A 1-Watt thulium-doped cw fibre laser operating at 2 μm

Abstract We report efficient high power (>62; 1 W) single transverse mode continuous-wave laser action at 2 μm in a thulium-doped silica-based fibre laser pumped by a Nd : YAG laser at 1.064 μm. The highest measured output power was 1.35 W. A threshold of 600 mW absorbed and slope efficiency of 37% with respect to absorbed power were observed.