Observation of an optical 'angular tractor' effect in a Bessel beam

We study an optical “angular tractor” effect, at which the energy flow in the cross-section of a rotationally symmetric vortex laser beam with the positive/negative topological charge and left-/right-handed circular polarization rotates in different directions (clockwise and counterclockwise) at different distances from the beam center. This effect is shown to take place both for paraxial vortex beams and in the focus of an aplanatic system focusing a nonparaxial optical vortex. Dielectric microparticles placed in a third-order circularly polarized Bessel beam are experimentally demonstrated to move in the opposite directions (clockwise and counterclockwise).