Material Superabsorbs Light

A metamaterial has been engineered that is capable of absorbing essentially all of the light that hits it.

Using standard optical lithography techniques, a team from Boston College in Chestnut Hill and Duke University in Durham, N.C., designed and engineered a metamaterial that uses tiny geometric surface features to successfully capture the electric and magnetic properties of a microwave to the point of total absorption, according to scientific standards.

Boston College and Duke University researchers have engineered a metamaterial that uses tiny geometric surface features to successfully capture the electric and magnetic properties of a microwave to the point of total absorption. (Image courtesy Boston College)

Metamaterial designs give them new properties beyond the limits of their actual physical components and allow them to produce "tailored" responses to radiation. Because their construction makes them geometrically scalable, metamaterials are able to operate across a significant portion of the electromagnetic spectrum.

Because some of these man-made materials can negatively refract light, electromagnetic metamaterials are being explored by researchers as foundations for cloaking devices (See also: 'Invisible' Objects Closer and Theoretical Blueprint for Invisibility Cloak Reported).

"Three things can happen to light when it hits a material," said Boston College physicist Willie J. Padilla. "It can be reflected, as in a mirror. It can be transmitted, as with window glass. Or it can be absorbed and turned into heat. This metamaterial has been engineered to ensure that all light is neither reflected nor transmitted, but is turned completely into heat and absorbed. It shows we can design a metamaterial so that at a specific frequency it can absorb all of the photons that fall onto its surface."

In addition to Padilla, the team included BC researcher Nathan I. Landy, Duke professor David R. Smith and researchers Soji Sajuyigbe and Jack J. Mock.

The group used computer simulations based on prior research findings in the field to design resonators able to couple individually to electric and magnetic fields to successfully absorb all incident radiation, according to their findings.

Because its elements can separately absorb the electric and magnetic components of an electromagnetic wave, the "perfect metamaterial absorber" created by the researchers can be highly absorptive over a narrow frequency range and could potentially be used in devices such as bolometers (a thermometric instrument used to detect and measure radiant energy).

The metamaterial is the first to demonstrate perfect absorption and unlike conventional absorbers it is constructed solely out of metallic elements, giving the material greater flexibility for applications related to the collection and detection of light, such as imaging, said Padilla, an assistant professor of physics.

The team reported their findings in the May 23 edition of Physical Review Letters.

For more information, visit: www.bc.edu