Tm,Ho:LiYF4 planar waveguide laser at 2.05  μm

The first holmium fluoride waveguide laser, to the best of our knowledge, is reported using a 25-μm-thick Gd3+-ion-modified 4.5 at. % Tm3+, 0.5 at. % Ho3+-codoped LiYF4 active layer grown by liquid phase epitaxy on (001)-oriented LiYF4 substrate. Pumped by a Ti:sapphire laser at 797.2 nm, the planar waveguide laser generates 81 mW of continuous-wave (CW) output at ∼2051 nm with a slope efficiency of 24%. Power scaling up to 186 mW at 2051 nm and 2065 nm in quasi-CW regime is demonstrated. The parameters of the Tm3+↔Ho3+ energy transfer are determined. Tm,Ho:LiYF4/LiYF4 epitaxies are promising for waveguide lasers and amplifiers at above 2 μm.