Influence of mixed alkalis on spectroscopic parameters of Sm3+, Dy3+ doped chloroborate glasses

This article reports the effect of mixed alkalis on the optical absorption and emission spectra of Sm3+ and Dy3+ doped chloroborate glass matrices of the compositions 69.5B2O3xLiCl(30 − x)NaCl0.5R2O3 and 69.5B2O3xLiCl(30 − x)KCl0.5R2O3 (where R = Sm and Dy and x = 5, 10, 15, 20 and 25). Using Judd–Ofelt theory, the spectral intensities and Judd–Ofelt intensity parameters (Ω2,Ω4 and Ω6) were obtained from the measured absorption bands of the spectra. Using these intensity parameters, total radiative transition probabilities (AT), radiative lifetimes (τR), branching ratios (β) and peak emission cross-sections (σP) were obtained for the two rare earth ions in these two glass matrices. Variation of these parameters with x in the glass matrix has been discussed. It is found that for Sm3+ ion, the transition, 4G5/2 → 6H9/2 shows highest emission cross-section and is maximum at x = 10 mol% in lithium–sodium and at x = 20 mol% in lithium–potassium glass matrices. For Dy3+ ion, the transition, 4F9/2 → 6H13/2 shows highest emission cross-section and is maximum at x = 20 mol% in lithium–sodium and at x = 10 mol% in lithium–potassium glass matrix.

Research highlights
► The authors have studied the spectral properties of Sm3+ and Dy3+ ions in lithium-sodium and lithium-potassium mixed alkali chloroborate glasses.
► From the Judd-Ofelt parameters, radiative lifetimes of certain excited states of both the ions are estimated in these two glass materials.
► From the emission spectra, peak emission cross-sections are obtained for the emission transitions.
► From these studies, certain transitions are identified for laser excitation.