包裹光束飞秒激光脉冲的传输特性研究

Propagation characteristics of femtosecond laser pulses with wrapped beams

摘要:

飞秒激光成丝传输中的线性和非线性效应对光束能量分布和传输有重要影响,研究其在介质中成丝的传输特性将会拓展相关应用前景。由于光束传播对输入光束的形状和波长极为敏感,可以通过改变输入光束的形状和波长来调控光束在介质中能量和光强的分布。本文基于非线性薛定谔方程,研究了变化的波长和形状下,超高斯光束和包裹光束的传输特性。研究发现超高斯光束能够促进光束更快聚焦,也促使介质中光束光强和等离子体密度数值发生改变；超高斯光束和周围环形部分构成的包裹光束,由于存在“能量池”的作用有利于促进和维持光束的传播。此外,减小光束的波长有助于获得更大的光强箝位,促进光束更快聚焦,光强的维持效果明显。

Abstract:

The propagation of a femtosecond laser pulse as a filament in a medium is subject to complex linear and nonlinear effects and it is significant to study the filamentation characteristics of femtosecond lasers in a medium.Since the beam propagation is highly sensitive to the shape and wavelength of the input beam,the distribution of energy and intensity in the medium can be controlled by modifying both the shape and wavelength of the beam.In this paper,we investigate the propagation characteristics of super-Gaussian and wrapped beams at varying wavelengths and shapes,based on the nonlinear Schrdinger equation.Our results show that super-Gaussian beams can facilitate faster beam focusing and induce changes in the intensity and plasma density values in the medium.Furthermore,we find that using wrapped beams composed of super-Gaussian beams and surrounding annular beams,which form an “energy reservoir”,is more favorable for promoting and sustaining beam propagation.Moreover,we observe that decreasing the wavelength of the beam leads to higher confinement intensity and faster beam focusing with better intensity preservation.