In-band pumping of Tm:LiYF4 channel waveguide: a power scaling strategy for ∼2  μm waveguide lasers

We report on a novel power scaling strategy for thulium waveguide (WG) lasers relying on in-band pumping by high-brightness Raman fiber lasers (RFLs) and the use of liquid-phase-epitaxy-grown fluoride crystalline thin films for better thermal management. Thulium channel WGs are produced by microstructuring the Tm3+:LiYF4/LiYF4 epitaxies via diamond-saw dicing. They are pumped by a RFL based on an erbium master oscillator power amplifier and a GeO2-doped silica fiber and emit polarized output at 1679 nm. A CW in-band-pumped (H63→F43) Tm3+:LiYF4 WG laser generates up to 2.05 W of a linearly polarized single-transverse-mode output at 1881 nm with a slope efficiency of 78.3% and a laser threshold of only 12 mW (versus the absorbed pump power).