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 <i>spin</i>; if the phase structure rotates, the light has <i>orbital angular momentum</i> (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.
© 2011 OSA
Original Manuscript: October 8, 2010
Revised Manuscript: January 5, 2011
Manuscript Accepted: January 5, 2011
Published: May 15, 2011
(2011) Advances in Optics and Photonics
Alison M. Yao and Miles J. Padgett, "Orbital angular momentum: origins, behavior and applications," Adv. Opt. Photon. 3, 161-204 (2011)