Strong collective currents of gold nanoparticles in an optical vortex lattice

TL;DR

This paper demonstrates how gold nanoparticles in an optical vortex lattice exhibit collective, synchronized motion resulting in strong unidirectional currents, driven by optical forces and hydrodynamic interactions, with potential for nanoscale control.

Contribution

It provides a detailed analysis of the collective optofluidic dynamics of gold nanoparticles under optical vortex lattices, revealing a critical transition to synchronized currents at certain intensities and concentrations.

Findings

Nanoparticles reach speeds of centimeters per second.

Synchronization occurs above a critical optical field and concentration.

Strong unidirectional currents are generated along lattice diagonals.

Abstract

Self-organized collective behaviour of active units is inspiring new designs of artificial swarms of micron-sized objects. However, active control at the nanoscale remains elusive. We have accurately solved the collective optofluidic dynamics of gold plasmonic 50 nm-radius nanoparticles moving in aqueous solution under a nonconservative optical vortex lattice. Above a critical field intensity and concentration, the interplay between optical forces, thermal fluctuations and hydrodynamic pairing leads to a spontaneous transition towards synchronised motion exhibiting a rich assortment of collective dynamics. The critical phenomenon creates strong unidirectional currents of nanoparticles, reaching speeds of centimeters per second along the diagonals of the lattice.