高阶克尔效应对氩气介质中飞秒光丝的影响

Effects of higher-order Kerr on the femtosecond filament in argon

利用飞秒光丝的强场非线性效应可大幅提高激光高精加工技术。在产生光丝的过程中,克尔效应起到了显著作用。由于以往没有测得高阶克尔折射系数,因此模拟计算只取低阶值。随着高阶克尔折射系数的测定,其作用受到了越来越多的关注。本文以氩气为传输介质,采用非线性薛定谔传输方程,分4组不同的折射系数情况来研究高阶克尔效应对成丝的影响。结果表明,尽管折射系数值相差不大,但其对成丝的影响却异常明显,甚至出现了不同的自聚焦-散焦过程和等离子体密度相差一个数量级等差异。这就意味着,在模拟利用光丝的强场非线性光学效应进行激光材料加工时,需选择与环境相一致的折射系数,以提高加工精度。

Laser high precision machining technology can be greatly improved by using the strong field nonlinear effect of femtosecond filament.In the process of producing light filament,Kerr effect played a significant role.In the past,the higher-order Kerr refractive index was not measured and the simulation adopted the lower-order ones.With the determination of higher-order Kerr refractive index,its role has attracted more and more attention.In this paper,the effect of higher-order Kerr on the filament in argon is studied by dividing 4 different refractive indices with the nonlinear Schro-dinger transmission equation.The results show that,although the difference of the refractive index number is small,the efect on the filament is very obvious,even resulting in different focusing-defocusing process and one order of magnitude difference of the plasma density.This means that when using the strong field nonlinear optical effect of filament to simulate material processing,it is necessary to choose the refractive index consistent with the environment to improve the machining precision.