On the change in electromagnetic wave polarization in a smooth one-dimensionally inhomogeneous medium

Propagation of an electromagnetic wave in a smooth one-dimensionally inhomogeneous isotropic medium is considered in the second approximation of geometrical optics. The polarization evolution is studied extensively. It is known that in the first (Rytov) approximation of geometrical optics, there is only the rotation of the plane of polarization (with no change in the polarization shape and sign) for rays with torsion. In the case considered, both the shape of polarization ellipse and the sign of polarization change proportionally to the integral of the squared ray curvature even for plane rays. The effect is of nonlocal geometrical nature and can be described in terms of the generalized geometrical phase incursion between two linear polarizations.