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Networking Technology

MIT Scientists Reach Fiber-Optic Breakthrough 39

Posted by CowboyNeal from the faster-than-ever dept.
kcurtis writes "The AP (via boston.com) has a story about how MIT scientists have detailed a breakthrough in optics that could lead to cheaper, more efficient optical communications. From the story: 'Like polarizing sunglasses that block light waves oriented in different directions, the MIT researchers created a clever device that splits the light beams as they pass through a circuit. The device then rotates one of the polarized beams, before both beams are rejoined on their way out of the circuit, retaining the signals' strength. But it's not just that device that the researchers are touting. They're also trumpeting the innovative method they devised to integrate the optical circuitry with electronic circuitry on the same silicon chip.'"
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MIT Scientists Reach Fiber-Optic Breakthrough More

MIT Scientists Reach Fiber-Optic Breakthrough

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  • Balanced optical? (Score:4, Informative)

    by rhowardiv ( 856443 ) on Saturday February 10, 2007 @12:00PM (#17963060) Homepage
    This sounds a lot like balanced audio [wikipedia.org] connections.

  • Integrating photonics and electronics not that new (Score:5, Informative)

    by MetaDFF ( 944558 ) on Saturday February 10, 2007 @12:42PM (#17963336)
    It seems what the MIT scientists have created is a purely optical equalizer in a convention CMOS process. This would probably be used at the receiving end of a single mode fiber link. Most of the equalization done today is done electronically using fancy optical receivers (expensive but very robust).

    The article is light on details but the idea of integrating photonics and electronics in a conventional CMOS process isn't a new idea. Maybe the way they did the integration is a breakthrough. A company called Luxtera demonstrated (with products) integrated photonic and electronic transmitters way back in 2005. Their press release from March 2005 http://www.luxtera.com/news_press_2005_0328.htm [luxtera.com] reveals that they created an optical modulator (a transmitter) in Freescale's CMOS process. The optical modulator they created is also based on the same idea of splitting light and combining it to create on/off pulses at extremely high speeds.

    If you want to read more about their technology and why integrating photonics with electronics is important visit: http://www.luxtera.com/technology_faq.htm [luxtera.com]

  • Polarization Mode Dispersion (Score:3, Informative)

    by Anonymous Coward on Saturday February 10, 2007 @01:11PM (#17963558)
    Something this article didn't even allude to, since the journalist probably had no clue about optics, is that these devices are used for tuneable polarization over long distance spans of fiber. Polarization Mode Dispersion (PMD), where different polarization "angles" travel at slightly different speeds through the fiber, makes it necessary for frequent regeneration devices, PMD correction operations, etc., over hundreds of kilometers, especially with older fiber. New fiber is available with very low PMD characteristics, but a lot of what's deployed 'round the world isn't that type. If you can tune the polarization of the laser feeding the fiber, you can, in effect, pre-compensate for the PMD characteristics of the fiber. I.e., if Polarization Mode A experiences X picoseconds of differential delay relative to a defined norm, this device would induce that same delay in the emitter. In effect, the emitter creates an optical signal with various skewed polarization modes, and the shitty fiber "fixes" it so that the signal received on the other end has minimum PMD characteristics, increasing your optical signal-to-noise ratio (SNR).

    Devices like this are going to be the future of long distance backbone networks, where they will enable the operators to remove most of the expensive regenerators, reshapers, and some of the Erbium-Doped Fiber Amplifiers (EDFAs). However, MIT is not the first to create these devices; all they have done is develop a new technique for building them on Si, which could reduce their cost and increase their reliability, while decreasing their size. Size is an issue with the current generation of these devices, which are often too large to fit on the smaller modular interface cards on new Internet core routers from Vendor C.

  • Unfortunately... (Score:1, Funny)

    by Anonymous Coward
    Unfortunately, once the Boston Bomb Squad saw the device involved blinking lights, they detonated the prototype after evacuating the MIT subway stop.

  • Bad Article (Score:4, Informative)

    by Steve525 ( 236741 ) on Saturday February 10, 2007 @02:22PM (#17964120)
    The article didn't give a whole lot of detail, and also exaggerated the importance of this work. I'm fairly sure the work being discussed in the article is work being done at MIT on splitting and rotating polorazations in using silicon nitride waveguides. There are a number of research groups (including Luxtera, as someone mentioned) looking at using silicon (and other silicon CMOS materials such as silicon nitride) to make highly integrated optical devices. A lot of progress has been made in the past few years on making modulators, detectors, wavelength splitters, and Raman lasers and amplifiers. One of the problems with these devices is most of them really only work on one polarization. For a telecom system however, you often can't control the incoming polarization. So, this work is a device that splits and rotates the two polarizations so they can be dealt with separately. (And can be integrated on the same chip as the rest of the devices). An important acheivement, but this achievement alone isn't going to make an impact. (It's all the pieces together that might). I've also seen that Luxtera has their own different way of dealing with this.

    The work is also over a year old (unless there's a new development I'm not aware of). I know two of the students who did the work, and they've gotten their PhDs and moved on.
  • ... that Verizon's FIOS wins and at&t's trailing-edge DSL fades into insignificance?

    Not so long as we lack free markets where Verizon and at&t can compete head-to-head.

    But it would seem that Verizon's customers might reap the benefits of cheap, high-quality fiber transmission, and Verizon will certainly be able to reap higher profits while charging less than the competition (what little competition there is in the USofA telecom markets).
  • Here's a cool article from my own university, about the recent breakthrough a professor here had with his Indium-Phosphide bonding to Silicon (which is obviously much cheaper to make electronics on. InP is the material needed to make photonics like lasers etc. at optical communications wavelengths). Maybe this will enlighten a few of you that wanted more detail. http://www.intel.com/research/platform/sp/hybridla ser.htm [intel.com] The technology splitting up the polarizations of a lightwave is probably a regenerat

  • Moo (Score:2, Insightful)

    by Chacham ( 981 )
    MIT Scientists.

    What's with all the "scientist" stories of late. Can't we just say researchers? Which would be more accurate.

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