Anomalous optical gradient force induced by polarization-tuned antisymmetry in energy density gradient.

ABSTRACT: The spatial inhomogeneity of electromagnetic energy density in an optical field typically gives rise to conservative gradient forces, which serve as the fundamental mechanism for trapping nanoparticles in optical tweezers. Surprisingly, however, we demonstrate that even in the absence of an energy density gradient, optical gradient forces can still act on isotropic, achiral particles when the incident field consists of counter-propagating plane waves engineered to exhibit polarization-controlled antisymmetry between the electric and magnetic energy density gradients. Through both numerical simulations and analytical derivations based on multipole expansion theory, we show that this anomalous gradient force arises from the electromagnetic symmetry breaking induced by the particle itself, ir

SUBMITTER: Feng L 

PROVIDER: S-EPMC12455292 | biostudies-literature | 2025 Sep

REPOSITORIES: biostudies-literature