Energy Transfer Studies in Tb(3+)-Yb(3+) Co-Doped Phosphate Glasses

Detailed optical properties of Tb(3+)-Yb(3+) co-doped phosphate glasses were performed based on their emission spectra and decay measurements. Under blue excitation of Tb(3+) at 488 nm, the intensity of Yb(3+) emissions gradually enhanced upon increasing the Yb(3+) content until 1 mol% indicated an energy transfer from Tb(3+) to Yb(3+). Otherwise, under near infrared excitation of Yb(3+) at 980 nm, these glasses exhibit intense green luminescence, which led to cooperative sensitization of the (5)D(4) level of Tb(3+) ions. A cooperative energy transfer mechanism was proposed on the basis of the study on the influence of Yb(3+) concentration on up-conversion emission intensity, as well as the dependence of this up-conversion intensity on near infrared excitation power. Moreover, the temporal evolution of the up-conversion emissions have been studied, which was in positive agreement with a theoretical model of cooperative up-conversion luminescence that showed a temporal emission curve with rise and decay times of the involved levels.