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In a Perspectives piece in the journal Science, researchers from the California Institute of Technology (Caltech) and Purdue University describe advances in a particular subtype of these materials—plasmonic metamaterials.

Metamaterials derive their properties from carefully engineered, nanostructured building blocks rather than from their chemical composition.

Two of the major limitations in the field: the loss of light or, rather, its absorption by metals such as silver and gold, which are contained in the metamaterial; and difficulties in precisely tuning the materials so they bend incoming light to the required index of refraction.

In their article, Caltech’s Harry Atwater and Purdue’s Alexandra Boltasseva suggest new approaches to overcoming these obstacles by replacing the silver and gold in the metamaterials with semiconductors made more metallic by the addition of metallic impurities, or by adding non-metallic elements to metals, making them less metallic.

Examples of these “intermetallic materials” include aluminum oxides and titanium nitride.

Some of the new metamaterials, the researchers say, are showing promise in uses involving near-infrared light, the range of the spectrum critical for telecommunications and fiber optics.

Other materials—such as the negative-index metamaterial developed by Atwater and Caltech graduate student Stanley Burgos and described in an April 2010 Nature Materials article—might even work with light in the visible range of the spectrum.

Future photonics technologies will revolve around new types of optical transistors, switches, and data processors, Atwater and Boltasseva note. “These materials can be tailored for almost any application because of their extraordinary response to electromagnetic, acoustic, and thermal waves that transcends the properties of natural materials.”

More news from Caltech: http://media.caltech.edu/