Optical spectroscopy of Eu 3+ ions in lithium borate and lithium fluoroborate glasses

Abstract

Optical absorption, excitation and emission spectra of Eu 3+ ions in lithium borate and lithium fluoroborate glasses have been investigated. Judd–Ofelt intensity parameters are derived from the integrated absorption spectra and also from the emission spectra under various constraints. The relative merits of thermal correction to the oscillator strengths of the transitions originating from the ground state ( 7 F 0 ) of Eu 3+ ion observed in the absorption spectra have been discussed. The Judd–Ofelt parameters obtained from the emission spectra have been used to calculate the total spontaneous emission probabilities ( A), lifetimes ( τ R) and branching ratios ( β R) for eight excited levels that include, 5 K 6, 3 P 0 , 5 H 3 , 5 L 7 , 5 D 3 , 5 D 2 , 5 D 1 and 5 D 0 . The predicted values of τ R and β R are compared with the measured values for 5 D 0 level. The stimulated emission cross-sections ( σ ( λ p)) are also evaluated for the 5 D 0→ 7 F J and 5 D 1→ 7 F J transitions. The variation of optical properties with compositional changes of lithium oxide and lithium fluoride contents in the glasses are discussed and compared with similar results.