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Scientists Stuff 661Tbps Down a Single Optic Fibre at High Efficiency

Friday, August 3rd, 2018 (8:13 am) - Score 3,788

A team of scientists from Japan and the EU have found a way to replace the use of many parallel lasers with a single frequency comb source, which has enabled them to push data at a speed of 661Tbps (Terabits per second) down a single-mode 30 core optical fibre cable.

Funnily enough the interesting development here isn’t that headline figure of 661Tbps, which has already been beaten by NTT’s transmission rate of 1.05Pbps via a similar multi-core single fibre (using fewer WDM channels and a greater per-channel bandwidth). Instead the focus is on some significant improvements in the underlying laser technology.

The problem is that lasers aren’t the most energy efficient bits of kit in the world (the best ones tend to be 30-50% efficient) and to push more data down an optical fibre cable you often need to stick on a bunch of them (i.e. all running in parallel with each colour requiring its own laser, which is where the usual Wavelength Division Multiplexing has its fun).

Suffice to say that power becomes a growing problem as you increase network capacity, not least by adding more lasers. According to the research team, the internet today transmits hundreds of Terabits per second, consumes 9% of all electricity worldwide and grows by 20-30% per year.

The solution they’ve come up with is to create a single frequency comb source that sends out pulses of light stacked with very pure colours, which are then separated via gaps in frequency (i.e. you don’t need all those individual lasers running in parallel anymore).

Researcher Hao Hu said:

We present a frequency comb realized by a non-resonant aluminium-gallium-arsenide-on-insulator (AlGaAsOI) nanowaveguide with 66% pump-to-comb conversion efficiency, which is significantly higher than state-of-the-art resonant comb sources. This enables unprecedented high data-rate transmission for chip-based sources, demonstrated using a single-mode 30-core fibre.

We show that our frequency comb can carry 661 Tbit s–1 of data, equivalent to more than the total Internet traffic today. The comb is obtained by seeding the AlGaAsOI chip with 10-GHz picosecond pulses at a low pump power (85 mW), and this scheme is robust to temperature changes, is energy efficient and facilitates future integration with on-chip lasers or amplifiers

The related research paper can be found online and Arstechnica also has a good write-up on the many clever changes and tricks that have gone into making this all work. The focus here is largely on high-capacity data links rather than consumer connectivity, although developments like this will all eventually feed into the same network ecosystem.

The work itself was funded by the Silicon Photonics for Optical Communications (SPOC) research centre of excellence (DNRF123), the Nanophotonics for Terabit Communications (NATEC) Villum centre of excellence and the European Union–Japan coordinated R&D project on Scalable And Flexible optical Architecture for Reconfigurable Infrastructure (SAFARI).

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Mark Jackson
By Mark Jackson
Mark is a professional technology writer, IT consultant and computer engineer from Dorset (England), he also founded ISPreview in 1999 and enjoys analysing the latest telecoms and broadband developments. Find me on Twitter, , Facebook and Linkedin.
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23 Responses
  1. Avatar FullFibre

    Yeah but I bet the upload was still only 20Mbps.

  2. Avatar Harry

    It’s great to hear about it but can we have some cables installed first please?

  3. Avatar StillWaitingForSuperfast

    And if you live in a rural area the last 2Km will be via 90 year old (often patched) copper which will reduce the speed to 1Mps.

    • Avatar TheFacts

      Many in rural areas get between 40M and 1G.

    • Avatar TheFacts_Works_in_BT_Marketing

      Dont spout your usual rubbish TheFacts. Most rural ‘areas’ cant get the 10Mbit USO.
      Maybe you should look at coverage instead of the usual commercially viable groups of premises.

    • Avatar GNewton

      @TheFacts: Wrong! I suggest you look at some coverage details on e.g. the Thinkbroadband site to get a realistic picture. Besides, if you are so desperate for a decent fibre connection, you could always start a local campaign to get an alternative fibre provider to build a faster access network in your area.

    • Avatar TheFacts

      What are the coverage numbers?

    • Avatar BrianH

      Constituancy figures
      Superfast UK (>24 Mbps): 81.24%
      Superfast EU (>30 Mbps): 80.55%
      So once you get away from the town and village centres, the coverage for rural properties is pretty poor, just told too far from the cabinet. 4km from the exchange and primary cabinet, 3 km from the infill cabinet.

    • Avatar GNewton

      @TheFacts: “What are the coverage numbers?”

      We don’t do your homework for you. If you are so desperate for better broadband, move to another town, or start a local campaign.

    • Avatar New_Londoner

      Based on ThinkBroadband data,@TheFacts is right that the position in rural parts of the U.K. is a lot better than other posts here suggest. The majority of premises in rural areas can connect to superfast services with download speeds of 24Mbps or better.

      Only a minority cannot get superfast speeds if they wish, and only an even smaller minority cannot get download speeds of at least 1Mbps. Whilst this may be frustrating for the few affected, let’s remember that more than 95% of UK premises can get 30Mbps+.

      A fact-based discussion would be most welcome!

    • Avatar New_Londoner

      The figures for July are:

      * GB Rural – 85.9% 24Mbps or faster, 0.2% under 2Mbps download
      * GB Deep Rural – 77% 24Mbps or faster, 4.3% under 2Mbps download

      Given this data, it’s clear that the majority have reasonable or better speeds (7.9% FTTP in Deep Rural), only a small minority are still limited to slow download speeds. So let’s not exaggerate the rural digital divide.

  4. Avatar TheFacts

    Not a single fibre – 30 core optical fibre cable

    Please change title.

    Meanwhile – BT, together with industry partner Huawei, has now developed a technique which combines multiple 400Gbps wavelengths over a single fibre. Using this new technique, BT’s researchers are confident that speeds of more than 13Tbps can be achieved using the same amount of light spectrum as the previous record.


    • Avatar un4h731x0rp3r0m

      BT brings to you another shill product coming to your home in the year twenty-never!

    • Avatar CarlT


      For all the things you can complain about with regards to BT their not selling supercore transmission technology requiring several rack units of multiple kWh consuming kit to residential users is an odd one.

    • Avatar un4h731x0rp3r0m

      Not as strange as thinking “Widespread adoption of HD and 4K streaming TV services” is not already a reality, particularly for HD which has been around years.
      But anyhow, just another BT thing that nobody cares about.

  5. Avatar Bib

    This research is all good, however, the backbones still run at 40Gbps, or perhaps 100Gbps over a single fibre. With people wanting gigabits to their homes, these links do not support many connections and the backbones will be very expensive to construct. Until these advances are made commercially, they means nothing to both home users and businesses.

    • Avatar CarlT

      Think you’re confusing the Ethernet interfaces on routers with the transmission network carrying them. 100GbE only consumes a dedicated fibre pair to the transmission network. The wavelengths it’s riding on then get multiplexed with others.

      Can support a lot of gigabit connections to homes on a single 100GbE interface, tens of thousands.

  6. Avatar Tim Rossiter

    Yes, in the backbone network you can currently get up to 88 x 100G or possibly 88 x 200G down a single fibre. So 8.8 – 17.6 Tbit on a single fibre.

    And as CarlT says, 100Gbit will support typically up to 50,000 subs. Despite having access rates of 10’s Mbits, the AVERAGE of all subscriber data consumption at peak times is rather surprisingly < 2 Mbit/s (i.e. not every subscriber is consuming HD content 24/7 ).

    • Avatar Bib

      Eh!!! that 17.6Tb is down a fibre BUNDLE of 88 fibres, NOT a single fibre.

      As for 100Gb supporting 50,000 subs. That’s idiotic. That is an average of only 2Mb. Try viewing hd video on that and see how far you get.

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