The optical properties of Cr3+ ions in a thin film of PZG (31.4PbF2-36
.2ZnF2-21.8GaF3-4.4CdF2-4.3InF3) fluoride glass have been investigated
. In order to analyze the Cr3+ site distributions, detailed time-resol
ved measurements have been performed. The line narrowing and blue shif
t of the time-resolved emission spectra together with the spectral dep
endence of the lifetimes provide evidence for the existence of two dif
ferent statistical distributions of Cr3+ ion environments. An investig
ation of the influence of thermal treatment on the fluorescence proper
ties of Cr3+ ions is also reported.