采用波长1064 nm, 功率为1 W的种子激光实现了两路光纤激光的相干合成, 采用了两只保偏光纤准直器接收两路光干涉信号, 与利用透镜直接把干涉信号会聚在探测器上相比, 这种耦合方式得到的光干涉信号的条纹对比度更高。对相位噪声以及相位噪声的带宽进行了研究, 结果表明, 相位噪声由电信号串扰以及环境扰动产生。通过人为拨动光纤来增加相位噪声带宽, 当相位噪声带宽增加时, 相位控制精度下降。提出了提高相位控制精度的方法, 实验获得了桶中功率为21.3%、斯特列尔比为79%、相位控制精度为0.008λ的相干合成效果。

The coherent combination system of two fiber lasers based on heterodyne method has been constructed using a 1064 nm, 1 W seed laser. In this system, two graded index (GRIN) lenses with polarization maintaining (PM) fiber is used to receive interference signals for getting better high-contrast strips, compared with interference signals directly received by detectors. The phase noise is studied, and the influence of phase noise on phase control precision is discussed. The phase noise is found to result from electrical crosstalk and environmental perturbation. When the phase noise bandwidth increases, the phase control precision drops. The ways to improve phase control precision are shown. When the phase of two fiber lasers is locked in the experiment, the power in the bucket(PIB) is 21.3%, the Strehl ratio is 79%, and the phase control precision is 0.008λ.