Up-conversion losses in Nd3+ doped lead fluoroborate glasses

In this paper we report the determination of the ETU processes of lead fluoroborate glasses produced at Faculty of technology of Sao Paulo, doped with concentrations of Nd2O3 ranging from 0.04wt% up to 3.49wt%. The samples have a high refractive index of 2.2 and density of about 6.9g/cm(3). Concentration quenching was observed at 3.49wt% doping. The spectroscopic results suggest that these materials can be considered as candidates for laser applications when compared to other known glasses used as laser media. The best spectroscopic performance was obtained for a sample doped with 1.75wt% of Nd2O3 : emission cross-section of 3.6 x 10(-20) cm(2) at 1060nm, fluorescence lifetime of 0.06ms and effective fluorescence bandwidth of 30.43nm. No visible emission from the F-4(3/2) level is observed when pumping with a diode laser at 797nm. From analysis of the temporal evolution of the infrared emission from the F-4(3/2) state pumped at two excitation powers, we estimated the macroscopic energy transfer up-conversion (ETU) parameter for the studied samples. The results show ETU probability has a quadratic dependence on neodymium concentration. (C) 2004 Elsevier B.V. All rights reserved.