1.06 μm laser transition characteristics of Nd 3+-doped fluorophosphate glasses

Abstract

The fluorophosphate glasses with the composition (mol%) of (56 − x)P 2O 5 + 17K 2O + (12 − x)MgO + 6MgF 2 + 9Al 2O 3 + xNd 2O 3 and (56 − x)P 2O 5 + 17K 2O + (12 − x)SrO + 6SrF 2 + 9Al 2O 3 + xNd 2O 3 (where x = 0.1, 1.0, and 2.0 mol%) have been prepared and characterized by absorption and luminescence spectra and decay curve analysis. The absorption band positions of Nd 3+ ions have been analyzed using the free-ion Hamiltonian model. From the absorption spectra, Judd–Ofelt intensity parameters have been evaluated which are in turn used to predict radiative properties such as total radiative transition probabilities, radiative lifetimes and branching ratios. The present glasses have high stimulated emission cross-sections, implying that they have potential for laser applications. Lifetime of the 4F 3/2 level decreases with increasing Nd 3+ ions concentration. The non-exponential decay curves have been fitted to the generalized Yokota and Tanimoto model and derived energy transfer and migration parameters, donor–acceptor coupling constants and diffusion coefficients. The free OH content in the 1.0 mol% Nd 2O 3-doped glasses has been estimated from their measured Fourier transform infrared transmittance spectra.