Anomalous optical forces on the anisotropic Rayleigh particles.

Abstract

We investigate the optical forces on the radially anisotropic spheres from an incident plane wave based on our generalized full-wave scattering theory and the Maxwell stress tensor integration techniques. We demonstrate that the optical force on the Rayleigh sphere with radial anisotropy does not always obey the well-known Rayleigh's law F~k04a(6) (where k(0) is the wave number and a is the radius of the sphere), but could be anomalous with the laws such as F~k00a(2), F~k0-2a(0), and F~k08a(10) under certain conditions. Therefore, the optical force on the anisotropic Rayleigh spheres is enhanced at the electric dipole resonance, and may be further increased by tuning the anisotropic parameters. On the contrary, the optical forces on the anisotropic spheres can be largely reduced for anisotropic spheres with electromagnetic transparency.