All-glass high NA Yb-doped double-clad laser fibres made by outside-vapour deposition

The first all-OVD, all-glass, high-NA (=>0.3), double-clad, Yb-doped laser fibres are reported. Yb is incorporated via vapour-phase transport. These fibres yield low passive loss (<3/10 dB/km in core/innerclad at 1310 nm) and high-conversion efficiency, suitable for power scaling and higher reliability. Fibre lasers with output power of 110 W, M/sup 2/~=1.07 and slope efficiency near 80% have been demonstrated.