Scientists Overcome One of the Biggest Limits In Fiber Optic Networks 62
Mark.JUK writes: Researchers at the University of California in San Diego have demonstrated a way of boosting transmissions over long distance fiber optic cables and removing crosstalk interference, which would mean no more need for expensive electronic regenerators (repeaters) to keep the signal stable. The result could be faster and cheaper networks, especially on long-distance international subsea cables. The feat was achieved by employing a frequency comb, which acts a bit like a concert conductor; the person responsible for tuning multiple instruments in an orchestra to the same pitch at the beginning of a concert. The comb was used to synchronize the frequency variations of the different streams of optical information (optical carriers) and thus compensate in advance for the crosstalk interference, which could also then be removed.
As a result the team were able to boost the power of their transmission some 20 fold and push data over a "record-breaking" 12,000km (7,400 miles) long fiber optic cable. The data was still intact at the other end and all of this was achieved without using repeaters and by only needing standard amplifiers.
As a result the team were able to boost the power of their transmission some 20 fold and push data over a "record-breaking" 12,000km (7,400 miles) long fiber optic cable. The data was still intact at the other end and all of this was achieved without using repeaters and by only needing standard amplifiers.
That's not what a concert conductor does (Score:3, Informative)
Conductor keeps them on the same rhythm. Concert master/mistress is the person in charge of getting everyone in tune.
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I always thought that the conductor is essential during rehearsals, but little more than showmanship during actual performances. After all, when Maurice Ravel, who was a rather poor conductor, was forced to conduct, he instructed the players to play as they would usually do, and he would just strive to keep up with them.
That's still not what a concert conductor does (Score:2)
Well, to be more specific the conductor facilitates a single interpretation in the change of pulse and other variables open to interpretation. A good orchestra can easily keep a steady pulse and play together rhythmically without a conductor just fine. They can even start together blindfolded, this is about listening to each other, esp breathing, it is actually not as hard as you might think. A very good orchestra can even come to a good consensus as to musical interpretation without a conductor, but will
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Never knew the concert conductor did that! (Score:2, Offtopic)
Re:Never knew the concert conductor did that! (Score:5, Interesting)
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Perhaps a bit of old school techniques need to be applied to modern communications to get more out of them.
I suspect that the problem isn't lack of knowledge of the subject but rather that the 80 years old principle is a bit more problematic to apply to optics than just knowing the theory.
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No, this is much more about co-channel interference between frequencies (colors). Coming from the RF world, imagine a non-linear filter that ends up looking like a comb on a spectrum analyzer, filtering the guard bands so as to reduce adjacent-channel interference.
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The electromagnetic spectrum (which includes light frequencies) has particular characteristics that do not change much with increases in frequencies, closed system or not.
Which is why you can take the same circuit that a grade school kid can build to make an FM radio and get frequency modulation at optical frequencies? Oh wait, it isn't that straightforward. Frequency shifting and nonlinear effects change drastically in different regimes, as does interaction of EM waves and matter. What you can do with circuits and traces at low frequency RF becomes different when you start needing waveguides, or get into non-linear fiber behavior that starts to introduce atomic physics e
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Maybe, but I suspect maybe not. The electromagnetic spectrum (which includes light frequencies) has particular characteristics that do not change much with increases in frequencies, closed system or not.
Granted, but optical signals are not generated by a coil of wire and interleaved metal plates. You can't just tweak a capacitor to adjust the frequency of a laser.
Re:this is moot--internet will continue to get slo (Score:4, Insightful)
Yes, but with this new technology their costs will be lower and so they'll be able to get more profits.
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Doesn't matter, fiber isn't pushed out anywhere anymore.
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not faster. Why? Comcast/TimeWarner et al want slower speeds so they can charge more for high speeds....
Wouldn't matter this is a backend/longhaul improvement. They can still charge you more for less.
Interesting problem (Score:1)
So the problem is cross contamination between fiber channels due to frequency differentials, I think they equalized all frequencies somehow but I don't fully get it. Red is longer than blue for example and if separate strands of fiber carry different 'colour' and frequencies 'bleed' from strand to strand how do you equalize that exactly? Have wave peaks correspond? How? Are they proportionate to remain synchronized? If this is a serious problem, why not add more isolation between strands?
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I think the problem is with multiple frequencies in the same fiber, not color bleeding between adjacent physical fibers.
But the article isn't very helpful at making any of this clear.
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It is interference caused by reflections off the ends of the fiber. Each fiber carries multiple colors (as the AC says above), which all reflect different amounts off the ends. Blocking these reflections is likely harder than RF as RF is all electrical in nature, light is harder.
Diameter of the Earth (Score:1)
Since the diameter of the earth is 7 926.3352 miles, this could conceivably remove any need for repeaters. I still bet it will not improve fiber rollout by big telcos in the U.S.
but not amplifiers (Score:2)
Since the diameter of the earth is 7 926.3352 miles, this could conceivably remove any need for repeaters.
I got the impression from the (sketchy) article that repeater AMPLIFIERS were still needed but repeater REGENERATORS were not.
I.e. you still needed to boost the strength of the signal to make up for the losses. But the progressive degradation of the quality of the signal - with data from different frequency bands bleeding into other bands (especially in the amplifiers themselves) due to nonlinear "mixi
Then again. (Score:2)
I got the impression from the (sketchy) article that repeater AMPLIFIERS were still needed but repeater REGENERATORS were not.
Then again - another part of the article makes it look like an additional result was that they could boost this less-subject-to-degradation-by-nonlinear-distortions signal at the start until the fibre itself was acting non-linearly, in order to get a signal strong enough to survive a much longer hop.
So it's not clear to me whether the distance was achieved by:
- long hops enab
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Since the diameter of the earth is 7 926.3352 miles, this could conceivably remove any need for repeaters.
true, although I'm not sure if "through the center of the earth" is the next big thing for high speed communications.
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although I'm not sure if "through the center of the earth" is the next big thing for high speed communications.
It won't be until we develop technology that can shoot neutrinos through earth, capture them on the other side, and demodulate the encoded message.
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Just comparing for scale, others did it better than me below.
The lameness of Dicedot (Score:1)
Literally, an autoplaying Dove shampoo commercial on Slashdot. Starts playing 10 minutes after the site loads when the tab has even been in focus for about that time. Fucking pathetic times for this website
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https://soylentnews.org/ [soylentnews.org]
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What are you even doing on the Internet without an ad blocker? Don't complain about things which are in your own responsibility, fool.
Link to actual paper (Score:4, Informative)
They need to overcome a bigger limit... (Score:2)
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Scale (Score:5, Informative)
To help understand the scale, the cable length is approximately the diameter of the earth (12742 km).
It is also 25-50% longer than the undersea hop for the longest cable paths (NY to London, LA to Sydney, San Francisco to Tokyo, Sao Palo to Gibraltar, etc.). This has the potential to allow electronics to stay on land, where they are easily maintainable and upgradable and with easy access to electricity.
Interesting development, indeed.
Re:Scale (Score:4, Interesting)
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To help understand the scale, the cable length is approximately the diameter of the earth (12742 km).
Spanning the diameter is cool and all but perhaps not the most useful comparison until we start laying cables through the core of the planet.
Perhaps a more useful comparison is to the circumference (40,075 km), so slightly over a quarter of the way around the planets surface.
does it work with frequency modulation? (Score:2)
My understanding that the transmissions over modern fibers use all sorts of tricks to pack more information into it, including frequency modulation [wikipedia.org], multiple polarization states [wikipedia.org], etc. I wonder how this new frequency comb technique plays with those.
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what crosstalk? (Score:1)
Re:what crosstalk? (Score:4, Informative)
Kerr effect (Score:4, Interesting)
Comment from another forum ... (Score:3, Informative)
From PBUK at ISPreview -
"The team have done an impressive experiment, but their press office could do with some wide reading.
Pre-distortion of signals is already used in the fibre systems deployed by BT, Virgin Media, Vodafone, O2, SSE, and many others. The same coherent technology is already doing 22,000km unrepeatered across the Pacific. A 20 fold launch power improvement is only 13dB, which is about 50km.
What is new is processing all the channels together to calculate the pre-distortion. Lovely idea for the lab, but wouldn’t work in practice where channels are deployed one at a time, as each transmitter costs as much as a house (so you don’t deploy them unless you use them)."
American Consumers Won't Benefit (Score:3)
Because of the monopolistic stranglehold that companies such as Comcast and Verizon hold over the last mile, American consumers won't see a dime of any cost savings from this.
Meanwhile consumers in Europe and Asia will continue to see faster cheaper broadband.
Absolutely no useful information. (Score:2)
No information on bandwidth, signal strength, channel separation or anything else. Only that it "acts like a concert conductor".
How low can a scientific article sink, and still be the basis for a slashdot story? This must be a new low.
Current trans oceanic fibers do transmit multiple colors at high speed with amplifiers on the seabed and no regenerators. New installations carry 64 Tb/s per fiber. and often 64 fibers are laid. Some are left dark, but theoretical capacity for a cable is therefore 8192 TB/s bi
Dispersion (Score:2)
Anchors Aweigh! (Score:2)