Watt-Level 100-nm Tunable 3- $\mu$m Fiber Laser

Watt-level erbium-praseodymium codoped ZBLAN midinfrared fiber laser with 100-nm continuously wavelength-tunable range (2.7-2.8 m) is demonstrated. Continuous-wave output of 1 W with a linewidth of 1.8 GHz over the entire tuning range is affordable. Owing to relatively small residual populations in the lower laser level I of Er ions in the Er-Pr-codoped system, the wavelength-tunable range shrinking with increasing pump power, which always happens in tunable singly Er-doped ZBLAN fiber lasers, was not observed in this tunable Er-Pr-codoped fiber laser.