Optical absorption and emission properties of Er3+ doped mixed alkali borosilicate glasses

This paper presents the optical absorption and luminescence properties of Er3+ doped mixed alkali borosilicate glasses: 59.5SiO2 · 20B2O3 · xLi2O · (20 − x)Na2O · 0.5Er2O3 and 59.5SiO2 · 20B2O3 · xLi2O · (20 − x)K2O · 0.5Er2O3, with x = 0, 4, 8, 12, 16 and 20 mol%. The variations of Judd–Ofelt intensity parameters (Ω2, Ω4, and Ω6), hypersensitive transition intensities, total radiative transition probability (AT), radiative lifetimes (τR), integrated absorption cross-sections (Σ) and stimulated emission cross-sections (σp) as a function of x are discussed in detail. The changes in Ω2 and intensities of hypersensitive transitions are attributed to optical basicity changes in the host glass matrix, which leads to variations in the covalency of the Er–O bond. The luminescence properties are reported for certain transitions, and the emission cross-section is high at x = 8–12 in the case of lithium sodium glass, whereas in lithium potassium glass it is high at x = 8.