Invisibility cloak shields bumpy 3D object in visible light

Scientists at the Berkeley Lab and UC Berkeley have created an invisibility cloak fit for Harry Potter – if the boy wizard were smaller than a grain of sand.

A 3D illustration of a metasurface skin cloak made from an ultrathin layer of nanoantennas (gold blocks) covering an arbitrarily shaped object. Light reflects off the cloak as if it were reflecting off a flat mirror. (Image courtesy of Xiang Zhang group)

A 3D illustration of a metasurface skin cloak made from an ultrathin layer of nanoantennas (gold blocks) covering an arbitrarily shaped object. Light reflects off the cloak as if it were reflecting off a flat mirror. (Image courtesy of Xiang Zhang group)

Unlike the fictional character, the ultrathin cloak is real, and it successfully concealed microscopic 3D objects from detection in visible light. The achievement is described in a study published today in the journal Science, and in a Berkeley Lab press release.

“This is the first time a 3D object of arbitrary shape has been cloaked from visible light,” said Xiang Zhang, a UC Berkeley professor of mechanical engineering and director of Berkeley Lab’s Materials Sciences Division. “Our ultra-thin cloak now looks like a coat. It is easy to design and implement, and is potentially scalable for hiding macroscopic objects.”

The scientists used gold nanoantennas to form the 80-nanometer-thick cloak, which conformed to the arbitrary bumps and dents in the 1,300-square-micrometer sample object. The cloak, a metamaterial engineered to bend light in ways not seen in nature, was able to reflect red light as if it were bouncing off a flat mirror.

The principles used to conceal the microscopic object should be possible to scale up to work with macroscopic items, said Zhang.

For more details about this work, see the Berkeley Lab press release announcing the discovery.

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