Excited-state absorption and fluorescence dynamics in Er:CaF2

Emission, ground- and excited-state absorption spectra of Er:CaF2 single crystals were registered from the visible to the mid-infrared. These spectra were calibrated in unit of cross section and analyzed to derive purely radiative lifetimes and branching ratios. Fluorescence decays were then recorded to determine effective emission lifetimes and branching ratios including non-radiative multiphonon relaxations. These fluorescence data along with population ratios and emission intensity measurements performed versus pumping rates were finally confronted with a rate equation model to derive energy transfer rates.