外文题目: Modeling of ablation threshold dependence on pulse duration for dielectrics with ultrashort pulsed laser
作者: Sun, Mingying; Zhu, Jianqiang; Lin, Zunqi
刊名: Opt. Eng.
年: 2017 卷: 56 期: 1 文章编号：11026
英文关键词:
laser-induced breakdown; laser ablation; ultrafast lasers; ablation threshold; dielectrics
TRANSPARENT MATERIALS; BIOLOGICAL TISSUES; INDUCED BREAKDOWN; PLASMA FORMATION; INDUCED DAMAGE; FEMTOSECOND; IONIZATION; MECHANISMS; DYNAMICS; GRATINGS
英文摘要:
We present a numerical model of plasma formation in ultrafast laser ablation on the dielectrics surface. Ablation threshold dependence on pulse duration is predicted with the model and the numerical results for water agrees well with the experimental data for pulse duration from 140 fs to 10 ps. Influences of parameters and approximations of photo- and avalanche-ionization on the ablation threshold prediction are analyzed in detail for various pulse lengths. The calculated ablation threshold is strongly dependent on electron collision time for all the pulse durations. The complete photoionization model is preferred for pulses shorter than 1 ps rather than the multiphoton ionization approximations. The transition time of inverse bremsstrahlung absorption needs to be considered when pulses are shorter than 5 ps and it can also ensure the avalanche ionization (AI) coefficient consistent with that in multiple rate equations (MREs) for pulses shorter than 300 fs. The threshold electron density for AI is only crucial for longer pulses. It is reasonable to ignore the recombination loss for pulses shorter than 100 fs. In addition to thermal transport and hydrodynamics, neglecting the threshold density for AI and recombination could also contribute to the disagreements between the numerical and the experimental results for longer pulses. (C) 2016 Society of Photo-Optical Instrumentation Engineers (SPIE)


文献类型: 期刊论文
正文语种: English
收录类别: SCI
DOI: 10.1117/1.OE.56.1.011026


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