INVESTIGATIONS ON DEFECT STRUCTURE AND LIGHT-INDUCED SCATTERING OF Mg:Ho:LiNbO3 WITH VARIOUS Mg2+ CONCENTRATION

Congruent Ho3+ (1 mol.%): LiNbO3 crystals codoped with MgO (X mol.%, X = 1, 3, 5 and 7) were grown by the Czochralski technique. The ultraviolet-visible (UV-Vis) and infrared (IR) spectra were measured in order to analyze the defect structure of the crystals. The concentrations of Mg, Ho, Li and Nb in the crystals were carried out with an inductively coupled plasma atomic emission spectrometer. Experimental results indicates as Mg2+ doping concentration increases in melt, the distribution coefficients of Mg and Ho ions decrease, the Li/Nb ratio in the crystals decreases first and then increases, and the absorption edge shifts to a shorter wavelength. The light-induced scattering of Mg: Ho: LiNbO3 crystals was quantitatively scaled via the incident exposure energy. The results demonstrated that Mg (7 mol.%): Ho: LiNbO3 crystal had the weakest light-induced scattering and the mechanism related to their defect structures was discussed.