Plasmon Coupling Induced Photon Scattering Torque

TL;DR

This paper theoretically demonstrates how coupled gold nanoparticles can generate optical scattering torques driven by circularly polarized light, enabling potential biomedical nanomotors without heating effects.

Contribution

It introduces a theoretical model showing plasmon coupling enhances optical torque transfer in nanoparticle structures for biomedical nanomotor applications.

Findings

Angular momentum transfer efficiencies can reach around 200%.

Optical torques depend strongly on plasmon coupling.

Coupled plasmonic oligomers are promising for nanomotor design.

Abstract

Bio-compatible Au nanoparticles exhibit great advantages in the application of biomedical researches, such as bio-sensing, medical diagnosis, and cancer therapy. Bio-molecules can even be manipulated by laser tweezers with the optically trapped Au nanoparticles as handles. In this Letter, optical scattering torque arising from the coupled Au nanoparticles driven by circularly polarized light is theoretically presented. The coupled plasmon resonance modes boost the angular momentum transfer from photons to the Au nanoparticle dimers and trimers through light scattering, which does not bring any optical-heating side effect. The generated optical torques on the nanostructures highly depend on the plasmon coupling in the structures. The angular momentum transfer efficiencies from scattered photons to nanostructures can reach around 200\%. The results suggest that coupled plasmonic nanoparticle oligomers are promising candidates to construct optically driven rotary nanomotors that can be applied in biomedical applications.