Diode‐pumped single‐mode fluorozirconate fiber laser from the 4I11/2→4I13/2 transition in erbium

Diode‐pumped cw lasing at 2.71, 2.75, and 2.78 μm from an erbium‐doped ZBLAN single‐mode fiber is reported for the first time. A threshold of 4 mW absorbed power at 792 nm was obtained for the 2.71 μm transition. 3% slope efficiency was obtained with an 80% reflecting output mirror. cw lasing was also observed from the fiber when a tunable pump was scanned across most of the 4I15/2→4I9/2 absorption band. cw lasing observed when pumping around 820 nm indicates that excited‐state absorption of the pump from the 4I13/2 may not be necessary for cw operation. However, excited‐state absorption of the pump around 810 nm from the 4I11/2 may limit performance.