Orbital motion of gold heterodimer driven by optical force of circularly polarized light and reactive drag of medium
Journal
Journal of Mechanics
Journal Volume
40
Start Page
545
End Page
551
ISSN
1811-8216
Date Issued
2024
Author(s)
DOI
10.1093/jom/ufae040
Abstract
This theoretical study explores the two-dimensional orbital motion of an optically bound heterodimer consisting of two gold nanoparticles (NPs) of different sizes, driven by circularly polarized (CP) light. Although a CP light possesses only spin angular momentum without orbital angular momentum, it can still induce orbital revolution in the plasmonic heterodimer. This phenomenon arises from the interaction between the optical force and torque generated by the CP light and the reactive drag force and torque from the surrounding medium. We calculate the optical forces acting on each NP by analyzing the Maxwell stress tensor at their surfaces, and we account for the reactive drag force using Stokes’ law. These forces are used to simulate the trajectories of the NPs through dynamic equations of motion. Our results demonstrate that, regardless of the initial conditions of the two NPs, they will become optically bound together, exhibiting rigid-body translation and rotation. Notably, the center of mass of the heterodimer undergoes an orbital revolution around a fixed point eventually. The CP light-manipulated heterodimer behaves like a boomerang, acting as a spinning rotor on a circular path. The heterodimer’s orbital radius and direction of revolution are influenced by the size disparity between the two NPs. Additionally, each NP experiences spin motion, with the spin direction determined by the handedness of the CP light. The optically bound gold heterodimer functions as a light-driven microrotor, with potential applications in microfluidic channels. These findings offer valuable insights into the optomechanical manipulation of non-monodisperse NP clusters using CP light.
Subjects
circularly polarized light
dynamic equation of motion
gold heterodimer
Maxwell’s stress tensor
optical force
optical torque
photophoresis
plasmon
reactive drag force
spin angular momentum
Stokes’ law
Publisher
Oxford University Press (OUP)
Type
journal article