Enhancement of non-resonant dielectric cloaks using anisotropic composites

TL;DR

This paper demonstrates that using optimized anisotropic composites in non-resonant dielectric cloaking significantly improves electromagnetic invisibility performance with fewer layers, facilitating easier manufacturing.

Contribution

It introduces a numerical optimization method to design anisotropic composites for enhanced cloaking, reducing the number of layers needed compared to isotropic designs.

Findings

Improved cloaking performance by 2.8% and 25% with fewer layers.

Optimized microstructures are simple lamination of two materials.

Achieved ~50% reduction in scattering width in octagonal objects.

Abstract

Cloaking techniques conceal objects by controlling the flow of electromagnetic waves to minimize scattering. Herein, the effectiveness of homogenized anisotropic materials in non-resonant dielectric multilayer cloaking is studied. Because existing multilayer cloaking by isotropic materials can be regarded as homogenous anisotropic cloaking from a macroscopic view, anisotropic materials can be efficiently designed through optimization of their physical properties. Anisotropic properties can be realized in two-phase composites if the physical properties of the material are within appropriate bounds. The optimized anisotropic physical properties are identified by a numerical optimization technique based on a full-wave simulation using the finite element method. The cloaking performance measured by the total scattering width is improved by about 2.8% and 25% in eight- and three-layer cylindrical cloaking materials, respectively, compared with multilayer cloaking by isotropic materials. In all cloaking examples, the optimized microstructures of the two-phase composites are identified as the simple lamination of two materials, which maximizes the anisotropy. The same performance as published for eight-layer cloaking by isotropic materials is achieved by three-layer cloaking using the anisotropic material. Cloaking with an approximately 50% reduction of total scattering width is achieved even in an octagonal object. Since the cloaking effect can be realized using just a few layers of the laminated anisotropic dielectric composite, this may have an advantage in the mass production of cloaking devices.