Mechanical Evidence of the Orbital Angular Momentum to Energy Ratio of Vortex Beams

Christine E. M. Demore, Zhengyi Yang, Alexander Volovick, Sandy Cochran, Michael P. MacDonald, Gabriel C. Spalding

    Research output: Contribution to journalArticle

    89 Citations (Scopus)
    296 Downloads (Pure)

    Abstract

    We measure, in a single experiment, both the radiation pressure and the torque due to a wide variety of propagating acoustic vortex beams. The results validate, for the first time directly, the theoretically predicted ratio of the orbital angular momentum to linear momentum in a propagating beam. We experimentally determine this ratio using simultaneous measurements of both the levitation force and the torque on an acoustic absorber exerted by a broad range of helical ultrasonic beams produced by a 1000-element matrix transducer array. In general, beams with helical phase fronts have been shown to contain orbital angular momentum as the result of the azimuthal component of the Poynting vector around the propagation axis. Theory predicts that for both optical and acoustic helical beams the ratio of the angular momentum current of the beam to the power should be given by the ratio of the beam’s topological charge to its angular frequency. This direct experimental observation that the ratio of the torque to power does convincingly match the expected value (given by the topological charge to angular frequency ratio of the beam) is a fundamental result.

    © 2012 American Physical Society

    Original languageEnglish
    Article number194301
    Pages (from-to)-
    Number of pages5
    JournalPhysical Review Letters
    Volume108
    Issue number19
    Early online date8 May 2012
    DOIs
    Publication statusPublished - 2012

    Fingerprint

    angular momentum
    vortices
    orbitals
    torque
    energy
    acoustics
    levitation
    radiation pressure
    absorbers
    transducers
    ultrasonics
    momentum
    propagation
    matrices

    Cite this

    Demore, Christine E. M. ; Yang, Zhengyi ; Volovick, Alexander ; Cochran, Sandy ; MacDonald, Michael P. ; Spalding, Gabriel C. / Mechanical Evidence of the Orbital Angular Momentum to Energy Ratio of Vortex Beams. In: Physical Review Letters. 2012 ; Vol. 108, No. 19. pp. -.
    @article{44bd3cd0d08b4691b07ca945f21490f4,
    title = "Mechanical Evidence of the Orbital Angular Momentum to Energy Ratio of Vortex Beams",
    abstract = "We measure, in a single experiment, both the radiation pressure and the torque due to a wide variety of propagating acoustic vortex beams. The results validate, for the first time directly, the theoretically predicted ratio of the orbital angular momentum to linear momentum in a propagating beam. We experimentally determine this ratio using simultaneous measurements of both the levitation force and the torque on an acoustic absorber exerted by a broad range of helical ultrasonic beams produced by a 1000-element matrix transducer array. In general, beams with helical phase fronts have been shown to contain orbital angular momentum as the result of the azimuthal component of the Poynting vector around the propagation axis. Theory predicts that for both optical and acoustic helical beams the ratio of the angular momentum current of the beam to the power should be given by the ratio of the beam’s topological charge to its angular frequency. This direct experimental observation that the ratio of the torque to power does convincingly match the expected value (given by the topological charge to angular frequency ratio of the beam) is a fundamental result.{\circledC} 2012 American Physical Society",
    author = "Demore, {Christine E. M.} and Zhengyi Yang and Alexander Volovick and Sandy Cochran and MacDonald, {Michael P.} and Spalding, {Gabriel C.}",
    year = "2012",
    doi = "10.1103/PhysRevLett.108.194301",
    language = "English",
    volume = "108",
    pages = "--",
    journal = "Physical Review Letters",
    issn = "0031-9007",
    publisher = "American Physical Society",
    number = "19",

    }

    Mechanical Evidence of the Orbital Angular Momentum to Energy Ratio of Vortex Beams. / Demore, Christine E. M.; Yang, Zhengyi; Volovick, Alexander; Cochran, Sandy; MacDonald, Michael P.; Spalding, Gabriel C.

    In: Physical Review Letters, Vol. 108, No. 19, 194301, 2012, p. -.

    Research output: Contribution to journalArticle

    TY - JOUR

    T1 - Mechanical Evidence of the Orbital Angular Momentum to Energy Ratio of Vortex Beams

    AU - Demore, Christine E. M.

    AU - Yang, Zhengyi

    AU - Volovick, Alexander

    AU - Cochran, Sandy

    AU - MacDonald, Michael P.

    AU - Spalding, Gabriel C.

    PY - 2012

    Y1 - 2012

    N2 - We measure, in a single experiment, both the radiation pressure and the torque due to a wide variety of propagating acoustic vortex beams. The results validate, for the first time directly, the theoretically predicted ratio of the orbital angular momentum to linear momentum in a propagating beam. We experimentally determine this ratio using simultaneous measurements of both the levitation force and the torque on an acoustic absorber exerted by a broad range of helical ultrasonic beams produced by a 1000-element matrix transducer array. In general, beams with helical phase fronts have been shown to contain orbital angular momentum as the result of the azimuthal component of the Poynting vector around the propagation axis. Theory predicts that for both optical and acoustic helical beams the ratio of the angular momentum current of the beam to the power should be given by the ratio of the beam’s topological charge to its angular frequency. This direct experimental observation that the ratio of the torque to power does convincingly match the expected value (given by the topological charge to angular frequency ratio of the beam) is a fundamental result.© 2012 American Physical Society

    AB - We measure, in a single experiment, both the radiation pressure and the torque due to a wide variety of propagating acoustic vortex beams. The results validate, for the first time directly, the theoretically predicted ratio of the orbital angular momentum to linear momentum in a propagating beam. We experimentally determine this ratio using simultaneous measurements of both the levitation force and the torque on an acoustic absorber exerted by a broad range of helical ultrasonic beams produced by a 1000-element matrix transducer array. In general, beams with helical phase fronts have been shown to contain orbital angular momentum as the result of the azimuthal component of the Poynting vector around the propagation axis. Theory predicts that for both optical and acoustic helical beams the ratio of the angular momentum current of the beam to the power should be given by the ratio of the beam’s topological charge to its angular frequency. This direct experimental observation that the ratio of the torque to power does convincingly match the expected value (given by the topological charge to angular frequency ratio of the beam) is a fundamental result.© 2012 American Physical Society

    U2 - 10.1103/PhysRevLett.108.194301

    DO - 10.1103/PhysRevLett.108.194301

    M3 - Article

    C2 - 23003045

    VL - 108

    SP - -

    JO - Physical Review Letters

    JF - Physical Review Letters

    SN - 0031-9007

    IS - 19

    M1 - 194301

    ER -