Numerical analysis of coherent combination for fiber lasers and application to beam steering

Huang, Zhiao; Liu, C. L.; Li, J. F.; Zhang, Diyu; Wang, Hongfan; Luo, Yufei; Hu, Qingyuan

doi:10.1134/s1054660x12080129

Cited by 4 publications

(4 citation statements)

References 14 publications

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“…The average combining efficiency is about 33% at 70 m, 23% at 311 m and 19% at 1 km. These experimental values are lower (by ~10%) than the theoretical simulations of CBC through turbulence from references [11,[14][15][16] (for the 7 beams case and a 𝐶 value an order of magnitude lower than the measured values in our experiments). This also indicates that further improvement is still possible.…”

Section: Operation Of the Lasbe Til-cbc/locset System And Observationscontrasting

confidence: 75%

“…The problematic of TIL-CBC has been extensively studied in simulations with different situations, including weak to moderate turbulences and various laser designs (e.g., the number of emitters, phase correction strategies, etc.) [13][14][15][16][17][18][19][20]. Most of those simulations agree on a Power in the Bucket of about 33% for km range propagation through atmospheric turbulence and that piston-only turbulence compensation is sufficient for weak to moderate turbulences; yet can be limited by power-leakage from the central lobe to the side lobes on the target.…”

Section: Introductionmentioning

confidence: 57%

“…These experimental observations are thoroughly examined in the Section 4 of this paper. Note that such FF behaviors have been observed to a lesser extent in the reference simulations [14][15][16][17][18] (where weaker turbulence was used). In the following, we present the NF and FF experimental criteria that have been used to quantify the coherent beam combining performances.…”

Section: Operation Of the Lasbe Til-cbc/locset System And Observationsmentioning

confidence: 89%

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Coherent beam combination of seven 1.5 µm fiber amplifiers through up to 1 km atmospheric turbulence: near- and far-field experimental analysis

et al. 2021

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A laser testbed based on active coherent beam combination (CBC) of seven 1.5 µm, 3 W fiber amplifiers was developed for applications requiring high power such as power density deposition on targets or free space laser communication. For the first time to our knowledge, the frequency-tagging locking of optical coherence by single-detector electronic-frequency tagging technique was implemented in the field in real atmospheric turbulence conditions in a target-in-the-loop configuration. Successful combination was achieved after horizontal propagation of 311 m and 1 km, at 1.5 m above the ground, while the estimated average turbulence strength was C n 2 ∼ 4.10 − 14 m − 2 / 3 . We present the CBC laser bench and an embedded near-field interferometer called PISTIL (PISton and TILt) able to measure the relative phase shift of each emitter. We show that this measurement can provide information on relative turbulence-induced phase variation of the combined laser beams. In particular, the far-field beam envelope wandering can be estimated through this diagnosis. Results are supported by an analytical model and confirmed by numerical post-analysis of measured far-field interference. This additional interferometer may improve CBC beam pointing through turbulence.

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Section: Operation Of the Lasbe Til-cbc/locset System And Observationscontrasting

confidence: 75%

Section: Introductionmentioning

confidence: 57%

Section: Operation Of the Lasbe Til-cbc/locset System And Observationsmentioning

confidence: 89%

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Coherent beam combination of seven 1.5 µm fiber amplifiers through up to 1 km atmospheric turbulence: near- and far-field experimental analysis

et al. 2021

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“…[1][2][3][4][5] There are mainly three kinds of active phasing methods, i.e., heterodyne phase detection, 6-8 a multi-dithering technique, 9,10 and a stochastic parallel gradient descent (SPGD) algorithm. 11,12 CBC with the heterodyne detection phase control technique requires a reference beam and a photo-detector array with the same element numbers as the beamlets in the whole MOPA system, and the system becomes increasingly complex and sophisticated when scaled to a large number of arrays.…”

Section: Introductionmentioning

confidence: 99%

Coherent beam combination of ten fiber arrays via stochastic parallel gradient descent algorithm

et al. 2015

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Coherent beam combination of ten fiber arrays using a stochastic parallel gradient descent (SPGD) algorithm is demonstrated. A high speed phase controller has been designed and manufactured based on the SPGD algorithm and a field programmable gate array (FPGA). The signal processing speed of the FPGA circuit is 50 MHz and its iteration rate is more than 200 kHz. Experimental investigation on coherent beam combination of 10 fiber laser beams is successfully demonstrated, with imposing additional phase disturbances to mimic the phase noises in the high power fiber amplifiers. The combining efficiency is about 96.4% and 92.6% without/with additional phase distortion, corresponding to the RMS phase error of λ∕35 and λ∕23.

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A high-speed, high-efficiency phase controller for coherent beam combining based on SPGD algorithm

Huang¹,

Liu²,

Li³

et al. 2014

Quantum Electron.

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Numerical analysis of coherent combination for fiber lasers and application to beam steering

Cited by 4 publications

References 14 publications

Coherent beam combination of seven 1.5 µm fiber amplifiers through up to 1 km atmospheric turbulence: near- and far-field experimental analysis

Coherent beam combination of seven 1.5 µm fiber amplifiers through up to 1 km atmospheric turbulence: near- and far-field experimental analysis

Coherent beam combination of ten fiber arrays via stochastic parallel gradient descent algorithm

A high-speed, high-efficiency phase controller for coherent beam combining based on SPGD algorithm

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