Researchers at UCL in London have shown data links over fibre cable with twice the current speeds to boost internet speeds.
The team, led by Dr Lidia Galdino of UCL Electronic & Electrical Engineering (above), achieved a data transmission rate of 178.08 Tbit/s over a single mode fibre cable used for the Internet.
The team worked with London-based sub-sea fibre cable developer Xtera and Japanese lab KDDI Research on the demonstration over a 40km link, which is twice that of current speeds and 20 percent higher than the previous record speed.
This was achieved by simultaneously using the S-, C- and L-bands with a total bandwidth of 16.83THz, compared to current bandwidth of 4.5THz and emerging systems using 9THz. The signal was optimised for each SNR, wavelength and transmission band to transmit 660 channels each of 25G baud. The 178.08 Tbit/s speed is close to the theoretical Shannon limit for data transmission over a single mode fibre.
The paper in IEEE Photonics Technology Letters describes newly developed Geometric Shaping (GS) constellations that manipulate the properties of each individual wavelength. A key advantage is that this technique can be deployed on existing infrastructure cost-effectively by upgrading the amplifiers that are located on optical fibre routes at 40-100km intervals. Upgrading an amplifier costs around £16,000, while installing new optical fibres can, in urban areas, cost up to £450,000 a kilometre.
“While current state-of-the-art cloud data-centre interconnections are capable of transporting up to 35 terabits a second, we are working with new technologies that utilise more efficiently the existing infrastructure, making better use of optical fibre bandwidth and enabling a world record transmission rate of 178 terabits a second,” said Dr Galdino, a Lecturer at UCL and a Royal Academy of Engineering Research Fellow.
“But, independent of the Covid-19 crisis, internet traffic has increased exponentially over the last 10 years and this whole growth in data demand is related to the cost per bit going