Slashdot is powered by your submissions, so send in your scoop


Forgot your password?
Technology Science

Engineers Report Breakthrough in Laser Beam Tech 208

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."
This discussion has been archived. No new comments can be posted.

Engineers Report Breakthrough in Laser Beam Tech

Comments Filter:
  • by TripMaster Monkey ( 862126 ) * on Wednesday October 26, 2005 @04:02PM (#13883633)

    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.
  • That I can disco dance a billion times faster?
  • Looks like the NY Times servers can't handle the /.ing!
  • by xmas2003 ( 739875 ) * on Wednesday October 26, 2005 @04:03PM (#13883643) Homepage
    NYT registration required to read this John Markoff (infamous at Slashdot because of his "sensational" coverage of Kevin Mitnick) article ... but fortunately, BugMeNot [] comes to the rescue with username/password of "twernt/twernt"

    This work was funded by Intel and DARPA with some assistance from an HP researcher and uses something called the Quantum-Confined Stark Effect [] with primary application in optical networking gear ... but hey, maybe we'll see a 100 GHz PC in the not-too-distant future.

    The halloween webcam is up [] ... but X10 technology isn't capable of 100 Billion times/second updates ... ;-)

  • by winkydink ( 650484 ) * <> on Wednesday October 26, 2005 @04:04PM (#13883648) Homepage Journal
    Is that the one across the bay from Berkly?
  • At about the same frequency. Now you can do a lasershow in the cloud of smoke. Does that count as research too?
  • by mcsestretch ( 926118 ) on Wednesday October 26, 2005 @04:05PM (#13883656)
    But will it pop a huge jiffy-pop container in my professor's house by shooting it from a plane?
  • by parasonic ( 699907 ) on Wednesday October 26, 2005 @04:05PM (#13883657)
    ...was chips with frickin' laser beams!
  • Who?? (Score:5, Funny)

    by Maradine ( 194191 ) * on Wednesday October 26, 2005 @04:12PM (#13883717) Homepage
    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.

  • by Stibidor ( 874526 ) on Wednesday October 26, 2005 @04:13PM (#13883728) Homepage
    So can they attach them to sharks' heads yet?
  • by Omega1045 ( 584264 ) on Wednesday October 26, 2005 @04:14PM (#13883730)
    and are one of the reasons the clock speeds on your desktop computer have not really been going up much in recent years

    This sounds silly to me since desktop power (say a $500 system - discounting monitor and keyboard) is increasing exponentially, doubling every two years compared to the price. The machine I built this spring was twice as powerful than a system I built in 2003 for the same money, but 8 times as powerful as a machine I built just 6 years ago and is about 128 times as powerful as the machine I had when I went to college in 92. And I am only considering pure clock speed, not increases in the efficiency of chips, growth of RAM and disk for the price, etc. While Moore's law concerning silicon chips will start faltering as we approach 2020, I have been nothing but impressed with how desktop performance continues to improve.

    These new laser improvements, and things like molecular computing, will help us continue on after the 2020 mark with our current exponential growth.

    Sorry to go off, I just got done reading The Sigularity Is Near []

    • I disagree, the slowed progress in PC speedups in the last couple years has been disappointing. Things really started to fall off at about 3ghz. 3ghz was released in 2002(!) over 2 1/2 years ago and we still haven't hit 4ghz, that says it all with respect to clock speed.

      More efficient processors are only just closing in on 3ghz... pretty bad when the P3 (also reasonably good IPC) came out at 1GHz *5 years* ago.

      Intel and AMD have clearly indicated that the good old days are over by introducing dual-cor

      • I am not referring only to pure clock cycles. I actually think the trend towards multi-core is a good thing. First, in modern computer enviros where multiple threads are running, multi-core systems should prove to be very effective. Second, multi-core systems will use less power than a single core system with the same total processing power. This is simple EE - multi-core means power consumption goes up in a linear style instead of as a square function. It does not matter how it is technically getting d
      • More efficient processors are only just closing in on 3ghz...

        Who cares? They're more efficient. They don't need to run at 3ghz to be faster that the old stuff. Just because the clock speed isn't there yet doesn't mean the performance hasn't gone up. Look how many times AMD has pulled ahead of Intel in performance, and they've never even shipped a 3ghz CPU. The only thing that has fallen off is the power of intel's old marketing. The only reason there's a 3ghz number to "catch up to" is that so much performa
  • by dada21 ( 163177 )
    A week or so ago, I mentioned decommissioning analog & digital TV broadcast spectrum to use for ore wireless data. I mentioned how fiber was just on serendipidous discovery away from massive data rates. I was shunned as "everyone knows" there are limits to light.

    While this may not be THE discovery I was alluding to, it proves that the door surely isn't closed.

    While science can find use in this discovery, I'm more interested in profitable consumer uses. What are the possibilities there?
    • by amliebsch ( 724858 ) on Wednesday October 26, 2005 @04:27PM (#13883857) Journal
      You might want to check out this article that appeared in IEEE Spectrum magazine:

      The Silicon Solution []

      It describes what I believe is the same breakthrough in considerable detail. The Big Deal is that lasers can now be made from standard CMOS silicon fab processes, meaning you can integrate the lasers and optoelectronics directly into the chip without needing radically new chip fab techniques. Really interesting stuff!

      • Dead link?

        10.4.5 404 Not Found
        The server has not found anything matching the Request-URI. No indication is given of whether the condition is temporary or permanent.
    • The problem isn't bandwidth, it's cost, getting those high data rates on and off the fiber at a reasonable price. Wavelength division multiplexing can be used to attain insanely high data rates, if you have enough money.

      The fundamental limits haven't changed.

  • OK, so this is a solid-state light switch that goes really fast.

    I've been wanting to know for some time if there is a material that can switch from transparent to reflective? It would need to be pretty fast (or slow, if you could also slow down the speed of light, which I have read somewhere can be done)
    • I only took 3 materials science classes in Undergrad, so this won't be a full answer, but it might get you started on the right track.

      I recall that some crystalline materials exhibit very different refractive and reflective properties when put under mechanical strain. Materials that do this but with electricity are how we make accelerometers these days. So a crystal that either transmits the light or refracts it off into a random direction depending on strain may be what you're looking for. No clue what

      • nope, that wont do it! I need something that can reflect normaly, or be transparent. Although I suppose being able to reflect normaly, or reflect at a slightly different angle, would also work (instead of being transparent). It needs to be pretty precise.

        Yeah, I know about MEMS and DLP devices, but I want something solid state.
    • Heat dissipation? (Score:5, Interesting)

      by andyo ( 109338 ) on Wednesday October 26, 2005 @04:30PM (#13883884) Homepage Journal
      It would also be interesting to know how much heat is generated by the absorbtion of the light. How does this compare to electrical units' heat?
      • Heat from absorption of an optical signal (at the levels used in communications) is negligable. First, the signals are very low, measured in mW, and the absorption per meter in fiber is incredibly small. (I can't remember the actual number, but you need to go tens of miles before you even lose half your light.) As you can imagine, dissipating a few mW over a hundred miles doesn't generate any heat.
    • Not sure if this is exactly what you are looking for, but acousto optic modulators uses acoustic waves to change the refractive properties to diffract the incoming light to a known specific angle. So by sending a pulse through the material the beam changes angle and you can then reflect this part of the beam back.
  • OC-768 laser runs at 40 giga bits per second. Also I wonder how such modulation will behave in a WDM system... more prone to non-linear effects and such.
  • If I remember correctly, QCSE uses excitons to absorb light.

    What is the wavelength of these excitons in SiGe? If it's significantly different than 1.3 microns - 1.5 microns, then this is a short-haul play -- like inside a box. In any case, 100 Gb/s is generally fragile stuff anyway over long distance, so it's highly unlikely that this is part of some global supercomputer, as the article suggests.

    That's OK, though. This might be great stuff for optical interconnection buses.

    BTW, D.A.B Miller is a big name
    • I'm reading the actual Nature article now (Vol 437|27 October 2005|doi: 10.1038/nature04204, refer here [] for those who have access). The structure they have built is a multilayer of Si and SiGe (10 nm Si and 16 nm SiGe, repeated ten times). You are correct that there are exciton peaks in the range of 1.3 microns to 1.5 microns. Specifically, there state:

      Clear quantum confinement is seen, with strong exciton peaks that we assign to electron-to-heavy-hole (e-hh; ,0.88 eV at 0 V) and electron-to-light-hole (
  • reducing the cost of fast switching. There's plenty of dark fiber [] out there for anyone who can afford the hardware and this may take OC12 fiber cards from ~$6000US to a couple of hundred.

    At the very least, it will make it possible for gigabit ethernet switches to use an optical brain to handle much larger total loads and likely at lower costs. (No, I don't know if this is cheaper to make but I figure the low grade parts that don't run at full speed will be sol
  • Like most unreleased technologies, I am skeptical. Many research groups publicize the possible miracle's their technology could fix while downplaying the downside of the technology. This is done in order to get more research dollars spent to fund your research. This sounds like publicity from a research group in order to get more funding. In that respect I think it is working.

    I'll stick to Journal articles to see if the technology actually works though.

    • Uh, it's in this week's Nature. That's a pretty important Journal.
    • RTFA:"He acknowledged, however, that there is a significant gap between research results and commercial availability of devices based on scientific breakthroughs.
      Other designers working in the field were also cautious about direct applications of the technology. Alex Dickenson, chief executive of Luxtera, a Carlsbad, Calif. start-up firm that announced a 10-billion bit per second optical modulator using a different silicon-based approach earlier this year, said that he believed there would significant hur
  • by G4from128k ( 686170 ) on Wednesday October 26, 2005 @04:36PM (#13883929)
    This tech will mean a new opportunity for a new kind of "PCB" maker. Circuit boards with embedded optical traces will replace (or layered on to) traditional electronic circuit boards. New optical chip-to-board interconnects will also become a new, growing business. I know that people do make all-optical circuits (I've seen these at Lucent's museum in NJ), but it looks like the current tech is very expensive (etched channels in a sliced wafer).

    The first company to develop a low-cost, high-quality tech for "printing" optical traces will make a mint once these interconnects become common. I'd bet that the ultimate technology will be a sandwich of resins with etched channels and vapor-deposited reflective layers, walls, corners (or high-index resin filling). For most applications, the optical interconnect can be single-layer because the non-interference on crossing beams will let two traces/channels cross each other with interference.

    Inventions like this one are a great start. But until they find away to make cheap circuits to route optical connections on a board, this tech won't see widespread adoption.

    • That was all very interesting lay speculation, and I do wish I could take you up on your bet.

      See, no one is going to "print" optical traces. Unless you consider gluing fiber to a board "printing." Fiber optic cables are cheaper than PCB by a long shot, which is why they are used for optical interconnect now, and will be in the forseeable future.
      • See, no one is going to "print" optical traces. Unless you consider gluing fiber to a board "printing." Fiber optic cables are cheaper than PCB by a long shot, which is why they are used for optical interconnect now, and will be in the forseeable future

        Yes, fiber is cheap for point-to-point routings, but I doubt it scales well. What happens when a motherboard becomes 100% optical interconnect -- with virtually every chip and attached device using optics to communicate? Optical connections would run from

        • Yes, fiber is cheap for point-to-point routings, but I doubt it scales well. What happens when a motherboard becomes 100% optical interconnect -- with virtually every chip and attached device using optics to communicate? Optical connections would run from the CPU (maybe each core of the CPU) to memory controller, cache, main memory banks (perhaps one fiber per optically connected RAM card), I/O controllers, mass storage devices, I/O ports, expansion bus slots (again, one fiber per slot), etc. A single mo
  • by jpellino ( 202698 ) on Wednesday October 26, 2005 @04:39PM (#13883958) come up with a frickin' shark that can keep up wih these new lasers.
  • How quick is 100 billion times per second? Well, if my calculation is correct then light, moving at 3*10^8 m/s, will, in 1/(100 billion) = 1/(10^11) seconds, have moved 3mm.

    At that rate, the universe is almost stationary.

  • We can finally cut through the Borg's shields now!
  • Why write '100 billion times' per second instead of 100GHz? My cell phone 'generates an electromagnetic field that changes orientation almost 1 billion times per second'. Wow!
  • Overstated results (Score:5, Interesting)

    by PhysicsPhil ( 880677 ) on Wednesday October 26, 2005 @05:29PM (#13884340)
    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.

    • Your points all seem valid, except for the polarization one. I think most modulators are polarization sensitive. You just polarize the input and accept the losses. In the case of the modulator attached to the laser (the usual case) the laser output is polarized.
  • Bring on the 93.1322575 gigabit/second [] ethernet!
  • "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."

    I'm pretty sure the wiring "bottleneck" has, uh, absolutely nothing to do with why clock speeds haven't been going up. CPUs can run at whatever speed they like, independent of the bus. (Well.. an arbitrary multiplier of the bus; not independent strictly speaking). The problem is t
    • This has nothing to do with CPU speed, but rather the bus speed that connects the CPU to other components. The last "major" upgrade on a common bus was increasing PCI frequency to 66 MHz from 33 MHz... and that took 10 years to accomplish, not the 18 month doubling of "Moore's Law" that everybody talks about. Even PCI-X is an "older technology" by many standards. And think about that too: If the bandwidth going to a peripheral card is limited by the fundimental bus architechture, why should peripheral d

When you make your mark in the world, watch out for guys with erasers. -- The Wall Street Journal