67 W of Output Power From an Yb-Free Er-Doped Fiber Amplifier Cladding Pumped at 976 nm

We report on an Yb-free Er-doped single frequency large mode area (LMA) fiber amplifier cladding pumped at 976 nm. Using a commercial 40/140-μm Er-doped double-clad fiber, output power levels of more than 67 W could be obtained. To the best of our knowledge, we demonstrate the power scalability of Yb-free Er-doped fiber amplifiers to output powers of multiple 10 W for the first time. The obtained output power is also the highest value ever reported for an Yb-free Er-doped fiber laser system pumped around 980 nm.