  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.
