Surface and bulk ultrashort-pulsed laser processing of transparent materials
Surface and bulk ultrashort-pulsed laser processing of transparent materials
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透明材料的表面和体超短脉冲激光加工
DOI：
10.1117/12.405703
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发表时间：
2000
期刊：
影响因子：
--
通讯作者：
E. Campbell
中科院分区：
文献类型：
--
作者：
I. Hertel;R. Stoian;D. Ashkenasi;A. Rosenfeld;E. Campbell
研究了超短脉冲激光烧蚀电介质材料的非原位形态观察和原位飞行时间质谱学研究。对烧蚀产物的能谱分析提供了有关飞秒激光烧蚀材料过程的丰富信息。本文将以蓝宝石(Al_2O_3)为例，讨论超短脉冲激光溅射的基本过程。已经确定了两个不同的烧蚀阶段，一个是烧蚀速率较低的平缓阶段，另一个是烧蚀速率较高的强腐蚀阶段，但结构质量有限。通过比较抛射离子、中性粒子和电子的能量和动量分布，可以区分导致宏观材料去除的非热过程和热过程。等动量的快正离子是在低注量和低照射脉冲数(温和蚀刻相)下，由上层的库仑爆炸产生的。利用飞秒激光脉冲的泵浦-探测研究揭示了激发和电子介导的能量转移到晶格的动力学。在较高的激光通量或较长的孵化时间后，可以从表面形貌和现场实验结果中获得相爆炸的证据。
Ultrashort pulsed laser ablation of dielectrics has been investigated using ex-situ morphological examinations in combination with in-situ time-of-flight mass spectrometry of the ablated species. Analysis of the energy spectrum of the ablation products provides a wealth of information on the processes occurring during femtosecond laser ablation of materials. The presentation will focus on the case of sapphire (Al2O3) and discuss the fundamental processes in ultrashort pulsed laser sputtering. Two different ablation phases have been identified, a gentle phase with low ablation rates and a strong etch phase with higher ablation rates, but with limitation in structure quality. A comparison of the energy and momentum distributions of ejected ions, neutrals and electrons allows one to distinguish between non-thermal and thermal processes that lead to the macroscopic material removal. Fast positive ions with equal momenta are resulting from Coulomb explosion of the upper layers at low fluence and low number of irradiating laser pulses (gentle etch phase). Pump-probe studies with fs laser pulses reveal the dynamics of excitation and electron mediated energy transfer to the lattice. At higher laser fluences or after longer incubation, evidence for phase explosion can be derived from both the morphology of the surface and the results of the in-situ experiments.