Spatial anisotropy of the linear electro-optic effect in lithium niobate crystals: Analytical calculations and their experimental verification

•Spatial anisotropy of the linear electro-optic effect in lithium niobate is reported.•Electro-optic anisotropy is studied by interferometric and polarimetric techniques.•Electro-optic measurements are supplied by relevant analytical calculations.•Validity of the analytical approaches is proved experimentally.

We demonstrate an experimental verification of analytical approaches used for evaluation of the spatial anisotropy of linear electro-optic effect in crystal materials. The electro-optic measurements have been performed on a series of crystal X/α-cuts (0° < α < 90°) of LiNbO3 crystals to get a cross section of the indicative surfaces. The experimental results are compared with analytical calculations. A fairly good agreement was found between the experiment and calculations for the effective electro-optic coefficients describing both electro-induced optical pathlength and birefringence. The discrepancy between experiment and theory remains within errors of the interferometric or polarization–optical measurements.