Laser spectroscopy of CaF2:Eu:Sm thin films grown by pulsed laser deposition

Thin films of CaF2 co-doped with low concentrations of Eu and Sm ions were grown by pulsed laser deposition (PLD) using a KrF (λ=248 nm) as the ablation source. To the best of our knowledge, the work presented here is the first report of rare-earth-doped CaF2 films grown by PLD with this source. Combined laser excitation-emission spectroscopy was used to map out electronic transitions of Eu3+ with 7F0→5D1 excitation and the 5D0→7F1 emission. At the low concentrations used here the crystal field center of cubic symmetry is dominant in the films that are same for laser targets. However, charge compensated centers are present in the bulk crystal precursor. The removal of the charge compensated centers in the films and the target is likely caused by the target preparation where high pressure and temperature were applied.