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Bell Labs moves bandwidth to 1.6 terabits
javac writes "Scientists and engineers
from Bell Labs have demonstrated a prototype long-distance
optical-transmission system that quadruples the capacity of today's
commercial systems to 1.6 terabits. Read the
full
story"
All his work was lab based synthisis of nano structures, and not commercial applications. So, his work was significantly beyond what is production ready by about a year (at LEAST). Anyone know of a solid referance for the basics in what communication hardware/structures/circut design is currently being used, and what directions they are moving? If what I saw was true (and the science behind it was solid), he could easily boost the best theoretical hardware by an order of magnitude from existing stuff. I understand the science, chemistry, and fabrication stuff he talked about, and I can see how it would be better, but I don't understand the protocols completely, and the designs that are back between the computers and the electric to light wave meterials he was designing.
No joking about this being accessable to common people or even something at least a few orders of magnitude slower. It would be nice to download the latest distribution cd in a minute or enjoy instant gratification on freshmeat. Point, click, make install! I tried 128K ISDN for a year and did not notice much improvement over 56K when surfing. The world would be a nice place with a big pipe to each computer.
The wavelength of the light spectrum used and thickness of the fiber are restrictions. Shorter wavelengths help, but distance suffers. Infrared is a longer, but efficient wavelenth. Ultraviolet does not have a chance. Skinnier fibers help due to the wavelength being refracted to the center.
To get an idea where the limit would be challenging for fiber, take the wavelength and invert it to get the frequency. That is the point where working with single pulses of light gets interesting. From there, you could share the same fiber with many different wavelengths and even use analog components of the waveforms like a modem. It just depends on how much money you want to throw at the hardware.
Actually, the article is describing practical application of known experimental technologies - exactly what is needed to bring it into real use in the backbone and (later) downstream. We've heard about multi-terabit transmission with DWDM before, but this is looking closer to an actual product.
This used a different approach to packing more information into the fiber - the use of many carriers, each modulated at a relatively low frequency, and spaced far enough apart that there wasn't cross-talk between them. The professor you refer to seems to be looking at ways of more quickly modulating a single carrier. This is certainly very useful, but there are other ways of increasing bandwidth. Frequency-domain schemes of the kind that I described are the ones that have been generating the recent news (though there are limits to how far it is practical to push this).
6x10^14 Hz. Unless we can make ultraviolet fibres, that is an upper bound.
Not quite. Your sampling rate is limited to 6.0e14 Hz, but you can have many signal levels that can be detected. The problem is that for n levels, you need n*n photons to compensate for measurement uncertainty, which means that for b bits per sample you need 2^(2b) photons per sample. The energy requirements for this get nasty very fast, but for a small number of levels it's practical.
You run into analogous problems with frequency-domain schemes (this was a time-domain scheme). You can increase the data rate by increasing power, but the power cost is ugly.
This was covered in a thread a couple of months back. A few limits apply.
Firstly, you are limited by the bandwidth of your optical carrier. For visible light and assuming reasonable power constraints, you won't be able to get more than about 1.0e15 bps. You could push this by pumping in a _lot_ more power or by using a higher frequency, but these have very serious problems. IMO, a better solution would just be to use bundles of fibers (or multiple lasers or what-have-you).
DWDM and other frequency domain techniques won't help here - as you modulate data onto a carrier, its frequency spreads out, limiting how densely you can do WDM, or how much data you can transmit per channel using a given density of carriers. 1.0e15 bps or thereabouts is as far as you can go without producing/using frequencies higher that the visible light range.
The other, more immediate limit is in the physical medium that is carrying your optical signal. In this case, fiber. Fiber is mainly limited by the operating frequency range of the amplifiers used to boost the signal (usually erbium-doped fiber lasers). I'm told that this is in the 1.0e11 to 1.0e14 Hz range (I honestly don't remember where within those bounds it fell). Other readers can probably give you more accurate information.
One of the points mentioned in the article was that they hoped to develop better amplifiers - that could process a wider range of frequencies and let them use another frequency range for transmitting data. This was a topic for future research, not an announcement of something they'd accomplished, though.
France Telecom did claim to have the record
a few days ago with a 1 Terabit demonstration
in March. It seems that this kind of record
is not easy to hold a long time. Note however
that FT demonstrated 1 Tb over 1000 km, while
Bell demonstrated 1.6 Tb over only 400 km
I've a several megabit ADSL connection to the internet at home, and a T1 at work, and I still spend most of my bandwidth at home reading news and sending email, and using local do-dads at work. The entire system is computer-centric. But the underlying philosophy is person centric and while we look at what we have for each computer, we often forget what we have for each person.
And the successiful in the future will be looking at what we will have in the future, which will be computer-independent, yet entirely person centric.
Someday, not so far off as many would hope, fear, wish, or believe, that which we will look at in a computer will not be what we value now, but rather the speed at which we communicate with others.
That is a step in the right direction. Next we must change how and what we communicate. Therein you will find the true leaders of this technological era.
There was a discussion on /. last week about a company claiming exobits/sec across power lines. They were roundly denounced as charlatains, and I'm pretty sure that press release was a hoax or a marketing dweeb was doing too much cocaine.
:-)
But this is the real thing, a nice incremental jump in leading edge telecoms. Granted, you won't be getting one of these thing in your living room in the next few years, but maybe in a decade you will see this level of technology pumping bits around fibered cities like Palo Alto.
We are only two orders of magnitude from exabit speeds. tera=10**12, peta=10**15, exa=10**18. Get to work!
the AntiCypher
Hemos is like...sci-fi fans;he thinks technology is cool, but he hasn't bothered to understand the science it's based on
If they want to test TCP/IP networking using this system, I will kindly allow then to run one of these bad boys to my house ;-)
Seriously though, it will be nice to watch phone prices come into the penny a minute range soon maybe...
At 6-10 bucks an hour phone calls to my gilrfriend add up fast...
In anouther random comment, when high bandwidth comes to the house, do you think we will have a digital subchannel for voice (like ISDN? I think that's how it works...) or TCP/IP phoning?
Blessed are the pessimists, for they have made backups.