Fabrication, microstructure and laser performance of Nd3+-doped Lu3Al5O12 transparent ceramics

Nd:LuAG transparent ceramics were fabricated by a solid-state reaction method using commercial high-purity oxide powders as raw materials. The microstructure, optical transmittance, fluorescence spectrum and laser performance of 0.8 at.% Nd:LuAG transparent ceramics were investigated. It is found that the relative density and grain size for Nd:LuAG ceramics increase with the increase of sintering temperature. The specimen sintered at 1830 °C for 30 h is dense and homogeneous in structure with an average grain size of about 39.6 μm, whose in-line transmittances are 82.8% at 1064 nm and 81.8% at 400 nm. The main fluorescence emission peak is centered at about 1063.5 nm and the fluorescence lifetime is 240 μs. The optimum laser properties are obtained with the 300 μm pumping beam and 25% output coupler, corresponding to a slope efficiency of 43.4% and an optical-optical efficiency of 39.3%. In addition, the depolarization caused by the thermally-induced birefringence was also investigated.