介绍了随机并行梯度下降(SPGD)算法,并设计了基于此算法的两路主振荡并联放大相干合成(MOPA-CBC)实验系统。该系统采用10 W级掺镱光纤放大器引入相位误差,同时采用铌酸锂相位调制器进行校正。开环时,分析了放大器工作在不同状态下系统中的相位噪声。闭环后,得到了稳定的相干合成光束,合成光束的平均亮度提高到之前的1.5倍,相位平移峰谷(PV)值降低到100.8 nm,系统校正精度达到1/(10λ),控制带宽约为100 Hz。实验结果表明,SPGD算法能有效地发挥锁相控制功能。

The stochastic parallel gradient descent (SPGD) algorithm is introduced,and the 2-channels master oscillator power amplifier coherent beam combination (MOPA-CBC) system based on this algorithm is designed. This system adopts a 10 W stage ytterbium fiber amplifier to import the phase noise. And the LiNbO3 phase modulator is adopted to compensate the piston error. When loop is open,the phase noise is analyzed at different working stages of amplifier. After loop closed,the stable coherent combined beam is obtained,the intensity of which increases 1.5 times than before,and piston peak-to-valley (PV) value decreases to 100.8 nm. The precision of correction reaches 1/(10λ),and the bandwith is 100 Hz. The experimental results indicate that the control ability of SPGD algorithm is effective in phase-locking.