Liu Meizhong, Shen Hui, Yang Yifeng, Xian Yuqiao, Zhang Jingpu, Wang Hanbin, Li Binglin, Niu Xiaxia, He Bing
Opt Express. 2021 Feb 15;29(4):5179-5192. doi: 10.1364/OE.413459.
Filled-aperture geometries can be obtained using a diffractive optical element (DOE) in the coherent beam combining (CBC) architecture. Minimizing the beam deviation is crucial to maintain single-aperture output and reduce the combining-efficiency losses. In this study, we developed a theoretical model for investigating the combining-efficiency losses with beam deviation in a DOE-based CBC architecture. The beam deviations induced by the DOE-mount-tilt error, emitter-incident angular error, and DOE-groove-tilt error are discussed theoretically in detail and verified experimentally. The combining-efficiency losses caused by the three error sources are calculated. Meanwhile, the combining-efficiency losses affected by the beam size and the DOE period are analyzed. For an 11-channel CBC architecture with a DOE period of 50 µm and a beam size of 30 mm, the maximum combining-efficiency losses caused by the three error sources were 3.2%, 1.87%, and 36.41%, respectively, whereas those in case of a DOE period of 20 µm and a beam size of 10 mm were 14.34%, 8.58%, and 25.29%, respectively. We found that the combining-efficiency loss is most sensitive to the DOE-groove-tilt error.
在相干光束合成（CBC）架构中，可以使用衍射光学元件（DOE）获得填充孔径几何结构。将光束偏差降至最低对于维持单孔径输出并减少合成效率损失至关重要。在本研究中，我们开发了一个理论模型，用于研究基于DOE的CBC架构中光束偏差引起的合成效率损失。从理论上详细讨论了由DOE安装倾斜误差、发射器入射角度误差和DOE凹槽倾斜误差引起的光束偏差，并进行了实验验证。计算了这三种误差源导致的合成效率损失。同时，分析了光束尺寸和DOE周期对合成效率损失的影响。对于一个具有50 µm的DOE周期和30 mm光束尺寸的11通道CBC架构，这三种误差源导致的最大合成效率损失分别为3.2%、1.87%和36.41%，而对于一个具有20 µm的DOE周期和10 mm光束尺寸的情况，相应的损失分别为14.34%、8.58%和25.29%。我们发现合成效率损失对DOE凹槽倾斜误差最为敏感。
