MIT Researchers Discover New Way to Trap Light

There are several different ways to trap light and now, researchers have designed another method to manage the feat. Scientists at MIT have developed a new system that pits light waves against light waves; the technique could have a wide variety of practical applications.

A beam of light is usually trapped with mirrors or other reflective materials. The other option to contain light is by using high-tech materials, such as photonic crystals and devices that rely on a phenomenon called Anderson localization. These techniques are usually used when building optical devices such as lasers, solar cells and fiber optics. In all of these cases, light's passage is blocked; in physics terminology, there are no "permitted" states for the light to continue on its path, so it is forced into a reflection. Yet developing new methods could potentially pave the way to better electronics.

The new technique was devised through computer modeling and then demonstrated experimentally. Essentially, the method sets up two waves that have the same wavelength but exactly opposite phases--when one wave has a peak and the other has a trough. These waves cancel each other out while the light of other wavelengths (or colors) can pass through freely. What makes this particular technique so useful is that it could be applied to any type of wave--from sound to radio.

In mathematical terms, the new system is an example of an "embedded eigenvalue." While this had been described as a theoretical possibility in 1929, it had yet to be seen in practice. The new experiment, though, shows that it's not only possible, but that it could be used in the future.

"New physical phenomena often enable new applications," said Chia Wei Hsu, one of the researchers, in a news release. These applications could include large-area lasers and chemical or biological sensors.

Currently, though, the researchers aren't focusing on the practical applications. Instead, they're examining the new, unexpected phenomenon.

The findings are published in the journal Nature.