Have Researchers Built the Perfect Invisibility Cloak?

Nathan Landy and his cloaking device. (Photo: Duke University).

From Plato’s ring of Gyges to H.G. Wells’ "The Invisible Man" to Harry Potter’s magic cape, we’ve been obsessed for millennia with the idea of invisibility.

In 2006, researchers from Duke University came close with the design for an invisibility cloak, yet the device was imperfect as it left reflections around the edges. Now a member of that team, graduate student Nathan Landy from Duke's Pratt School of Engineering, has redesigned the device with promising success.

Because the goal of this type of research involves transforming light or other waves and how they can be controlled or transmitted, a new field called “transformational optics” has emerged. Duke’s transformational optics team has been specializing in creating "meta-materials" — objects born in the lab that have properties not found in natural materials. Using these meta-materials, devices can be designed that direct electromagnetic waves around an object and then emerge again on the other side, creating the illusion that the item is no longer there.

The cloak built in 2006 relied on parallel, intersecting strips of fiberglass etched with copper. The new cloak is a 2-feet square diamond-shape device, looking more steampunk than high tech, in which Landy employed a similar row-by-row design but added copper strips to create a more complex material.

"We built the cloak, and it worked," said Landy. "It split light into two waves which traveled around an object in the center and re-emerged as the single wave with minimal loss due to reflections." Landy noted that this idea could have more applications beyond cloaks, such as significantly improving fiber optics performance.

The team is now hoping to apply the principles learned in the latest research to three dimensions, a much greater challenge than constructing a two-dimensional device.

It may come as little surprise that this research, which resulted in the ultimate sci-fi camouflage, was supported by the Office of Naval Research and the Army Research Office.

The results of the Duke experiments were published online in the journal Nature Materials.