The formation of optical vortices in the course of light diffraction on a dielectric wedge

It is theoretically and experimentally demonstrated that diffraction of a fundamental Gaussian beam at the edge of a dielectric wedge leads to the formation of a chain of optical vortices in the far wave zone. The conditions of phase synchronism are established under which a single optical vortex possessing the ideal shape is generated. A special mathematical approach is developed for description of the character of vortex distortion, which is analogous to the Jones column vector formalism used to describe the polarization of light. It is found that the plots of the degree of vortex ellipticity versus wedge angle and Gaussian beam waist radius exhibit pronounced peaks corresponding to the phase synchronism. The experimental and theoretical results are compared. The experimentally observed vortex ellipticity Q=0.93 at a diffraction efficiency of 0.98 is evidence that the proposed method has good prospects for implementation in real fiber-optic sensors of physical parameters employing optical vortices.