Plasmonics with a Twist: Taming Optical Tornadoes on the Nanoscale

TL;DR

This paper introduces a hydrodynamics-inspired method to control light at the nanoscale using plasmonic nanostructures, enabling high field intensities, vortex formation, and improved energy manipulation beyond diffraction limits.

Contribution

It presents a novel approach based on photon fluid dynamics to trap and mold light into vortices, enhancing nanoscale optical manipulation and energy transfer capabilities.

Findings

Localized high field intensities achieved

Optical vortices can be formed and controlled

Enhanced energy storage and magnetic response at the nanoscale

Abstract

This chapter discusses a hydrodynamics-inspired approach to trap and manipulate light in plasmonic nanostructures, which is based on steering optical powerflow around nano-obstacles. New insights into plasmonic nanofocusing mechanisms are obtained by invoking an analogy of the 'photon fluid' (PF). By proper nanostructure design, PF kinetic energy can be locally increased via convective acceleration and then converted into 'pressure' energy to generate localized areas of high field intensity. In particular, trapped light can be molded into optical vortices -tornado-like areas of circular motion of power flux - connected into transmission-like sequences. In the electromagnetic theory terms, this approach is based on radiationless electromagnetic interference of evanescent fields rather than on interference of propagating waves radiated by the dipoles induced in nanoparticles. The resulting ability to manipulate optical powerflow well beyond the diffraction limit helps to reduce dissipative losses, to increase the amount of energy accumulated within a nanoscale volume, and to activate magnetic response in non-magnetic nanostructures. It also forms a basis for long-range on-chip energy transfer/routing as well as for active nanoscale field modulation and switching.