空气中激光等离子通道的演变和控制

为精确再现超强飞秒脉冲激光在大气中的传输特性,有效控制激光诱导等离子体通道的性能参数,基于扩展的非线性薛定谔方程,研究了空气中产生的等离子通道的演变过程。该模型在考虑衍射、色散和多光子效应的基础上,引入了拉曼散射、等离子体尾波场和相对论自聚焦等多种效应。讨论了电子密度和光强通量的空间分布特性,运用分步傅里叶法和有限差分法得到了电子密度和光强通量的分布,仿真结果显示,激光波长、单脉冲能量、脉宽和束腰半径等初始参数的变化将对等离子体通道的演变产生显著影响,为超短脉冲强激光在大气中成丝位置和形态控制提供了可能的途径。

Evolution and control of laser-plasma channel in air

A theoretical analysis is carried out to study the evolution of a laser-induced plasma channel in air. The extended nonlinear Schr-dinger equation describing the propagation of laser pulses in air is presented and analyzed, which includes the influence of diffraction, dispersion and multiphoton ionization, Raman scattering, plasma wake fields and relativistic focusing. The electron density and the beam intensity flux along the filament are estimated by solving the Schr-dinger equation using split-step Fourier method and finite difference method. The numerical calculations confirm that the position and pattern of the filaments are dependent on the wavelength, energy, pulse duration and transverse waist of the initial laser pulse．