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Bell Labs moves bandwidth to 1.6 terabits

Posted by Hemos on from the move-the-data-move-the-data dept.

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"

2 of 56 comments (clear)

  1. Maximum bitrate of fiber by Christopher+Thomas · · Score: 3
    Does anyone know the theoretical maximum bitrate of fiber?


    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.

  2. Fine Young Cannibals by debrain · · Score: 3
    Nortel has several terabit fiberoptic line as well. The speed just keeps getting bigger and bigger. And I've got to ask, what will we do with it all?

    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.