Getting rid of basic obstacle brings invisibility cloak closer to reality

August 5th, 2010 - 1:09 pm ICT by ANI  

London, Aug 5 (ANI): By overcoming a fundamental obstacle in using new “metamaterials”, researchers have come closer to optical technologies, including ultra-powerful microscopes and computers and a possible invisibility cloak.

The metamaterials have been plagued by a major limitation-too much light is “lost,” or absorbed by metals such as silver and gold contained in the metamaterials, making them impractical for optical devices.

However, a Purdue University team has solved this hurdle, culminating three years of research based at the Birck Nanotechnology Center at the university’s Discovery Park.

“This finding is fundamental to the whole field of metamaterials. We showed that, in principle, it’s feasible to conquer losses and develop these materials for many applications,” Nature quoted Vladimir M. Shalaev, Purdue’s Robert and Anne Burnett Professor of Electrical and Computer Engineering as saying.

The material developed by researchers is made of a fishnet-like film containing holes about 100 nanometers in diameter and repeating layers of silver and aluminum oxide.

The researchers etched away a portion of the aluminum oxide between silver layers and replaced it with a “gain medium” formed by a colored dye that can amplify light.

Other researchers have applied various gain media to the top of the fishnet film, but that approach does not produce sufficient amplification to overcome losses, said Shalaev.

Instead, the Purdue team found a way to place the dye between the two fishnet layers of silver, where the “local field” of light is far stronger than on the surface of the film, causing the gain medium to work 50 times more efficiently.

Future work may involve creating a technology that uses an electrical source instead of a light source, like semiconductor lasers now in use, which would make them more practical for computer and electronics applications.

The findings are detailed in a paper appearing in the journal Nature. (ANI)

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