title: Direct observation of the transfer of orbital angular momentum to metal particles from a focused circularly polarized Gaussian beam.
abstract: It is well known that a circularly polarized Gaussian beam carries spin angular momentum, but not orbital angular momentum. This paper demonstrates that focusing a beam carrying spin angular momentum can induce an orbital angular momentum which we used to drive the orbital motion of a micron-sized metal particle that is trapped off the beam axis. The direction of the orbital motion is controlled by the handedness of the circular polarization. The orbiting dynamics of the trapped particle, which acted as an optical micro-detector, were quantitatively measured and found to be in excellent agreement with the theoretical predictions.
authors.affiliation: Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 947202, USA. yiqiong.zhao@notes.udayton.edu
authors.forename: Yiqiong
authors.initials: Y
authors.lastname: Zhao
authors.forename: David
authors.initials: D
authors.lastname: Shapiro
authors.forename: David
authors.initials: D
authors.lastname: McGloin
authors.forename: Daniel T
authors.initials: DT
authors.lastname: Chiu
authors.forename: Stefano
authors.initials: S
authors.lastname: Marchesini
mesh_terms: D004735:Energy Transfer; D008027:Light; D008670:Metals / Q000737:chemistry*; D016011:Normal Distribution; D052898:Optical Tweezers; D012031:Refractometry / Q000379:methods*; D012542:Scattering, Radiation
chemical_list: D008670:Metals