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A Holmium thin-disk laser based on a 3 at.% Ho:KY(WO 4 ) 2 / KY(WO 4 ) 2 epitaxy and single-bounce pumping by a 1960 nm Tm-fiber laser is passively Q-switched with a GaSb-based quantum-well semiconductor saturable absorber mirror. It generates an average output power of 551 mW at 2056 nm with a slope efficiency of 44% (with respect to the absorbed pump power). The best pulse characteristics (energy and duration) are 4.1 μJ / 201 ns at a repetition rate of 135 kHz and the conversion efficiency with respect to the continuous-wave regime is as high as 93%.

We report on the first holmium (Ho 3+ ) monoclinic double tungstate thin-disk laser. It is based on a 250 μm thick 3 at. % Ho:KY(WO 4 ) 2 active layer grown on a (010)-oriented KY(WO 4 ) 2 substrate. When pumped by a Tm-fiber laser at 1960 nm with a single-bounce (single double-pass) pump geometry, the CW Ho:KY(WO 4 ) 2 thin-disk laser generated 1.01 W at 2057 nm, corresponding to a slope efficiency η of 60% and a laser threshold of only 0.15 W. Implementing a double-bounce (second double-pass) for the pump, the output of this laser was scaled to 1.57 W with η=55%. The maximum stimulated emission cross section σ SE of the Ho 3+ ions in the epitaxial layer reaches 2.5×10 -20   cm 2 at 2056.5 nm for E‖N m . The Ho:KY(WO 4 ) 2 epitaxial structures are promising for multi-watt mode-locked thin-disk lasers at ∼2.06  μm.

A diode-pumped thin-disk laser based on Tm:KLu(WO4)2/KLu(WO4)2 epitaxies is realized. The emission is in the 1850-1945 nm spectral range for Tm-doping between 5 and 15 at. %. The maximum slope efficiency of 47% with respect to the absorbed power obtained with 5 at. % Tm:KLu(WO4)2/KLu(WO4)2 corresponds to a maximum output power of ~6 W in cw operation.