高强度飞秒激光脉冲烧蚀固体靶材的超快动力学过程的研究

本文报道了利用超快时间分辨阴影图方法对飞秒激光脉冲烧蚀金属铝的动态物理过程的研究。实验发现在50fs泵浦脉冲轰击靶表面后存在热与非热的烧蚀机制,证明在40J/cm^2激光流量下超快激光烧蚀过程是一个涉及到多种不同物理和力学作用的复杂过程。在1—1.5ns延迟的阴影图中清晰地看到被烧蚀物质即将发生相位爆炸时产生的衍射条纹,在4ns和9ns延迟的阴影图中观察到喷射物内部存在由于极强热弹力波的出现而引起的间歇性物质喷射。在硅和玻璃的烧蚀实验中也观察到了类似的物理过程。但对于玻璃样品,没有观察到间歇性物质喷射现象。

Study of the Ultrafast Dynamic Process of Intense Femtosecond Laser Ablation of Solid Targets

The dynamic process of intense 50 fs laser ablation of aluminum is investigated by ultrafast time-resolved shadowgraphs. It is found that ultrafast laser ablation of- ten does not involve only one type of mechanism but a composite physical process depending on both laser parameters and target properties. A stripe pattern preceding phase explosion is clearly seen in the shadowgraph of 1.5 ns time delay. Intermittent material ejections are observed within the ejected plume after 4 ns and 9 ns time delay, respectively, which may be attributed to the material response to the generation of an extremely strong thermoelastic wave. Similar processes are also recorded in the ablation of silicon and glass samples, except for the glass samples, the intermittent material ejections are not found.