Periodic intensity change for laser mode beams propagating in anisotropic uniaxial crystals

We analytically and numerically shown that the nonparaxial mode laser beams propagating in an anisotropic medium are experiencing periodic variation of intensity due to interference between ordinary and extraordinary rays. In the case of propagation along the axis of the crystal oscillation period is inversely proportional to the square of the spatial frequency of the laser beam and the difference in the dielectric constants. The resulting dependence allows indirectly estimate the parameters of the crystal. When singular mode beams are propagating perpendicular to the axis of the crystal the intensity dependence on the angle of rotation around the axis of beam propagation is visually observed. Such a dependence for propagation along crystal axis is not available. This fact can serve as information about the orientation of the axis of the crystal.