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.
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.
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.
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.”
The Latest on: Electromagnetic metamaterial
via Google News
The Latest on: Electromagnetic metamaterial
- Duke University researchers discover ‘perfect absorber’ anti-laser on February 18, 2019 at 7:14 am
built the first material capable of absorbing nearly 100 percent of an electromagnetic wave’s energy without containing even an atom of metal. The device was a metamaterial—synthetic materials compose... […]
- Researchers discover anti-laser masquerading as perfect absorber on February 15, 2019 at 8:15 am
The width, height and spacing of the cylinders depicted here dictates how the metamaterial described in the new paper absorbs electromagnetic energy. Credit: Kebin Fan, Duke University Researchers ... […]
- Flexible controls of broadband electromagnetic wavefronts with a mechanically programmable metamaterial on February 12, 2019 at 2:47 am
Coding and programmable metamaterials have experienced a rapid development since 2014, leading to many physical phenomena and engineering applications from microwave to terahertz frequencies, and even ... […]
- Global Metamaterials Market Outlook Report 2018 on February 6, 2019 at 3:30 pm
Metamaterials refer to specially engineered composite materials with superior electromagnetic properties, in comparison with traditional composites found in nature. Metamaterial show its exceptional p... […]
- Dalhousie University, Metamaterial Technologies Inc. and Mitacs announce $1.62M collaboration to explore light manipulation on January 15, 2019 at 9:50 am
Advances and discoveries in electricity, electromagnetic technology ... Our partnership with Mitacs and Metamaterial Technologies Inc. allows us to recruit and train a number of new PhDs in advanced m... […]
- Viewpoint: A Metamaterial for Next Generation Particle Accelerators on January 7, 2019 at 9:15 am
Their metamaterial is an 8-cm-long structure made of 40 stainless-steel “wagon-wheel” plates alternating with copper spacer plates (Fig. 1). The plates are closely spaced with a 2-mm period, well belo... […]
- Metamaterial-based light mixer generates 11 colours at once on June 29, 2018 at 6:20 am
Metamaterials are materials made up of tiny, repeating structures, which are capable of interacting with electromagnetic waves in unusual ... at Sandia National Laboratories have now created a metamat... […]
- Metal-free metamaterial can be swiftly tuned to create changing electromagnetic effects on May 1, 2018 at 7:16 am
Artistic representation of the new metasurface technology. Rays of light (red) bombard the silicon cylinders, changing their electromagnetic properties to precisely tune how they interact with electro... […]
- Metamaterial Market Research Industry Report by Material Type, Application, Vertical - 2018 Global Deep Insight on April 1, 2018 at 2:42 am
The global metamaterial market is segmented on the basis of material type into electromagnetic metamaterials, terahertz metamaterials, photonic metamaterials, tunable metamaterials, frequency selectiv... […]
via Bing News