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Nanoscale Terahertz Optical Switch Breaks Miniaturization Barrier

Posted by Soulskill on from the who-cleans-up-all-these-broken-barriers-anyway dept.

Science_afficionado writes "There is a general consensus that ultimately photons will replace electrons running through wires in most of our microelectronic devices. One of the current technical barriers to the spread of optoelectronics has been the difficulty in miniaturizing the ultrafast optical switches required. Now a team of physicists at Vanderbilt has made terahertz optical switches out of nanoparticles of vanadium dioxide, a material long known for its ability to rapidly change phase between metallic to semiconducting states (abstract). They report in the Mar. 12 issue of Nano Letters that they have created individually addressable switches that are 200 nm in diameter and can switch between transparent and opaque states at terahertz rates."

9 of 35 comments (clear)

  1. Isolation, Reflection and Cross-talk by Anonymous Coward · · Score: 2, Interesting

    There doesn't seem to be any mention of these. AFAIK these are important characteristics. If the switch has poor isolation, it's not a very good switch. If it reflects too much, it will cause havoc in the system. At the nano scale all of these properties become more and more significant.

    1. Re:Isolation, Reflection and Cross-talk by cas2000 · · Score: 2

      most chip production is still at 28nm or larger, so 200nm is less than 10 times larger....which is still a negative.

      on the positive side, though, it switches at terahertz rates - and even assuming that means only 1 Thz, that's still 200-250 times faster than the roughly 4-5 Gigahertz that current top-of-the-line CPUs switch at.

      10 times the size for 250 times the speed...for non-mobile applications like a desktop or server CPU - or for a GPU - the larger size would almost certainly be worth it.

    2. Re:Isolation, Reflection and Cross-talk by alannon · · Score: 2

      The problem is: current CPU designs are frequently limited by wire propagation delays. Optical circuits do have somewhat faster propagation than copper (1c vs 0.75c), but increasing the size of components necessarily increases the distance between them. 1 thz = 1 * 10^-12 light seconds, which is 0.3mm, I believe.

    3. Re:Isolation, Reflection and Cross-talk by Blaskowicz · · Score: 2

      Quantum mechanics is weird, I guess a photon crosstalks with itself if it feels like it.

    4. Re:Isolation, Reflection and Cross-talk by Blaskowicz · · Score: 2

      Why bother trying to make a CPU with it.
      It feels useful to make communication switches, for network cards or to connect a CPU with another CPU, the chipset, a memory pool and so on.

    5. Re:Isolation, Reflection and Cross-talk by fractoid · · Score: 2

      [...] if your new experimental thing isn't at *least* an order of magnitude better than current production, there's little point pursuing it in commercial directions [...]

      You have to take into account the potential of the new technology as well. Consider the transition from DC to AC power - initially there wasn't much in it, because voltages were low and transmission distances were short. It was only after the whole electricity industry scaled up that AC really showed its strengths... but the potential was there and so it was a worthwhile investment even early on.

      --
      Rampant carbon sequestration destroyed the Dinosaurs' tropical paradise. I'm here to help repair the damage.
    6. Re:Isolation, Reflection and Cross-talk by DMUTPeregrine · · Score: 2

      "Crosstalk" is a feature of electromagnetic induction: a changing current in one set of wires induces a current in the adjacent set. With light this won't happen at all. You can also have multiple frequency signals across a single wire/fiber optic cable, both will have interference from nearby frequency bands since you can't create ideal filters. These are entirely separate problems, even though they both deal with interference between two (or more) signals.

      --
      Not a sentence!
  2. First sentence of summary is false. by smaddox · · Score: 4, Interesting

    Integrated photonics has its place, but it's never going to replace CMOS for computing. Waveguides don't scale like transistors do. If you want to see what integrated photonics is good for, look no further than Infinera. They build photonic integrated circuits for fiber optics communications in 10 years they will own the market for long distance endpoint hardware.

  3. Never Replacing CMOS by darenw · · Score: 2

    Indeed. For Si-based electronic technology, CMOS or other, we routinely deal with two-digit nanometer scales. 22nm, for example.

    For optical technology, structure on that scale has no effect on EM radiation with wavelengths on scales of mm (THz) or microns (IR). This is seriously into UV territory. Bits of matter holding bits of information as a phase changes need to be of a certain size, probably larger than we would like (but I'm not expert on it), for phases to be meaningful.

    For a given energy of interaction, massless quanta tend to be more spread out than massive, as a rule of thumb for practical purposes. I think we'll be using electron-oriented information processing technologies for a long time, until someone figures out a way to stabilize muons. Then we can make some really tiny technology.