Spectroscopic investigations on Ho3+ doped mixed alkali phosphate glasses

Optical absorption and emission properties of Ho3+ doped mixed alkali phosphate glasses of the type 69.5NH4H2PO4 · xLi2CO3 · (30 − x)K2CO3 and 69.5NH4H2PO4 · xNa2CO3 · (30 − x)K2CO3 (where x = 5, 10, 15, 20 and 25) were studied. Racah (E1, E2, E3), spin–orbit (ξ4f) and configuration interaction (α, β) parameters are calculated and these values are compared for different x values in the glass matrix. Judd–Ofelt intensity parameters (Ω2, Ω4, Ω6) are calculated for all the Ho3+ doped mixed alkali phosphate glasses. From these parameters and from the spectral profiles of the hypersensitive transition structural studies have obtained. Radiative transition probabilities (A), radiative lifetimes (τ), branching ratios (β) and integrated absorption cross-sections (Σ) are obtained from the intensity parameters. Emission cross-sections (σ) are calculated for the two transitions, 5F4, 5S2 → 5I8 and 5F5 → 5I8 of Ho3+ in these two mixed alkali phosphate glasses. Optical band gaps (Eopt) for both direct and indirect transitions are reported.