Optical vortex

Diagram of different modes, four of which are optical vortices. Columns show the helical structures, phase-front and intensity of the beams

An optical vortex (also known as a photonic quantum vortex, screw dislocation or phase singularity) is a zero of an optical field; a point of zero intensity. The term is also used to describe a beam of light that has such a zero in it. The study of these phenomena is known as singular optics.