title: Ultrathin plasmonic chiral phase plate.
abstract: A thin free-standing gold membrane with complex plasmonic structures engraved on both sides is shown to perform as an ultrathin phase plate. Specifically, we demonstrate the generation of a far-field vortex beam propagating at a desired angle. The angular momentum of the beam is generated by the groove helicity, together with the geometric phase arising from a plasmonic spin-orbit interaction. The radial chirp of the back-side structure is used to modify the emission angle via a specific momentum matching condition.
authors.forename: Yuri
authors.initials: Y
authors.lastname: Gorodetski
authors.forename: Cyriaque
authors.initials: C
authors.lastname: Genet
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Ebbesen