实验研究了芯径为600 μm的全石英光纤传输脉宽为5 ns,波长为1064 nm的高峰值功率脉冲激光的传输特性。采用N-ON-1测试方法,获得光纤损伤阈值和光纤传能特性曲线。光纤50%概率损伤阈值为24 mJ,平均输出激光能量达到14 mJ,峰值功率接近3 MW。可将光纤传能特性曲线分为3个过程:未损伤段(平稳传输段)、光纤端面等离子体击穿段(非平稳传输段)和光纤体损伤段(传输截止段)。分析了光纤损伤形貌和损伤机理。研究表明,同时提高光纤端面等离子体击穿阈值和光纤初始输入段损伤阈值是提高光纤传能容量的关键。

The experimental study on transmission characteristics of high-peak power laser pulses with width of 5 ns and wavelength of 1064 nm via all-silica fibers with core diameter of 600 μm are demonstrated. According to N-ON-1 test mode,the laser induced fiber damage threshold and transmission efficiency curve are obtained. The 50% probability damage threshold is 24 mJ,the average output energy is 14 mJ,and the peak power approaches to 3 MW. The three processes of fiber delivery high-peak power laser pulsed are presented,which are undamaged stage (steady state),laser-induced plasma stage (unsteady state) and laser-induced fiber core damage stage (transmission cut-off). The damaged morphologies and damage mechanism are investigated. The synchronous increases of laser induced plasma threshold and entry damage threshold can improve optical fiber capability for high power laser delivery.