Isotropic Huygens dipoles and multipoles with colloidal particles

TL;DR

This paper introduces isotropic meta-atoms made of colloidal particles that act as efficient Huygens sources, enabling broadband forward scattering at optical frequencies for applications in nanoantennas, metamaterials, and sensing.

Contribution

It proposes a novel design of isotropic meta-atoms using colloidal particle clusters that achieve high-scattering Huygens dipoles at visible frequencies, surpassing previous simple spherical particles.

Findings

Achieved scattering cross-sections up to 5 times the particle size.

Predicted broadband forward scattering over 1000 nm wavelength range.

Demonstrated potential applications in nanoantennas and bio-sensing.

Abstract

Huygens sources are elements that scatter light in the forward direction as used in the Huygens-Fresnel principle. They have remained fictitious until recently where experimental systems have been fabricated. In this letter, we propose isotropic meta-atoms that act as Huygens sources. Using clusters of plasmonic or dielectric colloidal particles, Huygens dipoles that resonate at visible frequencies can be achieved with scattering cross-sections as high as 5 times the geometric cross-section of the particle surpassing anything achievable with a hypothetical simple spherical particle. Examples are given that predict extremely broadband scattering in the forward direction over a 1000 nm wavelength range at optical frequencies. These systems are important to the fields of nanoantennas, metamaterials and wave physics in general as well as any application that requires local control over the radiation properties of a system as in solar cells or bio-sensing.