纳秒激光诱导石英光纤端面损伤特性研究

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 关键词： 激光诱导损伤 高峰值功率 光纤传能 损伤阈值

Studies on nanosecond laser induced damage to fused fibers

The properties of high_peak pulsed laser induced damage to fibers have been investigated by damage experiments. It was found that all of damaged parts are located on fiber endings, and the damage topography fall into three classes: the pit damage, fusion damage and sputtering damage. The experimental setup of laser induced damage to fibers, fiber damage judgment criterions and data processing methods were developed and validated. The zero probability damage threshold was calculated by linear fitting to be 3.85GW/cm². The processes of laser induced damage to fibers were summarized and the fiber end face damage mechanism was studied. The experimental results indicated that the main factor that makes the fiber end faces susceptible to laser induce damage is the existence of surface imperfections. The nanosecond laser induce damage to fiber end faces are detected experimentally; the central areas of input end faces are damaged probably because the input laser beam is Gaussian. So the use of uniform beam for injecting the fiber is favorable to the laser-induced damage resistance.