Optical characterization of LiNbO3:Yb3+ crystals

A spectroscopic study of Yb3+ ions in LiNbO3 and LiNbO3:MgO monocrystals is presented. Polarized absorption and luminescence spectra at low and room temperature allow the identification of the energy levels of the Yb3+ ion in these matrices. The fluorescence decay time has also been investigated and shows an exponential behaviour with a lifetime value of 530 μs at 15 K for Yb3+ singly doped LiNbO3. Site selective spectroscopy measurements detect the existence of non-equivalent positions of the Yb3+ which can be related to the presence of Yb3+ in the Li+ octahedral site but with slightly different shifts from the regular Li site. Codoping with MgO induces new absorption and emission bands as a consequence of new Yb3+ centres which appear in the matrix due to the presence of Mg2+ ions. (author)