A high-brightness, linearly polarized laser output of 5 kW achieved by low-NA fiber

Shu Chang; Chen Dongxu; Xing Yingbin; Peng Jinggang; Li Haiqing; Dai Nengli; Li Jinyan

doi:10.11884/HPLPB202638.250251

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Article Navigation > High Power Laser and Particle Beams > 2026 > Accepted Manuscript

Shu Chang, Chen Dongxu, Xing Yingbin, et al. A high-brightness, linearly polarized laser output of 5 kW achieved by low-NA fiber[J]. High Power Laser and Particle Beams. doi: 10.11884/HPLPB202638.250251

Citation:

Shu Chang, Chen Dongxu, Xing Yingbin, et al. A high-brightness, linearly polarized laser output of 5 kW achieved by low-NA fiber[J]. High Power Laser and Particle Beams. doi: 10.11884/HPLPB202638.250251

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A high-brightness, linearly polarized laser output of 5 kW achieved by low-NA fiber

doi: 10.11884/HPLPB202638.250251

Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, 430074, China

Received Date: 2022-08-05
Accepted Date: 2025-10-31
Rev Recd Date: 2025-10-31

Available Online: 2025-12-15

Abstract

Abstract

Background
Fiber lasers have gained extensive adoption across medical, telecommunications, industrial processing, and defense sectors owing to their exceptional beam quality, operational stability, compact architecture, and high reliability. Among them, narrow-linewidth linearly polarized fiber lasers have become a key research focus due to their outstanding spectral purity and coherence, with current efforts concentrated on further scaling their output power and brightness.
Purpose
In this work, we demonstrate a 5.09 kW narrow-linewidth linearly polarized fiber laser system designed to overcome stimulated Brillouin scattering (SBS) and transverse mode instability (TMI).
Methods
A white-noise radio frequency phase modulation scheme is implemented to broaden the seed laser spectrum into a Gaussian profile with 89 GHz full width at half maximum, enabling effective SBS suppression. A polarization-maintaining ytterbium-doped fiber (PMYDF) with low numerical aperture (～0.05), large mode area (～237 μm²), and high birefringence coefficient (4.23×10⁻⁴) is employed to simultaneously mitigate SBS and intermodal thermal coupling.
Results
The system achieves 5.09 kW output power while maintaining an 89 GHz spectral linewidth, polarization extinction ratio above 19.6 dB, and beam quality factor of M² < 1.2. No self-pulsing or temporal instability is observed at maximum power, confirming suppression of both SBS and TMI.
Conclusions
By employing a white-noise radio frequency signal to modulate the phase of a single-frequency laser, the SBS effect in high-power fiber laser systems is effectively suppressed. Concurrently, intermodal thermal coupling and SBS are further mitigated using a fabricated low-numerical-aperture, large-mode-area PMYDF. The demonstrated performance supports the feasibility of high-power, narrow-linewidth polarized fiber lasers for long-term stable operation.
- High-power fiber laser,
- Ytterbium-doped polarization-maintaining fiber,
- Phase modulation,
- High-brightness fiber laser

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References(16)

References

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