What Do Bird Feathers And Lasers Have In Common?

There’s a new laser out intended to capture light in the same way that colorful bird feathers do. The laser copies the nano-scale structure of colorful bird feathers to make high intensity light; able to produce any color.

Traditional lasers operate by capturing light into a material that can emit a greater number of photons with the exact same wavelength or color. The photons coming in excite the atoms and make them produce identical photons. In order to gather enough photons for a laser beam the photons need to dwell in the material for a longer period of time.

A method that scientists often use to get the photons to linger is to bounce them back and forth. Standard lasers achieve this goal by utilizing mirrors. Recently, scientists constructed lasers from big pieces of customized glass and drilled air holes in the glass. The light gets trapped on a pathway between the holes and bounces around for just enough time to create laser light.

Physicists have experimented with the holes; sometimes putting them in ordered patterns and sometimes drilling them completely randomly. Each patterns comes with pros and cons. Ordered patterns are only effective at one particular wavelength and randomized patterns aren’t efficient at all.

A New Technique

Hui Cao, a physicist from Yale, and her team decided to try a tactic that was in between these patterns; a seemingly random pattern from afar but if one looks closely then it resembles a bit of a pattern. This is very similar to air pockets in bird feathers. The team’s findings have been published in Physical Review Letters. Some birds have brightly colored feathers that are embedded with patterns of air pockets. Different wavelengths of light get scattered and give the bird’s feathers their distinctive colors.

“After we learned this, we said, ‘Oh, that’s a smart idea!’” Cao said. For the experiment, the scientists drilled holes into a sheet of gallium arsenide. They made sure to keep the holes between 235 and 275 meters apart. The scientists also used quantum dots, in conjunction with the gallium arsenide. They predicted that when light hit the plastic it would bounce around and give the quantum dots sufficient time to produce lasers.

The researchers were able to produce a highly efficient laser that they could alter simply by changing the distance between holes. Cao compares the experiment to the birds’ feathers, saying “Just like the birds, who can tune their short-range order to get different color from their feathers. We can do the same thing.”

While the team doesn't have any particular use in mind for the laser, they do note that their laser was much cheaper to build than many models currently available.

The Next Level

Cao and her team are now taking the experiment to the next level by implanting tiny semiconductors onto the air holes present in bird feathers. They hypothesize that they may be able to complete lasers with shorter wavelengths using this method.

Matt Shawkey, from the University of Akron-Ohio, notes that finding the way birds build their feathers in the first place may be important information, “Birds seem to do it very cheaply. They have thousands of these feathers,” he said. “If you can get these things to build themselves, taking the painstaking process out, then you’d barely have to put any energy and time into it. It would be really cool to see which parameters the birds are changing to get these feathers to self-assemble.”

Wired Photo by : Tambako the Jaguar