饱和非线性介质中艾里-高斯光束的传输与交互作用

研究了艾里-高斯光束在饱和非线性介质中的传输与交互作用.结果表明,入射光为单艾里-高斯光束时,在一定功率范围内,调节初始振幅与光场分布,可形成传输方向可控的呼吸孤子.当初始振幅增加时,孤子的呼吸周期先减小后增大.入射光为两艾里-高斯光束时,同相位光束相互吸引,两光束中心位置两侧附近产生呼吸孤子和对称孤子对.反相位光束相互排斥,中心位置两侧仅产生对称的孤子对.光场分布越趋于高斯分布,两艾里-高斯光束相互作用就越强,孤子对的数目越少.     

竞争型非线性介质中艾里-高斯光束交互作用的调控

基于分步傅里叶法研究了艾里-高斯光束在三次聚焦和五次散焦竞争型非线性介质中交互作用的调控.结果表明:当入射角度为零时,同相位艾里-高斯光束相互吸引,五次散焦非线性强度较弱时,可形成周期逐渐缩短的呼吸孤子或强度不变的孤子.五次散焦非线性强度较强时,呼吸孤子的平均宽度变大甚至出现光束分叉现象,形成孤子对.反相位艾里-高斯光束相互排斥,排斥力随五次散焦非线性强度单调递增.当入射角度不为零时,通过控制光束入射角度的正负和初始间距.同相位和反相位艾里-高斯光束交互作用时可以同时表现出相互吸引和排斥的现象.     

（1+1）维光折变亮屏蔽孤子相互作用的数值分析

利用束传播法对（1+1）维光折变亮屏蔽孤子间的相互作用进行了详细地数值模拟研究.结果表明：两同相孤子相互吸引，并伴有孤子融合现象，且孤子融合发生时的作用距离随着孤子初始间距的增大而增大；两反相孤子相互排斥，且排斥作用随着孤子初始间距的减小而增强；当两孤子的相位差位于区间（0,π）和（－π，0）中时，其相互作用过程将伴有能量转移，但两区间内能量转移的方向相反，并表现出反转对称性；由于孤子间的距离和相对相位对孤子间的相互作用均有很大的影响，因此多个孤子间的相互作用过程非常复杂，但可以通过分析相邻孤子间的相互作用对其进行定性的预测.     

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     

艾里-厄米-高斯光束在克尔介质中的孤子控制

以非线性薛定谔方程为理论模型,采用分步傅里叶数值模拟方法,讨论了有限能量艾里-厄米-高斯光束在克尔介质中的传输特性以及相互作用。研究表明,通过控制介质的非线性强度和艾里-厄米-高斯光束的初始振幅,可以抑制光束的衍射效应,当它们满足一定条件时,能够产生孤子。通过研究两艾里-厄米-高斯光束的相互作用,发现调整两光束的初始间隔以及相位,可以控制孤子的数量和传输方向。     

高斯光束在有外电场的双光子光伏光折变材料中的演化

为了得到一束高斯光束和两束高斯光束的相互作用在有外电场的双光子光伏光折变材料中的演化结果,将高斯光束作为入射波,采用数值方法求解波传播方程。研究结果表明:在外加电场、光强峰值分别与晶体参量匹配的情况下,一束高斯光束能演化为稳定的屏蔽光伏明孤子,而在不匹配时,一束高斯光束在传播过程中则呈现周期性压缩或膨胀现象。同时也发现:在作用距离范围内,同相位的两高斯光束相互吸引,并伴随有融合现象;而相位相反的两高斯光束相互排斥,且其排斥作用随着光束初始间距的减小而增加,当两高斯光束的相位差位于区间(0,π)和(-π,0)时,其相互作用过程中伴有能量的转移,两区间中能量转移方向相反。     

饱和非线性介质中艾里孤子的产生与传输调控

采用分步傅里叶法,通过数值模拟研究了饱和非线性介质中艾里孤子的产生与传输调控。单艾里光束入射时,在一定的初始振幅范围内可以产生稳定传输的呼吸式孤子。初始振幅增加时,孤子的强度增加,呼吸周期变短,但宽度基本保持不变。衰减系数增加时,孤子的平均峰值强度先增大后减小之后再增大,存在两个极值点。光束入射角度为负值时,形成左倾艾里孤子;光束入射角度为正值时,形成右倾艾里孤子。双艾里光束入射时,入射角同为负值可以减弱光束间的相互作用,入射角同为正值可以增强光束间的相互作用。此外,不同的入射角可以控制孤子或孤子对的传输方向。     

(1+1)维光折变亮屏蔽孤子相互作用的数值分析

利用束传播法对(1 1)维光折变亮屏蔽孤子间的相互作用进行了详细地数值模拟研究.结果表明两同相孤子相互吸引,并伴有孤子融合现象,且孤子融合发生时的作用距离随着孤子初始间距的增大而增大;两反相孤子相互排斥,且排斥作用随着孤子初始间距的减小而增强;当两孤子的相位差位于区间(0,π)和(-π,0)中时,其相互作用过程将伴有能量转移,但两区间内能量转移的方向相反,并表现出反转对称性;由于孤子间的距离和相对相位对孤子间的相互作用均有很大的影响,因此多个孤子间的相互作用过程非常复杂,但可以通过分析相邻孤子间的相互作用对其进行定性的预测.     

高斯光束在有外电场的中心对称光折变材料中的演化

为了研究在有外电场的中心对称光折变材料中一束高斯光束及两束高斯光束相互作用的演化,将高斯光束作为入射波,采用数值方法求解波传播方程.结果表明,当外加电场,光强峰值和束腰参量分别与晶体匹配的情况下,一束高斯光束能演化为稳定的屏蔽空间明孤子,而在不匹配时,一束高斯光束在传播过程中则呈现周期性的压缩或膨胀现象.同时也发现,在作用距离范围内.两束同相位高斯光束相互吸引,并伴随着融合现象,两束反相位高斯光束相互排斥,且排斥作用随着光束初始间距的减小而增加.     

饱和对数非线性介质中非相干孤子碰撞对相干性的改善

基于相干密度理论，数值地研究了饱和对数非线性支持的部分非相干亮孤子对的相互作用.研究表明，两个非相干亮孤子碰撞不仅能增大碰撞区的光强，还可以大大改善部分非相干光束的相干性.同时还研究了非相干性对孤子碰撞的影响，非相干性不仅抑制了孤子间的相干作用如吸引、排斥和能量交换，同时还由于非相干叠加作用而引入了弱的相互吸引. 关键词： 非相干性 饱和对数非线性 空间光孤子     

Collisions between optical spatial solitons propagating in opposite directions

We formulate the theory describing the evolution and interactions between optical spatial solitons that propagate in opposite directions. We show that coherent collisions between counterpropagating solitons give rise to a new focusing mechanism resulting from the interference between the beams, and that interactions between such solitons are insensitive to the relative phase between the beams.     

Counterpropagating optical beams and solitons

Physics of counterpropagating optical beams and spatial optical solitons is reviewed, including the formation of stationary states and spatiotemporal instabilities. First, several models describing the evolution and interactions between optical beams and spatial solitons are discussed, that propagate in opposite directions in nonlinear media. It is shown that coherent collisions between counterpropagating beams give rise to an interesting focusing mechanism resulting from the interference between the beams, and that interactions between such beams are insensitive to the relative phase between them. Second, recent experimental observations of the counterpropagation effects and instabilities in waveguides and bulk geometries, as well as in one‐ and two‐dimensional photonic lattices are discussed. A variety of different generalizations of this concept are summarized, including the counterpropagating beams of complex structures, such as multipole beams and optical vortices, as well as the beams in different media, such as photorefractive materials and liquid crystals.     

All-optical steering of the interactions between multiple spatial solitons in isotropic polymers

All-optical steering of the nonlinear interactions between multiple spatial solitons can be performed in an isotropic photoisomerization polymer, by propagating an external control beam in perpendicular direction. Fusing, giving birth to another new soliton, and transferring energy can take place in the interactions of signal beams, which can be achieved by changing the incident position of the control beam, the initial relative phase and the power ratio between the signal beams and the control beam. These phenomena are physically explained, and they have significantly potential applications in optical signal readdressing, logic gating, and all-optical switching, etc.     

基于全息聚焦机理空间光孤子的相互作用势函数

利用变分法讨论了反向传输的基于全息聚焦机理空间光孤子的相互作用,导出了相干和非相 干相互作用的势函数.当孤子间的相对相位不随传输距离变化或相对相位对传输距离的偏导 数与孤子间距无关时,相干和非相干相互作用势函数都与孤子间的相对相位无关,出现孤子间 反常相互作用,这正好是近期文献的结果. 关键词： 空间光孤子 相互作用 变分原理     

Propagation properties of spatial optical solitons in different nonlocal nonlinear media with arbitrary degrees of nonlocality

We address the physical features exhibited by spatial optical solitons propagating in nonlocal Kerr-type media with Gaussian-shaped response and exponential-decay response, respectively. An iteration algorithm based on the split-step Fourier method is developed to obtain the numerical solutions of the solitons for the nonlocal nonlinear Schrödinger equation with arbitrary degrees of nonlocality. Our numerical results show that the soliton properties in the normalized system are different with the change of the degree of nonlocality and with the different responses. The profiles undergo a gradual and continuous transition from a Gaussian-shaped function in the strongly nonlocal case to a hyperbolic secant function in the local case for the Gaussian-shaped response, but for the exponential-decay response, the soliton profile is not Gaussian-shaped even in the strongly nonlocal cases. For the same response function, the stronger the nonlocality is, the higher the critical powers for solitons are and the larger of the phase shifts of the solitons. For the same degrees of nonlocality, when the degrees of nonlocality is larger enough, both the critical power and the phase shift for the Gaussian-shaped response are larger than that for the exponential-decay response.     

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.     

Dynamics of collinear Laguerre–Gaussian beams in nonlocal nonlinear media

We study the optical fields that are produced by two collinear Laguerre–Gaussian (LG) beams in strongly nonlocal nonlinear media. Various novel kinds of rotating breathers and solitons, such as quadrangle, pentacle, pentagon, etc. can be obtained by combining different mode-index LG beams with the different relative amplitude. The rotating and translating asymmetric breathers and solitons can be obtained when the difference of the azimuthal charge between the two combining LG beams is 1.     

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     

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     

Interaction of spatially overlapping standing electromagnetic solitons in plasmas

Numerical investigations on mutual interactions between two spatially overlapping standing electromagnetic solitons in a cold unmagnetized plasma are reported. It is found that an initial state comprising of two overlapping standing solitons evolves into different end states, depending on the amplitudes of the two solitons and the phase difference between them. For small amplitude solitons with zero phase difference, we observe the formation of an oscillating bound state whose period depends on their initial separation. These results suggest the existence of a bound state made of two solitons in the relativistic cold plasma fluid model.