Designing rotational motion of charges on plasmonic nanostructures excited by circularly polarized light

TL;DR

This paper demonstrates that circularly polarized light can induce complex rotational charge motions in plasmonic nanostructures, with potential for controlled angular momentum transfer at the nanoscale.

Contribution

It introduces a method to excite and manipulate rotational charge motions in various plasmonic structures using homogeneous circularly polarized light, expanding control capabilities.

Findings

Circularly polarized light can excite rotational charge motions in nanostructures.

Selective excitation of charge rotation is demonstrated in both isolated and array structures.

Complex charge rotations can be controlled by plane CP waves across different structures.

Abstract

Rotational motion of charges in plasmonic nanostructures plays an important role in transferring angular momentum between light and matter on the nanometer scale. Although sophisticated control of rotational charge motion has been achieved using spatially structured light, its extension to simultaneous excitation of the same charge motion in multiple nanostructures is not straightforward. In this study, we perform model calculations to show that spatially homogeneous circularly polarized (CP) light can excite rotational charge motions with a high degrees of freedom by exploiting the rotational symmetry of the plasmonic structure and that of the plasmon mode. Finite-difference time-domain simulations demonstrate selective excitation of rotational charge motion for both isolated nanoplates and periodic array structures, showing that complex charge rotations can be manipulated by plane CP waves in a wide range of plasmonic structures.