LD-pumped 6W cw Tm 3+ -Doped Silica Double-Cladding Fibre Laser

We report a thulium-doped silica fibre laser that generates a maximum cw output power of 6W in a 2μm wavelength range when cladding-pumped by a laser diode (LD) operating at approximately 791 nm at room temperature. The slope efficiency with respect to the launched pump power is 50% and 38.4%, with and without an output coupler mirror, respectively. The corresponding thresholds are 2.8 W and 4.8 W, respectively. The beam qualities M x 2 and M y 2 are 1.26 and 1.32, respectively. The experimental results are also analysed.