Free-space information transfer using light beams carrying orbital angular momentum Gibson, Graham ; Courtial, Johannes ; Padgett, Miles J. ; Vasnetsov, Mikhail ; Pas'ko, Valeriy ; Barnett, Stephen M. ; Franke-Arnold, Sonja Abstract Publication: Optics Express Pub Date: November 2004 DOI: 10.1364/OPEX.12.005448 Bibcode: 2004OExpr..12.5448G