1.8-kW simultaneous spectral and coherent combining of three-tone nine-channel all-fiber amplifier array

Abstract

We demonstrate simultaneous spectral and coherent combining of a three-tone nine-channel all-fiber amplifier array with a total output power of 1.8 kW in a master-oscillator power-amplifier (MOPA) configuration. Three single-frequency seed lasers are spectrally combined and employed as a master oscillator for an all-fiber power amplifier array, which provides robust performance on suppressing of the stimulated Brillouin scattering effect. Threestage power amplifiers are employed to scale the power from tens of mW to more than 300 W. Active phase locking of the nine-channel spectrally combined amplifiers is implemented by using the stochastic parallel gradient descent algorithm. In the experiment, a nine-channel spectrally combined MOPA array is coherently combined with a total output power of 1.8 kW. The power in the main lobe in closed loop is 4.6 times the value in open loop, and an average visibility of more than 85 % of the interference pattern at the receiving plane is obtained. By only adding pump power in the main amplifiers, the total power of the array could scale up to more than 3 kW.

Numerical analysis of the convergence speed of the SPGD algorithm with two different perturbation methods in coherent beam combination using active segmented mirror

“…In 2009, Northrop Grumman Corporation (NGC) unveiled their 105-kW system based on slab laser amplifiers by using heterodyne phase detecting technology with fiber phase modulator, but there was no tip/tilt correction in this experiment [3] . In 2012, National University of Defense Technology (NUDT) reported their 1.8kW system based on all-fiber amplifiers by SPGD algorithm with fiber phase modulator, there was also no tip/tilt correction [4] . In 2013, IOE of GUCAS reported their 7 beams combination system, the PZT phase modulator and adaptive fiber optics collimator(AFOC) were used as piston and tip/tilt correction respectively with SPGD algorithm as the control method [5] .…”

All-fiber wavelength-tunable passive phasing of eight channels of fiber amplifiers using optical feedback loop

“…By employing these beam combining technologies, output powers from fiber laser systems have increased markedly. [14][15][16][17][18][19] Coherent beam combining provides a method for scaling the overall output power while simultaneously maintaining good beam quality. Coherent beam combining can be classified as active phasing and passive phasing.…”

“…Coherent beam combining can be classified as active phasing and passive phasing. [14][15][16][17][20][21][22][23] Active phasing requires a complex phase control system consisting of phase modulators, a photoelectric detector, an electronic controller, and so forth. 8,14,24) On the other hand, passive phasing is notable for the simplicity of the phasing control, which is realized by optical feedback with a self-organizing mechanism.…”

高功率光纤激光相干合成的研究进展与发展分析

“…图 1 8 路激光相干合成实验结果 [46] 作 N 路, 每一路激光与一个电光相位调制器连接 [50,51] . 单频光纤放大器的研究 进展如表 2 所示 [52~65] , 可以看出, 受限于受激布里渊 散射(SBS)效应, 单频掺镱光纤放大器的输出功率多 年来一直停留在 500 W 级 [55] , 且大都采用空间结构 实现, 存在稳定性不足的缺陷, 致使光纤激光相干合 成系统的输出功率迟迟没有突破千瓦级.…”