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Networking Science

New Laser Data Transfer Rate Record Set At 26 Tbps 127

Posted by Roblimo
from the squeezing-gallons-of-data-through-a-straw dept.
MasterPatricko writes "Scientists at the Karlsruhe Institute of Technology (KIT), Germany have published a technique to push optical data transfer rates to new levels. The article says, 'The trick is to use what is known as a "fast Fourier transform" to unpick more than 300 separate colours of light in a laser beam, each encoded with its own string of information.'"
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New Laser Data Transfer Rate Record Set At 26 Tbps

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  • Makes Sense... (Score:3, Insightful)

    by WarpedCore (1255156) on Monday May 23, 2011 @01:23PM (#36219300)
    So that one episode in Voyager where Seven of Nine makes a "Fourier Analysis" wasn't total bullshit?
    • Re: (Score:3, Informative)

      by Anonymous Coward

      So that one episode in Voyager where Seven of Nine makes a "Fourier Analysis" wasn't total bullshit?

      No, we've been doing Fourier analysis for decades. Fourier himself invented it in the 19th century.

      Regarding the technique, it sounds like an optical-computing implementation of OFDM (orthogonal frequency division multiplexing) [wikipedia.org], which is a core technology for ADSL and many other communications protocols. Electronic and radio OFDM is limited by peaking factor (the ratio of peak level to RMS level); doing this optically may get around this problem.

      • But surely, if they are using Fourier techniques, they could just transfer on infinitely many frequencies at once, yeah? I mean, such a device would have Tbps, puking in the face of this measly 12 Tbps in TFA...
        • would have Tbps

          ... and silly me for assuming /. supported a character encoding that became the de facto standard years ago.

          :% s/Alt+221E/infinity/g

        • I am somewhat new to Fourier transforms but have been recently working with creating FFTs for audio. My understanding is this: at least in the audio field, you can think of a Fourier transform as pretty much a list of sine waves (frequency, phase and amplitude) that can be added together to recreate a particular window of sound. All sound is made up of it's constiuent sine waves and this is the basis for a lot of digital signal processing and other audio/sound crap we know today.

          Anyway, here is the thing: t

    • by elPetak (2016752)

      And if the technology using photons keeps advancing maybe some day we'll have bridges like the ones in "The Dig".

    • So the low slot tracking mod 'Fourier Transform' in EVE Online isnt total bullshit?
    • by pclminion (145572)
      Saying they used Fourier transforms is a "no shit" sort of statement. It's like saying you used a shovel when you dug a hole. You'd have to go out of your way NOT to use some aspect of Fourier theory in this problem space. By "used an FFT" they probably mean they're doing some form of OFDM modulation.
    • We do the same thing with MRI scans to reduce scan times, varying the extent of the transform to alternate between speed and quality.
  • by Anonymous Coward
    But the FIRST line in the article was:

    At those speeds, the entire Library of Congress collections could be sent down an optical fibre in 10 seconds.

    Well played, BBC. Well played, indeed...

    • by _0xd0ad (1974778)

      The best part is they were off by a factor of 8, since Tbps means terabits per second. Not so well played after all...

      • by toetagger (642315)

        I know, it sucks having to wait 1:20 minutes for my LoCs instead of the average 0.17 minutes - I'm so disappointed in this new technology, so yesterday!

    • by smitty97 (995791)
      I wanted to double check exactly what a "Library of Congress" was so I went right to the source [loc.gov]:

      "Today the Law Library’s expansive reading room and its administrative offices occupy the second floor of the Madison Building, while the sub-basement provides more than a football field of compact collection storage space."

      ugh.

    • by blair1q (305137)

      But why, you should have asked, is the BBC giving figures in units of LoCs?

      They don't have books in Blighty?

      • by tepples (727027)

        But why, you should have asked, is the BBC giving figures in units of LoCs?

        Is the Library of Parliament (or whatever they call it) as big as the Library of Congress? If not, that might be part of your answer.

        • by jd (1658)

          The British version of the Library of Congress would be the combination of the National Archives and the British Library. Given the BBC partly functions in the manner of the FCC, you may need to include the BBC archives in there as well. The sum total of these three collections probably exceeds the Library of Congress but there's no collective name for all of this information.

          • The BBC doesn't function anything like the FCC. The body you're looking for there is OFCOM. They handle frequency allocation*, what little broadcast content regulation we have**, the sort of thing the FCC would handle in the US. The US doesn't really have a counterpart to the BBC. The closest would be PBS, but they differ in some very important ways.

            *Much like the FCC, they'll occasionally say something about public benefit before auctioning it all off to the highest bidder.
            **As we don't have that many r
    • Boy, this will REALLY piss off the those entertainment fat cats...

      They got upset because transferring a portion of their catalog no longer had a "cost" associated with it. What are they gonna do when transferring their entire catalog no longer even has a time-cost associated with it?

  • they used the American measuring system I'm familiar with: the Library-of-Congress.

    At those speeds, the entire Library of Congress collections could be sent down an optical fibre in 10 seconds.

    It surprised me that this came from bbc.co.uk

    • by smitty97 (995791)

      what does that work out to in the metric system?

      • by idontgno (624372)
        I believe the SI version is the "Library of Progress", since the metric system is relatively progressive and "pro" is clearly the opposite of "con" (the key prefix in the Congressional System).
  • Lets see what happens when we send Congress through this thing?

    • by blair1q (305137)

      As this is a fairly large tube, they should all fit just fine, especially if the go in brain-first.

      • by mr1911 (1942298)

        As this is a fairly large tube, they should all fit just fine, especially if the go in brain-first.

        You realize he was talking about Congress, right?

        • by blair1q (305137)

          yes. it's always easier to get something into a narrower space if you start with the pointy end.

  • Serious question: It seems like it could be possible to use an infinite number of colors with interpolated laster on pulse modulation to transmit an infinite amount of information. Why won't this work?
    • by ledow (319597)

      An infinitely complex sender/receiver apparatus?

    • by vlm (69642)

      Serious question: It seems like it could be possible to use an infinite number of colors with interpolated laster on pulse modulation to transmit an infinite amount of information. Why won't this work?

      According to the Shannons theory it'll work just fine assuming you have infinite transmitter power with zero receiver noise so as to get that infinite SNR it would require.

      On the other hand, dispersion thru any media, optical fiber, even air, will totally screw it up at an infinitely short distance. Basically you will not be surprised to know that light travels at different speeds in glass or whatever depending on its frequency... that is pretty much how a prism makes a rainbow... So your 1500 nm bitstrea

      • by blair1q (305137)

        There's also the fact that amplitude is not constant across the spectrum of a pulsed carrier. So there's still a finite bandwidth.

        I'm pretty surprised they got 300 frequencies above the noise floor.

      • "Basically you will not be surprised to know that light travels at different speeds in glass or whatever depending on its frequency... that is pretty much how a prism makes a rainbow"

        Nope, try again. Link: http://en.wikipedia.org/wiki/Prism_%28optics%29
        Quote:
        The refractive index of many materials (such as glass) varies with the wavelength or color of the light used, a phenomenon known as dispersion. This causes light of different colors to be refracted differently and to leave the prism at different angles,
        • by sahonen (680948)
          The refractive index is the ratio of the difference in speed between light in a medium and light in a vacuum. If a material has a different index of refraction at different wavelengths, then by definition the light is traveling at a different speed at different wavelengths in that material.
    • Not being a hardware geek, this is what I heard: Is it possible to recalibrate the phased tetryon emitters to modulate the warp field and provide infinite information?

      On a moreassemble note, I would argue no, because of the limited amount of matter / energy in the universe, let alone any limits of the material.

      • Not being a hardware geek, this is what I heard: Is it possible to recalibrate the phased tetryon emitters to modulate the warp field and provide infinite information?

        No, because subspace interference would cause a tachyonic wave which would open a temporary worm hole which then would suck the information into a parallel universe.

        • by peragrin (659227)

          Not being a hardware geek, this is what I heard: Is it possible to recalibrate the phased tetryon emitters to modulate the warp field and provide infinite information?

          No, because subspace interference would cause a tachyonic wave which would open a temporary worm hole which then would suck the information into a parallel universe.

          ah so that is where Hawking radiation comes from. Parallel universes trying to send porn quickly.

    • by pclminion (145572)

      Serious question: It seems like it could be possible to use an infinite number of colors with interpolated laster on pulse modulation to transmit an infinite amount of information. Why won't this work?

      The uncertainty principle, basically. In the real world, there's no such thing as light of a single frequency. This is due to some basic properties of Fourier transforms. All real light pulses are finite in duration, which means they contain a range of frequencies, not a single frequency. The only way to ach

      • by kaiser423 (828989)
        Pretty much. It's a "god said" thing.

        Think of it this way, to encode bits onto the light stream, they're modifying both the amplitude and the phase of the light wave. Think of a nice sine wave, and then think about inverting or reversing the phase at various points to represent the data (http://en.wikipedia.org/wiki/Phase_modulation). Then try and calculate what that final frequency of light is. It's not a single frequency anymore. Amplitude modulation is similar, when you change the amplitude of th
    • by b4upoo (166390)

      Infinite being what it is one could never hope to complete even making discrete channels for colors as one would be creating each thread infinitely. Then there is the problem of little Johny digs into the cable. Who is going to be able to line up all of those color bands. Infinite speeds are for THE BIG GUY and not for mortals.

    • by jab (9153)

      Serious answer. An optical fiber is only transparent for a limited range of colors. As soon as you modulate a single color (monochromatic laser beam) the resulting light beam is by definition no longer monochromatic. Here's a fun, beginner oriented book [google.com] on the topic.

    • by LWATCDR (28044)

      A. You can not generate an infinite number of colors. Each frequency of radiation is caused by a specific change in quantum state. "See black body".
      B. Even with light you can have constructive and destructive harmonics. You would not want to use colors that can interfere with one another.
      C. Your transmitting medium will be limited to what "colors" it can pass. Fiber optics are not good with passing X-Rays or Radio.
      Yes Xrays, Gamma, and radio are really when you get down to it just other "colors" of light,

      • by pclminion (145572)

        A. You can not generate an infinite number of colors. Each frequency of radiation is caused by a specific change in quantum state. "See black body".

        The quantum nature of light is immaterial to the problem. The problem is that, by definition, a pure frequency is a sine wave of infinite extent into the past and future. Clearly this can't be achieved. Any finite pulse will contain a range of frequencies, thus, you cannot put the channels arbitrarily close to each other as they will overlap.

        B. Even with ligh

        • by LWATCDR (28044)

          "Interference is beside the point. You filter out the frequencies you don't care about." If you are filtering them out they are not available for use. So you do not have an infinite number of "Colors". There are many reasons why you can not have infinite bandwidth including the ones you gave. The thing is that most of them do not show up in classical physics which is all that most people know.

    • by Fleetie (603229)
      For exactly the same reason that you can't fit an infinite number of AM radio stations into a finite width of radio spectrum. The act of AM-ing a single frequency carrier f_c at data rate / frequency f generates sidebands each side of the carrier, so that the signal now spreads over (f_c - f) to (f_c + f), i.e. the bandwidth becomes (IIRC) 2f. Fleetie
  • I really wish HDD speeds could come even close to this :(
    • Why? Are there any practical home uses for that kind of speed?
      • by blair1q (305137)

        Anything that removes latency is useful.

        Just the time needed to load rendering library code as you browse around the web slows you down. A bigger cache only helps after the first time you load it; the first time is still bogged down in disk transfer. SSD would help, but then something else would become the tentpole.

      • by Anonymous Coward

        Under Comcast's current pricing model I pay about $60 for 250GB per month. This service would cost just over $15 billion per month. Or if they were going to keep my current cap of 250GB per month, and I were able to use the full 26Tb connection, I would hit that limit in 0.0096 seconds of use. HP printer ink and Comcast's internet pricing model tend to look very similar.

      • by aiht (1017790)

        Why? Are there any practical home uses for that kind of speed?

        Well, maybe 12Tbps is overkill, but I'm currently waiting for a five- to six-hour disk clone to finish.
        This is only about half a terabyte, so:
        12Tbps / 8 = 1.5TBps
        0.5 @ 1.5/sec = 0.33 seconds
        That would have made my day.

    • by geogob (569250)

      Just like channels in a fiber, if you get enough HDD in parallel, you might get somewhere close to it... (but don't ask me at what cost).

  • OFDM is the same modulation technique used for WLAN.

    Seems like the hard part is generating that wide variety of wavelengths.

    The thing which is kind of critical is that you need an FFT that you can process at several trillion operations a second.

    The FA says they are doing this photonically, which to me, is the cool part.

  • This comes from a lack of understanding of the field, but can someone explain to me what happens before and after, when transmitting data? The last I worked on hardware was with serial UARTs, so is someone willing to take a moment to explain better or to point me in the right direction to find more information on how it works? The data is encoded into beams of light and transmitted from point to point. Upon "re-entry" into system at the end point, how is the information gathered and processed internally fr
  • by Simon80 (874052) on Monday May 23, 2011 @01:57PM (#36219730)
    http://www.nature.com/nphoton/journal/vaop/ncurrent/full/nphoton.2011.74.html [nature.com] According to the abstract, the key contribution is an optical implementation of the Fast Fourier Transform (which is pretty cool). They only tested their work using fibre, not just laser beams or w/e is implied by the headline.
    • by b4dc0d3r (1268512)

      Just wanted to add, the FFT is not a good way to separate frequencies. The result is orthogonal, not necessarily the original input. It's like factoring non-primes. You can't be sure if someone did 4 x 3 x 2 or 6 x 2 x 2.

      So you can break it down into parts, but not necessarily the original parts. If we could always get the original parts, we would have software that can take your favorite CD and spit out a pretty good version of sheet music, guitar tab, etc. Lots of things claim to, but so far we can o

      • My experience, to use a sound analogy, is that yes, you can derive the sine waves that make up the window of sound you are transforming but yeah, you can't pull individual instruments out of the mix. However, presumably isn't the point to mix light together using different frequencies (colors) and then use an FFT to split the beam apart again like a prism? As an audio analogy, if you record two sine waves, one at 1000Hz and one at 10000Hz, you could run an FFT and break the resulting mix back into the origi

        • You can derive a set of sine waves that can reconstruct the original, but FFT will not break it down to the original sine waves. Only an orthogonal set. Two sine waves as you describe may be simple to pull apart reliably. Two sine waves is like factoring a prime.

          The article even calls the data "orthogonal frequency-division multiplexing (OFDM) data streams". The authors are aware of this problem. That's why I pointed out this isn't a simple FFT solution.

          Optical FFT means you don't have to decide which

  • Why not just use a prism?

    • by Soft (266615)
      You're right: in theory, it's the same as a prism plus a grid to separate the desired wavelengths. The point is, the optical setup described implements far finer and stabler a grid than remotely possible using conventional filters.
  • by i_b_don (1049110) on Monday May 23, 2011 @02:25PM (#36220114)

    I work in this field so let me see what I can do to translate what's happening and which parts are actually interesting. I dont' know the details of the experiment I'm only going off the article's summary and assuming they're correct. (BTW, while I"m an expert in a tiny slice of this field, my "expert" level knowledge doesn't extend to the whole pie. So some things I say may be assumptions I've made and can be wrong. If you see a mis-statement please correct me.)

    First off, we do fiber optics all day long for internet backbone communications. We even do "multi-mode" optical (different color/wavelength lasers) all day long but only for short cable lengths. Neither of which is article worthy. This thing called a "fast Fourier transform" is just math that is taught in school and is nothing even close to revolutionary, it is simply a fundamental mathematical tool of everything in this field.

    First off let me give you the basic framework. When you're talking about sending data at these speeds and over these lengths, you can forget the idea that you're sending lots of data down the line in nice waveforms. The data is so distorted that significant energy is put into compensating and un-distorting the waveforms. Fiber optics at these speeds just doesn't work at all without heavy duty data recovery techniques. So we send down the line data, get back garbled gibberish, apply techniques for removing errors and you can recover your data stream.

    So typically when we do "long haul" fiber (> 1k or so) we do single mode fiber, this means a single frequency or color (remember your physics, each color is a different frequency of light). This is because different frequencies of light travel at very slightly different speeds down the fiber and if you have long enough fiber this difference in speeds becomes significant and starts to harm your ability to regenerate the information. Additionally one frequency can cause noise in another frequency band so keeping things to a single frequency makes things more stable at long haul lengths. This is why "traditional methods to separate the different colours will not work".

    So Professor Freude and the article:
    There are two steps forward here:

    1. He's using a single laser to create different frequencies of light. I don't know if this is a common technique or not. I've typically hear of different colors of light being generated by different lasers but I am not an optics guy so I'm not sure.

    2. He's using an optical method in place of a Fast Fourier Transform (FFT) instead of silicon that somehow helps him decode the data. An FFT mathematically converts from frequency domain to time domain so maybe he's just using a prism or something to separate the different frequencies as a pre-processor step and then pumping this into his processor, but I can't tell.

    So Professor Freude and team and working on making "multi-mode" work at long haul. This is typically not done today so that's the step forward and since you can pack more information into your data stream if you include multiple frequencies, that's a nice win. but of course research success does not necessarily equal a marketable product.

    (Again, I am not a guru here, so if you are, please politely correct any mis-statements I've made.)

    d

    • I also work in the network field. Please allow me to correct a couple of your points.

      Single mode vs. MultiMode fiber does not mean what you think it means (one wavelength vs. many) and as the name may suggest.
      To simplify, MultiMode is for short distance runs, SingleMode is for long distance runs. A different wavelength (actually a "range" of wavelengths) are used for single mode to achieve longer distances.
      What you were describing is actually called Multiplexing [wikipedia.org]

      This is how super high data rates are
    • by Soft (266615) on Monday May 23, 2011 @03:25PM (#36220796)

      We even do "multi-mode" optical (different color/wavelength lasers) all day long but only for short cable lengths.

      I'm afraid you're mixing up frequency/wavelength modes with propagation modes. Most long-distance systems use several different wavelengths, that's what WDM is. But they use single-mode fibers, meaning that light at a given optical frequency (and polarization) can only propagate in a single way, thus at a given speed. Multi-mode fibers, with a wider core, let light propagate over different modes (different possible paths in the core for light rays, kind of), which plays havoc with the signal (pulses get echoes and whatnot), which is why they are used only for short distances.

      The experiment described here uses OFDM, which in principle is akin to WDM but squeezing many wavelengths as close together as theoretically possible, too close to be separated by classical optical filters. Instead, you can separate them mathematically using an FFT, but that takes a lot of computing power. What the authors did is to implement FFT optically, which is very neat. It enables the use of OFDM at ultrahigh bit rates; and the details of OFDM are such that, used in the right way, it can be extremely resistant to signal degradation (look e.g. at Figure 4(c) in the Nature Photonics article, and think about how tightly a conventional system at that bit rate would have to manage dispersion).

      What bugs me is that they describe their setup as performing better than plain coherent detection (Figure 5), which I have a hard time believing. Exactly how did they do the comparison, I wonder.

      • by i_b_don (1049110)

        Thank you for the correction.

        If you don't mind, I'll ask a few questions and try to flush out a few more bad assumptions I've made:

        What is the advantage of multi-mode then? (why allow multi-mode at all?) In electrical signals, the larger the transmission line the more modes can creep into the signal. Is this the same with fiber? Are you basically able to use a larger diameter fiber for multi-mode and therefore push more signal energy into larger diameter fiber thus allowing for a lower loss channel?

        d

        • by Soft (266615)

          What is the advantage of multi-mode then?

          Basically what you said: the fiber's core is larger, allowing one to inject power more easily (lower insertion loss, wider tolerances on connectors, so you can have them installed by a less-qualified technician). It doesn't change the loss per kilometer, though, AFAIK. The nonlinearity should be lower, as a given optical power would be spread over a larger area; however, that matters only for high-power applications, or long-distance transmission where you basicall

  • If spending profit to improve the worth of your company actually resulted in higher short term stock prices, maybe... Currently it does the opposite.

    Want faster Internet? Too bad, that kills our stock prices -- the investors won't allow it, we have to charge the customers more without letting the investors latch on to that profit so that we can spend it on improving our services. Too bad it's illegal to do that once you go public.

    If it costs anything beyond standard maintenance, it's not coming to t

  • by Anonymous Coward
    Here's a fast furry transform: http://media.fukung.net/images/5390/furries_internets_go.jpg [fukung.net]
  • Ughh. way to gut the summary I had written.

    Anyway here's the original paper in nature photonics
    http://dx.doi.org/10.1038/nphoton.2011.74 [doi.org]

    Basically the advancement in this technique is to take several incoming tributaries of data and use an optical FT method (OFDM) to encode into a single laser for transmission. Apparently the encoding/decoding is simple and low-power enough to fit on a silicon chip so this technology seems very implementable, just by upgrading the hardware on either end of existing fiber opt

  • What's the point if ISP caps are 4 - 5 GB per month?

    • by aXis100 (690904)

      Change ISPs then. I'm about to get 200GB/month for A$50. And that's in a rural town in the lowest density developed nation in the world.

      • So you are going to able to use your connection in full speed for about 0.0615 seconds. Whether Caps are good or bad is debatable, but the caps need to increase over time as technology progresses. I would not bet on the ISPs upgrading the Caps significantly any time soon, or in the future.
  • by Co0Ps (1539395) on Monday May 23, 2011 @03:21PM (#36220764)
    Wow, the summary is completely misleading and tells you nothing about the actual news. It reads like they just figured out that they can use multiple frequencies to send additional bands of data. Everybody with a slightest clue about how optical data transmission works knows this already. The news in TFA however is that they have figured out how to encode this data with a single laser instead of one laser per band making it enormously more economic. A car analogy would be if someone had figured out how to make cars fly without wings, and the summary would be "a new vehicle pushes transportation to its limits. by sitting in a container with an engine one can travel much faster than walking." Facepalm.
  • by Anonymous Coward

    ...Who read it as 26 tablespoons?

  • And AT&T will buy this technology and lock it away for the next 40 years then complain that they have to raise internet user rates to cover their yearly costs, a la the oil industry to alternative fuel sources.

Going the speed of light is bad for your age.

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