Fluorescence dynamics of YVO4:Tm3+, YVO4:Tm3+, Tb3+ and YVO4:Tm3+, Ho3+ crystals

The fluorescence dynamics of the 3H4 and 3F4 energy levels of Tm3+ in YVO4 single crystals codoped or not codoped with Tb3+ and Ho3+ ions was experimentally investigated and compared with classical energy-transfer models. In the YVO4:1% Tm3+ and YVO4:1% Tm3+, 1% Ho3+ crystals, the 3H4 state relaxes predominantly by internal cross-relaxation-type energy transfers, whereas in the YVO4:0.5% Tm3+, 1% Tb3+ and YVO4:1% Tm3+, 1% Tb3+ crystals the relaxation is dominated by direct energy transfers to the 7F1 state of the Tb3+ ions. In all of the codoped systems, strong energy transfers from the 3F4 state of the Tm3+ ions to the 7F1 and 5I7 states of the Tb3+ and Ho3+ codopants were evident. The electric dipole-electric dipole coupling parameter was evaluated for several cross-relaxation and direct-energy-transfer processes.