电激励重频HF激光器非稳腔设计及实验研究

为实现电激励重频HF激光远距离传输，在较短的谐振腔内产生大模体积的高质量激光束，开展了激光器正支虚共焦非稳腔的结构设计、仿真计算和实验研究。仿真结果表明，随着放大率M的增大，远场光斑中心亮斑包含的能量逐渐增大，能量向中心转移，远场光斑尺寸和远场发散角也随放大率M增大而减小。实验结果表明:随着放大率M的增大，远场光强分布、光斑尺寸和发散角变化规律与仿真结果一致，但输出激光能量以先增大后降低的规律变化。综合考虑高光束质量和高能量的指标要求，在流场正常工作情况下，当放大率M为3.0时，获得了远场发散角为2.37倍衍射极限和激光能量稍低于稳定腔（约为稳定腔激光能量的94.6%）的重频激光输出，满足激光远距离传输需求。

Design and experimental investigation of unstable resonator for discharge initiated repetitive-pulsed HF laser

In order to realize the long distance transmission of discharge initiated repetitive-pulsed HF laser, and produce a high quality laser of large volume in the shorter resonant cavity, the structural design, simulation calculation and experimental study of the passive branch confocal unstable resonant cavity were carried out. The simulation results show that with the increase of the magnification M, the energy of far-field light focal spot was gradually increased with the increase of magnification, and the energy transferred to the light spot center. In addition, the light spot size and the divergence angle of far-field were gradually decreased as well. The experimental results show that with the increase of the magnification M, the variation of the far-field intensity distribution, the light spot size and the divergence angle were consistent with the simulation results. But the output laser energy actually increases first and then decreases. Considering the requirements of high beam quality and high energy, in the case of normal flow field, the far-field divergence angle of repetitive-pulsed HF laser was 2.37 times diffraction limit magnification when M was 3, and the laser energy was slightly lower than the stable resonant cavity(about 94.6% of stable resonant cavity), which satisfies the requirements of long distance transmission.