Erbium:Ytterbium co-doped large-core fiber laser with continuous wave output power over 20 W at 1609.02 nm

We report a high-power cladding-pumped large-core Er,Yb co-doped fiber laser operating at 1609.02 nm. A maximum output power of 20.52 W was obtained for the launched pump power of 99.5 W, corresponding to a slope efficiency of −23.5% with respect to the launched pump power. This is, to the best of our knowledge, the highest output power reported from free-running Er,Yb co-doped laser oscillator architecture at 1609.02 nm long wavelength.