Lateral optical force on paired chiral nanoparticles in linearly polarized plane waves

Abstract

We demonstrate that a lateral optical force (LOF) can be induced on paired chiral nanoparticles with opposite handedness under the illumination of a linearly polarized plane wave. The LOFs on both chiral particles are equal and thus can move the pair sideways, with the direction depending on the separation between two particles, as well as the handedness of particle chirality. Analytical theory reveals that the LOF comes largely from the optical potential gradient established by the multiple scattering of light between the paired particles with asymmetric chirality. In addition, it is weakly dependent on the material loss of a particle, a feature of gradient force, while heavily dependent on the magnitude and handedness of particle chirality. The effect is expected to find applications in sorting and separating chiral dimers of different handedness.

Quantum formulation for nanoscale optical and material chirality: symmetry issues, space and time parity, and observables

“…One of the main or implicit motivations for several of the recent studies in this area is the prospect of achieving, by optical means, a separation of particles-especially chiral molecules-of opposite handedness [7,10,43,[98][99][100][101][102][103][104][105][106][107][108][133][134][135][136][137][138][139][140][141][142][143][144][145]. Certainly such a capacity might have important commercial applications-notably in the pharmaceutical industry, where oppositely handed compounds can deliver drastically different effects.…”

Quantum localization issues in nonlinear frequency conversion and harmonic generation

“…The leading terms in the multipolar expansion of H int are: (2) provides for calculations within the well-known electric-dipole approximation -a constraint adopted in the primary determination of non-local features in nonlinear optics. Higher order couplings become significant when studying chiral discriminatory effects in optical processes including forces [31][32][33] and non-linear optics. [34][35] A quantum field description that gives the correct results for condensed phase materials requires account to be taken of the modification of the fields experienced (and produced) by any specific optical centre(s), due to its surroundings by the other atoms and molecules in the material.…”

Precise Finite Difference Analysis of Lorentz Force Acting on Metal Nanoparticle Irradiated With Light

“…The Lorentz force is also crucial in fine manipulations of particles by light. Although light commonly pushes any object forward, but it is possible to induce backward and lateral forces under certain conditions of the light source and the medium of the particles [11][12][13].…”

“…Mie's theory gives us a rigorous solution when the particle is represented as spheres [13], but numerical simulations are needed to investigate the relation between the Lorentz force and aggregation for multiple particles of arbitrary sizes, shapes, materials, and locations. Several techniques have been reported to analyze electromagnetic fields and the Lorentz force under various geometric configurations in both the time and frequency domains.…”