10-W-level monolithic dysprosium-doped fiber laser at 3.24 µm.

We report, to the best of our knowledge, the first entirely monolithic dysprosium (Dy)-doped fluoride fiber laser operating in the mid-IR region. The system delivers 10.1 W at 3.24 µm in continuous operation, a record for fiber oscillators in this range of wavelengths. The Dy3+ fiber is pumped in-band using an erbium-doped fiber laser at 2.83 µm made in-house and connected through a fusion splice. Two fiber Bragg gratings directly written in the Dy-doped fiber form the 3.24 µm laser cavity to provide a spectrally controlled laser output. This substantial increase of output power in the 3.0-3.3 µm spectral range could open new possibilities for applications in spectroscopy and advanced manufacturing.