An improved method to capture rainbows has been developed by researchers at the University at Buffalo. The photonics breakthrough could very likely lead to significant improvements in solar energy, stealth technologies, and other areas of research, according to the researchers.
The researchers created a “hyperbolic metamaterial waveguide,” that works to separate and absorb every frequency of light at different locations in a vertical direction, as the photo above shows. It’s essentially a microchip that is composed of alternating layers of ultra-thin “metal and semiconductors and/or insulators.” The alternating layers then work to capture the rainbow.
“Electromagnetic absorbers have been studied for many years, especially for military radar systems,” said Qiaoqiang Gan, an assistant professor of electrical engineering at UB. “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.”
The extreme speed that light photons move at makes them very difficult to “tame.” There had previously been some success slowing the photons by utilizing light cryogenic gases, but that is impracticable outside of the lab. So the researchers started exploring other ways, which is when they came across the utilization of “nano-scale-sized grooves in metallic surfaces at different depths.” That system worked, but still had some limitations, mainly to do with efficiency.
But the hyperbolic metamaterial waveguide is not subject to these limitations, simply being a large area of patterned film that works very 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.”
The researchers are very excited about it, because of its wide range of potential uses, which could lead to advancements in solar panel technology, “being especially useful in mid-infrared spectral regions as thermal absorber for devices that recycle heat after sundown.” And it’s myriad range of potential uses in stealth technologies, which could help to make objects invisible to radar.
The research on the new method was just published February 13th in the journal Scientific Reports.
Source: University at Buffalo
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