非线性Schroedinger方程的动力学行为分析

采用辛算法数值求解非线性Schroedinger方程的周期初值问题，建立不同的相空间来分忻其动力学持性．首先比较分析了不同的相空间中立方非线性Sehroedinger方程在不同立方非线性参数下的长时间演化的动力学特性，然后讨论了相空间中立方一五次方非线性Sehroedinger方程在不同立方和五次方非线性参数下的长时间演化的动力学特性，数值结果显示，对于不同的立方非线性参数，随着五次方非线性参数的增加，动力学行为的演化路径是不一样的．     

非线性Schroedinger方程的包络形式解

扩展了最近提出的F展开方法以构造非线性演化方程更多的精确解，即将F展开法中的一阶非线性常微分方程和单变量的有限幂级数代之以类似的一阶常微分方程组和两个变量的有限幂级数，这两个变量是一阶常微分方程组的解分量．作为例子，用扩展的F展开法解非线性Schroedinger方程，得到了很丰富的包络形式的精确解，特别是以两个不同的Jacobi椭圆函数表示的解．显然，扩展的F展开方法也可以解其他类型的非线性演化方程．     

双环形Coulomb势Schroedinger方程束缚态的精确解

双环形Coulomb势是指在氢原子势外面再加上一个双环形平方反比势。该模型势是在讨论类似于苯环分子结构的基础上提出的，该模型势在分子和原子物理中有着广泛的应用．本文研究了双环形Coulomb势Schroedinger方程的束缚态精确解，所采用的方法是首先对双环形Coulomb势的Schroedinger方程在球坐标系中进行分离变量，得到相应的角向方程和径向方程；证明双环形Coulomb势在角向和径向具有超对称性和形不变性；根据超对称性和形不变性的性质，获得了角动量量子化条件和束缚态的能谱方程，并将归一化角向波函数用Jacobi多项式表示，将归一化径向波函数用Laguerre多项式函数表示．体系的波函数和束缚态能谱性质由三个量子数n、m和s及势参数a，a和b描述．本文说明量子物理中一些具有对称性的非中心势有精确解．用超对称性和形不变性方法还可以讨论其他形式的非中心势．     

求解径向Schroedinger方程解析解的一种方法以及由此延伸的讨论—叠加势基态能级与势参数关系

采用转化法，可得到一系列具有球对称势函数的径向Schroedinger方程的解析解和能级方程。这种方法是用一个恰当的尝试波函数代入Schroedinger方程后，将微分方程变成简单的可解的代数方程组，由此大大简化了运算。本给出了库仑势、库仑势与谐振子势的叠加势以及离子与原子相互作用势的径向Schroedinger方程解析解，并得到能级方程。由于此方法中涉及一个势参数制约关系，为此以叠加势V(r)=-A1r^-1-A2R^-3 A3r^-4为例，讨论其基态能级。得出重要结论：在库仑势上叠加上两项逆幂指数势作用后基态能量将增大，但是并不是单调增大，而是与各项势参数有关。     

高阶Schr(o)dinger方程的高精度辛格式

提出由第三类生成函数法构造高阶Schroedinger方程δu/δt=i(-1)^nδ^2mu/δx^2m的高精度辛格式．首先，给出它的典则Hamilton方程组；然后，成功地克服了本质上是困难的高阶变分导数的计算，并利用第三类生成函数法得到在时间方向具有任意阶精度的半离散方程，进而得到原始方程相关的修正方程的离散形式，最后得到各种精度的辛格式．数值结果表明该格式是有效的，具有高精度及良好的长时间数值行为等特性．     

位相共轭、自聚焦等相关效应

O4372007010308含高阶非线性效应的薛定谔方程的精确解研究=Exactwave solutions of higher-order nonlinear Schroedinger e-quation[刊,中]/马松华(浙江丽水学院物理系.浙江,丽水(323000)),朱加民//量子光学学报.—2006,12(3).—156-158利用孤子理论,研究了含三次和五次非线性项的非线性薛定谔方程,在参数取不同值时得到了方程的新型亮孤子解、新型暗孤子解和新的三角函数周期解。参16(于晓光)O4372007010309强激子-声子系统中电磁感应透明理论计算=Theoreticalcalculation of electromagnetically induced transparency instrongly cou…     

从Schroedinger方程引申到Dirac方程的一种简单方法

从Schroedinger方程出发，结合自旋的唯象描述、简单的相对论考虑和适当的猜测，写出了Dirac方程的正确形式     

耦合非线性Schr(o)dinger系统的多辛差分格式

近年来，Bridges等人在Hamiltonian力学意义下，直接把有限维Hamihonian系统推广到无穷维，通过引入新的函数坐标，使得偏微分方程在时间和空间的各个方向上都有各自不同的有限维辛结构，这样原偏微分方程就由各个有限维辛结构以及右端的梯度函数决定，称这样的方程为多辛Hamihonian系统．多辛Hamiltonian系统满足多辛守恒定律，满足多辛Hamihonian系统的多辛守恒律的离散算法称为多辛算法．以耦合非线性Schroedinger方程为例，研究无穷维Hamiltonian系统的多辛算法，验证了两孤立子碰撞后会发生相互通过、反射及融合现象．     

耦合Klein-Gordon-Schroedinger方程新的精确解

用函数变换法将耦合Klein—Gordon—Schroedinger方程化成可求解的不定积分形式，进而求出其精确解，包括有理函数型解、三角函数型解、双曲函数型解，以及椭圆函数型解．所得结果包含了文献中用齐次平衡法所得的解为特例．     

指数型变化有效质量的三维Schroedinger方程的解析解

对随径向坐标指数型变化的有效质量分布，通过坐标变换，得到了与Coulomb型势，Kratzer型势和无限深球方势阱三类势函数相联系的变质量三维Schroedinger方程的解析解，具体给出了这三类系统的能量本征值和本征函数的解析表达式．     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Theoretical analysis and simulation of conjugate heights for dual-conjugate AO system in lidar

A multi-conjugate adaptive optics （MCAO） can offer a possibility of widening field of view （FOV） characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle＇s expressions of two deformable mirrors （DMs） MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.     

Quick single-photon detector with many avalanche photo diodes working on the time division

Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.     

Improvement of four-wave mixing-based wavelength conversion efficiency in dispersion shifted fiber by 40-GHz clock pumping

40-GHz clock modulated signal as a pump to improve the efficiency of four-wave mixing (FWM)-based wavelength conversion in a 26.5-km dispersion shifted fiber (DSF) is investigated. The experimental results demonstrate that the conjugated FWM component has higher intensity with the clock pumping than that with the continuous-wave (CW) light pumping. The improvement of FWM-based wavelength conversion efficiency is negligible when the pump power is less than Brillouin threshold. But when the pump power is greater than Brillouin threshold, the improvement becomes significant and increases with the increment of pump power. The improvement can increase up to 9 dB if pump power reaches 17 dBm.     

Characterization of PolyA and PolyC mismatches by Raman spectroscopy

A.C mismatches are studied by Raman spectral characterization of PolyA, PolyC, and their equimolar complex in solution of 0.14 mol/L Na ,pH7.0.Experimental results show that A·C mismatches occur to be A/B (mainly A) conformers, and unlike Watson-Crick base pairing, this kind of mismatches is stabilized by only one hydrogen bond involving cytosine N4H2 and adenine N7.The formation of A·C complex makes the base stacking interactions much stronger, and conformation of the backbone more ordered, which leads to obvious Raman hypochromic effect with some shifts in corresponding bands.     

Speech enhancement by array crosstalk resistant ANC and spectrum subtraction

Microphone array-based speech enhancement has great importance for speech communications and speech recognition. To reduce the aperture of the microphone array and to increase the effect of the speech enhancement will greatly broaden the application areas of the microphone array. An array crosstalk resistant adaptive noise cancellation method is therefore presented. And then an improved spectral subtraction algorithm is further cascaded to obtain better enhancement results. Theoretic analysis and experiments indicate that the proposed scheme needs only a very small microphone array while it simultaneously achieves a higher SNR improvement. Besides, the proposed scheme can be used in many noisy environments and is easy for real-time implementation.     

Multi-pulse operation of a Kerr-lens mode-locked femtosecond laser

Our experimental results show that the presence of a proper amount of negative group velocity dispersion is essential to multi-pulse operation of a Kerr-lens mode-locked femtosecond laser. We demonstrate that the pulse separations and the number of pulses contained within a cavity round trip are strongly dependent on the initial perturbations. The results allow us to get a better understanding on the influences of the convoluted self-phase modulation and intra-cavity dispersions on the stable multi-pulse oscillation in a Kerr-lens mode-locked femtosecond laser.     

Propagation of Helmholtz-Gauss beams in weak turbulent atmosphere

Based on the Rytov approximation of light propagation in weak turbulent atmosphere,the closed-form expressions of field and average irradiance of each one of the four fundamental families of Helmholtz-Gauss (HzG)beams:cosine-Gauss beams,stationary Mathieu-Gauss beams,stationary parabolic-Gauss beams,and Bessel-Gauss beams,which are propagating in weak turbulent atmosphere,are obtained.The results show that the field and average irradiance can be written as the product of four factors:complex amplitude depending on the z-coordinate only,a Ganssian beam.a factor of complex phase perturbation induced by atmospheric turbulence,and a complex scaled version of the transverse shape of the non-diffracting beam.The effect of weak atmospheric turbulence on irradiance distribution of the HzG beam can be ignored.