理论研究了高Q Kerr介质腔中的二能级原子与双模光场相互作用系统中光场相位的演化特性,通过计算光场的相位几率分布函数,频率漂移量以相位涨落,分析讨论了Kerr效应对光场相位性质的影响。     

双随机相位加密系统的已知明文攻击

运用密码分析学的方法对双随机相位加密系统进行了初步的安全性分析.研究结果表明，该系统属于线性的对称分组密码系统，线性性质为其安全性留下隐患.在已知明文攻击下，攻击者可通过常规的相位恢复算法获得4-f系统输入平面的随机相位函数密钥，继而可轻易推出频谱平面的随机相位函数密钥，从而攻破此密码系统. 关键词： 光学信息安全 双随机相位加密 密码分析学 已知明文攻击     

任意形体微粒分布的概率表述及其测量方法

对任意形体的三维微粒，引入了等相位二维散射截面的概念，建立了半椭圆概率组合模型，提出了形体特征参数η、影响因子T（η）与其形体概率分布函数P^η（η）的概念，以特征分布函数P（α，η）取代了球形粒度概率分布函数P^s(a)，在洛伦兹－米（Lorenz-Mie)散射理论的基础上，建立了P（α，η）的数学反演方程和实验测量方法。理论结果经非球形煤粉微粒的实验验证，效果较好。     

低频无规入射声场通过矩形板入射到闭空间的隔声量──Ⅰ．理论部分

运用模态耦合方法，本文计算了低频无规入射声场通过矩形薄板入射到矩形闭空间的隔声量。在计算时，考虑了三种无规入射声场的模型：（１）单频无规入射声场为空间分布的随机过程；（２）单频无规入射声场中每点为δ函数，点点互不相关；（３）单频无规入射场是从各个方向以相同振幅和随机相位入射的平面波的迭加。对这三种模型，推导了其隔声量计算公式，并进行了计算机模拟，给出了所研究系统的无规入射声场频响。     

一种高效量子密钥分发系统主动相位补偿方法

针对相位编码量子密钥分发系统相位漂移的实际问题,详细分析了目前解决相位漂移的主要方案,提出了一种"五点法"快速相位漂移参数的扫描方法.该方法只需对五个相位点进行单光子水平的相位扫描,即可得出满足精度要求的相位漂移参数.通过将该方法和其他两种主要相位补偿方法的对比分析,表明该方法可以在更短的扫描时间内有效得到量子密钥分发的相位漂移参数并对相位漂移进行实时补偿.该方法适用于目前常用的相位编码系统,为量子密码系统提供了一种有实际应用价值的主动相位补偿方案.     

基于Allan方差的光纤陀螺随机漂移建模与仿真

随机漂移是影响光纤陀螺精度的主要因素之一,建立陀螺随机漂移模型以便在滤波时加以修正是提高系统精度的有效方法。针对传统随机漂移模型建模耗时长、过敏感等问题,提出基于Allan方差的光纤陀螺随机漂移模型。通过各噪声项的功率谱密度函数推导出随机微分方程,用Allan方差分析出光纤陀螺各噪声项量化参数,将量化参数代入以单位白噪声驱动的随机微分方程,得到随机漂移模型。实验结果表明,该模型拟合出的随机漂移单项噪声误差不超过8.6％,远低于传统模型产生的单项噪声误差58.3％,是一种有效的光纤陀螺随机漂移建模方法。     

Mathematical modeling of random coupling between polarization modes in single-mode optical fibers: XIV. Spectral characteristics of nonreciprocal phase difference of counterpropagating waves at the output of a fiber ring interferometer at a change in the fiber temperature

Distributions of the spectral density of the dependence of the phase difference of counterpropagating waves in a fiber ring interferometer (FRI) on the temperature of the single-mode optical fiber (SMOF) in the FRI loop (temperature spectra of the FRI zero drift) due to polarization nonreciprocity have been obtained by Fourier analysis for different spectral linewidths of the FRI radiation source and different linear birefringences of the SMOF in the FRI loop. It is shown that a change in the temperature of the SMOF in the FRI loop changes mainly the SMOF linear birefringence. This effect leads to a change in the phases of the radiation that is transferred from one polarization mode to another at those points in the SMOF where the random twisting of the axes of unperturbed linear birefringence of the SMOF changes. The effect of the magnitude of the jump under consideration, its location with respect to the nearest FRI loop end, and the magnitude of the cross-correlation (visibility) function of the radiation transmitted along the slow and fast SMOF axes from the loop end to the point where a jump in twisting of the SMOF axes occurs on the character of the temperature spectra of the FRI zero drift is determined. It is shown that in the case where the depolarization length of nonmonochromatic radiation in an SMOF is smaller than the average length of the SMOF segment on which random twisting is constant, the qualitative and quantitative characteristics of the temperature spectra of the FRI zero drift depend strongly on the polarization state of the radiation at the input of the FRI loop. The reason for this difference is explained.     

电流变材料构件的频率检测与响应控制

干涉式光纤应变传感器为构件的实时频率检测提供了抗电磁干扰的新型最佳技术手段.本文分析了其在新型的电流变材料构件应用时的若干现象.提出一个位相漂移模型并用以成功处理了有关问题.由此设计的嵌埋型干涉式光纤应变传感器首次使用于受到随机外部激励的电流变结构的振动控制过程.     

Asymptotic laws of superdiffusion

The dynamic and statistical characteristics of diffusion trajectories are studied by introducing the notion “fractional drift.” An equation for the random walk probability density for cases of subdiffusion and superdiffusion is derived. A solution to this equation is constructed on the basis of the Mittag-Leffler function properties.     

First-order probability density function of the laser speckle phase

An expression for the first-order probability density function of the laser speckle phase is analytically derived under the assumption that the speckle field obeys a non-circular, complex Gaussian, random process with a certain correlation between the real and imaginary parts of its complex amplitude. The probability density function of the speckle phase is actually evaluated for various cases and shown three-dimensionally as a function of the standard deviation of random object phase variations. The effect of random object phase variations on the probability density function is also investigated in detail.     

Effective long-time phase dynamics of limit-cycle oscillators driven by weak colored noise

An effective white-noise Langevin equation is derived that describes long-time phase dynamics of a limit-cycle oscillator driven by weak stationary colored noise. Effective drift and diffusion coefficients are given in terms of the phase sensitivity of the oscillator and the correlation function of the noise, and are explicitly calculated for oscillators with sinusoidal phase sensitivity functions driven by two typical colored Gaussian processes. The results are verified by numerical simulations using several types of stochastic or chaotic noise. The drift and diffusion coefficients of oscillators driven by chaotic noise exhibit anomalous dependence on the oscillator frequency, reflecting the peculiar power spectrum of the chaotic noise.     

Quantitative measurement of temperature by proton resonance frequency shift at low field: a general method to correct non-linear spatial and temporal phase deformations

MRI thermometry methods are usually based on the temperature dependence of the proton resonance frequency. Unfortunately, these methods are very sensitive to the phase drift induced by the instability of the scanner which prevents any temperature mapping over long periods of time. A general method based on 3D spatial modelling of the phase drift as a function of time is presented. The MRI temperature measurements were validated on gel samples with uniform and constant temperature and with a linear temperature gradient. In the case of uniform temperature conditions, correction of the phase drift proved to be essential when long periods of acquisition were required, as bias could reach values of up to 200 degrees C in its absence. The temperature uncertainty measured by MRI was 1.2 degrees C in average over 290 min. This accuracy is coherent with the requirements for food applications especially when thermocouples are useless.     

一种改进的MEMS陀螺信号去噪方法研究

 从工程实用的角度出发,探讨了MEMS陀螺仪随机漂移误差的有效补偿方法。根据小波阈值去噪原理,结合多项式函数插值法提出了一种MEMS陀螺仪输出信号的有效去噪补偿方法,克服了传统软、硬阈值去噪方法的缺陷,通过对MEMS陀螺数据分析研究,验证了该方法对于MEMS陀螺输出信号滤波消噪的优越性。     

Dynamics of <Emphasis Type="Italic">ab</Emphasis>-type domain walls in magnets with quadratic magnetoelectric interaction

The dynamics of the ab-type 180-degree domain walls was studied in weak ferromagnets with quadratic magnetoelectric interaction in alternating magnetic and electric fields. The features of the oscillatory and drift motion of the domain walls are discussed. The drift velocity of the ab-type domain walls as a function of the frequency and phase shift of the external fields is obtained. The possibility of the drift of the domain walls in a purely electric field is established.     

Self-Attractive Random Walks: The Case of Critical Drifts

Self-attractive random walks (polymers) undergo a phase transition in terms of the applied drift (force): If the drift is strong enough, then the walk is ballistic, whereas in the case of small drifts self-attraction wins and the walk is sub-ballistic. We show that, in any dimension d ≥ 2, this transition is of first order. In fact, we prove that the walk is already ballistic at critical drifts, and establish the corresponding LLN and CLT.