Effect of chemical composition on spectroscopic properties of neodymium doped heavy metal oxide glasses for lasing applications

Five Nd³⁺-doped bismuth based alumino-phosphate glass samples are prepared by melting the raw materials. Luminescent and radiative properties of the samples are studied to find their suitability in lasing applications. The effect of chemical composition on spectroscopic properties has also been studied. Nine bands owing to transitions from ⁴I_9/2 level to various higher levels of Nd³⁺-ion are observed in absorption spectroscopy. J–O parameters are observed to be influenced by the local structure of rare-earth ions. An intense emission band assigned to the transition ⁴F_3/2 → ⁴I_11/2 is observed on exciting the samples with 808 nm and its intensity varies as a function of concentration of Nd₂O₃. Stimulated emission cross-section σ_em(λ) and absorption cross-section σ_abs(λ)of transition ⁴F_3/2 → ⁴I_11/2 have also been examined using Fuchtbauer-Ladenburg equation and McCumber theory respectively. Large values of transition probability, high branching ratio and high stimulated cross-section of the transition ⁴F_3/2 → ⁴I_11/2 in comparison to previously reported Nd³⁺- doped similar phosphate glasses indicate its potential use in IR lasers. Luminescence intensity is maximum for GNdP(0.5) and GNdP(1.0) glass samples. Quenching of luminescence is observed on increasing the mole % of Nd₂O₃ beyond 1.0. The samples are further investigated for their up-conversion tendency by comparing excitation spectrum and absorption spectrum in the wavelength range 700–900 nm. Intense emission bands observed at 290 nm and 870 nm on exciting the samples at 582 and 585 nm respectively, confirms simultaneous up and down conversion in synthesized glass samples which makes them potentially useful in developing solar cells encapsulations, bio-imaging and display devices, and lasers.