Lateral optical force on linearly polarized dipoles near a magneto-optical surface based on polarization conversion

Abstract

Novel lateral optical forces acting on dipoles near surfaces have been investigated in the past few years: circularly polarized dipoles experience lateral optical forces when in proximity to a surface due to the recoil of directionally excited modes. Recent work shows that even linearly polarized dipoles may experience lateral forces when nonreciprocal substrates are used, due to the asymmetric propagation of modes in the surface. We theoretically show that a linearly polarized particle emitting in close proximity to a magneto-optical substrate may experience a lateral optical force even if the external magnetic field is normal to the surface plane. The polarization conversion of the magneto-optic material introduces a gradient in the quasistatic fields reflected from the surface, resulting in a lateral optical force, and also gives surface plasmons a hybrid polarization character, which alters the surface plasmon directional excitation from the dipole, resulting in an optical recoil force. We envisage potential applications in nanomechanical devices, since similar magnetoplasmonic architectures have already been developed experimentally.