Spectroscopic investigations on Ho3+ doped mixed alkali phosphate glasses

Abstract Optical absorption and emission properties of Ho 3+ doped mixed alkali phosphate glasses of the type 69.5NH 4 H 2 PO 4 · x Li 2 CO 3 · (30 − x )K 2 CO 3 and 69.5NH 4 H 2 PO 4 · x Na 2 CO 3 · (30 − x )K 2 CO 3 (where x = 5, 10, 15, 20 and 25) were studied. Racah ( E 1 , E 2 , E 3 ), spin–orbit ( ξ 4f ) 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 ( Ω 2 , Ω 4 , Ω 6 ) are calculated for all the Ho 3+ 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, 5 F 4 , 5 S 2 → 5 I 8 and 5 F 5 → 5 I 8 of Ho 3+ in these two mixed alkali phosphate glasses. Optical band gaps ( E opt ) for both direct and indirect transitions are reported.