Fabrication, microstructure and optical properties of Yb:LuxY3-xAl5O12 transparent ceramics

In this paper, we reported mixed garnet laser ceramic gain media with composition of 15 at.% Yb:LuxY3-xAl5O12 (x = 0, 0.75, 1.5, 3.0, Yb:LuYAG) fabricated by the solid state reactive sintering in vacuum. After being sintered at 1850 °C for 30 h, all the Yb:LuYAG ceramics have dense microstructure and high optical quality. The in-line transmittances of the 1.6 mm thick ceramics with x = 0, 0.75, 1.5 and 3.0 are 84.8%, 84.1%, 82.4% and 83.4% at 1100 nm wavelength, respectively. The influences of the Lu3+ content on the absorption and emission spectra were discussed. With the increase of Lu3+ content, the crystal field increases, causing a blue shift of position and bigger absorption coefficient of the about 938 nm absorption peaks. The main emission peaks for all Yb:LuYAG ceramics retain at 1030 nm. The samples have shown a high laser emission slope efficiency, near to exceeding 60% in optimized output coupling conditions. The comparable optical properties and excellent thermo-mechanical qualities mean that the Yb:LuYAG ceramics are promising gain media used for high power laser application.