We have studied strain wave generation in graphite induced by an intense ultrashort laser pulse. The study was performed in the intensity regime above the ablation threshold of graphite. The aim was to maximize the strain and, thus, also the internal pressure (stress). Laser pulses with a 1 ps temporal duration melt the surface of graphite resulting in a molten material which initially exists at the solid density. As the molten material expands, a compressive strain wave starts propagating into the crystal below the molten layer. The strain pulse was studied with time-resolved X-ray diffraction. At a temporal delay of 100 ps after laser excitation, we observed >10% compressive strain, which corresponds to a pressure of 7.2 GPa. This strain could be reproduced by hydrodynamic simulations, which also provided a temperature map as a function of time and depth.

中文翻译：

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通过超短脉冲激光照射在石墨中产生大压缩应变波。

我们研究了强超短激光脉冲在石墨中产生的应变波。该研究是在高于石墨烧蚀阈值的强度范围内进行的。目的是最大化应变，从而最大化内部压力（应力）。持续时间为 1 ps 的激光脉冲熔化石墨表面，形成最初以固体密度存在的熔融材料。当熔融材料膨胀时，压缩应变波开始传播到熔融层下方的晶体中。通过时间分辨 X 射线衍射研究了应变脉冲。在激光激发后 100 ps 的时间延迟下，我们观察到 >10% 的压缩应变，对应于 7.2 GPa 的压力。这种应变可以通过流体动力学模拟来重现，该模拟还提供了随时间和深度变化的温度图。