Now you see it, now you don’t: invisibility cloak nears reality

The microscopic material, developed by a team of scientists at the University of California (UC) Berkeley and the U.S. Department of Energy’s (DoE) Berkeley National Laboratory, is made from an ultra-thin 80 nanometre layer of gold rectangular nanoantennae from which the light is reflected. In contrast, the new cloak changes light waves bouncing off an object on a surface to erase the distortions the object would otherwise imprint on the waves, effectively hiding the thing from view.

“This is the first time a 3D object of arbitrary shape has been cloaked from visible light”, said Xiang Zhang, director of Berkeley Lab’s Materials Sciences Division and a world authority on metamaterials – artificial nanostructures engineered with electromagnetic properties not found in nature.

A tiny invisibility cloak has been invented by United States scientists who are edging ever-closer to a real version of what has until now been a staple of science fiction, researchers said Thursday.

The technology, described in the journal Science, holds promise for applications such as high resolution microscopes, super-fast optical computers, and 3D displays. As well, Ni and his colleagues claim that while testing their invention, they have actually performed the first-ever feat of concealing a random 3D shape in visible light. Further, their physical bulk made the invisibility cloaks impractical for all but microscopic purposes. That’s because each antenna has a specific reflecting job-each based on the orientation of the concealed device underneath it. Not only does this make designing one of Ni’s cloaks an arduous process…it also means a hidden object can’t move for the cloak to work.

“Then you’re in the [realm] of a real Harry Potter cloak”, he says.

It is the scattering of light – be it visible, infrared, X-ray, etc., – from its interaction with matter that enables us to detect and observe objects. “If you want to cloak people, that is possible with this new work”. Or it could be used to make a auto seem smaller and thus safer, reducing the driver’s blind spots around the vehicle.

However, existing designs have substantial limitations that render them unwieldy, unadaptable to different environments, or limited to cloaking only very tiny objects.

“That’s the next question – can you make this cloak adaptive?”

Although at this stage the “invisibility skin” measures just 36 micrometres square – about the size of a few living cells – the researchers say it has potential.