5.58 kW Narrow-Linewidth Fiber Laser Based on House-Made Confined-Doped Fiber

In the contribution, a 5.58 kW monochromatic narrow linewidth fiber laser centered at 1080 nm realized by combining house-made confined doped fiber and bidirectional pump scheme has been presented. At the maximum power of 5.58 kW, the beam quality factor M<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> is ∼1.5. Experimental results have revealed that 90% confined doping is competent to increase TMI threshold by 20% and fit well with numerical calculation, which proves confined doping has the potential for further power scaling of narrow linewidth fiber laser by TMI mitigation, and experimental results indicate that confined doping can also be regarded as a reference for the design and optimization of high-power narrow linewidth near-diffraction-limited fiber lasers.