Thulium-doped monomode fluoride fibre laser broadly tunable from 2.25 to 2.5 mu m

Tunable laser emission at 2.5 mu m has for the first time been observed in a thulium doped fluoride fibre laser. With simultaneous laser action at 1.91 mu m, continuous tuning could be achieved over a 250 mm range extending from 2.25 to 2.5 mu m. This performance was achieved for 300 mW of incident pump power at 790 nm.