120-W Q-switched cladding-pumped Yb-doped fibre laser

In this paper, Q-switched large-mode area (LMA) cladding-pumped Yb-doped fibre laser in terms of its high-power operation have been investigated. We have designed and fabricated an LMA fibre with 30 /spl mu/m diameter, 0.07 NA, core, and 350 /spl mu/m D-shaped inner cladding with 0.49 NA. The continuous wave slope efficiency of /spl sim/84 % with respect to the absorbed pump power at 975 nm was obtained.