Optical forces in nanowire pairs and metamaterials

TL;DR

This paper investigates optical forces in gold nanowire pairs and metamaterials, revealing stronger forces than nanospheres and how structural parameters influence attractive or repulsive forces.

Contribution

It provides new insights into how nanowire geometry and array configuration affect optical forces and their physical mechanisms.

Findings

Nanowire pairs experience stronger optical forces than nanospheres.

The force's nature (attractive or repulsive) depends on the unit cell size relative to nanowire length.

The physical mechanism behind force direction is elucidated.

Abstract

We study the optical force arising when isolated gold nanowire pairs and metamaterials with a gold nanowire pair in the unit cell are illuminated with laser radiation. Firstly, we show that isolated nanowire pairs are subject to much stronger optical forces than nanospheres due to their stronger electric and magnetic dipole resonances. We also investigate the properties of the optical force as a function of the length of the nanowires and of the distance between the nanowires. Secondly, we study the optical force in a metamaterial that consists of a periodic array of nanowire pairs. We show that the ratio of the size of the unit cell to the length of the nanowires determines whether the electric dipole resonance leads to an attractive or a repulsive force, and we present the underlying physical mechanism for this effect.