Working with two companies, Xtera and KDDI Research, the research team led by Dr Lidia Galdino (UCL Electronic & Electrical Engineering), achieved a data transmission rate of 178 Tbit/s – a speed at which it would possible to download the entire Netflix library. in less than a second.
The record, which is double the capacity of any system currently deployed in the world, was achieved by transmitting data through a range of colors of light or wavelengths much wider than that typically used in fiber. optical. (Current infrastructure uses a limited bandwidth of 4.5 THz, with commercial 9 THz bandwidth systems entering the market, whereas researchers have used 16.8 THz bandwidth.)
To do this, researchers combined different amplification technologies needed to increase signal power over this wider bandwidth and maximized speed by developing new geometric shaping (GS) constellations (patterns of signal combinations that best exploit the phase, luminosity and polarization properties of light), manipulating the properties of each individual wavelength. The exploit is described in a new article IEEE Photonics Technology Letters.
The advantage of the technique is that it can be deployed on already existing infrastructure in a cost-effective way, by upgrading amplifiers located on fiber optic routes at intervals of 40 to 100 km. (Upgrading an amplifier would cost £16,000, while installing new fiber optics can, in urban areas, cost up to £450,000 per mile.)
The new record, demonstrated in a UCL lab, is a fifth faster than the previous world record held by a team in Japan.
At that speed, it would take less than an hour to download the data that made up the world’s first image of a black hole (which, due to its size, had to be stored on half a ton of hard drives and transported by plane) . The speed is close to the theoretical limit of data transmission established by the American mathematician Claude Shannon in 1949.
Lead author Dr Galdino, a senior lecturer at UCL and a Royal Academy of Engineering Research Fellow, said: “While state-of-the-art cloud data center interconnects are capable of transporting up to 35 terabits per second, we work with new technologies that use existing infrastructure more efficiently, making better use of fiber optic bandwidth and enabling a world record transmission rate of 178 terabits per second.
Since the start of the COVID-19 crisis, demand for broadband communication services has exploded, with some operators experiencing an increase in internet traffic of up to 60% compared to before the crisis. In this unprecedented situation, the resilience and capacity of broadband networks have become even more critical.
Dr Galdino added: “But regardless of the Covid-19 crisis, internet traffic has grown exponentially over the last 10 years and all of this growth in data demand is tied to the falling cost per bit. . The development of new technologies is crucial to maintain this downward trend in costs while meeting future demands for data throughput that will continue to increase, with yet unimagined applications that will transform people’s lives.
This work is funded by the Royal Academy of Engineering, Royal Society Research Grant and EPSRC TRANSNET Program Grant (EP/R035342/1).
“Fiber Optic Capacity Optimization through Continuous Bandwidth Amplification and Geometric Shaping” is available here (abstract only freely available).
According to the newspaper:
Hybrid discrete Raman and rare-earth doped fiber amplifiers were used to enable wideband signal gain, with no spectral deviations between amplification bands.
The continuous coherent transmission bandwidth was 16.83 THz, achieved using the S, C and L bands simultaneously, and claimed to be the widest experimentally demonstrated to date.
A significant wavelength-dependent signal-to-noise ratio (SNR) existed, requiring the signal to be optimized for each SNR, wavelength, and transmission band.
178.08 Tbit/s was defined over 40 km using 660 channels of 25 GBd.
