Evaluation of the OH− influence on visible and near-infrared quantum efficiencies of Tm3+ and Yb3+ codoped sodium aluminophoshate glasses

This paper presents a throughout spectroscopic investigation of Yb3+∕Tm3+ codoped sodium aluminophosphate glasses in the visible and near-infrared spectral regions. Two sets of samples, prepared in air and nitrogen atmospheres, were characterized by transmission, absorption, luminescence, excited state lifetimes, and upconversion. The data are discussed in terms of OH− contents in the samples, and their influence on Tm3+ fluorescence quantum efficiencies. Besides, a theoretical analysis of radiative properties, by the Judd-Ofelt [Phys. Rev. 127, 750 (1962)]; J. Chem. Phys. 37, 511 (1962)] theory, is also presented in comparison to experimental data. Results indicate that samples prepared in N2 atmosphere, with lower OH− content, present superior properties than those prepared in air. Among these properties are a 30% more extensive infrared transmission of the host matrix, higher emission intensities, and decreased quenching effects, characterizing them as potential materials for high power laser generation, as well as efficient upconversion.