保持良好光束质量的输出对实际光谱合成系统的构建至关重要。从理论上研究光纤激光阵列指向偏差对合成系统光束特性的影响, 修正了带有指向偏转角激光队列的入射光场, 结合光谱合成的光传输模型和统计学分析, 讨论了合成激光光束质量随均匀分布随机扰动的变化规律。仿真结果表明, 指向偏差对合成系统的输出特性影响显著, 当激光队列的最大偏转角仅为0.05°时, 合成系统的光束质量就会退化到(6.49±1.73)。为实现合成光束亮度的定标放大, 逐步扩展激光队列的阵列规模, 合成系统光束质量的变化会逐渐趋于稳定, 以变化稳定时的阵列规模(30路子光束)作为参考, 拟合M2因子随最大指向偏转角的变化趋势。

Maintaining excellent beam quality is very important for the construction of the experimental spectral beam combining(SBC) system. The influence of pointing deviation on the beam characteristic was studied in SBC of fiber laser array theoretically. The incident light field of the laser array with the pointing deviation was corrected, and the variation rule of the combined beam quality with uniformly distributed random perturbations was discussed by the beam propagation model and the statistical analysis. The simulation result shows that the pointing deviation has a significant effect on the output characteristics of the SBC system. When the maximum deflection angle of the laser array is only 0.05°, the beam quality of SBC system will increase to(6.49±1.73). In order to achieve the brightness scaling of combined beam and gradually expand the scale of laser array, the combined beam quality tends to stabilize. As a reference for the array scale(30 fiber lasers) with the changes of relative stability, the variation tendency of the M2 factor and maximum pointing deflection angle is fitted for building the experimental system of SBC.