Spectroscopic properties of Er:NaLa(WO4)2 crystals and effect of Ce codoping onto the excited state energy transformation in this crystal Review Article

We report on the spectroscopic investigation of Erbium and Cerium co-doped Czochralski-grown NaLa(WO4)2 crystals. We measured the Er energy levels positions and calculated the Judd–Ofelt parameters as well as the radiative lifetimes and branching ratios for the transitions under investigation. The dynamics of population of the 4S3/2, 4I11/2 and 4I13/2 multiplets of Er3+ was analyzed in order to determine the influence of the energy transfer mechanism Er–Ce onto the 1.5 μm emission. The results of Er room temperature lifetimes measurements show that the 4I11/2 lifetime reduces significantly as the Ce concentration increases, starting from 183 μs for the 0.4 at% Er doped sample to 15 μs for the 16% Ce-codoped crystal. On the contrary, the lifetime of 4I13/2 Er state reduces simultaneously of only about 10%. The obtained results suggest the possibility to obtain efficient 1.5 μm laser emission from NaLa(WO4)2.