Nanostructured Hyperbolic Meta-Antennas Enable Arbitrary Control of Scattering vs Absorption

TL;DR

This paper demonstrates that hyperbolic meta-antennas can be engineered to selectively control scattering and absorption in the visible and near-infrared spectrum, enabling tailored optical responses for practical applications.

Contribution

It introduces a novel hyperbolic meta-antenna design that allows independent and arbitrary control of scattering and absorption by tuning plasmonic modes.

Findings

Pure scattering achieved with electric dipolar mode

Pure absorption achieved with magnetic dipolar mode

Tunable scattering and absorption by geometric modifications

Abstract

We show that meta-antennas made of a composite material displaying type II hyperbolic dispersion enable precise and controlled spectral separation of absorption and scattering processes in the visible/near-infrared frequency range. The experimental evidence is supported by a comprehensive theoretical study. We demonstrate that the physical mechanism responsible for the aforementioned effect lies in the different natures of the plasmonic modes excited within the hyperbolic meta-antennas. We prove that it is possible to have a pure scattering channel if an electric dipolar mode is induced, while a pure absorption process can be obtained if a magnetic dipole is excited. Also, by varying the geometry of the system, the relative weight of scattering and absorption can be tuned, thus enabling an arbitrary control of the decay channels. Importantly, both modes can be efficiently excited by direct coupling with the far-field radiation, even when the radiative channel (scattering) is almost totally suppressed, hence making the proposed architecture suitable for practical applications.