Luminescence and upconversion dynamics of praseodymium in LiLuF4 laser crystals

We have investigated the spectroscopic properties of Pr3+ ions in LiLuF4 laser host doped with 0.5% Pr3+ ions as a function of temperature. We obtained the luminescence spectra by exciting selectively the sample at 439nm into the 3P2 level and at 593nm into the 1D2 level. With excitation in the 3P2 level we obtained emission only from the 3P0 level but not from the 1D2 level at all temperatures between 24 and 300K. With excitation into the 1D2 level we observed the luminescence emitted by the same level and a strong blue up-conversion emission from the 3P 0 level. We used the decay pattern inspection to assign spectral lines to specific radiative transitions and to study the dynamics of the excited ions in the crystal. Under direct excitation, the 1D2 decay curve is nonexponential at all temperatures, whereas the 3P0 decay is exponential only at low temperatures. The experimental data indicate that the 3P0 level is populated via upconversion due to mainly energy transfer. © 2005 Materials Research Society