A technique for improving the data rate and transmission distance of an optical fibre communications system is reported in Nature Photonics this week. The approach minimizes the amount of distortion imparted to optical-data signals travelling in long fibre links, which are commonly employed to transport Internet and voice data around the globe.
Rather than encoding data onto a single light beam, Xiang Liu and co-workers used two specially prepared ‘phase-conjugate’ beams, which were effectively mirror images of each other. Because any distortion occurred in the opposite manner in the two beams, combining the beams at the end of the fibre link resulted in significant cancellation of signal distortion.
This scheme reduced nonlinear distortions, which limit the performance of long-distance optical communication links, by a factor of nearly ten. This new configuration allows a 400 Gbit s-1 ‘superchannel’ consisting of eight pairs of such twin beams to be transmitted over a record distance of 12,800 km.