Optical vortex

An optical vortex is a type of light field characterized by a helical or twisted wavefront. In such a field, the phase of the light wave wraps around in a spiral pattern, leading to a region of zero intensity at the center—this is typically referred to as a "phase singularity." Optical vortices are often associated with beams of light that carry orbital angular momentum (OAM), which means they can be described by a quantum mechanical analogue of angular momentum.