纳秒激光诱导K9元件体损伤研究

Research on Bulk Damage of K9 Glass Induced by Nanosecond Laser

利用1064 nm和355 nm两种波长的纳秒激光研究了K9光学元件体内成丝损伤的特点及损伤增长规律。结果表明,当以高于元件体损伤阈值的能量辐照样品体内时,必然会在体内形成丝状损伤。两种激光辐照都会在元件体内首先形成等离子通道,在后续激光的辐照下,靠近入射激光处的损伤点吸收更多能量发展为更大的成核损伤点,逐渐向前表面增长,并伴随大量裂纹的纵向扩展。所不同的是,355 nm激光诱导元件体内成丝损伤时存在多条丝状通道;而1064 nm激光即使在远大于初始损伤阈值的激光能量辐照下,也没有观察到非常明显的丝状损伤。同时实验也发现,两种波长诱导的丝状损伤的损伤增长面积随激光辐照发次的增加呈现指数趋势增长,355 nm导致的损伤增长速度大于1064 nm对应的速度。

The characteristics and growth behavior of filamentation damage in K9 optical elements are researched by nanosecond laser with 1064 nm and 355 nm.The results show that when the sample is irradiated with energy higher than the bulk damage threshold,the filamentous damage will be inevitably formed.The two kinds of laser irradiation will firstly form plasma channel in K9 optical elements,under subsequent laser irradiation,the damage sites near the incident laser absorb more laser energy,developing into a larger nucleation damage points,and gradually grow to the front surface,which is accompanied by the longitudinal expansion of a large number of cracks.The difference is that there are many filamentous channels when 355 nm laser induces filamentous damage,while 1064 nm laser does not observe very obvious filamentous damage even when it is irradiated by laser energy far greater than the initial damage threshold・At the same time,it is found that the damage growth area of filamentous damage induced by two wavelengths increases exponentially with the increasing of laser irradiation times,and the damage growth rate caused by 355 nm is faster than that of 1064 nm.