Abstract

Various unexplained experimental observations suggest that the physics of light forces in two or three dimensions gives rise to phenomena which cannot be accounted for in a one-dimensional model. We report on the first observation of microscopic radiation pressure vortices (RPV). RPV’s occur in any 2D and 3D configuration produced by intersecting one-dimensional standing waves which provide interfering polarization components (e. g. the σ+σ– polarization scheme used in optical molasses and magneto-optical traps). To study a particulary simple example of RPV’s, we have investigated the kinematics of rubidium atoms in a two-dimensional light field produced by crossing two mutually orthogonal optical standing waves. When the two standing waves oscillate synchronously the resulting light field and the corresponding light forces posses a 90° rotation symmetry. However, when the standing waves oscillate with different phases, a two-dimensional cubic array of radiation vortices with a periodicity of half an optical wave length arises which can be identified by the breaking of this symmetry.

© 1992 IQEC