Efficient single-mode operation of a cladding-pumped ytterbium-doped multimode helical-core fiber laser has been demonstrated. The laser yielded 60.4W of output at 1043nm in a beam with M2<1.4 for 92.6W launched pump power from a diode-stack at 976nm. The corresponding slope efficiency was ~84%, which compares favourably with best slope efficiencies achievable with conventional straight-core Yb-doped double-clad fiber lasers. A theoretical model was also used in the design of the helical-core fiber and the theory fit with the experimental results well.

© 2005 Optical Society of America

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