Up-conversion cascade laser at1.7 µm with simultaneous 2.7 µm lasingin erbium ZBLAN fibre

The authors report on an excited-state-absorption pumped transversally singlemode cascade laser in an erbium ZBLAN fibre. Simultaneous lasing occurred at 1.7 µm on the transition 4S3/2 → 4I9/2 supported by 2.7 µm lasing on the transition 4I11/2 → 4I13/2. The slope efficiency is 1.8% with a threshold of 227 mW launched pump power at 791 nm.