Superfast and sub-wavelength orbital rotation of plasmonic particles in focused Gaussian beams

TL;DR

This paper demonstrates that plasmonic particles can be optically manipulated to achieve superfast, sub-wavelength orbital rotation using focused Gaussian beams, with potential applications in nanomachines and biological research.

Contribution

It introduces a method for inducing superfast, tunable orbital rotation of plasmonic particles in focused Gaussian beams, advancing optical manipulation techniques at the nanoscale.

Findings

Achieved superfast rotation speeds (>10^4 r/s) in water.

Controlled off-axis trapping at sub-wavelength scales.

Proposed applications in nanomachines and biological research.

Abstract

The use of nanophotonics for optical manipulation has continuously attracted interest in both fundamental research and practical applications, due to its significantly enhanced capabilities at the nanoscale. In this work, we showed that plasmonic particles can be trapped at off-axis location in Gaussian beams assisted by surface plasmon resonance. The off-axis displacement can be tuned at the sub-wavelength scale by the incident light beams. Based on these, we propose that a superfast orbital rotation of particles in continuous-wave laser beam can be realized in tightly focused circularly polarized Gaussian beams. The rotation has a tunable orbital radius at the sub-wavelength scale and a superfast rotation speed (more than 10^4 r/s in water under common laboratory conditions). Our work will aid in the development of optically driven nanomachines, and find applications in micro/nano-rheology, micro-fluid mechanics, and biological research at the nanoscale.