Orbital angular momentum: origins, behavior and applications

TLDR

Light beams can carry angular momentum, either as spin from rotating polarization vectors or as orbital angular momentum (OAM) from rotating phase structure, which can be much larger than spin. In the past two decades, laboratory-generated OAM beams have been shown to spin microscopic particles, induce rotational frequency shifts, enable novel imaging modalities, and reveal new quantum‑optical effects in nonlinear media.

Abstract

As they travel through space, some light beams rotate. Such light beams have angular momentum. There are two particularly important ways in which a light beam can rotate: if every polarization vector rotates, the light has spin; if the phase structure rotates, the light has orbital angular momentum (OAM), which can be many times greater than the spin. Only in the past 20 years has it been realized that beams carrying OAM, which have an optical vortex along the axis, can be easily made in the laboratory. These light beams are able to spin microscopic objects, give rise to rotational frequency shifts, create new forms of imaging systems, and behave within nonlinear material to give new insights into quantum optics.