An ultra-broadband electromagnetically indefinite medium formed by aligned carbon nanotubes

TL;DR

This paper demonstrates that aligned carbon nanotube arrays can act as low-loss, ultra-broadband indefinite media in the infrared, supporting backward waves with potential applications in subwavelength imaging and enhanced radiation.

Contribution

It introduces a novel low-loss indefinite medium using periodic CNT arrays that operate effectively over a broad infrared spectrum.

Findings

Supports backward wave propagation with small attenuation

Operates as a low-loss indefinite medium in the infrared range

Enables potential applications in subwavelength focusing

Abstract

Anisotropic materials with different signs of components of the permittivity tensor are called indefinite materials. Known realizations of indefinite media suffer of high absorption losses. We show that periodic arrays of parallel carbon nanotubes (CNTs) can behave as a low-loss indefinite medium in the infrared range. We show that a finite-thickness slab of CNTs supports the propagation of backward waves with small attenuation in an ultra-broad frequency band. In prospective, CNT arrays can be used for subwavelength focusing and detection, enhancing the radiation efficiency of small sources.