Researchers at Yale University are studying how two types of nanoscale structures on the feathers of birds produce brilliant and distinctive colors. The researchers are hoping that by borrowing these nanoscale tricks from nature they will be able to produce new types of lasers — ones that can assemble themselves by natural processes.
Nanaoscales structures, invisibly small, are measured in nanometers. A nanometer is equal to one-billionth of a meter. When things are this small, you can’t see them with your eyes, or even a light microscope. Objects this small require a special tool called a scanning probe microscope
Many of the colors displayed in nature are created by nanoscale structures that scatter light strongly at specific frequencies. In some cases, these structures create iridescence, where colors change with the angle of view—like the shifting rainbows on a soap bubble. In other cases, the hues produced by the structures are steady and unchanging. The mechanism by which angle-independent colors are produced stumped scientists for 100 years
At first glance, these steady hues appeared to have been produced by a random jumble of proteins. But when researchers zoomed in on small sections of the protein at a time, quasi-ordered patterns began to emerge. The scientists found that it is this short-range order that scatters light preferentially at specific frequencies to produce the distinctive hues of a bluebird’s wings, for example.
Inspired by feathers, the Yale physicists created two lasers that use this short-range order to control light.
What makes these short-range-ordered, bio-inspired structures different from traditional lasers is that, in principle, they can self-assemble, through natural processes similar to the formation of gas bubbles in a liquid. This means that engineers would not have to worry about the nanofabrication of the large-scale structure of the materials they design, resulting in cheaper, faster, and easier production of lasers and light-emitting devices.
One potential application for this work includes more efficient solar cells that can trap photons before converting them into electrons. The technology could also yield long-lasting paint, which could find uses in processes such as cosmetics and textiles. “Chemical paint will always fade,” says lead author Hui Cao. But a physical “paint” whose nanostructure determines its color will never change. Cao describes a 40-million-year-old beetle fossil that her lab examined recently, and which had color-producing nanostructures. “With my eyes I can still see the color,” she said. “It really lasts for a very long time.”
The team will present their findings at the Optical Society’s (OSA) Annual Meeting, Frontiers in Optics (FiO) 2011 in San Jose, CA in October, 2011.
Bottom line: Researchers at Yale University are developing a new type of laser inspired by nanoscale structures in birdfeathers that can self-assemble by natural processes.
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