Wave and ray spatial dynamics of the light field in the generation, evolution, and annihilation of phase dislocations

The spatial dynamics of the light field during the generation, evolution, and annihilation of screw phase dislocations in Gaussian optical beams is analyzed. The regularities of transformation of an aberration wave front of a beam into a singular front are exposed. The structure of the field of directions of the energy-flux density vector is analyzed on the basis of a solution of a parabolic wave equation for the complex amplitude of a monochromatic light field with the construction of streamlines and investigation of the full set of critical points in the corresponding dynamic system. It is established that the energy redistribution in the beam and appearance of dislocations occur in accordance with the transformation of singularities: local focusing of a streamline in the vicinity of a node is a precursor of a generated pair of screw dislocations, and the streamline takes on a helix shape near an unstable focus. (C) 2002 MAIK "Nauka/Interperiodica".