Efficient high-power continuous wave Er:Lu2O3 laser at 2.85 μm.

We report on crystal growth, spectroscopy, thermal conductivity and (4)I(11/2)→(4)I(13/2)-laser performance of Er:Lu(2)O(3). Pumping with an optically pumped semiconductor laser at 971 nm, 1.4 W of cw output power with a slope efficiency of ∼36% at 2.85 µm was obtained at room temperature. This exceeds the Stokes efficiency due to an upconversion process recycling population of the lower laser level back into the upper laser level, yielding the highest efficiency of any Er-sesquioxide laser around 3 µm. Under diode pumping, 5.9 W of output power with 27% of slope efficiency was achieved with an M(2) of 1.2 to 1.4.