Optical properties of lithium niobate crystals

According to optical absorption spectra the width of the forbidden band of nominally pure congruent and stoichiometric lithium niobate crystals, as well as a series of congruent crystals doped with cations of Mg2+(0.35 wt.%), Zn2+(2.05), B3+(0.12), Gd3+(0.26, 0.44, 0.51), Y3+(0.46), Gd3+(0.23):Mg2+(0.75), Mg2+(0.86):Fe3+(0.0036), Ta5+(1.13):Mg2+(0.01), Y3+(0.24):Mg2+(0.63), Er3+(3.1) is determined. The photorefractive effect in crystals, their structural and optical homogeneity was studied by photo induced and Raman scattering methods, laser conoscopy.