EPR and optical studies of optical bleaching of Cr3+ in near-stoichiometric LiNbO3:Cr, MgO

Results of EPR and optical studies of chromium ions substituting niobium that undergoes photo-bleaching in LiNbO3:Cr,MgO crystals are reported. Two-component kinetics of photo-bleaching are observed in EPR and optical measurements. The different CrNb centers exhibit very similar EPR signals in lithium niobate crystals. The possible mechanisms of different photo-bleaching kinetics are proposed.