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Monday, May 24, 2010

Light at a weird angle, is invisibility next?

Harry Atwater and Stanley Burgos of Caltech, and Rene de Waele and Albert Polman of the Center for Nanophotonics, Amsterdam, have invented a way to bend visible light the 'wrong' way. This may be a first step toward creating an invisibility cloak.

The scientists engineered a ‘metamaterial that has a negative index of refraction, causing entering light waves to exit at an unexpected angle. This part has been done before. What's new is that Atwater's negative-index metamaterial (NIM) was effective for a wide range of incoming light angles and polarization levels. In other words, this new NIM is the first optical material to be able to negatively refract light in the visible spectrum. According to Atwater, among other applications, this could open the door to invisibility cloaking.

Another advantage over earlier NIM's is that the new material consists of only a single layer, making it easier to manufacture. In addition, the new NIM is tunable to different incoming wavelengths and outgoing angles. Atwater and his team believe that their new metamaterial will be especially useful for collecting sunlight for use in solar cells.

Arrays of coupled plasmonic coaxial waveguides offer a new approach by which to realize negative-index metamaterials that are remarkably insensitive to angle of incidence and polarization in the visible range.
Credit: Caltech/Stanley Burgos.