Directional Dipole Dice Enabled by Anisotropic Chirality

TL;DR

This paper introduces a helix particle-based directional dipole dice that can switch among circular, Huygens, and Janus dipoles at the same frequency, enabling high-dimensional control of light directionality for advanced photonic applications.

Contribution

It presents the first unified realization of multiple directional dipoles in a single structure using chirality and anisotropy, with experimental validation.

Findings

Demonstrated all three dipoles in one structure at the same frequency.

Achieved face-multiplexed routing of guided waves in three orthogonal directions.

Enabled high-dimensional control of optical directionality.

Abstract

Directional radiation and scattering play an essential role in light manipulation for various applications in integrated nanophotonics, antenna and metasurface designs, quantum optics, etc. The most elemental system with this property is the class of directional dipoles, including the circular dipole, Huygens dipole, and Janus dipole. A unified realization of all three dipole types and a mechanism to freely switch among them are previously unreported, yet highly desirable for developing compact and multifunctional directional sources. Here, we theoretically and experimentally demonstrate that the synergy of chirality and anisotropy can give rise to all three directional dipoles in one structure at the same frequency under linearly polarized plane wave excitations. This mechanism enables a simple helix particle to serve as a directional dipole dice (DDD), achieving selective manipulation of optical directionality via different "faces" of the particle. We employ three "faces" of the DDD to realize face-multiplexed routing of guided waves in three orthogonal directions with the directionality determined by spin, power flow, and reactive power, respectively. This construction of the complete directionality space can enable the unprecedented high-dimensional control of both near-field and far-field directionality with broad applications in photonic integrated circuits, quantum information processing, and subwavelength-resolution imaging.