Universal lateral optical force on an isotropic particle near a dielectric substrate via polarization-induced mirror...

Lateral optical forces (LOFs) provide a powerful degree of freedom for particle manipulation perpendicular to the optical axis, yet their implementation typically necessitates complex structured light, chiral media, or nanofabricated substrates. In this work, we establish a universal mechanism for generating robust, polarization-switchable LOFs on an isotropic spherical particle near a planar dielectric substrate using a single linearly polarized plane wave. A comprehensive multi-scale analysis, spanning the Rayleigh dipole, Mie scattering, and geometric optics regimes, reveals that the force originates fundamentally from the polarization-induced mirror symmetry breaking of the scattered field, mediated by the intrinsic interference between the incident wave and its substrate reflection. Our results demonstrate that the LOF follows a scale-invariant sin(2α) dependence on the polarization angle, enabling deterministic bidirectional switching and precise magnitude tuning across the Rayleigh, Mie, and geometric-optics regimes. Furthermore, the incident angle is identified as a decisive parameter for force modulation, with dramatic enhancement and directional reversals observed particularly under near-grazing incidence in the Mie and geometric-optics regimes. By eliminating the requirement for sophisticated beam shaping or material chirality, this work offers a simple and scalable paradigm for the manipulation of particles from nano- to micro-scales, bridging the gap between fundamental symmetry principles and versatile optical sorting applications.