Flat-face approximations of invisibility cloaks with planar metamaterial layers

TL;DR

This paper introduces a method to approximate transformation optics invisibility cloaks with flat-faced, layered metamaterials, simplifying fabrication while maintaining cloaking performance, demonstrated through a cylindrical cloak example.

Contribution

It presents a novel faceting approach for transformation optics structures, enabling easier fabrication of invisibility cloaks with arbitrary shapes using standard layered metamaterials.

Findings

The numerical method successfully designs cloaks with arbitrary boundaries.

The approximation reduces metamaterial complexity while preserving cloaking effectiveness.

Scattering cross section analysis quantifies the approximation's validity.

Abstract

Transformation optics (TO) is a powerful tool for the design of artiffcial materials with unprecedented optical properties. Here, we propose the approximation of TO structures of arbitrary shape by faceting, in which curved surfaces are approximated by at metamaterial layers that can be implemented by standard fabrication and stacking techniques. We illustrate the approximation approach for the specific example of a cylindrical invisibility cloak. First, we introduce a numerical method for the design of cloaks with arbitrary boundary shapes, and apply it to faceted shapes. Subsequently, we reduce the complexity of the metamaterials needed to implement the perfect faceted cloak by introducing several approximations, whose validity is quantified by an investigation of the scattering cross section.