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Scientists Double Optical Fiber Transmission Capacity
ms writes: "Yesterday golem.de reported that the Optical Communication and High-Frequency Engineering Group at the University of Paderborn (Germany) claims to have made a technology practical which doubles the transmission capacity of optical fibers to 80 GBit/s. In their so-called "polarization division multiplex data transmission system" they don't only send one but two mutually orthogonal light waves through the fiber. They say the only big problem was the dispersal of the light waves which limits the data rate. Additional they had to fight against the phenomena that the polarization direction of the light waves changes while it goes through the fiber. Now, after two years of research, they invented an "automatic optical compensator of polarization mode dispersion" which fights both the limitations. With this gadget they were able to send data at a rate of twice 40 GBit/s (that's 85,899,345,920 Bps) over a test-line of 212 km. And "only the available equipment limited distance and data rate". As we all know, optical fibers build the (cronically overloaded) backbone of our beloved Net. (BTW: That's Net., not .Net!)" Here's the babelfish translation, too.
Any chance I can get a hookup into this? :-) I wouldnt mind downloading directly off that fiber line..
Moderation: Humor=+1 Underrated=+1 Insightful=+1
Just trying to grok "mutually orthogonal". Is that redundant, or just over my head? Not trying to nitpick, but to understand something my networking prof never explained.
"What is the sound of one belly slapping?"
Sweet... Can we use this new technology to ease the congestion over the trans-atlantic/pacific backbones???
---
Programming is like sex... Make one mistake and support it the rest of your life.
-Foxxz
Now we have the next question that comes to mind. I want to know if there's a software solution to all of this, or if the hardware itself has to be upgraded to take advantage of these speeds.
Also, I know it can be done over existing lines, which is great for the installed base, but it still doesn't help run them all over. I'm just lamenting the fact that they don't have, and probably won't have in my lifetime, fiber as widespread as telephone line. Sorry for the OT part.
Two things are infinite: the universe and human stupidity, though I'm not yet sure about the universe. - A Einstein
Great, now bring it to my casa...or maybe light all the fiber that is already in the ground.
that's 85,899,345,920 Bps
Up from 300 Bps 14 years ago. Not too shabby.
300km worth of cable = 10MBytes of storage with access times of 1 msec... So I guess we have to wait until we can pump bandwidth up 4 orders of magnitude to have a neat little system... (with 300km worth of cable in a drum...)
I demand a million helicopters and a DOLLAR!
Additionally it possesses a controlling mean, which is to after-pursue even largest polarization modifications, as they occur on very long transmission circuits contrary to competitive systems also, noly-break.
Once I figure out what a noly-break is, I should be able to build my very own high speed home network!
I Am My Own Worst Enemy
The "backbone" of the whole internet and telephone net consists of optical fibers. For transmission capacity doubling each optical wavelength may carry two signals with mutually orthogonal vibration directions. The results of this technology could be outstanding.
Now when can I get this to the curb?
Maybe some day cutting a fiber line would yield deadly results. Imagine accidently digging through a fiber line only to be cut in half by the power of the beam. That would rule! As if being electrocuted to death wasn't enough, soon we can be killed by data...I can see where the 'freak accident causes supergenius to be born' movies are going to come from..
Job? I don't have time to get a job! Who will sit around and bitch about being broke and unemployed then?
to be able to throughput at that speed, I can't imagine the hardware that is needed...
I mean, I hope that nobody had the idea that he will be able to have it directly into his Athlon 1.4 Ghz... Poor fool...!
Does anyone have a link to a good translation of the article? The translation at altavista is incomprehensible!
Thanks!
Beware of he who would deny you access to information, for in his heart he dreams himself your master.
Does orthagonality relate to the wavelength or the relative angles the light is sent? If the latter, any reason they couldnt' use colour as a second channel? (particular wavelengths)
-
ping -f 255.255.255.255 # if only
It's ironic that this article comes on the heels of some articles I just saw (in metamoderation) about how oversold services (DSL/Cablemodem) are. This would be a great thing, if any company still has the capital to lay new fiber, though I expect many are just trying to eke out a returns on what they already have. My ISP, Concentric/XO was last listed at $0.40 a share, and they're advertising cheep long distance, etc. right now.
A feeling of having made the same mistake before: Deja Foobar
It seems every year we find a way to double the amount of data that we can send down fiber. As a result of this, companies are actually deploying less new fiber in the field and taking older lines out of commission.
One of the things that worries me about this is the increased vulnerability. In the past, huge fiber networks were used that can be one tenth the size today. All too often a clueless construction worker rips up a section of fiber and causes some havok.
Won't this kind of thing happen more frequently if less fiber is deployed that can handle more traffic? And does this bring us any closer to fiber to the curb - it doesn't seem like it.
First, twice 40Gbps is not 85,899,345,920 bps, it is actually 80,000,000,000 +/- 1,000,000,000. We don't measure Gbps in powers of 2. Secondly, the internet backbone is not overloaded, but is running at about 20% capacity according to the people who operate it.
Knee-jerk /.'ers, ask yourself: Once you've realized what a cool thing this is, and understand that hard work went into making it happen, are you then going to demand they make it "Open" and "Free" and not patent it, because Patents Are Bad and Sharing Intellectual Property is the Right of All Mankind? Or will you realize that they have a right to benefit from their hard work and wish them luck?
Great job, and I wish them great success, for the selfish reason that I wish to benefit from this technology and think it could actually reduce infrastructure costs, thus (somewhat slightly) reducing my costs (or at least delaying the next inevitable increase).
Hmm, and same Timothy posted this article on June 25th about a lot of fiberoptic cables that have been put into the ground but haven't been put to work. :)
You gotta love the consistency of Slashdot posts
"A door is what a dog is perpetually on the wrong side of" - Ogden Nash
In geometry, orthogonal just means perpendicular. But, according to searchStorage: "In computer terminology, something - such as a programming language or a data object - is orthogonal if it can be used without consideration as to how its use will affect something else. " So, the light waves are mutually orthogonal (they are data objects in this case), but I'm not exactly sure how to apply the definition to exactly what the scientists are doing with fiber optic cables.
F-bacher
James Tiberius Kirk: "Spock, the women on your planet are logical. No other planet in the galaxy can make that claim."
"mutually orthogonal" means (for a set of two or more elements) that each pair of elements is orthogonal--AFAIK, it's a synonym for "pairwise orthogonal". "orthogonal," of course, has lots of synonyms, including "linear independence," "at right angles," "having zero dot-product," "statistically uncorrelated," etc.
So, the three spacial dimensions, the set {phase of the moon, day of the week, time of day}, etc. are all "mutually orthogonal." When talking about a set of only two elements, the "mutually" is superfluous, but not redundant.
-- MarkusQ
Imagine if HTML was patented way back in the 1.0 days. By now the owners of the patent would have:
Instead they gave freely and changed the world. ;)
"What is the sound of one belly slapping?"
"Mutually orthogonal" refers to the fact that the optical carriers are travelling perpendicular to each other, but are travelling through the same space (transmitted concurrently), as opposed to being transmitted using a tdma-type technology where the signal would be pulsed on one axis and then other consecutively. This is very much like the technology used in satellite communications, where each transponder has A and B poles.
the above is my personal opinion and does not necessarily reflect that of the little voices in my head
dispersal of the light waves
Modal or spectral dispersion? I'm assuming they're using singlemode fiber, so it's likely spectral dispersion, for those who wonder (and lazy to read the article).
How does their technique differ from dense wave divisional multiplexing? Anyone know?
-- Minds are like parachutes... they work best when open.
80 Gbit/s != 85 899 345 920 bps
The prefixes kilo, mega, giga are SI prefixes and are always powers of 10, and should never, I repeat never, be used when talking about powers of 2. Use the terms "large gigabits/gigabytes" or "kibis, mebis and gibis" instead, to avoid confusion.
In telecommiunication measurements like bps, the SI prefixes have traditionally always been used properly.
I work for williamscommunications.com and we already use DWDM (Dense Wave Division Mulitiplexing), which allows multiple freqs of light down the same strand. OC-192 transport systems with DWDM, operate in duplex on a single fiber, delivering up to 80 Gbps in eight waves in each direction.
Work w/ this everyday, why is this news???
We already have much more fiber capacity than we can use. The real bottleneck of the Internet right now is... the switching. OC-768 units (38.8 gigabits/sec) won't even reach volume production until 2003 or later, and they wouldn't even handle half of one of these fibers, let alone multiple fibers coming from various locations. It's like running a 2" diameter fuel line to the engine of your Hyundai.
All-optical switches have been developed, but are not going to be widely deployed for some time. I have a feeling that even all-optical switches will be many years before they reach the speeds needed for 80 gb/s fibers.
The true improvement of the Internet will occur when switching capacity increases by at least an order of magnitude in a very short amount of time. Right now, good, guaranteed bandwidth is barely any less than it was back in 1997. Sure, as switching capacity slowly progresses to fill the needs of the backbone providers, the Internet keeps running - but you still end up paying out the nose for guaranteed bandwidth. Once the switches catch up with the fibers, however, that *might* change. Maybe.
steve
Oh, you're not stuck, you're just unable to let go of the onion rings.
I propose that in response to Microsoft's usurping of the dot, we counter-respond with an acquisition of the asterisk.
.NET, or The Net, or 'net, or Net, we all start using *Net.
Thus, instead of using
That way we can pretty much cover all bases, since everyone knows that * is a wildcard - the All-unifying Infinite Eternal Symbol of All.
All those in favor, say "*me"...
; -- the corruption of government starts with its secrets. a truly free people keep no secrets. --
I know it ain't easy. You try to be a troll, and some asshole moderator gives you (+1, Funny)...
I don't understand the importance of this discovery. I'm pretty sure existing DWDM systems can put at least 16 wavelengths on a single fiber at OC-192 (10 Gbps) speeds for a total capacity of 160 Gbps...
This is kind of an intresting experiemnt, but this is not news. The "otherwise possibe" part makes it sound like no one has done PMD compensation before, this is false. Here is why:
1. PMD compensators are being built by many research groups. You still can't call up an order one (AFAIK), but soon.
2. PMD (mean DGD, differential group delay). DGD changes with time and wavelength.
3. PMD on buried fiber varies slowly. It is easy to compensate.
4. Nortel, Alcatel and others with be releasing 40 GB/s (per WAVELENGTH) systems next year. They are suppose to run 100's of km, between regens and at many wavelengths (160?).
Here is a link with almost all peer reviewed papers on PMD:
Here one can see many references to PMD compensation and even some at bit rates of 160 GB/s. With PMD compensation the line speed isn't that important, it is the accuracy and speed of your compensation.
This is not a break through.
cronically overloaded eh? Well, can't we just eliminate some crontab files? Usually when I have cronic problems, it's because users have improperly setup their cron tasks or set up too many of them. So we just get Al Gore (He invented the net, so he must have admin priveleges, right?) to go out and tidy up some of those crontab files, and we'll have this internet running at tip top speed in no time!
Your
I see some others posting explanations about physics behind this, but it seems a bit unsatisfactory for some. Here's my best shot at it:
There are two orthogonal polarization modes that propagate down fiber, meaning the there's a sort of up-down oscillation of the electric field (one mode), and a left-right oscillation (other mode). If fiber were perfect, you could send a signal along each polarization, and they wouldn't bother (interfere with) one another, but it's not. If you send polarized light down a fiber, it will not keep the same polarization (unless you use polarization-maintaining fiber, but that's a pain, and you can only send one polarization down).
So people generally send down (relavitively) unpolarized light. They modulate this one signal as fast as they can (getting about 40Gb/s), and then deal with dispersion as best they can.
Dispersion results from the spread in frequencies (colours) of your signal (each colour travels a different speed in the fiber) and also from the fact that a fiber has polarization mode dispersion (the part of the signal along one polarization axis travels at a different speed than the other part, called PMD from here on in). Both of these effects cause a pulse that you send down the fiber to be distorted (part of the pulse travels at a different speed than the other part). Chromatic dispersion (the first kind) has been dealt with (fibers have a wavelength at which the loss is lowest and a wavelength at which the chromatic dispersion is lowest, and it's been worked such that these two things are at basically the same wavelength), but PMD is a big limitation to pushing the capabilities of fiber. This was stated on the front page post:
They say the only big problem was the dispersal of the light waves which limits the data rate.
I think that should read "dispersion", not "dispersal".
So, what these guys have done is made a PMD compensator. Somehow it automatically makes sure that a given polarization of light stays in that polarization as it travels down the fiber. If one can preserve the polarization of both modes (which is different than polarization maintaining fiber, which takes ONE polarization of light and keeps it polarized), and then send a signal along each polarization axis, then one doesn't need to deal with PMD, because within a given signal, all the pulses are travelling at the same rate.
Then, if you don't have to deal with PMD, then there's very little to slow you down in pushing data through the fiber, basically just how fast you can modulate your laser (I think you could drive a LiNbO3 Mach-Zhender modulator up to about 80Gb/s or so, whereas I think in the article they were driving it at 40Gb/s). That's why they say the data rate was only limited by available equipment. I'm not sure how the PMD compensator works, I'll have to read the actual article more closely. I hope this helps!
"Now gluttony and exploitation serves eight!" - TV's Frank
Making bigger and bigger pipes is the way of the net. The technology just has to get better by making the rates higher and the packages smaller.
The next question is, what do we do with all this new capacity? The telecommunications industry is finding all this out since so much infrastructure was built during the boom and everything went bust. There was so much infrastructure out there that was completely useless (think dark fiber) because of incomplete implementation.
They put plenty of fiber in the ground and run out of money before they can get any equipment to light it up. They put plenty of DWDM equipment to light the fiber but they can't sell a whole OC-48 to anyone at a competitive price. They get tons of metro networking equipment but they've just spent all their money and can't make a management system to turn up any metro circuits.
So, these kinds of technological improvements are the greatest thing in the world and they have to keep pushing the envelope. However, there must be concurrent development along all other lines to manage all these ass-kicking boxes and make them usable! If not, no one will buy it because it can't contribute to a sustainable business model.
"Money often costs too much" -- Emerson
Ok... I've heard different things about this all over the place. When you're talking about bandwidth, does a kilo mean 1000 or 1024? I read somewhere on the MRTG page that in bandwidth terms kilo is 1000, mega is 1000000, etc, and that in storage terms a kilo is 1024, mega is 1048576, etc.
In this post the submitter went against that and said giga is 10737418240 (which is not equal to 1024^3, but this is confusing enough as it is, so lets forget about it).
Which one is it? Is there an RFC that makes some kind of standard for all of this?
SuPz.orG
No. you see, it's funnier to troll at +2, so I must keep mny karma above +25. If you look right above, funny: +1, offtopic: -1, trolling at (+2, offtopic): Priceless!
..."automatic optical compensator of polarization mode dispersion"...
Next it'll be a nanite-enhanced inverse tachyon pulse Heisenberg compensator.
I could use one of those...
I got my Linux laptop at System76.
OT: Your .sig about kermit is not entirely true.
See this
I don't really mind double posts on
Remember when 14,400 bps was fast? Heck, remember when 56k was fast? :-)
--
"Karma can only be portioned out by the cosmos." - Homer Simpson [1F10]
How many differently-polarized light streams can be put through a single fibre before they can't be differentiated? Would it be technically possible to have hundreds, with a single "control" signal to let the receiver know where all of the other signals are relative to each other?
Last post!
The maximum possible bandwidth on an optical wire depends on how much energy you use to transmit it. For 1J/s it is 2*10^17 bit/s. Compared to their achievement of 1*10^11 bit/s, we have 21 doublings to go. That's not too many years.
- As we all know, optical fibers build the (cronically overloaded) backbone of our beloved Net.
If it's overloaded by cron, couldn't we just kill the cron daemon?I/O Error G-17: Aborting Installation
Best you can get in openair is about 4 polorizations at any given frequency.
horizonal, vertical, left circular, and right circular. They're a bitch to collect all 4 at the receiving end though.
I doubt that fibre could handle the circular modes -- but I'm not a fibre person.
Rod Taylor
I know this is a little off topic, but I think the correct term is "Backhoe Fade". A quick search turned up an "official" government project .
BTW, the word "fade" is a throwback to the time when most longhaul communications was done using troposcatter microwave systems. Small atmospheric changes such as rain, volcanic dust, solar flares and sunspots would cause the Recieve Signal Level to drop. Ok, Ok, who am I kidding; those bastards would fade at dawn, dusk, mid-day, mid-night, summer and winter solstace, equinox, and any time someone stood too close to the radio. A guy I knew actually shot a radio once for excessive fade. He claimed it was an accident, but the investigator was clued in by the fact that there were 3 holes in the radio...
I'd rather you do it wrong, than for me to have to do it at all.
Bytes per second != bits per second
Somebody please correct the story.
echo '[q]sa[ln0=aln80~Psnlbx]16isb572CCB9AE9DB03273snlbxq' |dc
"polarization division multiplex data transmission system" [using an] "automatic optical compensator of polarization mode dispersion"
If it's twice as fast but takes four times as long to say it, does that actually mean its effect is half the speed? The article didn't say if the "test-line of 212 km" was just so they could write the name on the side.
And to think people believe we IT staff make up impenetrable terminology in an attempt to justify our salaries!
I strongly suspect that this technique is pretty useless for large networks. Those use optical repeaters that work like a laser where the signal initiates the avalanche effect.
And I'm quite sure that the polarization will be lost that way. Since polarized signals cannot be made to work on the existing backbone, this idea will likely not make it to the market.
While I am always for extending bandwidth, I jump on the term "chronically overloaded" (note the letter "h", which seperates chronic from mere cronjobs)... Not long ago, regarding the 9/11 effects of everyone and their dog logging on to the net on the search for information, I read that the net backbone currently is anywhere between 40% and 50% at any given time. It took 9/11 to get peaks up to 80%-85%.
I tend to think being at half load most of the time is not anywhere near "chronical overload".
+++ath0
This is really good news - more bandwidth over existing fibre is great.
But I question the assertion that our backbone is 'cronically overloaded'
Take a look at this, pulled off ft.com on 2001-09-06
> The enduring legacy of all this money is a glut of "bandwidth" - the
> capacity to transmit volumes of data and the basic raw material of all
> communications networks. This glut is so great that if the world's 6bn
> people were to talk solidly on the telephone for the next year, their words
> could be transmitted over the potential capacity within a few hours.
> Analysts estimate that only 1 or 2 per cent of the fibre optic cable buried
> under Europe and North America has even been turned on, or "lit". Some
> people point out that the remaining "dark" fibre needs additional investment
> to activate it and that it therefore does not represent a surplus. But that
> is of little comfort to the beleaguered telecoms industry. There are enough
> new ways of squeezing extra capacity out of existing, lit fibre to have
> caused a collapse in bandwidth prices.
> With new techniques to send multiple wavelengths of light down a single
> fibre, up to 160 separate "colours" of light can now be used to transmit
> data down a single strand of glass. Most modern networks use just a tenth of
> this potential today - or less than a thousandth if dark fibre is included.
> A similar overcapacity exists in undersea links, where each new Atlantic
> cable adds as much bandwidth as all the previous infrastructure put
> together. And mobile phone companies have committed more than $200bn in
> Europe alone to boost the bandwidth of their wireless internet services
> without any proof that consumers will use it or that the technology will
> work.
No, 2 is the max. Circular polarisation is just horizontal AND vertical at the same time, with the same amplitude and 90 out of phase. So you will not be able to discriminate the channels if you add in extra horizonal and vertically polarised light as well.
And yes, fibre can handle circular modes, or any other polarisation state for that matter.
Last geeky point. Orthogonal can be rephrased as '2 polarisation states occupying antipodean points on the Poincaré Sphere'
-- MarkusQ
in Newark, NJ. Nobody was using it for data back then of course, but squeezing 1.544 megabits/sec onto a copper pair, in order to move voice circuits around, is nothing new.
I wish the Slashdot team knew a bit more about telecom, they'd accept fewer of these stories and say fewer stupid things about them. "Chronically overloaded backbone" my ass, there are millions of miles of dark fiber out there. The glass isn't the problem, it's the silicon, the greenbacks, and the red tape that make things suck.
I always wondered what the fuck circular polarization was. So you don't really need those curlicue antennae, you could just make two antennae, orient them 90 degrees from each other, and then set one a quarter wavelength behind the other, right?
I don't personally have any experience with Erbium-doped fiber amplifiers, but someone here must...
Do EDFA's clobber polarization or not?
isn't even the net access part. It's the bandwidth itself as an interconnect between all those processors and RAM distributed all over the place.
It's not even being considered a commodity yet in real terms. The idea has been floated in the past, but it always lacked scale and interconnectedness at CPU speeds has been non-existant.
There are projects out there like SETI and whatever DIY stuff goes on, but a market hasn't evolved well. I guess it's because there are no apps.
Hmm.