Optical force on toroidal nanostructures: toroidal dipole versus renormalized electric dipole

Abstract

We study the optical forces acting on toroidal nanostructures. A great enhancement of optical force is unambiguously identified as originating from the toroidal dipole resonance based on the source-representation, where the distribution of the induced charges and currents is characterized by the three families of electric, magnetic, and toroidal multipoles. On the other hand, the resonant optical force can also be completely attributed to an electric dipole resonance in the alternative field-representation, where the electromagnetic fields in the source-free region are expressed by two sets of electric and magnetic multipole fields based on symmetry. The confusion is resolved by conceptually introducing the irreducible electric dipole, toroidal dipole, and renormalized electric dipole. We demonstrate that the optical force is a powerful tool to identify toroidal response even when its scattering intensity is dwarfed by the conventional electric and magnetic multipoles.

25 pages, 7 figures

References in corpus (5)

• Backward Pulling Force from a Forward Propagating Beam
• Lateral Optical Force On Chiral Particles Near a Surface
• Dielectric Metamaterials with Toroidal Dipolar Response
• Toroidal metamaterial
• Sizable electromagnetic forces in parallel-plate metallic cavity

Cited by in corpus (11)

• An electromagnetic multipole expansion beyond the long-wavelength approximation
• Nonradiating anapole states in nanophotonics: from fundamentals to applications
• On the dynamic toroidal multipoles from localized electric current distributions
• A Generic Minimal Discrete Model for Toroidal Moments and Its Experimental Realization
• Multipolar expansions for scattering and optical force calculations beyond the long wavelength approximation
• Optical Forces in Coupled Chiral Particles
• Tuning toroidal dipole resonances in dielectric metamolecules by an additional electric dipolar response
• Chiral discrimination by polarization singularities of a metal sphere
• Electric and magnetic toroidal dipole excitations in core-shell spheres
• Anapole mode excitation in novel perforated all-dielectric metamaterials
• Gain-controlled directional scattering in core-shell nanoparticles mediated by magnetic toroidal dipoles