SITE SELECTIVE SPECTROSCOPY OF Nd3+ AND Cr3+ SITES IN LiNbO3 CRYSTALS CODOPED WITH Mg2+ IONS

The fluorescence properties of Nd3+ in Nd : MgO : LiNbO3 and Cr3+ in Cr : MgO : LiNbO3 systems have been systematically studied after site selective laser excitation. Three kinds of sites have been detected for the active (Nd3+ or Cr3+) ions. Two sites correspond to the active ion located in Li+ and Nb5+ lattice positions, and also appear in the singly (without MgO) doped systems. Codoping with Mg2+ ions induce the appearance of a new site for the active ion, together with a decreasing in the Li/Nb occupation ratio