[HN Gopher] Fiber-optic data transfer speeds hit a rapid 301 Tbps
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Fiber-optic data transfer speeds hit a rapid 301 Tbps
Author : Brajeshwar
Score : 78 points
Date : 2024-03-29 13:51 UTC (9 hours ago)
(HTM) web link (www.livescience.com)
(TXT) w3m dump (www.livescience.com)
| judge2020 wrote:
| The University's article: https://www.aston.ac.uk/latest-
| news/aston-university-researc...
|
| Although even the university article doesn't link the paper..
| tombert wrote:
| I know basically nothing about computer engineering or
| electronics, so bare with me on this, but conceivably could tech
| like this be used _inside_ a computer?
|
| As in, instead of just using fiber to make different computers
| talk to each other really fast, could we use it for like a RAM
| bus or something? Is there too much latency associated with it
| compared to the copper we've been using? 301 Tbps seems like
| insane speeds, even inside a computer.
| 486sx33 wrote:
| The biggest problem I see from 10,000 feet is you'd need to
| constantly be converting electricity to light and back again...
| there is a penalty for that in speed... so far putting ram on
| die with the cpu has been the best way to reduce that
| particular form of latency...
| op00to wrote:
| There is also a heat penalty.
| 486sx33 wrote:
| Great point!
| tw04 wrote:
| This specific tech perhaps not. But yes, silicon photonics is a
| thing.
|
| https://www.tomshardware.com/news/intel-demoes-8-core-528-th...
| alex_duf wrote:
| Theoretically? Yes
|
| https://en.m.wikipedia.org/wiki/Optical_computing
| Workaccount2 wrote:
| I almost get nostalgic reading about optical computing, it's
| something I remember reading about 20 years ago as a
| promising field for future development. As far as I can tell
| though, it's something that still hasn't gotten out of the
| lab.
| Aurornis wrote:
| Optical interconnects within a system are very much a
| possibility, but they are prohibitively expensive.
|
| Going from copper to optics and back again at the other end is
| significantly more expensive than using mechanical connectors.
| The complexity of optical fibers and their interconnects also
| adds a lot more assembly difficulty and failure opportunity.
|
| We still have a lot of headroom in copper interconnects, but
| it's getting more and more difficult to squeeze bandwidth out
| of longer distances interconnects like those between your CPU
| and your GPU slot. Next generation systems might need retimer
| chips at the halfway point to basically rebuild and retransmit
| the signal so it can make it the full distance. We also have to
| use more expensive PCB materials to reduce the cost. There may
| come a day when we have to connect the CPU and GPU optically,
| but it's going to be a while before we get there.
| morphle wrote:
| Yes, basic physics shows [1] that we can use (free space)
| optics instead of wires inside chips. This will improve energy
| use and speeds by 3 orders of magnitude. Next to a transistor
| you put a photon detector. You can flip the transistor with the
| voltage from the photon detector by sending 10000 photons (or
| less). Pictures of such systems in the slides [2].
|
| We can beam billions of optical channels with different
| frequencies in parallel across chips, exabits (yettabits,
| yottabits) per second.
|
| We will not compute with photons tough [4][5], the optical
| structures are to large and it would only work for very
| specific types of computations.
|
| We design wafer scale integrations (very large chips) this way
| we can start making these fast on-chip interconnects around
| 2027 if we invest a few billion today in making free space
| optics. A layman's introduction in my talk here [3].
|
| [1] Stanford Seminar - Saving energy and increasing density in
| information processing using photonics - David B. Miller
| https://www.youtube.com/watch?v=7hWWyuesmhs
|
| [2] https://www.researchgate.net/profile/David-
| Miller-65/publica...
|
| [3] Smalltalk and Self Hardware https://vimeo.com/731037615
|
| [4] D. A. B. Miller, "Are optical transistors the logical next
| step?" Nature Photonics, vol. 4, pp. 3-5, 2010.
| https://www.researchgate.net/profile/David-Miller-65/publica...
|
| [5] Attojoule Optoelectronics for Low-Energy Information
| Processing and Communications - a Tutorial Review
| https://arxiv.org/pdf/1609.05510.pdf
| freedomben wrote:
| Amazing, thank you!
|
| How much parallelization is required? Any idea how fast a
| single channel could get with optical transport and photon-
| detecting transistors?
|
| As an Elixir dev (where parallelization is relatively easy),
| I think there is a lot of potential for parallelization that
| isn't being used by most programs, but for serial algorithms
| where multi-core can't be used, I wonder what the ceiling
| will be.
| morphle wrote:
| > Any idea how fast a single channel could get with optical
| transport and photon-detecting transistors?
|
| Terabits per second per channel would be possible but it
| would require to much high energy SerDes (serializer-
| deserialiser) circuits. It will be more energy efficient to
| have more parallel optical channels (bundled) switching at
| the low power optimal speed of the transistors, around 1-2
| Ghz instead.
|
| >I wonder what the parallelisation ceiling will be? How
| much parallelization is required?
|
| There is no ceiling, no limit, for example look at an
| "existence proof": there are around a hundred trillion
| cells in your body that perform billions of computations
| chemically and also with DNA processing by ribosomes in
| parallel. No limit. Those 8 billion bodies theoretically
| could learn to work together with the aid of internet and
| personal computers. There are 10^24 stars in the universe.
|
| Your thinking, your imagination, your thinking brain
| modelling of parallel systems is the ceiling, the limit.
| But you can learn, experiment and improve over time so your
| limits on thinking up better ways to parallelise
| computation will improve. Humanity could dedicate itself to
| the open ended creation of knowledge (of knowing how to
| compute in parallel with photons without limits) [1].
|
| Right now our computation limits are limited by our
| knowledge (of manufacturing at atom scales), the energy
| output of the sun and the amount of atoms in the solar
| system we could rearrange [4]. We should fund our
| scientists to create the knowledge we need to enlarge the
| limits [5]. I hope you'll fund me as well :-)
|
| > Elixir development
|
| Smalltalk, LISP, Erlang, Elixer, Actor Language are some of
| the best message passing programming languages for
| massively scaling parallelism.
|
| Alan Kay [2][3] has great lectures to get you started in
| thinking better (including about (computational)
| parallelism, scaling and message passing). A few others
| have written some papers as well (see links in my HN
| comments the last 12 weeks). I can teach you a bit too,
| write to morphle73 at gmail dot com.
|
| [1] Chemical scum that dream of distant quasars https://www
| .ted.com/talks/david_deutsch_chemical_scum_that_d...
|
| [2] Alan Kay lecture: putting Turing to work
| https://www.heidelberg-laureate-forum.org/video/lecture-
| putt...
|
| [3] Is it really "Complex"? Or did we just make it
| "Complicated"?
| https://www.youtube.com/watch?v=ubaX1Smg6pY&t=2557s
|
| [4]
| https://gwern.net/doc/ai/scaling/hardware/1999-bradbury-
| matr...
|
| [5] https://internetat50.com/references/Kay_How.pdf
| freedomben wrote:
| Thank you! Minor clarification, for performance ceiling I
| was wondering about for serial (not parallel)
| morphle wrote:
| The sequential process performance ceiling will be set by
| physical limits. Photons at high frequenties have too
| much energy, for example gamma rays.
|
| The practical ceiling will be set by manufacturing
| limitations for the next few decades: can we build
| structures atom by atom? [1]
|
| [1] Richard Feynman "Tiny Machines" Nanotechnology
| Lecture - aka "There's Plenty of Room at the Bottom"
| https://www.youtube.com/watch?v=4eRCygdW--c&t=1390s
| bgnn wrote:
| Theoretically yes. Though it makes 0 sense and difference in
| practice. The conversion between electrical and optical isn't
| straightforward and it isn't cheap to implement now. Let's say
| we've resolved this. We are still limited by the same latency
| of the channel, i.e. speed of light is roughly the same in
| fibre-optics and metal interconnects we use on chip now for
| electrical signals. Meaning, electrical signals we use are as
| fast as light. So, no delay advantage.
|
| The biggest advantage of optical is less loss, which makes a
| huge difference for a long channel. By this I mean really long,
| like meters. Till that point it has literally no advantage
| while it is so much more complicated.
| nsteel wrote:
| I think this original question was between devices within a
| computer, rather than within a single chip/package. Optical
| interconnects within high-end servers/routers are being
| designed today for use in the next generation. We previously
| reached the limits of copper pcb traces, coax has lots of
| problems, optical is next. It's not about latency, it's about
| signal integrity.
|
| Ironically, the heat produced by the optical transceivers is
| one of the biggest problems.
| shutupnerd0000 wrote:
| > bare with me
|
| I would prefer to keep my clothes on, thanks.
|
| (It's spelled "bear with me")
| tombert wrote:
| Ugh, for some reason my brain can never remember which
| version to use for that. It's always a 50/50 shot and I guess
| I came up tails this time.
| 0_____0 wrote:
| Language is funny. Some of the best engineers I know have
| terrible spelling.
| qwertyuiop_ wrote:
| Yet my ComcastUniversalNBC Cable sputters at 30 Megabits per
| second.
| ejb999 wrote:
| Yea, but at least you get to pay thru the nose for it. </sarc>
| ksec wrote:
| > Japan breaks world record ( 319 terabits per second ) for
| fastest internet speed (freethink.com) 2021.
| https://news.ycombinator.com/item?id=28673726
|
| So nothing really new. I am still looking forward to 1 Pbps. And
| more undersea cable being built.
| bolp wrote:
| At the end of the article they mention the world record of 22.9
| Pbps was set by a team at NICT in November 2023.
|
| See this link for more info:
| https://www.nict.go.jp/en/press/2023/11/30-1.html
| sjm wrote:
| Does this mean anything for actual latency, or only bandwidth?
|
| e.g. speed of light could mean a ~40ms ping between LA and
| Sydney, but best we get today is probably around 150ms?
| greggyb wrote:
| The speed of light in fiber (or electrical signal in copper) is
| less than the speed of light in vacuum.
|
| There are delays (very small) converting a signal from
| electrical on one end of the fiber to light and back to fiber
| on the other end. For this reason, DAC tends to have measurably
| lower latency compared to fiber for in-rack networking.
|
| The length of an undersea cable is greater than both the
| straight line and the great circle distance between two points
| on the earth's surface.
|
| These things do not explain all (probably not even most) of the
| difference between the latency you suggested and that in the
| real world, but I hope they help to suggest why the naive
| calculation is not achievable.
| denotational wrote:
| > both the straight line and the great circle distance
|
| Curious what you mean by "straight line"; Rhumb line?
| greggyb wrote:
| I meant the equivalent of boring a very deep and long
| tunnel (: I should have been more specific.
| cycomanic wrote:
| This is only throughput. The latency is given by the speed of
| light in the fibre (~c/1.5). That said Microsoft bought a
| company that develops hollow core fibre which yields a factor
| 1.5 improvement in latency. They just presented their latest
| results which is a 0.11 dB/km loss. This is actually the
| biggest result from the conference, because it is a massive
| improvement over regular fibre which has been hovering at about
| 0.15 dB/km loss for the last 40 years, with improvements below
| 1% over that time.
| foobiekr wrote:
| I'm not so sure it will matter much. The earth is 42ms across
| at light speed, 66ms if traversing a great circle.
|
| Network hops are notoriously slow. In the datacenter the best
| I have ever seen is 200ns or so per packet which is very
| rare, most in DC hops are closer to 3-9 usec (especially
| modular chassis); then you hit the routers. With moderate
| congestion your routing hops are going to be twice that or
| more ignoring queuing, and you are likely six hops at least
| between two points in each direction.
|
| The hollow core stuff mostly will jot help since it gains
| with distance, but distance means more hops on average, so we
| are talking about an application where low latency is
| required but distances are high (where the improvement
| applies) but the minimum latency achievable is still tens of
| ms.
|
| It is interesting technology but I think it's more
| interesting for hypothetical materials savings than for
| latency improvement.
| falsandtru wrote:
| The latest world record is updated to 378.9 Tbps by the same
| research group. Probably not yet published in English.
|
| https://www.nict.go.jp/press/2024/03/29-1.html
| virtuallynathan wrote:
| Pretty wild for a single fiber, but super involved, using 5
| different doping type amps. Current systems use just EDFAs
| (Erbium). These guys used Erbium, Thallium, Bismuth, and
| others.
| foobiekr wrote:
| The latest one is also just more lambdas. Like that's
| impressive but DWDM itself took a decade+ after gear was
| introduced.
|
| Most of the time it's easier to just add another few dozen
| fibers when laying cables.
| kyleleelarson wrote:
| I am curious why the term "fiber optic" seems to have declined in
| popularity, as least when it comes to big companies' annual
| reports: see
| https://searchsecdata.com/search?stockindex=S%26P+500&search...
| rkagerer wrote:
| Is the 1 really important here? I would have rounded down the
| headline.
| 0cf8612b2e1e wrote:
| How congested are undersea network cables? I naively assumed that
| the deployment was so expensive that the cable diameter(stands?)
| would be hilariously over provisioned so that the available
| bandwidth would far eclipse present needs.
| okdood64 wrote:
| I had understood past a certain point diameter doesn't add
| bandwidth?
| lukevp wrote:
| I think they mean diameter of multiple strands, routed
| together in the same jacket
| supertrope wrote:
| Deployment is most of the cost so based on that you'd think
| they'd choose 288 strands. But amplification requirements go up
| with strand count. So the solution used is single digit number
| of strands with many wavelengths.
| larodi wrote:
| This magazine contains ridiculous amount of ads - more than
| actual content on a single screen span. Wonder whether we really
| need to get news this way and especially on a renowned aggregator
| like HN.
|
| Note: ad blockers don't work on iOS.
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