Millijoule-level ultra-large core ytterbium-doped pulsed fiber amplifier operating at 980 nm

We report a record-high 5.5-mJ amplified pulse energy at 980 nm, achieving 0.55 kW peak power using a 1-meter long ultra-large-mode-area ( 290 μ m core) ytterbium fiber in a co-directional, amplifier configuration. Pumped at 915 nm and seeded by a modulated 980-nm laser diode. We provide a detailed fiber spectroscopy analysis, optimizing key parameters—such as seed and pump repetition rates to mitigate thermal load and other detrimental effects (e.g., re-absorption), enabling high-energy output. The amplifier’s performance highlights its applications for high-brightness ultraviolet and visible light generation, and as an efficient pump for erbium-doped fiber systems, advancing their performances in fluorescence imaging, marine engineering and biophotonics. To the best of our knowledge, the achieved output energy of 5.5 mJ is the highest reported to date in an ytterbium-doped-fiber amplifier at 980-nm, while offering simpler fabrication, configuration and enhanced compatibility compared to other fiber systems at similar wavelengths.