Optical spectra of Nd3+:CaO–La2O3–B2O3 glasses

This paper reports on different physical and absorption spectral properties of Nd3+-doped calcium lanthanum borate glasses with and without Ta2O5 content to understand its influences on the hypersensitive absorption band intensities. From the recorded absorption spectra, Judd–Ofelt intensity parameters (Ωλ, λ = 2, 4, 6) have been calculated and are used to compute the radiative properties of the Nd3+:glasses. The calculated Judd–Ofelt parameters are found to be increasing with the increased substitution of calcium for lanthanum in the glass composition, which may be due to the increase of Nd–O bond covalency. The glass with the tantalum (Ta5+) as one of the constituent, has displayed a significant increase in the intensity of the hypersensitive transition (4I9 / 2 → 4G5 / 2, 2G7 / 2) of Nd3+ ions which is attributed to the asymmetry around the rare earth ion site aroused due to the occurrence of structural changes in the glass network and as well as mixed cationic effect with the addition of Ta5+ ions. Besides the spectral property analysis, different important physical properties have also been investigated from the measured density and refractive indices. The substitution of lanthanum with calcium increases the optical basicity of the glass with an increase in the oxide ion polarisability.