Transfer of Orbital Angular Momentum from an Optical Vortex Beam to a Nanoparticle

Orbital angular momentum has been transferred to optically confined particles from light fields possessing an optical vortex. These experiments have to date been restricted to microparticles in the Mie or Lorentz-Mie regime, that where the particle is comparable to or larger than the wavelength of the trapping light. We demonstrate the first conclusive experimental transfer of orbital angular momentum to metallic nanoparticles in an optical trap created by a vortex light field: the trapping geometry utilizes a blue-detuned laser and confines the particles to the dark region of the vortex beam.