title: Intrinsic orbital angular momentum of paraxial beams with off-axis imprinted vortices.
abstract: We investigate the orbital angular momentum (OAM) of paraxial beams containing off-axis phase dislocations and put forward a simple method to calculate the intrinsic orbital angular momentum of an arbitrary paraxial beam. Using this approach we find that the intrinsic OAM of a fundamental Gaussian beam with a vortex imprinted off axis has a Gaussian dependence on the vortex displacement, implying that the expectation value of the intrinsic OAM of a photon can take on a continuous range of values (i.e., integer and noninteger values in units of h). Finally, we investigate, both numerically and experimentally, the far-field profiles of beams carrying half-integer OAM per photon, these beams having been created by the method of imprinting off-axis vortices.
authors.affiliation: Huygens Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands. soemraws@molphys.leidenuniv.nl
authors.forename: S S R
authors.initials: SS
authors.lastname: Oemrawsingh
authors.forename: E R
authors.initials: ER
authors.lastname: Eliel
authors.forename: G
authors.initials: G
authors.lastname: Nienhuis
authors.forename: J P
authors.initials: JP
authors.lastname: Woerdman