New Metamaterial a 'Perfect' Absorber of Light

Jun 03, 2008
New Metamaterial a 'Perfect' Absorber of Light
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.

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.

“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.

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.

Published by the American Physical Society, the article can be viewed at
scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=PRLTAO000100000020207402000001&idtype=cvips&gifs=yes

Source: Boston College

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User comments : 15

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x646d63
4.5 / 5 (4) Jun 03, 2008
For those of us who are not experts in this field it would be nice to understand the practical applications of 100% absorption of a narrow spectrum of light.
mrlewish
4.6 / 5 (5) Jun 03, 2008
Actually this seems like important news. If they could be made to absorb a wider spectrum and different wavelengths real and light weight radiation shielding is forseeable.
Mercury_01
4.5 / 5 (4) Jun 03, 2008
The military should be interested in this for high dollar optics, camouflage, and perhaps radar shielding, if it can be made to absorb in that spectra.
earls
2 / 5 (7) Jun 03, 2008
More importantly, where does the energy go?
googleplex
5 / 5 (5) Jun 03, 2008
More importantly, where does the energy go?

"...turned completely into heat and absorbed".
snwboardn
4 / 5 (5) Jun 03, 2008
Would it be possible to use this in Solar Panels?
am_Unition
1.5 / 5 (4) Jun 03, 2008
The military should be interested in this for high dollar optics, camouflage, and perhaps radar shielding, if it can be made to absorb in that spectra.


Doubtful - most radar uses frequency modulation, not to mention that the wavelengths are generally much larger than those of microwaves. The geometry would have to be much more macro than what was developed to absorb microwaves, not to mention encompass a broader spectrum if you're going to outsmart frequency modulation radar.
Bbrhuft
3.8 / 5 (5) Jun 03, 2008
If a material can absorbs all light (energy), it seems possible to create photovoltaic or thermoelectric cells with nearly perfect efficiency. Lets turn Swords to ploughshares.
earls
5 / 5 (2) Jun 03, 2008
Granted, googleplex, but what is the upper limit?

"We experimentally demonstrate a peak A(omega) greater than 88% at 11.5 GHz."

Certainly it can't endlessly absorb.
Graeme
4.2 / 5 (5) Jun 03, 2008
The peak absorption of over 88% is nowhere near "perfect". Black paint can already achieve this. So I was misled by the heading and hype in the Physorg article. And for those who want to build solar cells like Bbrhuft, you don't want heat, you want electricity.
Fausttt
3.8 / 5 (4) Jun 04, 2008
@Graeme
actually a large number of "solar" energy comes from the direct use of the heat generated, not the electricity. Many solar collectors use the focused sunlight to heat a core that is then used to transfer the heat to what is basically a steam turbine to generate electricity. So heat is valuable.
Glis
5 / 5 (1) Jun 04, 2008
This material could prove very useful for blackbody radiation studies if in fact it is a 100% absorber at a given frequency range.
lengould100
4 / 5 (1) Jun 10, 2008
Appears they're exploiting the well-known "optical rectenna" absorbtion system without acknowledging it.
TimESimmons
not rated yet Jun 19, 2008
One important application would be in the obilisk things in "2001 a space odyssey". They were perfectly black. Hmm 7 years late.
TimESimmons
1 / 5 (1) Jun 19, 2008
(in the book anyway)

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