Optical image of surface plasmon-polariton propagation through two plasmonic reduced visibility devices at 532 nm. The area inside the circle of radius r1 is cloaked, except for a very small fraction of plasmon rays, which propagate exactly through the centre of the cloak. The illumination direction is shown by the arrow. The inset demonstrates plasmon scattering by a typical concentric ring structure, which is not optimized for cloaking at 532 nm. The plasmons are strongly scattered by the edge of the structure and by the circular area in the middle.
Image Credit: Christopher Davis