Description of the morphology of optical vortices using the orbital angular momentum and its components

A description of the local properties of the transverse profile of a light beam near a screw dislocation of the wavefront (an optical vortex) based on the examination of a model beam obtained upon transmission of the original vortex beam through an imaginary infinitely small aperture with the center on the beam axis is proposed. Such an aperture should not violate the symmetry of the closest vicinity of the vortex and should have “soft” edges ensuring the complete applicability of the theory of paraxial beams. The geometric characteristics of the anisotropy of the optical vortex are connected with the orbital angular momentum of the model beam and, thus, with the physical characteristics of the transverse energy circulation near the axis of the vortex. Such an approach allows the establishment of an additional physical meaning of the parameters of the optical vortex and the orbital angular momentum. In particular, the “vortex” part of the angular momentum in the closest vicinity of the vortex turns out to be equivalent to the previously introduced anisotropy factor of the vortex.