Pinoy physicists find way to slow down light by 'twisting' it

Two Filipino physicists have just found a way to slow light down without touching it, by making it "twist" as it moves through space.

The discovery has potential practical applications in telecommunications and computer technology.

Researchers Nestor Bareza and Nathaniel Hermosa from the University of the Philippines' National Institute of Physics have been working with a special kind of laser called a Laguerre-Gauss (LG) beam, which has orbital angular momentum—or, put simply, it "twists"—as it travels through space.

In their paper published today, May 27, in the journal Scientific Reports, Bareza and Hermosa were able to precisely describe in mathematical terms how the direction of the momentum affects the speed of the laser beam.

It's possible to manipulate the orbital angular momentum of an LG beam without touching it, so the scientists found a way to make the laser slow down by a predictable amount.

Since LG beams are also used in telecommunications and computer applications, Bareza's and Hermosa's work can help engineers compensate for the inherent slowdown of optical data transmissions.

Their research was funded by the "Balik PhD" program of the University of the Philippines' Office of the VIce President for Academic Affairs.

Einstein long ago gave an upper limit to the speed of light, which we know as "c" in his famous equation, E=mc². And even before his time, scientists have long known that you can slow a beam of light down by passing it through special materials, such as a prism.

But it's only recently that scientists have been able to slow down light without using a medium.

Just last year, another team of physicists—including a Filipina, Dr. Jacquiline Romero—also found a way to slow down light by changing the shape of moving photons, also without directly touching the beam. — GMA News