Efficient upconversion pumping at 1.064 mu m Tm³⁺-doped fluoride fibre laser operating around 1.47 mu m

1.064 mu m upconversion pumping was used to operate a highly efficient CW and Q-switched thulium (Tm³⁺)-doped fluoride fibre laser at around 1.47 mu m. The maximum CW output power was 100 mW for a launched pump power of 570 mW. The threshold power was 200 mW, the slope efficiency 27% and the wavelength width 20 nm. A peak power of 70 W was generated for Q-switching at a launched pump power of 300 mW.