Non-paraxial beam to push and pull microparticles

Abstract

We discuss a feasibility of the pulling (backward) force acting on a spherical microparticle in a non-paraxial Bessel beam. The effect can be explained by the strong interaction of particle's multipoles or by the conservation of momentum in the system "photons-particle." It is remarkable that the puling force revealed does not require the beam focusing or high-index ambient medium. The necessary condition of arising of the backward force is the strong non-paraxiality of an electromagnetic beam. We expect this phenomenon will open new horizons in optical micromanipulation. © 2011 American Institute of Physics.