Comparison of electro-optic effect between stoichiometricand congruent LiNbO 3

Comparison of the electro-optic (EO) effect between stoichiometric and congruent lithium niobate (LiNbO3) crystals has been investigated using the Mach-Zehnder interferometer at 0.633 µm wavelength. Anisotropic changes of EO coefficients, r33 and r13, have been found between the stoichiometric and congruent LiNbO3 crystals. The measured r33 value in the stoichiometric LiNbO3 is at least 20% larger than that of LiNbO3 with congruent composition, whereas the r13 coefficient of stoichiometric LiNbO3 is the same as that of congruent LiNbO3.