Fishnet refraction

Researchers at the US Department of Energy’s Ames Laboratory have developed a material with a negative refractive index for visible light.

Ames Laboratory senior physicist Costas Soukoulis, working with colleagues in Karlsruhe, Germany, designed a silver-based, mesh-like material that is said to mark the latest advance in the rapidly evolving field of metamaterials, materials that could lead to a wide range of new applications as varied as ultrahigh-resolution imaging systems and cloaking devices.

The discovery, detailed in recent issues of Science, Optic Letters, and Nature, marks a significant step forward from existing metamaterials that operate in the microwave or far infrared – but still invisible –regions of the spectrum. Those materials, announced last summer, were heralded as the first step in creating an invisibility cloak.

Metamaterials, also known as left-handed materials, are artificially created materials that provide optical properties not found in natural materials. Natural materials refract light, or electromagnetic radiation, to the right of the incident beam at different angles and speeds. However, metamaterials make it possible to refract light to the left, or at a negative angle. This backward-bending characteristic provides scientists the ability to control light similar to the way they use semiconductors to control electricity, which opens a wide range of potential applications.