The 2014 game of “leapfrog with fibre speed records” has a new and probably temporary leader, with boffins from China, the US and The Netherlands claiming a 255 Tbps record in a single fibre over 1 km.
As always with such things, it pays to understand the conditions under which the boffins are claiming the record, and the constraints on their technology in the real world.
The fundamental building block of the achievement is a seven-core fibre, and if that sounds familiar, it's because a similar configuration* was recently used by Danish researchers to claim a speed record.
Those multiple cores within the fibre provide seven spatial paths, without needing seven individual fibres (the downside being that to implement the multicore technologies that are now driving speed records means pulling new cables).
However, as Dr Chigo Okonkwo, an assistant professor at Eindhoven explains, the 200 micron diameter of the multicore fibre means they're close to conventional fibres now deployed.
In the record-setting demonstration, a single fibre was able to reach 5.1 Tbps using one wavelength, so with dense WDM of 50 wavelengths, the researchers could hit 255 Tbps aggregate transmission. Even taking into account a discount for overheads, the study (abstract here) claims a net traffic of 200 Tbps over 1 km. ®
*Bootnote: The Register has asked NTT whether its seven-core fibre was used in the latest research.