Thulium channel waveguide laser with 1.6 W of output power and ∼80% slope efficiency

Laser experiments were performed on buried, ridge-type channel waveguides in 8 at.% thulium-doped, yttrium-gadolinium-lutetium co-doped potassium double tungstate. By pumping with a Ti:sapphire laser at 794 nm, 1.6 W of output power at 1.84 μm with a maximum slope efficiency of ∼80% was obtained in a laser resonator with a high output-coupling degree of 89%. To the best of our knowledge, this result represents the most efficient 2-μm channel waveguide laser to date.