arXivDaily arXiv每日学术速递 周一至周五更新
arXiv nlin/0209025nlin.PS
收藏

耦合非线性Schroedinger系统孤立波的标量非局部分支

A scalar nonlocal bifurcation of solitary waves for coupled nonlinear Schroedinger systems

Alan Champneys, Jianke Yang

摘要:

给出了解释以前的数值结果,这表明一定的“矢量孤子”从标量(单分量)孤立波在耦合非线性薛定谔(NLS)系统的分支。在这个意义上的矢量孤子没有一个小振幅的组件,而是接近孤立波的一个组件与两个无限远分离的波在其他组件的分歧是非本地的。然而,有人认为,这种高度非本地的事件可以预测从一个纯粹的本地分析的中央孤立波。具体地说,围绕中心波的线性化应包含渐近性,该渐近性恰好以两翼上的其他分量孤立波的速度增长。这种近似的论点是支持基于匹配的渐近展开式的详细分析,和两个例子系统的数值实验。第一个是通常的耦合NLS系统,涉及任意比例之间的自相位和交叉相位调制项,第二个是耦合NLS系统与饱和非线性,最近已被证明支持稳定的多峰孤立波。渐近分析进一步揭示了当定义标量非局部分岔判据的曲线与某些局部分岔的边界相交时,非局部分岔在交点处可以从标量分岔变为非标量分岔.在第一个例子中观察到这种现象。最后,我们也有选择地测试了几个孤立波的线性稳定性的标量非局部分岔。我们发现它们是线性不稳定的。然而,它们可以通过参数延拓得到稳定的孤立波。

英文摘要:

An explanation is given for previous numerical results which suggest a certain bifurcation of `vector solitons' from scalar (single-component) solitary waves in coupled nonlinear Schroedinger (NLS) systems. The bifurcation in question is nonlocal in the sense that the vector soliton does not have a small-amplitude component, but instead approaches a solitary wave of one component with two infinitely far-separated waves in the other component. Yet, it is argued that this highly nonlocal event can be predicted from a purely local analysis of the central solitary wave alone. Specifically the linearisation around the central wave should contain asymptotics which grow at precisely the speed of the other-component solitary waves on the two wings. This approximate argument is supported by both a detailed analysis based on matched asymptotic expansions, and numerical experiments on two example systems. The first is the usual coupled NLS system involving an arbitrary ratio between the self-phase and cross-phase modulation terms, and the second is a coupled NLS system with saturable nonlinearity that has recently been demonstrated to support stable multi-peaked solitary waves. The asymptotic analysis further reveals that when the curves which define the proposed criterion for scalar nonlocal bifurcations intersect with boundaries of certain local bifurcations, the nonlocal bifurcation could turn from scalar to non-scalar at the intersection. This phenomenon is observed in the first example. Lastly, we have also selectively tested the linear stability of several solitary waves just born out of scalar nonlocal bifurcations. We found that they are linearly unstable. However, they can lead to stable solitary waves through parameter continuation.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑