I jst saw this on web.
By Maggie Fox, Health and Science Editor
WASHINGTON (Reuters) – Scientists have created two new types of materials that can bend light the wrong way, creating the first step toward an invisibility cloaking device.
One approach uses a type of fishnet of metal layers to reverse the direction of light, while another uses tiny silver wires, both at the nanoscale level.
Both are so-called metamaterials — artificially engineered structures that have properties not seen in nature, such as negative refractive index.
The two teams were working separately under the direction of Xiang Zhang of the Nanoscale Science and Engineering Center at the University of California, Berkeley with U.S. government funding. One team reported its findings in the journal Science and the other in the journal Nature.
Each new material works to reverse light in limited wavelengths, so no one will be using them to hide buildings from satellites, said Jason Valentine, who worked on one of the projects.
“We are not actually cloaking anything,” Valentine said in a telephone interview. “I don’t think we have to worry about invisible people walking around any time soon. To be honest, we are just at the beginning of doing anything like that.”
Valentine’s team made a material that affects light near the visible spectrum, in a region used in fiber optics.
“In naturally occurring material, the index of refraction, a measure of how light bends in a medium, is positive,” he said.
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