On the transfer of optical orbital angular momentum to matter

Abstract

The prevailing notion is that the orbital angular momentum (OAM) of an optical vortex can only be transferred to the internal degrees of freedom (i.e. electronic motion) of materials through electric quadrupole and higher-order multipole interactions. Here it is highlighted how this is an artefact of the paraxial approximation and that optical OAM can be transferred to electronic motion via dipole transitions under the correct experimental conditions where non-paraxial, longitudinal fields must be accounted for.