Notes about communications

To be filed under “research I like reading about even if I don’t quite understand how it works”, new studies from the University of Oregon into altering and controlling the color of light on the scale of individual photons in fiber optic signalling:

In experiments led by Raymer’s doctoral student Hayden J. McGuinness, researchers used two lasers to create an intense burst of dual-color light, which when focused into the same optical fiber carrying a single photon of a distinct color causes that photon to change to a new color. This occurs through a process known as Bragg scattering, whereby a small amount of energy is exchanged between the laser light and the single photon, causing its color to change. […] 

“In the first study, we worked with one photon at a time with two laser bursts to change the energy and color without using hydrogen molecules,” he said. “In the second study, we took advantage of vibrating molecules inside the fiber interacting with different light beams. This is a way of using one strong laser of a particular color and producing many colors, from blue to green to yellow to red to infrared.”

The laser pulse used was 200 picoseconds long. A picosecond is one-trillionth of a second. Combining the produced light colors in such a fiber could create pulses 200,000 times shorter – a femtosecond (one quadrillionth of a second).

(Via ACM TechNews)