Light reflects off the cloak (red arrows) as if it were reflecting off a flat mirror in this 3D illustration of a
metasurface skin cloak made from an ultrathin layer of nanoantennas (gold blocks)
covering an arbitrarily shaped object is shown in this handout image courtesy...
The cloak, 80 nanometers in thickness, was wrapped around a three-dimensional object shaped with bumps and dents. The cloak's surface rerouted light waves scattered from the object to make it invisible to optical detection. It may take five to 10 years to make the technology practical to use, according to Xiang Zhang, director of the Materials Sciences Division of the U.S. Department of Energy's Lawrence Berkeley National Laboratory and a professor at the University of California, Berkeley. "We do not see fundamental roadblocks. But much more work needs to be done," said Zhang, whose research was published in the journal Science.
The technology involves so-called metamaterials, which possess properties not present in nature. Their surfaces bear features much smaller than the size of a wavelength of light. They redirect incoming light waves, shifting them away from the object being cloaked. The cloaking "skin" boasts microscopic light-scattering antennae that make light bouncing off an object look as if it were reflected by a flat mirror, rendering the object invisible. "The fact that we can make a curved surface appear flat also means that we can make it look like anything else. We also can make a flat surface appear curved," said Penn State University electrical engineering professor Xingjie Ni, the study's lead author.
The researchers said they overcame two drawbacks of previous experimental microscopic cloaks that were bulkier and harder to "scale up," or become usable for larger objects. Ni said the technology eventually could be used for military applications like making large objects like vehicles or aircraft or even individual soldiers "invisible."