FOR KIDS: Lasers of a feather
Lasers are everywhere: They scan bar codes at the supermarket, they read data from DVDs, and they can even be used to remove unwanted body hair. Scientists have shown that lasers can be built in many different ways — now even by taking cues from animals.
A laser produces a beam of light of a single color. In most modern lasers, light starts bouncing back and forth between mirrors. The space between the mirrors contains a crystal or a gas that adds high-energy photons, or light energy, to the light beam as it bounces around. These photons, traveling in the same direction, create the beam.
In recent years, researchers have found ways to build lasers without mirrors. Scientists have now found inspiration for a new type of mirrorless laser in an unusual place — bird feathers.
It may be hard to imagine how feathers and lasers go together. The new laser doesn’t look like a feather, and it won’t help birds fly. The scientists who invented the laser got their idea from the way some bird feathers — like the blue plumage of the plum-throated cotinga — get their color.
The feather connection comes from a 1998 discovery by Richard Prum, an ornithologist — someone who studies birds — at Yale University. Prum found that some bird feathers get their color from tiny pockets of air trapped in the barbs. Barbs are the tiny, hairlike filaments that form the soft, flexible part of the feather.
“Birds use these structures to create colors that they can’t make in other ways,” Prum told Science News.
When light strikes these air pockets, it scatters, or is redirected — sometimes in many different directions. In the case of the cotinga, the scattering produces blue light, so the bird’s feathers appear blue. The laser inventors used tiny holes drilled into thin sheets of a semiconductor to simulate the air bubbles. (Semiconductors can conduct electricity and are very important in devices like computer chips and solar cells.)
These tiny holes did the same thing as the tiny bubbles: They scattered light. It went in one side of the hole, and as it came out the other, it shot off in all different directions. Then the light gained energy as it passed through a material that built up the beam.
The team says it can change the color of the beam by changing the size and arrangement of the holes. The laser still needs some work. But Hui Cao, the Yale University physicist who led the team, told Science News that the new laser is more efficient than some other mirrorless lasers.
“The lesson we learned from nature is that we don’t need something perfect to get control,” Cao said.
The researchers hope these early tests of the featherlike laser will lead to a new, cheaper laser. But there’s one thing the laser can’t do, no matter where it came from: It won’t help us fly.
POWER WORDS (adapted from the New Oxford American Dictionary)
laser A device that generates an intense beam of single-colored light (or other radiation). A laser’s beam is made of photons produced by excited, or energetic, atoms or molecules. Lasers are used in drilling and cutting, alignment and guidance, and in surgery. The word laser comes from an acronym: Light Amplification by Stimulated Emission of Radiation.
semiconductor A solid substance that conducts electricity better than insulators but worse than metals. Devices made of semiconductors, notably silicon, are essential components of most electronic circuits.
ornithology The scientific study of birds.
barb One of the fine, hairlike filaments growing from the shaft, or rigid center, of a feather.