Researchers achieve optical data transmission speed of 44.2 terabits per second

Abstract:

> Micro-combs - optical frequency combs generated by integrated micro-cavity resonators – offer the full potential of their bulk counterparts, but in an integrated footprint. They have enabled breakthroughs in many fields including spectroscopy, microwave photonics, frequency synthesis, optical ranging, quantum sources, metrology and ultrahigh capacity data transmission. Here, by using a powerful class of micro-comb called soliton crystals, we achieve ultra-high data transmission over 75 km of standard optical fibre using a single integrated chip source. We demonstrate a line rate of 44.2 Terabits s−1 using the telecommunications C-band at 1550 nm with a spectral efficiency of 10.4 bits s−1 Hz−1 . Soliton crystals exhibit robust and stable generation and operation as well as a high intrinsic efficiency that, together with an extremely low soliton micro-comb spacing of 48.9 GHz enable the use of a very high coherent data modulation format (64 QAM - quadrature amplitude modulated). This work demonstrates the capability of optical micro-combs to perform in demanding and practical optical communications networks.

I agree with you that microcombs come with their specific kind of challenges (and SNR is the big one), however making many semiconductor lasers so small as too fit 100 on a single chip poses lots of challenges (in particular thermal management and wavelength stability). That said, combs (not necessarily microcombs) over opportunities for additional functionality/optimizations. Because the comb lines are locked to each other (normally individual lasers have small wavelength fluctuations) let's you space channels even closer together, as well as process multiple channels at the same time.

Regarding your comment about these hero experiments not being hard, I would argue it's actually the other way around, we are now so close to the limits that it is becoming incredibly hard to observe further gains. Also regarding not modulating lines independently, this is the common way how everyone (even the industry labs) demonstrates these systems, using 100 independent transceivers would be prohibitevely expensive, moreover research has shown that you actually receive a penalty from using this approach so the demonstration is a lower bound on what could be achieved with individual tx modules.

Yes, we will find ways to spoil the gains arguing it doesn't matter.

Yes, we need better software (engineers).

The improvement here seems to be "single chip" source.

Ah ok, so according to the article (https://www.nature.com/articles/s41467-020-16265-x.pdf),

> To dramatically increase bandwidthcapacity, ultrahigh capacity transmission links employ massivelyparallel wavelength division multiplexing

and

> All of this is driving the need forincreasingly compact, low-cost and energy-efficient solutions

and

> The ability to supply all wavelengths with a single, compact integrated chip,replacing many parallel lasers, will offer the greatest benefits

So it's not really so much news in the sense that existing speeds over fiber have been improved, but instead in the sense that the speed produced by this single chip is a viable compact, low-cost and energy-efficient alternative to many parallel chips

This has actually been a big research topic over the last 8 years or so. The keywords are space division multiplexing (SDM) and in particular Mode division multiplexing (MDM)

I think latency of a network will always lag behind that of local storage.

Even traveling at the speed of light, going around the circumference of the earth takes over 100ms. Obviously not all network requests go around the globe, but the fact that local storage is physically closer to your computer will always be a sizeable advantage.

It’s not even the future. 40 gig Ethernet is already faster than most SSDs. And you can get a card on eBay for $200.

Memory access latency is already the biggest bottleneck when it comes to optimization, both disk and RAM.

Electro-optic conversion is expensive in terms of power, so you better be sure it's necessary. There are still some people looking at hybrid computers with both optics and electronics. To be practical, you'd need both to be realized in the same platform, but they don't exactly work on the same scales, and laser integration is a big issue.

I'm sending right now at home 7TB from my server to my NAS and it's taking aaages over my internal 1Gb/s ethernet network.

Am I right thinking that there are (still) no SOHO network switches that can handle faster speeds (at least 2Gb/s) that don't have active fans & don't get hot and that aren't super-expensive? The last time I checked, about 1 year ago, I didn't manage to find anything.

That was over 1km utilising 7 cores. Typical fibre plants use one core per direction (transmit / receive).

This is over 75km utilising a single core per direction. IE this is actually something that has potential to be deployed in the world without having to replace all the existing fibre plants that already exist (eg undersea cables)

Bundled links via ECMP or even round robin are a valid strategy.

I wonder if that figure includes WISPs and cellular, which would bring down the average considerably.

Because that assumption would means everyone is getting a GPON / Fibre Network. In reality even if 20% of the nation is still connected via ADSL, your average speed would have been significantly lowered.

I still think we haven't fully solved the last mile problem yet. Fibre installation still sucks for most people. And vast majority of new home dont have additional pipes for Fibre built in.

We will be able to make comments complaining about bloated JavaScript libraries at lightning speed.

Aren’t gamers primarily concerned with latency rather than speed?

This isn't the kind of thing that we're going to see in home internet for a long time. The newest WiFi standard is only 10Gbps at best, and routers and wired standards aren't affordable over 10Gbps yet either for home use. For internet connections, there are currently already consumer standards that can do 10Gbps symmetric (like NG-PON2) which hopefully we see being deployed more widely soon. Even in 15 years I would be surprised if the high-end of available speeds for home connections are more than 2-5x that (Of course, companies that can pay for dedicated links can already get 100Gbps+ today).

The technology in the article, if commercially practical, would first go in to carrier networks and the larger enterprise market for backhaul transit links in the next few years, then over time filter down to general enterprise networking.

Even if transit providers upgrade, it wouldn't actually be a noticeable change, because they can already do this kind of link, just with a rack with dozens of laser modules that are optically multiplexed together. This does that in a single chip which would reduce cost a lot.

This improves the speed achieved with a single chip, not the actual maximum speed possible with fiber. We already have links that can go faster than this, this invention will likely just make those high speed links cheaper / more compact / easier to manufacture.

This would never be for a home access point. This would be used for long-haul communications (i.e. between metro areas). The data rates there are already pretty ludicrous. The current standard is called 800G, for 800 Gbit/s per wavelength.

The research here is all about core and metro networks, so those are the networks connecting metropolitan areas to each other and the ones connecting the big users within metro areas. The home users and mobile users are not directly connected to these networks, but through e.g. your providers passive optical network. You can think about this similar to a road network, you are living on the little side roads, these are the big highways and ring roads. But because everyone is using more and more data on their home and mobile devices, there needs to be bigger pipes in the core network (despite more and more local data centres for caching)

This is a field that's constantly being worked on, not sure why you say there isn't a "push" in it.

This specific thing is not faster than previous results, but more compact.

Long-distance fiber lines also have amplifiers along the way, so you can't just scale them up by changing the endpoints if it doesn't match the capability of the in-line hardware.

One can barely get 1Gbps connections in the UK, and in most parts even 10Mbps is a lot. TBps may have to wait a few eons.

Yeah, this confuses me. Gigabit is available in several places in North America. I had to check the date on the article.. posted 20 hours ago. Yep. Still confused.

Err dude, you aren't reading. This is AVERAGE speed. The average internet speed in the US or UK is nowhere near 197 megabits. In the UK it's 28.9Mb and in the US 32Mb.

Much better, because what the heck is "internet speed". The most sensible definition to me is payload over IP protocol possibly on an existing commercial link. That's the only way I see relation to internet and the internet.

But it is directly internet related. If you check the actual paper [0] - I had to search for it - you will see this quote:

  We demonstrate transmission over 75 km of fibre in the
  laboratory as well as in a field trial over an installed
  network in the greater metropolitan area of Melbourne,
  Australia.

Technically that 75 km was between two different labs running on dark fiber. They state more detail in this quote:

  These cables were routed from the labs access panels, 
  to an interconnection point with the AARNet’s fibre
  network.

[0] - https://www.nature.com/articles/s41467-020-16265-x

I've taken a crack at it.