New Metamaterial a ‘Perfect’ Absorber of Light

14 Jun

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 of Boston College

A number of scientists believe that solar power could be the best choice for energy generation of the three renewable resources available (solar, wind or geothermal). This latest research outlining the discovery of “an absorbing metamaterial with near unity absorbance” could help ensure that we are able to break free of fossil fuel use for energy generation (oil, coal and natural gas), thereby reducing both our dependency on foreign imports of fossil fuels and our carbon emissions.

The nature of our problem is this: global consumption of energy is at present 15TW (One terawatt equals one billion kilowatts). The total available energy from the sun is about 86,000 TW, from wind about 870 TW and geothermal about 32 TW (figures from Wikipedia). It’s readily apparent in viewing these numbers that each resource could singularly prove sufficient if one were able to capture the energy in an efficient and acceptable manner. Currently, solar panels can only convert approximately 15% of the sunlight in our atmosphere into electricity. That inefficiency, along with the current high entry price to develop and deploy panels, continues to make the use of solar energy infeasible to say the least. That is why this new discovery is so fascinating…

Solar power pulls firmly to the front if this new metamaterial proves to be viable. We could soon see the end of fossil fuel as a means for energy generation.

However, until the metamaterial discovery bears the weight of peer scrutiny, do your part won’t you? Save energy wherever you can…you might even start here?

Here is the story:

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 of Boston College] A team of scientists from Boston College and Duke University has developed a highly-engineered metamaterial capable of absorbing all of the light that strikes it – to a scientific standard of perfection – they report in Physical Review Letters.


Perfect Metamaterial Absorber

N. I. Landy,1 S. Sajuyigbe,2 J. J. Mock,2 D. R. Smith,2 and W. J. Padilla1

  1. Department of Physics, Boston College, 140 Commonwealth Avenue, Chestnut Hill, Massachusetts 02467, USA
  2. Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina 27708, USA

“We present the design for an absorbing metamaterial (MM) with near unity absorbance A(omega). Our structure consists of two MM resonators that couple separately to electric and magnetic fields so as to absorb all incident radiation within a single unit cell layer. We fabricate, characterize, and analyze a MM absorber with a slightly lower predicted A(omega) of 96%. Unlike conventional absorbers, our MM consists solely of metallic elements. The substrate can therefore be optimized for other parameters of interest. We experimentally demonstrate a peak A(omega) greater than 88% at 11.5 GHz.”

PRL Citation


The team 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. 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. 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.

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.

“Three things can happen to light when it hits a material,” says 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 University 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.

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Posted by on June 14, 2008 in Physics, Science News


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