Site selective spectroscopy of Yb3+ in NaT(WO4)2, T = Bi, Gd, Y, Lu, laser crystals: Assessment with simulated crystal field effects

Abstract The sequences of the energy levels of Yb 3+ for the two different 2 b and 2 d crystal sites in tetragonal I 4 ¯ disordered double tungstate NaT(WO 4 ) 2 , T = Bi, Gd, Y, Lu, laser crystals have been determined by 6 K site selective emission and excitation of the photoluminescence spectra. The results were assessed with predictive simulations of crystal field interactions for these Yb 3+ sites in current NaT(WO 4 ) 2 hosts. The method allows the interpretation of low temperature optical absorption spectra containing unresolved information of all Yb centres in such disordered laser crystal hosts.