University at Buffalo engineers have created a more efficient way to catch rainbows, an advancement in photonics that could lead to technological breakthroughs in solar energy, stealth technology and other areas of research.
Qiaoqiang Gan, PhD, an assistant professor of electrical engineering at UB, and a team of graduate students described their work in a paper called "Rainbow Trapping in Hyperbolic Metamaterial Waveguide," published Feb. 13 in the online journal Scientific Reports.
They developed a "hyperbolic metamaterial waveguide," which is essentially an advanced microchip made of alternate ultra-thin films of metal and semiconductors and/or insulators. The waveguide halts and ultimately absorbs each frequency of light, at slightly different places in a vertical direction, to catch a "rainbow" of wavelengths.
Gan is a researcher within UB's new Center of Excellence in Materials Informatics.
"Electromagnetic absorbers have been studied for many years, especially for military radar systems," Gan said. "Right now, researchers are developing compact light absorbers based on optically thick semiconductors or carbon nanotubes. However, it is still challenging to realize the perfect absorber in ultra-thin films with tunable absorption band.
"We are developing ultra-thin films that will slow the light and therefore allow much more efficient absorption, which will address the long existing challenge."
Light is made of photons that, because they move extremely fast (i.e., at the speed of light), are difficult to tame. In their initial attempts to slow light, researchers relied upon cryogenic gases. But because cryogenic gases are very cold – roughly 240 degrees below zero Fahrenheit – they are difficult to work with outside a laboratory.
Before joining UB, Gan helped pioneer a way to slow light without cryogenic gases. He and other researchers at Lehigh University made nano-scale-sized grooves in metallic surfaces at different depths, a process that altered the optical properties of the metal. While the grooves worked, they had limitations.
For example, the energy of the incident light cannot be transferred onto the metal surface efficiently, which hampered its use for practical applications, Gan said.
The hyperbolic metamaterial waveguide solves that problem because it is a large area of patterned film that can collect the incident light efficiently. It is referred to as an artificial medium with subwavelength features whose frequency surface is hyperboloid, which allows it to capture a wide range of wavelengths in different frequencies including visible, near-infrared, mid-infrared, terahertz and microwaves.
It could lead to advancements in an array of fields.
For example, in electronics there is a phenomenon known as crosstalk, in which a signal transmitted on one circuit or channel creates an undesired effect in another circuit or channel. The on-chip absorber could potentially prevent this.
The on-chip absorber may also be applied to solar panels and other energy-harvesting devices. It could be especially useful in mid-infrared spectral regions as thermal absorber for devices that recycle heat after sundown, Gan said.
Technology such as the Stealth bomber involves materials that make planes, ships and other devices invisible to radar, infrared, sonar and other detection methods. Because the on-chip absorber has the potential to absorb different wavelengths at a multitude of frequencies, it could be useful as a stealth coating material.
University at Buffalo: http://www.buffalo.edu
This press release was posted to serve as a topic for discussion. Please comment below. We try our best to only post press releases that are associated with peer reviewed scientific literature. Critical discussions of the research are appreciated. If you need help finding a link to the original article, please contact us on twitter or via e-mail.
An extension of Einstein's gravity would let us build a wormhole – if we could send messages to invisible aliens via space-time ripples
John Eric Goff, the chair of the physics department at Lynchburg College, explains the science of the 2014 World Cup soccer ball.
When an asteroid plows into the Earth, it destroys pretty much everything in its path. But new research has shown that glass created during a searing asteroid impact can actually trap microscopic signs of life for millions of years, providing scientists with a snapshot of the biology in the area just before and after the strike.
It's not often that we think about deep time. Lucky to live for a century, humans flitter like mayflies across Earth's surface, our own epoch an eyeblink in a planetary history that's largely hidden from everyday consciousness. Every now and then, though, that history punches right through into the present.
Ancient grasses from the Pampas of Argentina were preserved when asteroids struck the area, scientists report.
The longest-running experiment in the world has for the first time glimpsed a drop of viscous pitch fall – although the event comes too late for one man
A playfully named subatomic particle is confirmed, and beats rivals Bert and Ernie in terms of energy. Next step: to find a cluster of space neutrinos
Can matter be made of four quarks bound together? The discovery of a new particle has been confirmed at the LHC and may be our best hope of an answer
Traditional spice producers and synthetic biologists don't have to compete – there's room for both
Cortines School's Greg Schiller was removed by L.A. Unified after two students' projects were deemed to resemble weapons. A popular Los Angeles high school science teacher has been suspended after students turned in projects that appeared dangerous to administrators, spurring a campaign calling for his return to the classroom.