Fabrication and properties of highly transparent Yb:LuAG ceramics

We reported on the fabrication and properties of 2.5 at.% Yb:LuAG ceramics prepared by a solid-state reactive sintering method using commercial available powders as starting materials. The Yb:LuAG ceramics sintered at 1850°C for 50 h have a dense and homogeneous structure with the average grain size of about 60 μm. The transmittances of the Yb:LuAG ceramics with the 3 mm thickness are 82.6% at 400 nm and 84.0% at 1100 nm. The maximum luminescence peak is located at about 1029 nm and the fluorescence lifetime is 1.3 ms. It is demonstrated that the Yb:LuAG ceramics have excellent mechanical properties, furthermore the thermal expansivity and thermal conductivity are even better than those of Yb:YAG ceramics. Continuous-wave (CW) laser operation is obtained with the maximum output power of 2.1 W and a slope efficiency of 41.7% for non-coated Yb:LuAG ceramics with the output coupler of T = 10%.