Stokes and anti‐Stokes luminescence from cubic elpasolite Cs2NaYF6 crystals doped with Er3+and Yb3+ ions

Er3+ and Yb3+ doped cubic elpasolite Cs2NaYF6 crystals including stoichiometric compositions Cs2NaErF6 and Cs2NaYbF6 have been synthesized under hydrothermal conditions. Absorption, stimulated-emission and gain cross-sections spectra have been determined for the 2F5/2→2F7/2 (Yb3+) and 4I13/2→4I15/2 (Er3+) transitions at room-temperature. The maximum σSE values are 1.8×10−21 cm2 at 993 nm (Yb3+) and 3.8×10−21 cm2 at 1535 nm (Er3+). Elpasolite crystals provide exceptionally long radiative lifetimes of the excited-states for both ions, namely τ(2F5/2)=6.3 ms and τ(4I13/2) ~32 ms for 10 at% Yb3+:Cs2NaYF6 and 10 at% Er3+:Cs2NaYF6 which can be used in high pulse energy Q-switched lasers. Up-conversion luminescence has been studied for Er3+ doped and Er3+, Yb3+ codoped Cs2NaYF6 crystals.