Negative Forces for a Dimer of Identical Nanoparticles

In this work, the optical forces acting on a dimer composed of nanoparticles are considered. The calculation of optical forces (Lorentz forces) is carried out on the basis of electromagnetic fields obtained as a result of solving a self-consistent system of field equations. An analytical formula is derived showing the dependence of the optical force acting on the dimer on the parameters of the dimer system and a structured wave composed of two crossing plane waves. It is shown for the first time that a dimer of identical dipole particles in a structured optical field can be subject to a pulling force towards the source, the so-called “negative radiation pressure”. The corresponding scattering diagram of the dimer system shows enhanced forward scattering, which confirms the indicated mechanism for the generation of attractive forces. The results of the study will be useful for expanding the possibilities of optical manipulation of nano- and micro-particles. #CSOC1120