Effect of hydroxyl concentration on Yb3+ luminescence properties in a peraluminous lithium-alumino-silicate glass

Ytterbium doped lithium-alumino-silicate glasses suitable for diode-pumped laser applications were investigated concerning the hydroxyl quenching of the Yb3+ fluorescence. Glasses of the nominal composition 18 mol% Li2O, 22 mol% Al2O3 and 60 mol% SiO2 with variable OH concentrations N-OH (between 0.04 and 6.01.1019 cm(-3)) and Yb3+ concentrations N-Yb (between 0.1 and 9.1020 cm(-3)) were produced and a direct correlation between spontaneous emission decay rate and the product N-Yb.N-OH was observed. The radiative spontaneous emission rate in the glass host is around 1,000 s(-1) (radiative lifetime 1.0 ms) and the microparameter for Yb-Yb energy migration, CYb-Yb, was found to be 1.358.10(-38) cm(6) s(-1). It was calculated that on average 17% of the OH groups in the glass contribute to the quenching of the Yb3+ fluorescence. By analysis of the UV edge of the glass it was concluded that melting under inert conditions leads to reduction of iron impurities to Fe2+, which can act as quenching sites for the Yb3+ ions and therefore may additionally reduce the energy storage capability of the laser material. (C) 2015 Optical Society of America