Structural-phase state and lasing of 5-15 at% Yb3+:Y3Al5O12 optical ceramics

Yttrium aluminum garnet (Yb3+:Y3Al5O12) laser ceramics doped by 5, 10 and 15 at% of ytterbium ions were obtained by reactive sintering. Optimal sintering temperature range for the formation of highly-dense transparent Yb3+:Y3Al5O12 ceramics under normal recrystallization conditions was found to be T = 1750-1800 °C. The influence of Yb3+ ions on structural-phase state, phase composition, microstructure, optical and luminescent properties of sintered samples was experimentally investigated. It was shown that lattice parameter a of Yb3+:Y3Al5O12 ceramics decreases linearly with increasing of Yb3+ concentration in a good agreement with L. Vegard's rule, that indicates to the formation of (Y1−xYbx)3Al5O12 (х = 0.05-0.15) substitutional solid solutions. No concentration quenching of Yb3+ luminescence was observed in Yb3+:Y3Al5O12 within the 5-15 at% doping range. Quasi-CW lasing of Yb3+:Y3Al5O12 ceramics was studied under diode-pumping at 970 nm. A highest slope efficiency of about 50% was obtained for 15 at%-doped Yb3+:Y3Al5O12 ceramics sintered at T = 1800 °C for 10 h.