Propagation of light in the lithium niobate crystal along directions close to an optical axis

Theoretical and experimental results are given of studying some characteristics of electrooptical modulator from lithium niobate when propagating in it linear-polarized light in directions close to the optical axis, the electric field being applied along the X axis. It has been shown that an increase in an angle of deviation from the optical axis of a light beam passing in the crystal changes the value of the controlling voltage. This is accompanied by the rotation of the polarization plane and the change in the intensity of the light being passed. The methods have been proposed of increasing the modulator aperture, determining the main refraction indices and some electrooptical coefficients fo the lithium niobate crystal