为了研究光纤激光的非相干合成特性, 建立了圆环状排布的光纤激光阵列光束合成模型, 模拟分析了单元光束束腰半径w0、波前畸变和光束间距对非相干及相干合成远场光束质量的影响。讨论了多路激光平行性对非相干合成效果的影响, 并进行了相关实验验证。结果表明,单元光束无波前畸变时, 当光束间距为d0=2.8w0时, 非相干与相干合成光束质量相等; 单元光束存在波前畸变时, 光束间距有所减小, 这是因为波前畸变对非相干合成影响更小; 对于非相干合成, 随着多路激光之间不平行度的增大, 非相干合成光束质量逐渐变差, 并且单元光束质量越好, 对多路激光平行性要求越高。该研究可为实际光纤激光合成系统设计分析提供参考。

To study the incoherent beam combination characteristics of fiber lasers, a beam combination model of a circular array of multiple fiber lasers was established, and effect of waist radius w0, wave-front distortion of unit beam and beam separation distance on the far field beam quality of incoherent and coherent combination was simulated and analyzed. In addition, the influence of axis parallelism of multiple laser beams on the incoherent beam combination effect was studied, and experimental verification was carried out. The results show that, when the beam separation distance is d0=2.8w0, the beam quality β factor of incoherent combination of multiple laser beams without wave-front distortion is equal to that of coherent combination. The beam separation distance d0 decreases when the wave-front phase of laser beam is distorted, and the influence of wave-front distortion on the incoherent combination is less than that on the coherent combination. With the increasing of the parallel error among multiple laser beams, the beam quality of incoherent combination becomes worse. And the better the beam quality of unit beam is, the higher the demand for the axis parallelism of multiple laser beams. This research can provide references for the design and analysis of beam combination system of fiber lasers.