Dy3+ doped CaF2 crystals spectroscopy for the development of Mid-infrared lasers around 3 µm

In this communication, we present a spectroscopic study of Dy³⁺ -doped and Tm³⁺ -Dy³⁺ codoped CaF₂ as promising candidates to develop solid-state laser sources around 3 μm. In view of the preliminary experimental results, we first demonstrate the advantage of Tm³⁺ ions as sensitizers to improve the excitation of Dy³⁺ ions in CaF₂ and then is highlighted a singular behavior of Dy³⁺ doped CaF₂ crystals that present a multisite character due to clustering of rare earth ions. The spectroscopic characteristics of each site is studied and discussed, as well as the potential of Tm³⁺ codoping for laser applications around 3μm.