We determine the laser-induced ablation threshold fluence in air of aluminum and tungsten excited by single near-infrared laser pulses with duration ranging from 15 to 100 fs. The ablation threshold fluence is shown to be constant for both metals, extending the corresponding scaling metrics to few-optical-cycle laser pulses. Meanwhile, the reflectivity is measured providing access to the deposited energy in the studied materials on a wide range of pulse durations and incident fluences below and above the ablation threshold. A simulation approach, based on the two-temperature model and the Drude–Lorentz model, is developed to describe the evolution of the transient thermodynamic and optical characteristics of the solids (lattice and electronic temperatures, reflectivity) following laser excitation. The confrontation between experimental results and simulations highlights the importance of considering a detailed description and evolution of the density of states in transition metals like tungsten.

中文翻译：

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通过反射率测量研究铝和钨的超短激光激发

我们确定了由持续时间为 15 到 100 fs 的单个近红外激光脉冲激发的铝和钨空气中的激光诱导烧蚀阈值通量。两种金属的烧蚀阈值通量显示为常数，将相应的缩放度量扩展到少光周期激光脉冲。同时，测量反射率以提供在宽范围的脉冲持续时间和低于和高于烧蚀阈值的入射通量下获得研究材料中沉积能量的途径。开发了一种基于双温度模型和 Drude-Lorentz 模型的模拟方法来描述激光激发后固体的瞬态热力学和光学特性（晶格和电子温度、反射率）的演变。