一种非稳腔调腔干涉条纹的建模与仿真

非稳腔的计算机辅助准直技术对于保证高能激光器运行参数的稳定性具有非常重要的作用.文章从理论上阐明了非稳腔调腔干涉条纹形成的物理机理,建立了正支共焦非稳腔内多光束干涉的物理模型,引入失调元件的增广矩阵来描述腔镜失调引起的椭圆高斯光束传输效应、高斯光束中心的偏移效应和附加的相位倾斜效应.使用高斯光束传输的ABCD矩阵计算了调腔光束在腔内多次往返后的高斯光束复参数,将多次往返的高斯光束进行相干叠加,获得了非稳腔不同失调角情况下的调腔干涉条纹图样,定量计算了不同失调角情况下调腔干涉条纹间距的偏移量,并与实验结果进行了对比分析.结果表明在实验误差允许的前提下,仿真得到的干涉条纹图样与实验获得的干涉条纹图样具有一致性,从而证实了理论模型的正确性.理论模型的成功建立使谐振腔的失调量与干涉条纹的形态变化精确对应起来,从而可以为非稳腔计算机辅助调节的闭环控制研究提供理论指导.

A physical model and simulation of the interference fringes for the aligment of unstable resonator

The physical model of multiple beams interference fringes was established for unstable resonator alignment,and the characteristics of interference fringes with different misalignment angles were calculated by a homemade software,in which augmented matrices of misaligned optical systems was applied to compute the decentration and tilt of Gaussian beams.The ABCD law was applied to calculate the multi-pass propagation of Gaussian beam q parameter.Furthermore,the interference fringe for unstable resonator alignment was calculated by adding the complex electrical field of multiple Gaussian beams.The calculated interference fringe was found to fit well with the experimental results,which shows that the physical model is correct.Therefore,this model can quantitatively explain the relation between the characteristics of interference fringes and the misalignment of the resonator,and then can be a theoretical guidance for compute-aided automatic alignment of the resonators.