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Engineers Report Breakthrough in Laser Beam Tech

Posted by ScuttleMonkey on from the really-fast-morse-code dept.

petralynn writes to tell us the New York Times is reporting that Stanford engineers have discovered a method to modulate a beam of laser light up to 100 billion times a second. The new technology apparently uses materials that are already in wide use throughout the semiconductor industry. From the article: "The vision here is that, with the much stronger physics, we can imagine large numbers - hundreds or even thousands - of optical connections off of chips," said David A.B. Miller, director of the Solid State and Photonics Laboratory at Stanford University. "Those large numbers could get rid of the bottlenecks of wiring, bottlenecks that are quite evident today and are one of the reasons the clock speeds on your desktop computer have not really been going up much in recent years."

5 of 208 comments (clear)

  1. More informative article: by TripMaster+Monkey · · Score: 5, Informative


    The NYT story is pretty light on the technical details....a more detail-oriented write-up can be found here... and you don't have to register to read it.

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  2. All I wanted... by parasonic · · Score: 5, Funny

    ...was chips with frickin' laser beams!

  3. Who?? by Maradine · · Score: 5, Funny
    petralynn writes to tell us the New York Times is reporting that Standford engineers. . .

    That's awesome. I can't wait for Hraverd and Yalle to catch up.

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  4. Re:Speed of light vs. speed of electrons in wire? by joe_bruin · · Score: 5, Informative

    The speed of electricity in a wire is not really the issue (it's about half the speed of light, I think. I'm sure someone will correct me). The real issue is signal propagation. When a transistor switches from closed to open or back, the electrical signal travelling through the wire is not a perfect on/off. The voltage ramps up or ramps down as some function of the length of the connection, width of the wire, conductivity, leakage from the transistor, inductance, ... The system needs a bit of time to "settle" into the new high or low state. This is a big limiting factor in the clocking of modern CPUs. For communication off the chip, it's far worse. Now the lines are no longer 90nm (or whatever the chip was made at) in width, and have to go through a far longer distance. That's why today's processors are limited at around 1GHz to the outside world, while internally they can be faster.

    Optical interconnects alleviate many of these problems. With a laser, the ramp up time is significantly shorter, there's no capacitance in the system, and it is far less prone to interference. So, on a 100 GHz optical link you can multiplex 100 1GHz pins (essentially running a P4's FSB on two wires instead of something like 180), thereby significantly reducing the pin count. Or you could run the pins 100 times as fast, meaning much less processor waiting on RAM or bus data.

  5. Overstated results by PhysicsPhil · · Score: 5, Interesting
    Somewhere between the lab and the press release things got overstated. Since my PhD is in silicon-based optoelectronics, I am familiar with this kind of work. A few thoughts crossed my mind after reading the paper.

    What these guys have found is a physical effect that possibly could lead to fast modulation of light. Neglected in the press release are a few fairly important issues:

    • They haven't demonstrated any time-resolved optical effect, and are inferring it strictly from what might be possible. I have no doubt they can modulate, but the operational speeds are still guesstimates.
    • The effect that was demonstrated is not within the 1550 nm wavelength window used for telecom traffic. Their current work shows the effect right in the middle of an H2O absorption peak. Can the effect be shifted? Probably, but these sorts of things are always more work than expected.
    • From a practical standpoint, other Quantum Confined Stark Effect devices often show a strong sensitivity to the polarization of the input light. Ensuring a known input polarization is a major problem right now in optoelectronics. Lord knows it was (still is, actually) a major hassle in my research
    • This device is not quite as CMOS compatible as might be hoped. Building strained germanium quantum wells on a silicon substrate requires depositing atoms layer by layer, and is a slow process. Process throughput will no doubt be an issue.

    All that being said, this is still very exciting. It is a new physical effect demonstrated in a silicon-based material, and a physical effect that has been used elsewhere to do useful things. Hopefully a real modulation device will come along shortly.