BUFFALO, N.Y. 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 (see image at http://www.buffalo.edu/news/releases/2013/02/016.html), 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 helpe
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