Device could improve satellite and molecular imaging.

In many respects, metamaterials are supernatural. These manmade materials, with their intricately designed structures, bend electromagnetic waves in ways that are impossible for materials found in nature. Scientists are investigating metamaterials for their potential to engineer invisibility cloaks — materials that refract light to hide an object in plain sight — and “super lenses,” which focus light beyond the range of optical microscopes to image objects at nanoscale detail.

Researchers at MIT have now fabricated a three-dimensional, lightweight metamaterial lens that focuses radio waves with extreme precision. The concave lens exhibits a property called negative refraction, bending electromagnetic waves — in this case, radio waves — in exactly the opposite sense from which a normal concave lens would work.

Concave lenses typically radiate radio waves like spokes from a wheel. In this new metamaterial lens, however, radio waves converge, focusing on a single, precise point — a property impossible to replicate in natural materials.

For Isaac Ehrenberg, an MIT graduate student in mechanical engineering, the device evokes an image from the movie “Star Wars”: the Death Star, a space station that shoots laser beams from a concave dish, the lasers converging to a point to destroy nearby planets. While the researchers’ fabricated lens won’t be blasting any planetary bodies in the near future, Ehrenberg says there are other potential applications for the device, such as molecular and deep-space imaging.

“There’s no solid block of any material in the periodic table which will generate this effect,” Ehrenberg says. “This device refracts radio waves like no other material found in nature.”

Ehrenberg published the results of his research in the Journal of Applied Physics. His co-authors on the paper are Sanjay Sarma, the Fred Fort Flowers and Daniel Fort Flowers Professor of Mechanical Engineering at MIT, and Bae-Ian Wu, a researcher at the Air Force Research Laboratory.

Read More