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

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 S-4(3/2), I-4(11/2) and I-4(13/2) multiplets of Er3+ was analyzed in order to determine the influence of the energy transfer mechanism Er-Ce onto the 1.5 mu m emission. The results of Er room temperature lifetimes measurements show that the I-4(11/2) lifetime reduces significantly as the Ce concentration increases, starting from 183 mu s for the 0.4 at% Er doped sample to 15 mu s for the 16% Ce-codoped crystal. On the contrary, the lifetime of I-4(13/2) Er state reduces simultaneously of only about 10%. The obtained results suggest the possibility to obtain efficient 1.5 mu m laser emission from NaLa(WO4)(2). (c) 2012 Elsevier B.V. All rights reserved.