The mechanisms and dynamics of the upconversion emissions in Er3+-doped flu
oroindate glasses by exciting in the range from 955 to 975 nm have been inv
estigated. The upconversion emissions observed at 545 and 660 nm have been
analysed studying their dependence on excitation intensity and Er3+ concent
ration. Temperature dependence of the upconversion efficiency for these emi
ssions has been measured in the range from 10 to 295 K. The temporal evolut
ion of the 545 nm upconversion emission has been obtained as a function of
the wavelength of the pulsed excitation. From the analysis of these measure
ments with a proposed model, the relative weight of excited state absorptio
n and energy transfer has been obtained. (C) 1999 Elsevier Science B.V. All
rights reserved.