Toggling Near-field Directionality via Polarization Control of Surface Waves

TL;DR

This paper demonstrates a method to actively control and toggle the near-field directionality of surface waves by adjusting polarization, enabling dynamic manipulation of light at the nanoscale.

Contribution

It introduces a novel scheme to actively switch near-field directionality using polarization control, including transforming dipoles and flipping Janus dipoles.

Findings

Surface wave polarization tuning can toggle near-field directionality.

The scheme can transform a circular dipole into a Huygens dipole.

Active flipping of Janus dipole coupling faces is achieved.

Abstract

Directional excitation of guidance modes is central to many applications ranging from light harvesting, optical information processing to quantum optical technology. Of paramount interest, especially, the active control of near-field directionality provides a new paradigm for the real-time on-chip manipulation of light. Here we find that for a given dipolar source, its near-field directionality can be toggled efficiently via tailoring the polarization of surface waves that are excited, for example, via tuning the chemical potential of graphene in a graphene-metasurface waveguide. This finding enables a feasible scheme for the active near-field directionality. Counterintuitively, we reveal that this scheme can transform a circular electric/magnetic dipole into a Huygens dipole in the near-field coupling. Moreover, for Janus dipoles, this scheme enables us to actively flip their near-field coupling and non-coupling faces.