Towards Ultimate High-Power Scaling: Coherent Beam Combining of Fiber Lasers

Fathi, Hossein; Närhi, Mikko; Gumenyuk, Regina

doi:10.3390/photonics8120566

Cited by 35 publications

(11 citation statements)

References 308 publications

(448 reference statements)

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“…Coherent Beam Combining (CBC) is a method for increasing the power output of lasers by combining multiple laser amplifiers initially seeded by a common source. The goal is to create a single multiplied high-power beam while maintaining the beam's quality [13]. Along with preserving the spatial properties, CBC also ensures that the spectral properties of the lasers are retained.…”

Section: Introductionmentioning

confidence: 99%

Power scaling of optical vortices by the filled aperture coherent beam combining technique

Fathi,

Närhi,

Gumenyuk

2024

Solid State Lasers XXXIII: Technology and Devices

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This paper presents a first-ever experimental demonstration of coherent beam combining for optical vortexes with topological charges from 1 to 5 realized in a Yb-doped fiber short-pulsed laser system. The combing efficiency varies depending on the topological charge and beam pattern quality generated by the spatial light modulators. The maximum combining efficiency of 96.9% was achieved for the topological charge 1. These results open a pathway to highintensity optical vortexes with enormous potential applications in science and industry by utilizing advances in lightmatter interactions.

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Section: Introductionmentioning

confidence: 99%

Power scaling of optical vortices by the filled aperture coherent beam combining technique

Fathi,

Närhi,

Gumenyuk

2024

Solid State Lasers XXXIII: Technology and Devices

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“…Developing active optical fibers that can achieve significant average power levels while performing sufficiently well with respect to nonlinear effects to be relevant to demanding, niche approaches such as coherent beam combining or single-frequency amplification, has been a significant challenge for the better part of the last decade [1]. The fields of research and associated applications requiring those technical approaches can greatly benefit from advanced fiber designs that increase the Stimulated Brillouin Scattering (SBS) threshold while favoring at the same time the preferential amplification of the fundamental mode; confined doping [2] can help achieve that.…”

Section: Introductionmentioning

confidence: 99%

Novel 30/400 ytterbium-doped LMA polarization-maintaining fiber with very efficient higher-order modes filtering capabilities

Desbiens¹,

Roy²,

Boivin³

et al. 2023

Fiber Lasers XX: Technology and Systems

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The optimization of large-mode-area fiber design for the amplification of narrow-linewidth content or short pulses, susceptible to nonlinear effects, while reaching average powers exceeding the kW level is not a simple endeavor. The rapidly decreasing TMI-threshold with increasing core size leaves very little room in the 20 to 30 μm core diameter space for improved performance with respect to nonlinear effects while still delivering significant average power. We present results on a 29 μm core, polarization-maintaining LMA fiber, with a 400 μm cladding for high average power scaling. A carefully designed depressed-clad surrounds the core and enhances the bending losses for the Higher-Order Modes (HOM). Even when the fiber is loosely coiled (25 cm diameter), the filtering is very efficient which is advantageous for spreading out the fiber heat load and minimizing the effective area reduction resulting from the coiling-induced mode deformation. The fiber has been tested in a CW MOPA configuration, seeded with a longitudinally single-mode source emitting at 1064 nm, phase-modulated for Stimulated Brillouin Scattering (SBS) mitigation. The resulting slope efficiency has been measured at 88%, the PER was in the 12-15 dB range. The main feature of this fiber is its highly efficient HOM filtering capability, consequently one can maintain single mode-like operation up to the TMI threshold (slightly below 1 kW) without significant beam quality (BQ) degradation. As soon as coupling occurs between the fundamental mode and the first higher-order mode through the thermo-optic long-period grating, the energy is shed away and is coupled out in the fiber cladding.

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“…This technique is often used to achieve significant production volumes in the automotive and aerospace industries. For instance, the introduction of disk and fibre lasers achieved laser power ceiling scales of up to 16 and 100 kW, respectively [1][2][3][4]. The main parameters arising in a conventional continuous laser welding process are laser power, laser collimation (vertical position of the beam waist relative to the workpiece), welding speed, the type of shielding and/or root gas, and the flow rate of the gas.…”

Section: Introductionmentioning

confidence: 99%

Improvements in the Microstructure and Mechanical Properties of Aluminium Alloys Using Ultrasonic-Assisted Laser Welding

Teyeb

Silva

Kanfoud

et al. 2022

Metals

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Welding high-strength aluminium alloys is generally a delicate operation due to the degradation of mechanical properties in the thermally affected zone (TAZ) and the presence of porosities in the molten metal. Furthermore, aluminium alloys contain compounds that solidify before the rest of the base alloy, therefore acting as stress concentration points that lead to the phenomenon of hot cracking. This paper investigates the process of applying ultrasonic vibrations to the molten pool aluminium alloy AA6082 to improve both its microstructure and mechanical properties. We analysed conventional and ultrasonic-assisted laser welding processes to assess the sonication effect in the ultrasonic band 20–40 kHz. Destructive and nondestructive tests were used to compare ultrasonically processed samples to baseline samples. We achieved a 26% increase in the tensile and weld yield strengths of laser welds in the aluminium plates via the power ultrasonic irradiation of the welds under optimum ultrasonic variable values during welding. It is estimated that the ultrasound intensity in the weld melt, using a maximum power of 160 W from a pair of 28 kHz transducers, was 35.5 W/cm2 as a spatial average and 142 W/cm2 at the antinodes. Cavitation activity was significant and sometimes a main contributor to the achieved improvements in weld quality.

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Towards Ultimate High-Power Scaling: Coherent Beam Combining of Fiber Lasers

Cited by 35 publications

References 308 publications

Power scaling of optical vortices by the filled aperture coherent beam combining technique

Power scaling of optical vortices by the filled aperture coherent beam combining technique

Novel 30/400 ytterbium-doped LMA polarization-maintaining fiber with very efficient higher-order modes filtering capabilities

Improvements in the Microstructure and Mechanical Properties of Aluminium Alloys Using Ultrasonic-Assisted Laser Welding

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