Coherent Beam Combining of Pulsed Fiber Amplifiers in the Long‐Pulse Regime (Nano‐ to Microseconds)

Lombard, Laurent; Gouët, Julien Le; Bourdon, P.; Canat, Guillaume

doi:10.1002/9783527652778.ch08

Cited by 4 publications

(5 citation statements)

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“…According to [36], the typical optical turbulence coherence time is on the order of 1 to 10 ms (cutoff frequency ranging from 100 Hz to 1 kHz). On the other hand, the accumulated phase noise of fiber amplifiers is up to 𝑓 = 10 kHz [9]. In order to properly sample the phase noise and distinguish the contribution of different channels, the tagging frequencies must fit within an octave and should be spaced by at least ~10 × 𝑓 .…”

Section: Fiber Amplifiers and Optical Headmentioning

confidence: 99%

“…In order to properly sample the phase noise and distinguish the contribution of different channels, the tagging frequencies must fit within an octave and should be spaced by at least ~10 × 𝑓 . This leads to tagging frequencies ranging from 𝐹 = 10 × 𝑁 × 𝑓 = 0.6 MHz to 𝐹 = 10 × (2𝑁 − 2) × 𝑓 = 1 MHz with 𝑁 = 6 and 𝑓 = 10 kHz [9]. The effective bandwidth of the control loop is 30 kHz.…”

Section: Fiber Amplifiers and Optical Headmentioning

confidence: 99%

“…This laser power increase brings out new limits such as optical damage or nonlinear effects in power amplifiers [4][5][6]. To overcome these limits, the coherent beam combination (CBC) of elementary laser sources is an interesting solution, enabling modularity, robustness and efficiency [7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

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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: Fiber Amplifiers and Optical Headmentioning

confidence: 99%

Section: Fiber Amplifiers and Optical Headmentioning

confidence: 99%

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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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“…[11][12][13][14][15] A challenge in pulse fiber laser development for remote sensing is to address ASE and NLOEs while retaining the primary fiber benefits of low SWaP, good BQ, and overall ruggedness and reliability. Achieving such performance in fiber is generally viewed as challenging as it requires containment of amplified spontaneous emission (ASE) and mitigation of in-fiber nonlinear optical effects (NLOEs).…”

Section: Introductionmentioning

confidence: 99%

Development of pulsed fiber lasers for long-range remote sensing

et al. 2014

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Pulsed fiber lasers bear great promise as optical transmitters for remote sensors, having tight size, power consumption, and ruggedness constraints. We discuss recently introduced laser architectures and components supporting power scaling of efficient fiber-based laser sources for long-range operation consistent with imaging and/or spectroscopic sensing from high-altitude and space-based platforms.

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“…Phase control is a key technique in CBC, which aims to compensate phase errors and achieve the phase locking of the combined lasers. According to the method of phase information detecting, active phase-control techniques can be divided into two categories [1]: direct phase-locking techniques such as the heterodyne detection phase-control technique [2,3], shearing interferometer method [4], and Hänsch-Couillaud detector method [5,6]; and indirect phaselocking techniques such as the stochastic parallel gradient descent algorithm [7][8][9][10] and single/multi-frequency dithering techniques [11][12][13][14][15][16][17][18].…”

mentioning

confidence: 99%

Efficient coherent beam combining of fiber lasers based on joint multiple access

Jiang¹,

Su²,

Zhang³

et al. 2018

Laser Phys.

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Coherent beam combination (CBC) is a promising method of obtaining high-power and highbrightness laser output. To further enhance the combination capacity of CBC systems, we present a novel phase-control technique based on joint multiple access. Using this technique, the CBC of eight fiber lasers is successfully demonstrated. When the phase-control system is in the closed loop, the residual phase error is less than λ/36. According to the experimental results, the average phase-control speed of the CBC system is nearly four times as much as that of the single-frequency dithering technique.

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Coherent Beam Combining of Pulsed Fiber Amplifiers in the Long‐Pulse Regime (Nano‐ to Microseconds)

Cited by 4 publications

References 84 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

Development of pulsed fiber lasers for long-range remote sensing

Efficient coherent beam combining of fiber lasers based on joint multiple access

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