35 W highly effective Ytterbium-Erbium-Thulium tandem all-fiber 1.947 µm laser system at 975 nm diode pumping

Abstract We report on progress towards effective mid-IR lasing using a tandem Ytterbium-Erbium/Thulium all-fiber laser system at near-IR diode pumping. ∼35 W 1.947 µ m continuous-wave output power at ∼120 W 975 nm pump power (29% overall efficiency) is reached.