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实验研究了石英光纤的纳秒激光诱导损伤行为.实验条件下全部为光纤端面损伤,按照损伤形貌可以分为坑状损伤、熔融损伤和溅射损伤三类.提出了光纤端面损伤的判断方法和损伤阈值的测试方法,通过线性拟合得出实验条件下石英传能光纤的零概率损伤功率密度阈值为3.85GW/cm2.总结了光纤端面损伤的过程,分析了激光诱导光纤端面损伤机理,指出光纤端面的杂质缺陷是造成光纤抗激光损伤能力下降的内因.因此,通过改善光纤端面质量还可较大程度提高光纤传输激光能量.实验发现光纤注入端面损伤点几乎全部发生在端面中心区域,这个现象是由于注入光斑中心点功率密度极高,从而造成光斑中心点辐照区域损伤的概率大大增加.因此,通过光束匀化可以提高注入光纤激光能量,减小光纤端面的损伤概率.
The nanosecond laser-induced damage behavior of quartz optical fiber was experimentally studied, all of them were optical fiber end-face damage under the experimental conditions, and were classified into pit-like damage, melted damage and sputtering damage according to the damage morphology. And the threshold value of the damage threshold, the zero-probability power density threshold value of the quartz-propagating fiber under the experimental conditions is 3.85GW / cm2 by linear fitting.The process of fiber end-face damage is summarized, the laser-induced fiber end-face damage mechanism is analyzed, It is pointed out that the defect of the end face of the fiber is the internal cause of the decrease of anti-laser damage ability of the fiber, so the energy of the laser fiber can be greatly improved by improving the fiber end face quality. This phenomenon is caused by the extremely high power density at the center of the spot, which greatly increases the probability of damaging the irradiation spot at the center of the spot. Therefore, the energy of the injected laser can be increased and the damage probability of the fiber end face reduced.