title: Observation of the orbital angular momentum spectrum of a light beam.
abstract: We demonstrate an experimental scheme that allows the elucidation of the orbital angular momentum discrete spectrum of an arbitrary light signal. The orbital angular momentum spectrum is represented in a Laguerre-Gaussian mode base, and the spectral components are resolved in the frequency domain by exploiting the Doppler frequency shift that is imparted to rotating light beams.
authors.affiliation: ICFO-Institut de Ciencies Fotoniques, Department of Signal Theory and Communications, Universitat Politecnica de Catalunya, 08034 Barcelona, Spain. vasnet@hotmail.com
authors.forename: M V
authors.initials: MV
authors.lastname: Vasnetsov
authors.forename: J P
authors.initials: JP
authors.lastname: Torres
authors.forename: D V
authors.initials: DV
authors.lastname: Petrov
authors.forename: Lluis
authors.initials: L
authors.lastname: Torner