Optical whirlpool near absorbing metallic nanoparticle

TL;DR

This paper investigates nanoscale optical vortices formed by light interacting with metallic nanoparticles near plasmon resonance, revealing two types of vortices with distinct behaviors depending on wavelength.

Contribution

It identifies and characterizes two different vortex types in the power-flow lines around metallic nanoparticles near plasmon resonance, enhancing understanding of nanoscale light behavior.

Findings

Outward vortices occur at wavelengths shorter than the plasmon resonance.

Inward vortices occur at wavelengths longer than the plasmon resonance.

Vortex behavior depends on the wavelength relative to the resonance.

Abstract

The power-flow lines of light interacting with a metallic nanoparticle, in the proximity of its plasmon resonance, form whirlpool-like nanoscale optical vortices. Two different types of vortex have been detected. The outward vortex first penetrates the particle near its centerline then, on exiting the particle, the flow-lines turn away from the centerline and enter a spiral trajectory. Outward vortexes are seen for the wavelengths shorter then the plasmon resonance. For the wavelengths longer that the plasmon resonance the vortex is inward: the power-flow lines pass around the sides of the particle before turning towards the centerline and entering the particle to begin their spiral trajectory.