用于千赫兹高能量MOPA激光系统的大口径锥度光纤相位共轭镜特性研究

Investigation on Characteristics of Large Aperture Tapered Fiber Phase Conjugation Mirror for kHz High Energy MOPA Laser System

在1000 Hz高重复频率条件下,对单一大口径锥度光纤相位共轭镜(PCM)进行了详细的实验研究。对采用普通红宝石切割刀和进口LDC-200光纤切割刀切割的锥度光纤受激布里渊散射(SBS)反射率进行了比较,结果表明光纤表面切割好坏对反射率提升具有重要的影响。在两种抽运脉宽24 ns和15 ns下,对均由LDC-200光纤切割刀切割的锥度光纤SBS反射率进行了比较,在同样注入近40 mJ时,分别得到最高70%和50%的反射率。对抽运脉冲宽度为15 ns时,应用该锥度光纤PCM的双通输出激光能量、脉冲宽度、光束质量变化情况进行了测量,得到42 mJ,脉宽约1.5 ns的双通输出,光束质量得到明显改善。

With repetition rate of 1000 Hz,detailed experimental investigation on single large aperture tapered fiber phase conjugation mirror（PCM） has been done.Comparison of stimulated Brillouin scattering（SBS） reflectivity between tapered fibers incised by simple ruby cutter and imported LDC-200 fiber cutter is shown,which implies that the quality of fiber′s end surface plays an important role in enhancing SBS reflectivity.For fibers incised by LDC-200 fiber cutter,comparison of SBS reflectivity with pump pulse widths of 24 ns and 15 ns is also given and maximum SBS reflectivities of 70% and 50% with pump energy about 40 mJ have been achieved respectively.Keeping the pump pulse width to 15 ns and applying the tapered fiber PCM,the double pass output energy,pulse width and beam quality are measured.1000 Hz,42 mJ,1.5 ns laser output has been obtained and obvious beam quality improvement has been observed.