Spectroscopic investigations on Yb~(3+) doped and Pr~(3+)/Yb~(3+) codoped tellurite glasses for photonic applications

In this work, we report on structural and spectroscopic properties of Yb³⁺ doped and Pr³⁺/Yb³⁺ co-doped TeO₂-Bi₂O₃-ZnO-Li₂O-Nb₂O₅ (TBZLN) tellurite glasses. Bending and stretching modes of TeO₂ and Te–OH bond (strong and weak) were analysed from the deconvolution of observed Raman and FT-IR spectra. Based on the absorption measurements, the energy bands of Yb³⁺ and Pr³⁺ ions are assigned. The spectroscopic properties for the radiative transitions of Yb³⁺ and Pr³⁺ ions were reported using McCumber and Judd-Ofelt theories. Visible emission bands originating from ³P₁ and ³P₀ to lower lying levels of Pr³⁺ were registered under 447 nm excitation. The emission band around 1334 nm assigned to the Pr³: ¹G₄→³H₅ was observed when excited at 980 nm. The stimulated emission cross-section (σ_emi(λ)) and effective linewidth (Δλ_eff) for the ³P₁→³H₆, ³P₁→³H₅, ³P₀→³H₆, ³P₀→³F₂, ³P₁→³F₃, ³P₁→³F₄, ³P₀→³F₄ and ¹G₄→³H₅ transitions of Pr³⁺ are reported. Upconversion luminescence in Pr³⁺/Yb³⁺ co-doped glass upon 980 nm excitation was measured. Possible resonant transfer processes between Yb³⁺ and Pr³⁺ ions are presented and discussed. The chromaticity co-ordinates were also evaluated from the visible emission spectra showing that Pr³⁺/Yb³⁺ co-doped glass may be suitable for the development of yellow-orange (λ_exc = 447 nm) and near white light (λ_exc = 980 nm) emitting devices in photonics.