Abstract

Singular light beams, that contain topological wave front dislocations, are ubiquitous entities that display fascinating properties with widespread important applications [1] Screw dislocations, or vortices, are a common dislocation type. They are spiral phase-ramps around a singularity where the phase of the wave is undefined and its amplitude vanishes Vortices appear spontaneously in several settings, including in speckle-fields, in optical cavities and in the doughnut laser modes, and otherwise they can be generated with phase masks, or with astigmatic optical components The order of the screw dislocation multiplied by its sign is referred to as the topological charge of the dislocation Vortices also form by self-wave front modulation in nonlinear optical media In this context, parametric mixing of multiple waves containing wave front dislocations in quadratic nonlinear media constitutes a fascinating scenario (see, e g., [2]).

© 2000 IEEE