脉冲激光辐照硅材料引起表面波纹的特性研究

Study of the Characteristics of the Surface Ripple on Si Material Irradiated by Pulsed Laser

叙述了激光与材料相互作用过程中引起相干受激光散射的机制 ,以及形成材料表面波纹的特性。在激光波长 1.0 6 μm、能量 15mJ、光斑直径 2mm、脉冲半峰全宽约 10ns和入射方向为布儒斯特角的条件下 ,进行了脉冲激光辐照硅材料形成表面波纹的实验研究。在脉冲激光辐照硅材料表面功率密度略大于材料损伤阈值的条件下 ,发现了硅材料表面形成的平行等间距直线条纹结构。用光学显微镜和原子力显微镜分别测量了被辐照硅材料表面的波纹形貌特征。在假设硅材料表面波纹的产生与声波在材料中的传播速度有关的条件下 ,由声波传播速度和激光辐照硅材料的脉冲宽度较好地解释了材料表面形成条纹的宽度 ,并认为在形成表面波纹的过程中 ,热应力起主要作用。

The mechanism of coherent stimulated light scattering and the characteristics of the surface ripple in the laser interaction with materials is described. Experimental research on the surface ripple with Si material irradiated by pulsed laser, is carried out with 1.06 μm laser wave length, 15 mJ energy, 2 mm spot diameter, about 10 ns pulse width and Brewster angle incidence. The surface ripple′s modality of the laser-induced Si material is measured by optical microscope and atomic microscope. A set of liner ripple structure with parallel, equal spaces is found at the surface of silicon material after pulsed laser irradiation under a little higher laser intensity than damage threshold. If this ripple phenomena is related to sound wave velocity in material, the ripple period could be well explained according to the sound wave velocity and pulse duration, and thermal stress is a main role in the formation of surface ripple.