White light emission from Sm³⁺/Tb³⁺ codoped oxyfluoride aluminosilicate glasses under UV light excitation

In this paper, we report on the absorption and photoluminescence properties of oxyfluoride aluminosilicate and boro-aluminosilicate glasses codoped with Sm³⁺ and Tb³⁺ ions. The differential thermal analysis profiles of these glasses have been obtained to confirm their thermal stability. From the measured absorption spectrum, Judd-Ofelt (J-O) intensity parameters (Ω₂, Ω₄ and Ω₆) have been evaluated for the Sm³⁺ ion. When excited by ultraviolet light these glasses emit a combination of blue, green and orange-red wavelengths forming white light. The ratio of the intensities of orange-red to green emissions can be tuned by varying both the concentration of the Sm³⁺ ion and the composition of the glass matrix. The excitation and emission spectra have shown a self-quenching effect for the Sm³⁺ ions and an efficient energy transfer from Tb³⁺ : ⁵D₄ → Sm³⁺ : ⁴G_5/2 was observed which was also confirmed by the decay lifetime measurements.