激光诱导光纤损伤可持续利用技术

Continued-use technology of fiber damage induced by laser

研究了光纤损伤对光纤传能特性的影响。由小到大注入激光能量时,光纤端面偶尔会产生微弱火花并出现微小坑状损伤,但并不影响光纤的注入耦合效率。当光纤端面发生等离子闪光后出现了比较严重的灾难性损伤,光纤输出端激光能量明显下降。光纤端面损伤降低了激光注入耦合效率,从而导致光纤传输效率下降。建立光纤端面损伤理论模型,由于光纤端面损伤引起的注入激光能量损失与损伤面积的对应关系,当注入激光光斑能量为高斯分布时,注入激光能量损失率与损伤面积成负指数关系。实验结果还表明光纤端面损伤存在增长效应。通过实验研究和理论分析证明了提出的光纤损伤后仍可持续利用设想的可行性,它为高功率光纤传输系统设计,特别是单脉冲激光点火或起爆系统的设计提供了新的思路。

The effects of laser damage to optical fiber on fiber delivery characteristics were investigated. With the increase of input laser energy, the weak sparkles appeared accidentally on the fiber end faces, which could induce some small damaged sites. The damaged sites would not reduce the coupling efficiency.However, after the plasma sparking, the fiber end faces were damaged catastrophically, the output energy from fiber decreased evidently, and the decreased degree was in proportion to the damage degree. The damage brought-down the laser-fiber coupling efficiency, resulting in the decrease of output energy obviously. The theoretical model of fiber damage was designed. The output energy had dependence on damaged area. When the input laser beam profile was Gaussian, the ratio of injection energy loss was the negative exponent function of damaged area. Experimental results show that the damage growth effect exists at the fiber end faces. Experimental and theoretical analyses show the feasibility of new idea that the damaged fiber can continue to be used to a great extent. This idea provides some new design ways for high power laser fiber delivery systems, especially for single pulsed high peak power laser ignition or detonation systems.