Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Absorbing electromagnetic energy while avoiding the heat

30.01.2017

First demonstration of a metal-free metamaterial that can absorb electromagnetic energy

Electrical engineers at Duke University have created the world's first electromagnetic metamaterial made without any metal. The device's ability to absorb electromagnetic energy without heating up has direct applications in imaging, sensing and lighting.


A closer look at one of the cylinders comprising a new non-metal metamaterial. The arrows depict how different aspects of an electromagnetic field interact with the cylinder.

Credit: Willie Padilla, Duke University

Metamaterials are synthetic materials composed of many individual, engineered features that together produce properties not found in nature. Imagine an electromagnetic wave moving through a flat surface made of thousands of tiny electrical cells. If researchers can tune each cell to manipulate the wave in a specific way, they can dictate exactly how the wave behaves as a whole.

For researchers to manipulate electromagnetic waves, however, they've typically had to use electrically conducting metals. That approach, however, brings with it a fundamental problem of metals -- the higher the electrical conductivity, the better the material also conducts heat. This limits their usefulness in temperature-dependent applications.

In a new paper, electrical engineers at Duke University demonstrate the first completely dielectric (non-metal) electromagnetic metamaterial -- a surface dimpled with cylinders like the face of a Lego brick that is designed to absorb terahertz waves. While this specific frequency range sits between infrared waves and microwaves, the approach should be applicable for almost any frequency of the electromagnetic spectrum.

The results appeared online on Jan. 9 in the journal Optics Express.

"People have created these types of devices before, but previous attempts with dielectrics have always been paired with at least some metal," said Willie Padilla, professor of electrical and computer engineering at Duke University. "We still need to optimize the technology, but the path forward to several applications is much easier than with metal-based approaches."

Padilla and his colleagues created their metamaterial with boron-doped silicon -- a non-metal. Using computer simulations, they calculated how terahertz waves would interact with cylinders of varying heights and widths.

The researchers then manufactured a prototype consisting of hundreds of these optimized cylinders aligned in rows on a flat surface. Physical tests showed that the new "metasurface" absorbed 97.5 percent of the energy produced by waves at 1.011 terahertz.

Efficiently absorbing energy from electromagnetic waves is an important property for many applications. For example, thermal imaging devices can operate in the terahertz range, but because they have previously included at least some metal, getting sharp images has been challenging.

"Heat propagates fast in metals, which is problematic for thermal imagers," said Xinyu Liu, a doctoral student in Padilla's laboratory and first author of the paper. "There are tricks to isolate the metal during fabrication, but that becomes cumbersome and costly."

Another potential application for the new technology is efficient lighting. Incandescent light bulbs make light but also create a significant amount of wasted heat. They must operate at high temperatures to produce light -- much higher than the melting point of most metals.

"We can produce a dielectric metasurface designed to emit light, without producing waste heat," Padilla said. "Although we've already been able to do this with metal-based metamaterials, you need to operate at high temperature for the whole thing to work. Dielectric materials have melting points much higher than metals, and we're now quickly trying to move this technology into the infrared to demonstrate a lighting system."

###

This work was supported by the Department of Energy (DE-SC0014372).

CITATION: "Experimental realization of a terahertz all-dielectric metasurface absorber," Xinyu Liu, Kebin Fan, Ilya V. Shadrivov, Willie J. Padilla. Optics Express, 2017. DOI: 10.1364/OE.25.000191

Media Contact

Ken Kingery
ken.kingery@duke.edu
919-660-8414

 @DukeU

http://www.duke.edu 

Ken Kingery | idw - Informationsdienst Wissenschaft

More articles from Materials Sciences:

nachricht Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern
20.07.2018 | Princeton University

nachricht Relax, just break it
20.07.2018 | DOE/Argonne National Laboratory

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Future electronic components to be printed like newspapers

A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.

The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

A smart safe rechargeable zinc ion battery based on sol-gel transition electrolytes

20.07.2018 | Power and Electrical Engineering

Reversing cause and effect is no trouble for quantum computers

20.07.2018 | Information Technology

Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern

20.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>