Self-adaptiue tilt control method based on second order moment of beam for laser array
-
摘要: 针对阵列光束相干合成中存在的倾斜相差大的问题，提出了基于合成光束远场光斑二阶矩的阵列光束倾斜相差自适应控制方法。以合成光束远场光斑二阶矩作为评价函数，理论上模拟了采用随机并行梯度下降算法实现7路光束的倾斜闭环控制过程。实验上搭建了7路光纤激光相干合成系统，利用自适应光纤准直器对倾斜相差进行校正。以合成光束远场光斑的二阶矩作为评价函数，采用随机并行梯度下降算法，实现了7路光束的倾斜的闭环控制，合成光束模拟远场光斑的桶中功率由0.05 V提升至1.95 V。实验中将倾斜扰动的增益系数变为与二阶矩相关的函数，实现了自适应变增益系数的倾斜闭环，在一定程度上提升了倾斜控制的带宽。从理论上和实验上验证了基于光斑二阶矩的倾斜相差自适应控制方法在光束合成及合成孔径探测领域应用的可行性。
-
关键词:
- 相干合成 /
- 倾斜控制 /
- 光斑二阶矩 /
- 阵列光束 /
- 随机并行梯度下降算法.
Abstract: Aiming at the problem of tilt control in coherent beam combining of laser array, a tilt control method, of which the evaluation function is based on second order moment of combined laser beam, is proposed. The performances of the tilt control method are investigated theoretically and experimentally. In the theoretical study, adopting the second order moment of the combined beam as the evaluation function, the tilt control process of 7 laser beam is simulated based on stochastic parallel gradient descent algorithm. In the experiments, a coherent beam combining system of 7-channel fiber array is built and an adaptive fiber collimator is used as the tilt-control device. Adopting the stochastic parallel gradient descent algorithm, the closed-loop operation of tilt control is achieved with the second order moment of the combined spot as the evaluation function. The theoretical and experimental results show that the tilt control method based on the second order moment of laser beam has great potential on coherent beam combination. -
图 1 不同倾斜相差下，阵列光束相干合成远场光斑分布
Figure 1. Far-field spot distribution of coherent beam under different tilt phase error
图 3 倾斜闭环过程中光斑二阶矩的变化
Figure 3. Variation of second order moment of spot in tilt control process
图 4 7路光纤激光相干合成系统
Figure 4. Coherent beam combining system of 7-channel fiber laser array
图 6 倾斜闭环过程中光斑二阶矩的变化
Figure 6. Variation of second order moment of spot in tilt closed-loop
图 7 相位、倾斜闭环过程中，PD内桶中功率的变化情况
Figure 7. Variation of power in the bucket in phase and tilt control process
图 8 不同变增益下，光斑二阶矩的变化情况
Figure 8. Variation of second order moment of spot under different gain parameter
表 1 不同倾斜相差对应的光斑二阶矩
Table 1. Second order moment of coherent beam under different tilt phase error
tilt phase error (RMS)/ μrad σx/cm σy/cm 0 0.73 0.73 10 0.83 1.04 20 1.60 1.52 30 1.51 2.58 
下载: 导出CSV
-
[1] Richardson D J, Nilsson J, Clarkson W A. High power fiber lasers: current status and future perspectives[J]. Journal of the Optical Society of America B, 2010, 27(11): B63-B92. doi: 10.1364/JOSAB.27.000B63 [2] Augst S J, Ranka J K, Fan T Y, et al. Beam combining of ytterbium fiber amplifiers[J]. Journal of the Optical Society of America B, 2007, 24(8): 1707-1715. doi: 10.1364/JOSAB.24.001707 [3] Zhou Pu, Ma Yanxing, Wang Xiaolin, et al. Coherent beam combination of three two-tone fiber amplifiers using stochastic parallel gradient descent algorithm[J]. Optics Letters, 2009, 34(19): 2939-2941. doi: 10.1364/OL.34.002939 [4] Ma Yanxing, Wang Xiaolin, Leng Jinyong, et al. Coherent beam combination of 1.08 kW fiber amplifier array using single frequency dithering technique[J]. Optics Letters, 2011, 36(6): 951-953. doi: 10.1364/OL.36.000951 [5] Thielen P A, Ho J G, Burchman D A, et al. Two-dimensional diffractive coherent combining of 15 fiber amplifiers into a 600 W beam[J]. Optics Letters, 2012, 37(18): 3741-3743. doi: 10.1364/OL.37.003741 [6] 黄智蒙, 唐选, 刘仓理, 等. 倾斜相差对大阵列光纤相干合成的影响与分析[J]. 中国激光, 2015, 42:1102003 doi: 10.3788/CJL201542.1102003Huang Zhimeng, Tang Xuan, Liu Cangli, et al. Analysis of influence of tip/tilt phase error on a large scale coherent beam combination of fiber laser[J]. Chinese Journal of Lasers, 2015, 42: 1102003 doi: 10.3788/CJL201542.1102003 [7] 耿超, 李新阳, 张小军, 等. 倾斜相差对光纤激光相干合成的影响与模拟校正[J]. 物理学报, 2011, 60:114202 doi: 10.7498/aps.60.114202Geng Chao, Li Xinyang, Zhang Xiaojun, et al. Influence and simulated correction of tip/tilt phase error on fiber laser coherent beam combination[J]. Acta Physica Sinica, 2011, 60: 114202 doi: 10.7498/aps.60.114202 [8] Johansson M, Hård S, Robertson B, et al. Adaptive beam steering implemented in a ferroelectric liquid-crystal spatial-light-modulator free-space, fiber-optic switch[J]. Applied Optics, 2002, 41(23): 4904-4911. doi: 10.1364/AO.41.004904 [9] 郑轶, 王晓华, 沈锋, 等. 基于能动分块反射镜的七路激光阵列倾斜校正与相干合成实验研究[J]. 中国激光, 2011, 38:0802009 doi: 10.3788/CJL201138.0802009Zheng Yi, Wang Xiaohua, Shen Feng, et al. Tip-tilt correction and coherent combination of seven-channel laser array based on active segmented mirrors[J]. Chinese Journal of Lasers, 2011, 38: 0802009 doi: 10.3788/CJL201138.0802009 [10] Liu Ling, Vorontsov M A, Polnau E, et al. Adaptive phase-locked fiber array with wavefront phase tip-tilt compensation using piezoelectric fiber positioners[C]//Proceedings of SPIE 6708, Atmospheric Optics: Models, Measurements, and Target-in-the-Loop Propagation. 2007. [11] Beresnev L A, Vorontsov M A. Design of adaptive fiber optics collimator for free-space communication laser transceiver[C]//Proceedings of SPIE 5895, Target-in-the-Loop: Atmospheric Tracking, Imaging, and Compensation II. 2005. [12] 王雄, 王小林, 周朴, 等. 光纤激光相干合成中倾斜波前控制的研究进展[J]. 中国激光, 2012, 39:s101001Wang Xiong, Wang Xiaolin, Zhou Pu, et al. Recent research and development of tilt-tip wavefront control in coherent beam combination of fiber lasers[J]. Chinese Journal of Lasers, 2012, 39: s101001 [13] Wang Xiong, Wang Xiaolin, Zhou Pu, et al. Numerical simulation of tilt-tip control in coherent beam combining using SPGD algorithm[J]. Optics & Laser Technology, 2013, 48: 343-350. [14] Li Feng, Geng Chao, Huang Guan, et al. Experimental demonstration of coherent combining with tip/tilt control based on adaptive space-to-fiber laser beam coupling[J]. IEEE Photonics Journal, 2017, 9: 7102812. [15] Wang Xiong, Wang Xiaolin, Zhou Pu, et al. Coherent beam combination of adaptive fiber laser array with tilt-tip and phase-locking control[J]. Chinese Physics B, 2013, 22: 024206. doi: 10.1088/1674-1056/22/2/024206 [16] 耿超, 罗文, 谭毅, 等. 基于自适应桶中功率评价函数的光纤放大器相干合成实验研究[J]. 物理学报, 2013, 62:224202 doi: 10.7498/aps.62.224202Geng Chao, Luo Wen, Tan Yi, et al. Experimental study on coherent beam combination of fiber amplifiers using adaptive power-in-the-bucket cost function[J]. Acta Physica Sinica, 2013, 62: 224202 doi: 10.7498/aps.62.224202 [17] ISO 11146-2-2021,Lasers and laser-related equipment — Test methods for laser beam widths, divergence angles and beam propagation ratios[S]. -
点击查看大图
计量
- 文章访问数: 439
- HTML全文浏览量: 169
- PDF下载量: 78
- 被引次数: 0
