High-power continuous-wave ytterbium-doped fiber oscillator at 1018 nm

We have demonstrated a 1018 nm continuous wave fiber oscillator pumped by LDs operating at 976 nm. Three kinds of Ytterbium-doped dual-clad fibers, 15/130 μm fiber, 25/250 μm fiber and 30/250 μm fiber, are employed separately in the experiments. We achieve 67 W total output power with the 15/130 μm fiber for 100 W of pump power with a slope efficiency of 67%. And with the 25/250 μm fiber, 276 W total output power is generated for 372 W of pump power with a slope efficiency of 74%. In the end, 300 W output power with the slope efficiency of 81% is successfully achieved with the 30/250 μm fiber for 372 W of pump power. To the best of our knowledge, this is the highest output ever reached by a dual-clad fiber oscillator at this wavelength that ever reported in open detail.