Practical Cloaking Devices

Invisibility cloaks get a step closer to realization, with the demonstration of a new material that can bend (visible) light the 'wrong' way for the first time in three dimensions. In Nature this week, researchers report a metamaterial that produces negative refraction of visible light, and show that it can be can be easily probed from free space, paving the way for practical optical device applications. Metamaterials are artificially engineered structures that have properties, such as negative refractive index, not attainable with naturally occurring materials. Only thin, effectively two-dimensional materials have been demonstrated until now, limiting practical applications.Jason Valentine, Xiang Zhang and colleagues at the University of California, Berkeley create a multilayered, ‘fishnet’ structure which unambiguously exhibits negative refractive index. (PhysOrg.com)



Shown is a schematic and two scanning electron microscope images with top and side views of a metamaterial developed by UC Berkeley researchers. The material is composed of parallel nanowires embedded inside porous aluminum oxide. As visible light passes through the material, it is bent backwards in a phenomenon known as negative refraction.