title: Mechanical Faraday effect for orbital angular momentum-carrying beams.
abstract: When linearly polarised light is transmitted through a spinning window, the plane of polarisation is rotated. This rotation arises through a phase change that is applied to the circularly polarised states corresponding to the spin angular momentum (SAM). Here we show an analogous effect for the orbital angular momentum (OAM), where a differential phase between the positive and negative modes (±ℓ) is observed as a rotation of the transmitted image. For normal materials, this rotation is on the order of a micro radian, but by using a slow-light medium, we show a rotation of a few degrees. We also note that, within the bounds of our experimental parameters, this rotation angle does not exceed the scale of the spatial features in the beam profile.
authors.forename: Emma
authors.initials: E
authors.lastname: Wisniewski-Barker
authors.forename: Graham M
authors.initials: GM
authors.lastname: Gibson
authors.forename: Sonja
authors.initials: S
authors.lastname: Franke-Arnold
authors.forename: Robert W
authors.initials: RW
authors.lastname: Boyd
authors.forename: Miles J
authors.initials: MJ
authors.lastname: Padgett