Couairon A, Gaizauskas E, Faccio D, Dubietis A, Di Trapani P
Centre de Physique Théorique, Centre de la recherche sciencifique UMR 7644, Ecole Polytechnique, F-91128 Palaiseau, France.
Phys Rev E Stat Nonlin Soft Matter Phys. 2006 Jan;73(1 Pt 2):016608. doi: 10.1103/PhysRevE.73.016608. Epub 2006 Jan 17.
We investigate the formation of X waves during filamentation in Kerr media. From the standard model developed for femtosecond filamentation in liquids, solids, and gases, the influence of several physical effects and parameters is numerically studied in the strongly nonlinear regime where group velocity dispersion alone is insufficient to arrest collapse. The collapse is shown to be arrested by multiphoton absorption and plasma defocusing, but not by dispersion. The postcollapse dynamics takes the form of a pulse splitting, which induces large gradients in the near field and seeds the formation of X waves, appearing both in the near and far fields. We discuss the universal features of the X-wave patterns, among which the long arms in the far field that follow the linear dispersive properties of the medium [Conti, Phys. Rev. Lett. 90, 170406 (2003); Kolesik, Phys. Rev. Lett. 92, 253901 (2004)] and are accompanied by a strong modulated axial emission.
我们研究了克尔介质中丝状化过程中X波的形成。从为液体、固体和气体中的飞秒丝状化所建立的标准模型出发，在群速度色散单独不足以阻止坍缩的强非线性区域，对几种物理效应和参数的影响进行了数值研究。结果表明，坍缩是由多光子吸收和等离子体散焦阻止的，而不是由色散阻止的。坍缩后的动力学表现为脉冲分裂形式，这在近场中产生了大梯度，并引发了X波的形成，X波出现在近场和远场中。我们讨论了X波模式的普遍特征，其中远场中的长臂遵循介质的线性色散特性[康蒂，《物理评论快报》90，170406（2003）；科莱西克，《物理评论快报》92，253901（2004）]，并伴有强烈调制的轴向发射。
