title: Observation of orbital angular momentum sidebands due to optical reflection.
abstract: We investigate how the orbital angular momentum of a paraxial light beam is affected upon reflection at a planar interface. Theoretically, the unavoidable angular spread of the beam leads to orbital angular momentum sidebands, which are found to be already significant for a modest beam spread (0.05). In analogy to the polarization Fresnel coefficients, we develop an analytical theory based upon spatial Fresnel coefficients; this allows a straightforward prediction of the strength of the sidebands. We confirm this by experiment and numerical simulation.
authors.affiliation: Huygens Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, Netherlands.
authors.forename: W
authors.initials: W
authors.lastname: Löffler
authors.forename: Andrea
authors.initials: A
authors.lastname: Aiello
authors.forename: J P
authors.initials: JP
authors.lastname: Woerdman