Dynamics of the excitation and upconversion processes in YAlO3: Pr single crystals

This work focuses on the phenomenon of upconversion in YAlO3:Pr crystals with particular attention to the mechanism responsible for it and to the processes that affect the upconversion efficiency. We have investigated the spectral features of Pr3+ ions in YAlO3 host crystals with various Pr3+ concentrations. We observed upconverted emission in YAlO3:Pr when exciting the system in the 1D2 level with light from a dye laser at ∼599 nm: this emission is due to transitions originating in 3P0, a level more energetic than the 1D2 level. The dynamics of the upconversion process was studied by measuring decay patterns and emission intensities as a function of excitation and temperature in the range 24-300 K. The experimental data indicate that the mechanism responsible is energy transfer, and that the efficiency of the transfer decreases significantly as the temperature increases. The reasons for this temperature dependence are discussed.