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采用可调节延迟、共线的双束飞秒激光脉冲列烧蚀ZnO表面,验证随着延迟时间的变化,其表面周期波纹结构的转变及结构转变的机理。在ZnO表面上可以分别观察到低空间频率的周期波纹结构(LSFL)和高空间频率的周期波纹结构(HSFL)。随着延迟时间的增加,发现低空间频率的周期波纹结构开始向高空间频率的周期波纹结构转变的现象。利用电子产生的速率方程分别去计算由800nm激光和400nm激光辐照所激发的电子密度。最终的计算结果结合Sipe理论可以对该现象的发生进行解释。该研究表明,可以通过可调节延时的双束激光脉冲列来控制激发的电子水平从而改变飞秒激光辐照在材料表面诱导的周期波纹结构。
The ZnO surface was ablated by an adjustable delay and collinear double-beam femtosecond laser pulse train, and the mechanism of the transition of periodic surface corrugation structure and the structure transition was verified with the change of delay time. Periodic corrugation structure (LSFL) with low spatial frequency and periodical corrugation structure (HSFL) with high spatial frequency can be observed on ZnO surface. With the increase of delay time, it was found that the periodic corrugated structure with low spatial frequency started to change to the periodic corrugated structure with high spatial frequency. The electron-generated rate equations were used to calculate the electron density excited by 800 nm laser and 400 nm laser respectively. The final calculation combined with Sipe’s theory can explain the occurrence of this phenomenon. The study shows that the periodic wave-induced structure induced by femtosecond laser irradiation on the material surface can be changed by controlling the excited electron level through the adjustable delay dual-beam laser pulse train.