Optical Angular Momentum

Abstract That light may possess optical angular momentum is a fact that has been known and exploited for over a hundred years. At first, it was entirely associated with the spin angular momentum of light, through light's polarization. More recently, the orbital angular momentum of light has been studied and exploited for a plethora of applications. This component is associated with the spatial profile of the field. This article outlines the basic concepts of spin and orbital angular momentum, their connectedness through vector beams, and Poincaré sphere representations of optical angular momentum carrying fields and reviews the present state of the field and its many opportunities for advancement.