title: Efficient generation and control of different-order orbital angular momentum states for communication links.
abstract: We present an optical scheme to encode and decode 2 bits of information into different orbital angular momentum (OAM) states of a paraxial optical beam. Our device generates the four light angular momentum states of order ±2 and ±4 by spin-to-orbital angular momentum conversion in a triangular optical loop arrangement. The switching among the four OAM states is obtained by changing the polarization state of the circulating beam by two quarter-wave plates, and the 2 bit information is transferred to the beam OAM exploiting a single q plate. The polarization of the exit beam is left free for an additional 1 bit of information. The switching among the different OAM states can be as fast as a few nanoseconds, if suitable electro-optical cells are used. This may be particularly useful in communication systems based on light OAM.
authors.affiliation: Dipartimento di Scienze Fisiche, Università di Napoli Federico II, Complesso Universitario di Monte S. Angelo, 80126 Napoli, Italy.
authors.forename: Sergei
authors.initials: S
authors.lastname: Slussarenko
authors.forename: Ebrahim
authors.initials: E
authors.lastname: Karimi
authors.forename: Bruno
authors.initials: B
authors.lastname: Piccirillo
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Marrucci
authors.forename: Enrico
authors.initials: E
authors.lastname: Santamato