In-depth study of emission dynamics in (Dy,Tb):LuAG transparent ceramics

Dy:Lu₃Al₅O₁₂ ceramics co-doped with Tb³⁺ have been fabricated by vacuum pre-sintering at high temperature and hot isostatic pressing (HIP) and characterized from a spectroscopic point of view in order to assess their potentialities as yellow emitting laser materials. The intensities of the room temperature absorption transitions of Dy³⁺ have been reproduced in the frame of the Judd-Ofelt parametrization scheme and the resulting Ω_t (t = 2, 4, 6) parameters have been used to estimate its radiative properties in this host material; the calculation has taken into account the near-infrared absorption bands as well as the hypersensitive ⁶F_11/2←⁶H_15/2 transition. The emission measurements at 10 K carried out upon 262 nm laser excitation provide information on the Stark structures of the lowest levels of both Tb³⁺ and Dy³⁺, thanks to an efficient energy transfer process between the two ions. The complex excited state dynamics of the studied ceramics have been investigated at room temperature in different experimental conditions. In particular, a new approach is proposed for assessing the beneficial effect of the Tb³⁺ co-doping ions on the Dy³⁺ yellow emission channel, based on the comparison between the decay profiles measured in different excitation conditions.