NTT demos petabit transmission on single fibre
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Japan’s NTT has announced an impressive speed/distance demonstration, achieving one petabit per second over a distance of 50 Km.
The test, which was conducted in conjunction with Fujikura Limited, Hokkaido University, and the Technical University of Denmark, is described as a “new world record over a single strand,” surpassing the previous 305 Tbps mark.
While higher raw speeds have been achieved in the laboratory, at the Petabit range optical transmissions start bumping into rapid distance attenuation. Alcatel-Lucent’s 2009 demonstration of a 100 Pbps.km needed 155 lasers operating at 100 Gbps each to hit its mark, whereas the NTT demonstration runs a much more practical 12 lasers, each operating at 84.5 Tbps.
NTT designed a special fibre that packed 12 cores into a single strand. Mulicore fibre isn’t new, but the company explains that current hexagonal core layouts were unsuitable for this experiment due to crosstalk. The researchers also had to create fan-in and fan-out devices suitable for their fibre.
Rather than an on-off modulation scheme, the researchers created a 32-channel quadrature amplitude modulation (32QAM) technology based on the polarization of the light.
NTT published the research in a presentation to the European Conference on Optical Communications on September 20 – but hasn’t offered an English translation of the document. ®
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