Judd-Ofelt analysis and spectroscopic study of Tb:CaF2 and Tb/Pr:CaF2 co-doped single crystals

High quality of Tb3+-single doped and Tb3+/Pr3+ co-doped CaF2 crystals were grown by the temperature gradient technique (TGT). Pr3+ ions were used as sensitizing ions of Tb3+. Optical properties including ab-sorption spectrum, emission spectrum, and fluorescence decay curve were recorded. Through co-doping sensitizing ions of Pr3+, the absorption cross section around 480 nm increased from 0.007 x 10(-20) cm(2) to 0.3 x 10(-20) cm(2), the large value is beneficial for the absorption of LD pump source. Judd-Ofelt theory was used to analyze the spectroscopic parameters. Fluorescence branch ratio, transition probability, radiative and fluorescence lifetimes, and quantum efficiency were determined as well. The emission cross section of Tb,Pr:CaF2 for the green emission at 544 nm and yellow emission at 587 nm corresponding to the transition of 5D4-*7F5 and 5D4-*7F4 were calculated to be 5.56 x 10(-22) cm(2) and 8.78 x 10(-23) cm(2), respectively, which is comparable to the Tb3+ doped CaF2 crystal.