Friday 28 November, 2014

Miniature invisibility ”carpet cloak” shows promise for the optical world

Published On: Wed, Apr 20th, 2011 | Photonics | By BioNews

Scientists have developed invisibility “carpet cloaks” using metamaterials – artificial materials engineered to have optical properties not found in nature - which can conceal a much larger area than other cloaking techniques of comparable size.

Jingjing Zhang, a postdoctoral researcher at Technical University of Denmark’s (DTU), explains that the team”s new carpet cloak, which is based on an alternating-layer structure on a silicon-on-insulator (SOI) platform, introduces a flexible way to address the limitation of cloaking techniques to be orders of magnitude larger than the object being cloaked.

“This new cloak, consisting of metamaterials, was designed with a grating structure that is simpler than previous metamaterial structures for cloaks,” she said.

Grating structures channel light of a particular wavelength around an object. A grating structure is simply a series of slits or openings that redirect a beam of light.

The cloak is made exclusively of dielectric materials, which are highly transparent to infrared light, so the cloak itself is very efficient and absorbs a negligible fraction of energy.

By precisely restoring the path of the reflecting wave from the surface, the cloak creates an illusion of a flat plane for a triangular bump on the surface—hiding its presence over wavelengths ranging from 1480nm to 1580nm.
The study is published in the Optical Society”s (OSA) open-access journal Optics Express.

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