Dynamic all-optical control in ultrashort double-pulse laser ablation
Dynamic all-optical control in ultrashort double-pulse laser ablation
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DOI：
10.1016/j.apsusc.2020.147940
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发表时间：
2021-01-30
影响因子：
6.7
通讯作者：
Mikhailovskii, Vladimir Yu
中科院分区：
文献类型：
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作者：
Kudryashov, Sergey, I;Samokhvalov, Andrey A.;Mikhailovskii, Vladimir Yu
双脉冲飞秒激光烧蚀铝薄膜和铝块材的结果与直觉相反，脉冲间延迟为20-200ps时，铝薄膜和块材的厚度阈值显著升高(60%-70%)，从而阻止了材料在高于阈值的流量下被去除。进行了时间分辨的光抽运-探测反射和双泵浦光传输研究，证实了烧蚀阈值随脉冲间延迟的变化。为支持实验测量，采用原子-连续介质联合模型模拟了双脉冲激光烧蚀过程。该模型可以在原子精度上描述激光诱导的非平衡相变过程，而自由载流子的影响对超短激光脉冲的情况起着决定性的作用。模拟揭示了热的、声学松弛的铝熔体中潜在的烧蚀前激光诱导的应力动力学，这对第二次泵浦脉冲压缩加压非常敏感。理论和实验研究结果为超快激光烧蚀提供了有效的动态全光控制。
Double-pulse femtosecond laser ablation of thin aluminum films and bulk aluminum counterintuitively demonstrated a strong (60-70%) raise of the thickness-dependent thresholds for inter-pulse delays of 20-200 ps, preventing material removal at above-threshold fluencies. Time-resolved optical pump-probe reflection and double-pump transmission studies were performed and confirmed the variation of the ablation threshold depending on the interpulse delay. To support the experimental measurements, the process of double-pulse laser ablation was modelled with the combined atomistic-continuum model. The applied model can describe the laser-induced non-equilibrium phase transition processes at atomic precision, whereas the effect of free carriers, playing a determinant role for the case of ultrashort laser pulses, is accounted for in the continuum. The simulations revealed the underlying pre-ablative laser-induced stress dynamics in the hot, acoustically relaxed Al melt, crucially sensitive to the second pump-pulse compressive pressurization. The results of theoretical and experimental study enable efficient dynamic all-optical control of ultrafast laser ablation.