This has taken more than a decade to do

Jan 25, 2010 14:02 GMT  ·  By

Polymers, or electrically conducting plastics, were discovered more than ten years ago to be able to generate what researchers referred to as random lasers. This was a very peculiar phenomenon, which some physicists even refused to believe existed. Now, all these years later, scientists at the University of Utah, where these lasers were first found, show not only that they are real, but also shed light on the mechanisms that led to their creation. The group also adds that, in the near future, technologies based on these lasers could help fight cancer, ScienceDaily reports.

The UU team was able to determine that the lasers were formed inside natural cavities that appeared in the polymers, which resemble a mirror. “Nobody knew how it worked until now. We succeeded in imaging the cavities. This is a big step in our understanding of this bizarre phenomenon, which not many people believed,” UU Distinguished Professor of Physics Z. Valy Vardeny says. He is the senior author of the new investigation, which is detailed in the January 24 online issue of the respected scientific journal Nature Physics.

When designing lasers, experts usually place the components, known as gain media, in a very specific order. This ensures that, as light is being generated, not much of it is lost to interference or other natural factors. However, when the lasers occur on their own, such as in polymers, the materials that give birth to them are not arranged in the optimum setting, so they tend to lose some of their light. “You can get lasing out of junky materials if they contain molecules that glow. Out of disorder comes perfect order,” Vardeny adds.

In their studies of natural cavities inside pi-conjugated polymer films (DOO-PPV), the UU researchers determined that the mirror-like structures, which are basically small irregularities in the material itself, acted just like artificial mirrors in regular laser resonators. “Surprisingly, there is a class of lasers where laser emission happens from materials that are literally shaken together. These are called random lasers since the emission happens from an uncontrolled configuration,” the coauthor of the new study, UU Dixon Laser Institute senior optical engineer Randy Polson, explains.