Frequency modulation spectroscopy of erbium–cerium codoped fluoride glasses for optical amplifiers

We report frequency modulation spectroscopy measurements performed on erbium doped fluoride glasses: PZG (39% PbF 2 , 19% ZnF 2 , 42% GaF 3 ) and ZBAC (57% ZrF 4 , 34% BaF 2 , 5% CeF 3 , 4% AlF 3 ). For the ZBAC glass, no changes of lifetime in channel waveguides versus bulk were observed as well as no pump power dependence from 1 to 100 mW. On the contrary, for the PZG glass, the lifetime of the 4 I 13/2 level was reduced from 7 ms in bulk to 2 ms into the waveguides. In this glass, upconversion effects appear very efficient at high incident pump power.