» ISP News » 

New World Record as Fibre Optic Speeds Pushed to 319Tbps

Friday, July 16th, 2021 (2:22 pm) - Score 4,368

Scientists in Japan have just shattered last year’s world record for the fastest fibre optic internet data transfer speed by using a four core fibre cable to transmit data at 319Tbps (Terabits per second) over a whopping distance of 3001km, which compares with the previous record (here) of 178Tbps over 40km in London UK.

The team used an existing 4-core fibre cable for their test, albeit with the very latest in amplification technologies (some doped in rare earth elements like thulium and others in erbium), as well as Distributed Raman Amplification (DRA), and across three signal bands (S, C and L). 

NOTE: The use of the S band is less common as in past tests it has significantly reduced the transmission distance, but this team were able to overcome that.

After that a 552-channel comb laser was then used to send the signal across the various wavelengths and down the fibre (i.e. 552 PDM-16QAM, wavelength-division multiplexed [WDM] channels). The cable itself had the same cladding diameter (125 µm) as standard single-core optical fibre, which ensures some compatibility with conventional cabling infrastructure and reduces concerns over the mechanical reliability of larger fibres.

In order to boost the signal, the aforementioned amplifiers were deployed at intervals of 69.8km along the cable.


The team, which are based at the National Research and Development Agency (NICT) in Japan, plan to continue their development of wide-band, long-distance transmission systems, with the aim of achieving further improvements in transmission speed and range.

As we always say, you’re unlikely to see this sort of speed being delivered to homes anytime even remotely soon, but it is the sort of work that could be harnessed in the future to boost the performance of longer international (e.g. subsea) and national fibre routes. The ability to carry more data down existing cables also tends to result in cheaper capacity from suppliers, which ultimately benefits broadband ISPs and their customers too.

Share with Twitter
Share with Linkedin
Share with Facebook
Share with Reddit
Share with Pinterest
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.
Leave a Comment
18 Responses
  1. André says:

    The London test you mentioned was in a single fibre, though.
    Impressive data rates for sure!

    1. Billy Nomates says:

      yeah this is the thing, i’ll wager if the UK test had used 4 cores instead of 1 they could well have exceeded this record, but the distance is vastly different too, it’s not really a comparable test. But we should maybe set a standard length for tests then we can compare apples to apples.

  2. Aled says:

    “you’re unlikely to see this sort of speed being delivered to homes anytime even remotely soon”

    300Tb/s? Pah, I only wish I could get those speeds here. I can only achieve 300meg here in rural Wales. Can barely use the telly with that! When will Virgin sort their act out??


    1. Billy Nomates says:

      Gigabit will be available in my area soon, they’re pulling the fibres right now. I may end up getting gigabit because I want the 200mbit upload speed. I’d be much happier with a cheaper 200/200 though as that would be perfect.

    2. Aled says:

      Ha, good luck! Openreach vans are everywhere right now.

      I think 10meg makes internet viable. 40 is comfortable. Anything North of 200meg is luxury!

    3. GNewton says:

      “I’d be much happier with a cheaper 200/200 though as that would be perfect”

      Agreed, though some regular posters here on ISPReview claim there is no need for symmetric fibre. Good upload speeds are essentials for certain types of applications and businesses, broadband is not always about down-streaming services only.

    4. Ryan says:

      Only 300 – poor you!

      Max 25/4 here and now in the rural up to 2026 so not changing anytime soon. Luckily only 4 people needing to WFH/Xbox download/Stream everything.

    5. Aled says:

      Ryan, I was being sarky!!!

  3. Chris Ambition knows no bounds Sayers says:

    Beam me up Scotty, getting on a jet plane will be a thing of the past, once they have mustered the little thing of teleportation, we are going to need all the bandwidth we can lay our hands on.

  4. Ig Og says:

    If only they’d used hollow fibres.

    1. Josh Welby says:


      BT is trailing it at the moment

  5. Bib says:

    Who cares if they are sending it 3000km if they need amplifiers every 70km.

    I only care about numbers where amps are not used.

    The transatlantic cables are anywhere from around 7000km to 13,000km. Having 100+ amps on that is just another large points of potential failure.

    1. Gary says:

      Rather bigger problem than the points of failure would be the provision of power to the amplifiers.

    2. CarlT says:

      Whether this is intentional trolling or being poorly informed it’s not funny either way which kinda makes it lose the impact.

      Gary – the power is delivered over copper incorporated into the transatlantic cable. One custom made cable, optics and power in one.

    3. 125us says:

      Bib, transatlantic cables have amplifiers. Any optic link over a significant distance has amplifiers.

  6. Essa says:

    truly mind-blowing numbers, and like many have already said. As the global demand for data grows, we will see the transatlantic cable getting to their maximum utilization so this is a good way to get more out of the same cable.

    One thing I can’t get my head around:

    – Sure the cable can handle that speed, but what is the equipment to measure the speed, I.E there is nothing on planet earth which can write that fast to a disk or even computer memory, unless I have missed my math somewhere!? So my question is how the hell did they manage to measure the speed?


    1. CarlT says:

      That capacity was the sum of 552 wavelengths. It would’ve been measured at the transmission equipment either side.

      Each wavelength was carrying less than 600 Gbit/s as a 16-QAM modulated carrier.

      A swift Google points to http://www.nict.go.jp/en/press/2021/07/12-1.html which carries more information.

    2. 125us says:

      The throughput is the sum of the line rate of each wavelength. It can be calculated rather than measured because the speeds that get summed are not variable.

      Using an analogy – if I buy and strap together a thousand two litre bottles, I don’t need to fill them and empty them to know the total capacity.

Comments are closed.

Comments RSS Feed

Javascript must be enabled to post (most browsers do this automatically)

Privacy Notice: Please note that news comments are anonymous, which means that we do NOT require you to enter any real personal details to post a message. By clicking to submit a post you agree to storing your comment content, display name, IP, email and / or website details in our database, for as long as the post remains live.

Only the submitted name and comment will be displayed in public, while the rest will be kept private (we will never share this outside of ISPreview, regardless of whether the data is real or fake). This comment system uses submitted IP, email and website address data to spot abuse and spammers. All data is transferred via an encrypted (https secure) session.

NOTE 1: Sometimes your comment might not appear immediately due to site cache (this is cleared every few hours) or it may be caught by automated moderation / anti-spam.

NOTE 2: Comments that break our rules, spam, troll or post via known fake IP/proxy servers may be blocked or removed.
Cheapest Ultrafast ISPs
  • Gigaclear £17.00
    Speed: 200Mbps, Unlimited
    Gift: None
  • Community Fibre £20.00
    Speed: 150Mbps, Unlimited
    Gift: None
  • Hyperoptic £20.00
    Speed: 158Mbps, Unlimited
    Gift: Promo code: HYPERSALE
  • Virgin Media £25.00
    Speed: 108Mbps, Unlimited
    Gift: None
  • Vodafone £25.00
    Speed: 100Mbps, Unlimited
    Gift: None
Large Availability | View All
New Forum Topics
Morecambe fttp
Author: Gingeee85
Huawei B818-263
Author: teleman6868
Anyone on Giganet?
Author: jalzoo
Cheapest Superfast ISPs
  • Hyperoptic £17.99
    Speed 33Mbps, Unlimited
    Gift: Promo code: HYPERSALE
  • NOW £20.00
    Speed 36Mbps, Unlimited
    Gift: None
  • Shell Energy £21.99
    Speed 35Mbps, Unlimited
    Gift: None
  • Vodafone £22.00
    Speed 38Mbps, Unlimited
    Gift: None
  • Plusnet £22.99
    Speed 36Mbps, Unlimited
    Gift: £70 Reward Card
Large Availability | View All
The Top 20 Category Tags
  1. FTTP (4126)
  2. BT (3154)
  3. Politics (2121)
  4. Building Digital UK (2028)
  5. Openreach (1970)
  6. FTTC (1923)
  7. Business (1836)
  8. Mobile Broadband (1607)
  9. Statistics (1513)
  10. 4G (1380)
  11. FTTH (1371)
  12. Virgin Media (1277)
  13. Ofcom Regulation (1242)
  14. Fibre Optic (1235)
  15. Wireless Internet (1234)
  16. Vodafone (927)
  17. EE (907)
  18. 5G (899)
  19. TalkTalk (821)
  20. Sky Broadband (787)
Helpful ISP Guides and Tips

Copyright © 1999 to Present - ISPreview.co.uk - All Rights Reserved - Terms , Privacy and Cookie Policy , Links , Website Rules , Contact