Energy transfer and upconversion processes in Nd3+-doped GeO2-PbO-Nb2O5 glass

;The optical properties of Nd3+ -doped lead germanate glass of composition tin mel. %) 60GeO(2)-25PbO-15Nb(2)O(5) have been investigated for several Nd3+ concentrations at various temperatures by steady-state and time-resolved laser spectroscopy. Judd-Ofelt parameters were derived from the absorption spectrum and used to calculate the F-4(3/2) --> I-4(11/2) stimulated-emission cross section and the 4F(3/2) radiative lifetime. The spectral features of the time-resolved fluorescence line narrowing 4F(3/2) --> I-4(9/2) emission spectra obtained under resonant excitation reveal the existence of spectral migration of excitation among the Nd3+ ions. Analysis of the time evolution of the 4F(3/2) --> I-4(9/2) narrowed emission showed that the electronic mechanism responsible for the ion-ion interaction can be identified as a dipole-dipole energy-transfer process. Green, orange, and red emissions were observed in this glass under continuous-wave infrared laser excitation and are attributed to transitions from the (4)G(7/2) level. (C) 2000 Optical Society of America.