Laser action along and near the optic axis of a holmium-doped KY(WO_4)_2 crystal

Abstract

We demonstrate the first (to our knowledge) quasi-three-level conical refraction laser operating at 2 mum, with 1.6 W of output power at 2074 nm, using a holmium-doped KY(WO 4) 2 crystal. A maximum slope efficiency of 52% has been achieved, along the optic axis with respect to the absorbed pump power. Furthermore, lasing operation around the optic axis has been performed. In this case, a maximum output power of 3 W has been reached, with a slope efficiency better than 70%, which are the best performances ever reported on this material.