Spectroscopic Properties and Energy Transfer in Lead Bismuth Gallium Borate Glasses Codoped with Tm3+ and Yb3+

Abstract

Lead bismuth gallium borate (GTY) glasses codoped with Tm 3+ /Yb 3+ were prepared by melt quenching technique. The glasses were characterized by X-ray diffraction spectra. Optical absorption, FTIR and photoluminescence spectra of these glasses have been studied. The optical absorption spectra exhibits a band at 980 nm due to transitions from the ground states 4 I15/2 and 2 F7/2 to excited states of Yb 3+. The other absorption bands at 658 nm (3 H6 → 3 F2), 686 nm (3 H6 → 3 F3), 792 nm (3 H6 → 3 H4), 1211 nm (3 H6 → 3 H5) and 1663 nm (3 H6 → 3 F4) are attributed to 4f-4f transitions of Tm 3+ ions, respectively. Judd-Ofelt theory has been applied to the f  f transitions for evaluating Ω2, Ω4 and Ω6 parameters. Radiative properties like branching ratio r and the radiative life time τR have been determined on the basis Judd-Ofelt theory. Upconversion emissions have been observed under 980nm laser excitation at room temperature. The spectra exhibited two emission bands centered at 468 nm and 654 nm due to 1 G4 → 3 H6 (blue) and 1 G4 → 3 H4 (red) transitions, respectively. The results obtained are discussed quantitatively based on the energy transfer between Yb 3+ and Tm 3+ .