Strong water absorption at 2 μm generated recent interest in lasers at this wavelength for soft tissue surgery. A fiber
Bragg grating-based, all-fiber, continuous-wave, cladding pumped, thulium-doped fiber laser at 1.95 μm is configured.
The thulium-doped active fiber with octagonal-shaped inner cladding is pumped at 808 nm (total power of 17 W) with
six laser diodes through a combiner. The laser power of 3.3 W (after elimination of unabsorbed pump power through a
passive fiber) with slope efficiency of 23% (against launched pump power) is achieved. The linear variation of laser
power with pump offers scope of further power scaling.