150-W Tm³⁺-Doped Fiber Lasers With Different Cooling Techniques and Output Couplings

A home-made double-clad Tm³⁺−doped silica fiber laser with over 150-W output power is reported. Pumped with a diode bar at 793 nm, the fiber laser is operated at 2.04 μm with a slope efficiency of 56.3%. A quantum efficiency of >140% is achieved owing to the efficient cross−relaxation process in heavily Tm³⁺-doped fibers. By using different fiber-cooling techniques, the slope efficiency shows a deviation over 10%. The influence of output coupling on the laser characteristics is also investigated.