Photoluminescence and Particular Features of the Defect Structure of Congruent and Near-Stoichiometric Lithium Niobate Crystals Obtained Using Different Technologies

Bulk photoluminescence of congruent and near-stoichiometric lithium niobate crystals that were obtained by different technologies is studied. It is found that the luminescence intensity in crystals whose composition is close to stoichiometric is lower than that in congruent crystals. It is shown that not only luminescence centers of the main types, which are caused by the occurrence of Nb_Li, V_Li, etc., point defects, but also complex defects that are caused by the occurrence of OH groups in the structure can contribute to luminescence.