Power scaling of resonantly cladding-pumped, Yb-free, Er-doped LMA fiber lasers

The results of the recent major efforts in power scaling of resonantly cladding-pumped Yb-free Er fiber lasers are presented. Commercially available Yb-free Er-doped large mode area Er60-20/125 (LMA) DC fibers were tested in two regimes: (i), as a booster amplifier in a single-frequency (SF) MOPA configuration and, (ii), in a Bragg grating (FBG) based narrowband fiber laser configuration. We obtained ～28.5 W of output power at 1590 nm, the highest power reported so far out of Yb-free Er-doped LMA fiber with resonant cladding pumping. The achieved optical-to-optical conversion slope efficiency of ～56.6% is also believed to be the highest efficiency ever reported from Yb-free Er-doped fiber laser with resonant cladding pumping.