Judd-Ofelt parameters and multiphonon relaxation of Ho3+ ions in ZnCl2-based glass

摘要

Spectroscopic properties of Ho3+-doped ZnCl2-based glasses are investigated. The Omega (2) value of the glass is especially large compared with those in fluoride glasses while the Omega (4) and Omega (6) parameters are relatively small. Decay measurements for three excited states F-5(5), S-5(2)+F-5(4), and F-5(2,3)+K-3(8) were performed and multiphonon relaxation (MPR) rates of the respective states were estimated. The experimental data are approximately on a line expressed by W-MPR=C exp(-alpha DeltaE) with C=5.0x10(7) s(-1) and alpha =4.0x10(-3) cm. The host-dependent constant C is very small, contributing to high quantum efficiencies of emissions. The Ho3+ concentration dependence of the fluorescence lifetime of the F-5(5) and S-5(2)+F-5(4) levels was also investigated. The concentration quenching of the S-5(2)+F-5(4) level can be explained by the cross-relaxation mechanism: S-5(2)--> I-5(4) and I-5(7)<-- I-5(8) transitions. (C) 2001 American Institute of Physics. References: 36