Experimental demonstration of a nonmagnetic metamaterial cloak at microwave frequencies

Metamaterials have paved the way to unprecedented control of the electromagnetic field. The conjunction with space coordinate transformation has led to a relativity inspired approach for the control of light propagation. Invisibility cloak is the most fascinating proposed device. However, the realized structures up to now used a graded metamagnetic so as to achieve the cloaking function. Artificial magnetism is still very challenging to obtain in optics despite the currently promising building blocks, not suited for optical cloaking. We report here the experimental demonstration of a nonmagnetic cloak at microwave frequencies by direct mapping of the magnetic field together with the experimental characterization of a cloak in free space configuration. The diameter of the concealed region is as big as 4.4 in wavelength units, the biggest reported experimentally so far. The principle can be scaled down to optical domain while keeping the compatibility with current nanofabrication technologies.