Theoretical analysis of ultra-short pulsed laser ablation of SiO_2 material based on a Coulomb explosion model  

超短脉冲激光烧蚀SiO_2材料的库仑爆炸模型理论分析(英文)

作　　者：林晓辉[1] 任维松[1] 

机构地区：[1]东南大学机械工程学院,南京211189

出　　处：《Journal of Southeast University(English Edition)》2011年第3期261-265,共5页东南大学学报（英文版）

摘　　要：Based on the kinetic theoretical Vlasov-Poisson equation, a surface Coulomb explosion model of SiO2 material induced by ultra-short pulsed laser radiation is established. The non-equilibrium free electron distribution resulting from the two mechanisms of multi-photon ionization and avalanche ionization is computed. A quantitative analysis is given to describe the Coulomb explosion induced by the self-consistent electric field, and the impact of the parameters of laser pulses on the surface ablation is also discussed. The results show that the electron relaxation time is not constant, but it is related to the microscopic state of the electrons, so the relaxation time approximation is not available on the femtosecond time scale. The ablation depths computed by the theoretical model are in good agreement with the experimental results in the range of pulse durations from 0 to 1 ps.基于动理论Vlasov-Poisson方程,建立了超短脉冲激光引起的SiO2材料表面库仑爆炸烧蚀机理的理论模型,计算了在多光子吸收与雪崩2种电离机制下材料中自由电子的非平衡态分布,并在此基础上定量分析了自洽电场导致的材料表面库仑爆炸的机理及激光参数对材料表面烧蚀的影响.结果表明,在飞秒激光作用下自由电子弛豫时间不是常数,而是与自由电子微观状态有关,表明弛豫时间近似模型在飞秒时间尺度下是不适用的.理论模型的烧蚀深度数值计算结果在0～1ps脉宽范围均与实验吻合得较好.

关 键 词：ultra-short pulsed laser Coulomb explosion nonequilibrium distribution material ablation 

分 类 号：O434[机械工程—光学工程] TH161[理学—光学]