New class of fibre laser based on lead-germanate glass

The first fibre laser based on rare-earth doped lead-germanate glass is reported. The thulium-doped fibre had a background loss of 2 dB/m and a maximum phonon energy of ~920 /cm. Lasing was achieved on the Tm3+ 3H4 - 3H6 transition at 1.905µm with a 3.6mW threshold, when diode-pumped at 790nm. A quantum efficiency of 30% was obtained.