Analysis of down conversion and back-transfer processes in Pr3+-Yb3+ co-doped phosphate glasses

• Published in: Optical materials Vol. 131; p. 112604
• Main Authors: Benrejeb, H., Soler-Carracedo, K., Hraiech, S., Martin, I.R.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.09.2022
• Subjects: Down conversion; Optical properties; Phosphate glass; Rare earth; Phosphate glass; Rare earth; Down conversion; Optical properties
• ISSN: 0925-3467; 1873-1252
• DOI: 10.1016/j.optmat.2022.112604

The visible to near-infrared spectral modification in Pr3+ and Yb3+ co-doped phosphate glasses were verified through the energy transfer from Pr3+ to Yb3+ ions. A series of 0.1Pr3+-xYb3+(x = 0.5, 1, 1.2 mol%) co-doped phosphate glasses were prepared by the melt quenching method. The absorption, excitation and emission spectra and fluorescence decays were measured and analyzed. The emission in the visible region and the luminescence decay times of the Pr3+ confirmed the coexistence of the down-conversion processes from Pr3+ to Yb3+ due to the mechanism: Pr3+(1D2) + Yb3+(2F7/2) → Pr3+(3F3) + Yb3+(2F5/2) and the cross relaxation processes between Pr3+ ions. The down conversion produces an important population of Yb3+ ions and consequently an intense emission at 975 nm. However, when the concentration of Yb3+ is larger than 0.5 mol% the emission from the Yb3+ start to decrease. In order to analyze all the transfer processes is proposed a generalized energy transfer model. Therefore, in basis to this model the luminescence decay curves of Yb3+ ions confirm an important back-transfer mechanism from these excited ions to the Pr3+ ions. This process limits the emission intensity of Yb3+ ions in the near-infrared region obtained by down-conversion under direct excitation of Pr3+ ions. •Pr3+-Yb3+co-doped phosphate glasses were prepared by the melt quenching method.•Thermal and optical properties have been measured and analyzed.•The non-exponential behavior of the decay curves for 1D2 level confirm the ET by DC from Pr3+ to Yb3+.•Emission intensity of Yb3+ decreases gradually due to the existence of back energy transfer (BET) from the Yb3+ to the Pr3+.•The down and backtransfer processes have been analyzed in basis to a proposed generalized Parent energy transfer model.