High-efficiency 1.9 µm Tm3+:LiLuF4 thin-disk laser.

We present the first demonstration of a 792 nm diode-pumped Tm3+:LiLuF4 thin-disk laser operation around 1.9 μm. In multimode configuration, up to 21 W of output power and a maximal slope efficiency of 49% with an optical-to-optical efficiency of 40% was demonstrated. A tuning range from 1899 nm to 1927 nm could be achieved by inserting an etalon into the cavity.