Scientists Alter Rainbow Color Order
November 20, 2012

Scientists Alter Order Of Rainbow Colors On Nanoscale

Lee Rannals for — Your Universe Online

King's College London researchers reported in the journal Nature's Scientific Reports they have demonstrated how to separate colors and create "rainbows" using nanoscale structure on a metal surface.

The team was able to trap light of different colors at different positions of a nanostructured area using specially designed nanostructures.

Depending on the geometry of the nanostructure, a trapped rainbow could be created on a gold film that has the dimension on the order of a few micrometers, which is about 100 times smaller than the width of a human hair.

"Nanostructures of various kinds are being considered for solar cell applications to boost light absorption efficiency," Professor Anatoly Zayats in the department of physics said in a statement. "Our results mean that we do not need to keep solar cells illuminated at a fixed angle without compromising the efficiency of light coupling in a wide range of wavelengths. When used in reverse for screens and displays, this will lead to wider viewing angles for all possible colors."

The difference between natural rainbows, where red always appears on the outside and the blue on the inside, and the created nanostructure, the team was able to control where the rainbow colors would appear.

The researchers also discovered that it is possible to separate colors in the different sides of the nanostructures.

"The effects demonstrated here will be important to provide 'color' sensitivity in infrared imaging systems for security and product control," co-author Dr. Jean-Sebastien Bouillard from King's, said in a statement. "It will also enable the construction of microscale spectrometers for sensing applications."

Coupling light to nanostructures with multicolor characteristics could be of major import for light capturing devices, such as displays, photo detectors and solar cells.

The research may ultimately lead to improved solar cells and LED displays due to the scientists having discovered exactly how to separate colors and create these rainbows on such a small scale.