High efficiency 110 W monolithic FBG tuned 2 μm fiber laser

The paper reports a robust fibre Bragg grating (FBG) tuned Tm-doped fiber laser pumped with 793 nm delivering 110 W CW at 2 μm with 55% slope efficiency. The laser operated in single transverse mode at 2050 nm (FWHM ˜2 nm) determined by the reflectivity of the FBG. This demonstration was enabled by recently developed true large mode area (LMA) Tm-doped fibers which employ the use of an undoped pedestal region surrounding the rare earth doped core.