非局域克尔介质中空间光孤子的相互作用

研究了强非局域克尔介质中光束的演化规律，通过相位分析得到了空间孤子相互作用所满足 的非局域非线性薛定谔方程的简化近似模型，并获得了双光束传输的解析解.结果表明在传 输过程中相互作用的高斯光束的相位决定于它们的输入总功率.以振幅一强一弱共同传输的 高斯光束为例进行了具体研究，得到了强光和弱光的解析式，相位分析显示弱光在相当短的 传输距离之内能产生大的相移，可以通过对强光能量的调控来实现对弱光的相位调制. 关键词： 非局域克尔介质 空间光孤子 孤子相互作用 相位调制     

光诱导平面波导阵列中离散空间光孤子的相干相互作用

采用Petviashvili迭代法对光诱导平面波导阵列中的一维离散空间光孤子进行求解,利用分步束传播法对离散空间光孤子间的相干相互作用进行了详细的数值模拟.探讨了离散孤子间的相位差、孤子光强、波导阵列写入光的强度和周期以及外加电场对相互作用过程的影响.结果表明：离散孤子间的相位差对相互作用的影响与连续介质中的情况类似,不同相位差情况下的相互作用也表现为吸引、排斥以及能量转移等现象.同时,离散孤子间的相干相互作用过程(如融合距离和排斥间距等)均会受到孤子光强、波导阵列写入光的强度和周期以及外加电场大小的影响 关键词： 光诱导平面波导阵列 离散空间光孤子 相干相互作用     

Partially coherent nonparaxial modified Bessel--Gauss beams

The concept of partially coherent nonparaxial modified Bessel--Gauss (MBG) beams is proposed. Based on the generalized Rayleigh-Sommerfeld diffraction integral, the analytical propagation equations of nonparaxial MBG beams in free space are derived and analysed, and some special cases are discussed. In particular, under the paraxial approximation our results reduce to the corresponding paraxial ones. Numerical calculation examples are given to illustrate the dependence of intensity and spectral degree of coherence on the beam order $m$, \textit{$\xi $} and $f$ parameters, and to compare the difference between the paraxial and nonparaxial results.     

Incoherent interaction between one- and two-dimensional solitons in noncentrosymmetric photorefractive media

The incoherent interaction between solitons with different transverse dimensions in a noncentrosymmetric photorefractive crystal is studied both in theory and in experiment. An anomalous incoherent interaction between one- and two-dimensional solitons, whose attractive and repulsive effects depend on the soliton separation, is numerically demonstrated by employing an anisotropic model. By launching a one-dimensional green beam and a two-dimensional red beam into a biased SBN:60 crystal, the hybrid-dimensional soliton interaction is performed. The experimental results are in good agreement with the numerical ones.     

暗-暗与亮-暗光伏孤子相互作用

用数值方法分析了平行传播异色光伏暗孤子之间及亮-暗孤子之间的相互作用.结果表明，光伏暗孤子共轴传播能在有限的距离内保持准孤子形态，靠近传播时存在着相互吸引的作用 ，而相距较远传播时表现为一孤子暗区使另一孤子的缓变光场部分发生局部会聚作用.光伏暗孤子与亮孤子的相互作用随距离的不同可使亮孤子光强分布变尖锐或变平缓，以及使亮孤子发生能量转移.从两束信号光共同引起折射率波导这一物理机理对光伏孤子这些相互作用给出定性物理解释. 关键词： 光伏空间孤子 暗孤子 亮孤子 相互作用     

非傍轴部分相干厄米-高斯光束的相干和非相干合成

推导出二维非傍轴部分相干厄米-高斯（H-G）光束相干合成和非相干合成的交叉谱密度和光强的解析公式,并分析了一些特例. 合成光束的光强不仅决定于f参数,f_σ参数,离轴参数,合成光束的束数和阶数以及传输距离z,而且还决定于合成方式. 对部分相干光的相干合成和非相干合成概念做了物理诠释,其正确性为数值计算例证实. 关键词： 部分相干光的相干和非相干合成 非傍轴部分相干厄米-高斯（H-G）光束 自由空间中的传输方程     

Spectral switches of partially coherent nonparaxial beams diffracted at an aperture

Based on the generalized Rayleigh diffraction integral, the spectral shifts and spectral switches of nonparaxial partially coherent beams diffracted at an aperture are studied. Our main attention is paid to the effect of beam nonparaxiality on the spectral switches of partially coherent beams. It is shown that the spatial coherent parameter β, trunction parameter δ and waist width-to-central wavelength ratio w₀/λ₀ affect the behavior of spectral switches. Only when β, δ and w₀/λ₀ satisfy certain conditions, can the difference between the nonparaxial and paraxial results be negligible. The discrepancy arises physically from the change of the spectral modifier by using the paraxial approximation.     

扩散效应对光伏孤子相互作用的影响

用数值方法研究扩散效应对两个平行传播相干光伏孤子光束相互作用的影响. 结果表明，在扩散效应的影响下，两相干孤子光束同相相互作用不是使它们相互融合, 而是使它们趋向相互分离，且光束之间存在能量耦合；异相孤子相互作用不再是简单地互相排斥，在一定的条件下，两光束既互相排斥，又同时向同侧偏转. 关键词： 光伏空间孤子 相干相互作用 扩散效应     

Partially coherent nonparaxial Hermite-Gaussian beams and their propagation properties

The concept of partially coherent nonparaxial Hermite-Gaussian (HG) beams is proposed. By using the generalized Rayleigh-Sommerfeld diffraction integral, the closed-form propagation equations of partially coherent nonparaxial HG beams in free space are derived. The on-axis intensity, far-field and paraxial expressions, and specifically, the free-space propagation equations of partially coherent nonparaxial Gaussian Schell-model beams are given, and treated as special cases of our results. It is found that the f and f_σ parameters play a crucial role in determining the nonparaxiality of partially coherent TEM_mn-mode HG beams. Only if the f and f_σ parameters are small enough, the paraxial approximation is applicable.     

Polarization locking and nonparaxial spatial solitons in media with electronic Kerr nonlinearity

The polarization structure of nonparaxial spatial solitons in a transparent medium with the electronic mechanism of Kerr nonlinearity is studied theoretically. It is demonstrated analytically in the weak nonparaxiality approximation that the regime of polarization locking, in which all the field components have the same propagation constant, is the only stable regime. Estimates of the rate of transition of the initial metastable regime of rotation of the polarization ellipse to the regime of polarization locking are presented. Based on a numerical solution of the nonlinear Maxwell equations, the presence of the nonparaxial regime of polarization locking is confirmed and the main characteristics of the corresponding spatial solitons are obtained.     

Coherent interactions of multi bright spatial solitons in biased photorefractive crystals

The coherent interaction scenarios of two solitons, three solitons, and four solitons are presented. For two-soliton interactions, energy transfer and fusion between solitons are dependent on the relative phase of the interaction solitons, and for multi-soliton interactions, energy transfer will occur in all three relative phase conditions. The magnitude and direction of energy transfer can be controlled respectively by adjusting the interval and the relative phase of solitons.     

克尔介质中皮秒亮孤子多光子J-C模型粒子数反转特性

利用全量子理论研究了克尔介质中皮秒孤子光场与二能级原子多光子相互作用系统中粒子数反转随时间的变化特性,用MATLAB软件编程模拟并讨论了初始平均光子数、克尔介质与场模非线性相互作用强弱、孤子光场与原子耦合强度及相互作用过程中跃迁光子数目对粒子数反转的影响.数值计算结果表明：初始平均光子数越大、克尔介质与场模的非线性相互作用越强、孤子光场与原子耦合强度越小或相互作用过程中跃迁光子数目越多,粒子数反转崩坍与恢复的振荡幅度越小、平均值越大.     

亮暗屏蔽光伏孤子在LiNbO3晶体中的大自偏转

用数值方法证实了亮、暗屏蔽光伏孤子在有外加电场的LiNbO₃晶体中都可以发生大自偏转,并验证了这种自偏转现象不但与晶体中受主浓度N_A有关而且还与外加电场E₀有关. 在E₀相同的条件下,N_A越小这种自偏转现象越明显,在N_A相同的条件下,E₀越大自偏转现象越明显. 还发现亮、暗屏蔽光伏孤子的自偏转现象不同：亮屏蔽光伏孤子整体都发生明显偏转,暗屏蔽光伏孤子的偏转只是发生在一侧,其极值位置和另一侧几乎不发生偏转. 关键词： 自偏转 空间孤子 光折变效应     

多个部分非相干光孤子的相互作用

基于相干密度理论，数值地研究了在饱和对数非线性介质中多个部分非相干光空间孤子之间的相互作用. 数值结果表明，在非相干参量较小情况下，非相干光孤子的相互作用与相干光孤子的相互作用规律较类似. 当非相干参量较大时，强的非相干性模糊了孤子之间的相位关系，孤子间的相互作用主要以非相干相互吸引作用为主. 特别是在非相干参量较大而且孤子初始相对相位差为π的情况下，多个部分非相干光孤子可并行传播形成稳定的阵列孤子. 利用多个非相干光孤子的不同相互作用形态写入各种阵列波导，为实现光控制光、导向光提供了一种可能性. 关键词： 多个部分非相干光空间孤子 空间光孤子的相互作用 相干密度理论 饱和对数非线性     

部分相干光光束的振荡自陷特性

用互相干函数法研究了圆形横截面的部分相干光光束在光折变晶体中的自陷行为.光束的初态及材料的非线性决定了光束自陷的变化形式,导出空间周期表达式,获得了光束相干半径的解析表达式,发现部分相干光光束的相干特性会随传播距离发生周期性的演化,并将圆形光束的讨论结果扩展到椭圆形光束中. 关键词： 空间孤子 部分相干光光束 相干半径     

Precisely controllable bright nonautonomous solitons in Bose-Einstein condensate

We study on bright nonautonomous solitons of Bose-Einstein condensate analytically in a time-dependent harmonic trap with an arbitrary time-dependent linear potential and complex potential. The explicit ways to control dynamics of soliton are presented through observing the evolution of its width, peak, and the motion of its center analytically. Furthermore, we present two-solitons solution in generalized form to observe the collision of solitons conveniently.     

Merging and splitting dynamics between two bright solitons in dipolar Bose-Einstein condensates

We numerically study the interaction dynamics of two bright solitons with zero initial velocities in the one-dimensional dipolar Bose-Einstein condensates. Under different dipolar strengths, the two bright solitons can merge into a breathing wave, and then split or propagate constantly after several oscillating periods. We quantitatively study the breathing frequency of wave after merging and the asymmetry property of solitons after splitting, and analyze their formation mechanism by the system's energy evolution. Also, the change of initial phase difference brings distinct effects on the soliton interaction. Our results provide insight into the new dynamical phenomena in dipolar systems and enrich the understanding for interaction between dipolar solitons.     

异色光伏孤子之间的相互作用

用数值方法模拟异色光伏孤子的相互作用.结果表明孤子间相互作用是非弹性的，相互作用的孤子只在有限的传播距离内保持孤子形状.不同频率光伏孤子间的相互作用除了相互吸引外，还存在光能在孤子诱导波导间的耦合. 关键词： 光伏空间孤子 异色 相互作用     

Spatial solitons in Kerr and Kerr-like media

This is a review paper of basic knowledge and recent advances in the area of spatial solitons in Kerr and Kerr-like media. We consider spatial bright and dark solitons, solitons in waveguide geometries, optical bullets, vortex solitons and, briefly, dissipative cases. In our treatment, we use a Hamiltonian approach when considering stability issues.     

亚强非局域空间光孤子的相互作用

研究了亚强非局域空间光孤子的相互作用规律,从光线方程出发得到了孤子光束中心的演化性质以及相互作用周期的解析解.发现亚强非局域条件下孤子的初始间距和非局域特征长度的关系对孤子的相互作用周期有很大的影响,在斜入射时存在一个最大入射角, 小于这个角度孤子才会吸引.数值模拟验证了理论解析的结果. 关键词： 亚强非局域 相互作用 空间光孤子 全光开关