  In this manuscript, we demonstrate the design and experimental proof of an
optical cloaking structure which multi-directionally conceals a perfectly
electric conductor (PEC) object from an incident plane wave. The dielectric
modulation around the highly reflective scattering PEC object is determined by
an optimization process for multi-directional cloaking purposes. And to obtain
the multi-directional effect of the cloaking structure, an optimized slice is
mirror symmetrized through a radial perimeter. Three-dimensional (3D)
finite-difference time-domain method is integrated with genetic optimization to
achieve cloaking design. In order to overcome the technological problems of the
corresponding devices in the optical range and to experimentally demonstrate
the proposed concept, our experiments were carried out on a scale model in the
microwave range. The scaled proof-of-concept of proposed structure is
fabricated by 3D printing of polylactide material, and the brass metallic alloy
is used as a perfect electrical conductor for microwave experiments. A good
agreement between numerical and experimental results is achieved. The proposed
design approach is not restricted only to multi-directional optical cloaking
but can also be applied for different cloaking scenarios dealing with
electromagnetic waves in nanoscales as well as other types of such as acoustic
waves. Using nanotechnology, our scale proof-of-concept research will take the
next step towards the creation of "optical cloaking" devices.
