Cooperative energy transfer frequency upconversion in Tb 3+/Yb 3+-codoped oxyfluoride glasses

Abstract

In this report, we investigate the cooperative energy transfer frequency upconversion in Tb 3+/Yb 3+-codoped SiO 2–Al 2O 3–Na 2O–ZnF 2 oxyfluoride glasses under 980 nm diode laser excitation. The influence of both Tb 3+ and Yb 3+ concentration on the emission bands were investigated. With a lower Tb 3+ concentration, the emission bands around 381, 416 and 438 nm, and 489, 545, 587 and 623 nm associated with 5D 3, 5G 6 → 7F J ( J = 6, 5, 4) and 5D 4 → 7F J ( J = 6, 5, 4, 3) transitions were observed. However, only 5D 4 → 7F J ( J = 6, 5, 4, 3) transitions appear in a higher Tb 3+ concentration. The integrated upconversion luminescence intensity was examined when the temperature of sample was varied from 40 to 450 K. The dependence of the upconversion emission intensity upon the excitation power was also examined, and the upconversion mechanisms were discussed.