通过数值求解非线性近轴波方程,详细描述了在钕玻璃介质中传输的强激光圆对称超高斯光束形成的自聚焦环,并展示了初始光束受到扰动引起环分裂的现象。对于峰值光强一定的光束,合理地选择其阶数和宽度,可以降低自聚焦成环效应,从而降低因自聚焦环分裂在光束边缘出现的细光束对介质造成的成丝破坏。

In this work, the self-focusing ring originated from a rotation symmetric super-Gaussian beam (RSSGB) incident on the Nd:glass medium is described in detail, with the aid of the numerical solution to the nonlinear paraxial wave equation. For a RSSGB with initial undulations, the self-focusing ring may split after traveling certain distance inside the nonlinear medium, resulting in some high intensity filaments near the verge of the beam. For a RSSGB with a certain peak power, one can select the width and rank of the beam to suppress the formation of the self-focusing ring, so that the filaments due to the breakup of self-focusing rings may be eliminated finally.