Nanoscale Terahertz Optical Switch Breaks Miniaturization Barrier 35
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."
Isolation, Reflection and Cross-talk (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.
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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.
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Worse, C is the speed of light in a vacuum. In any other medium it's slower. I'd need to check what current light fiber speeds are, but it's guaranteed to be less than C, unless there's a vacuum in the center of the fiber. (I think there needs to be a relatively smooth gradient of speeds, with the center being the fastest and the edges being the slowest for an optical fiber to work, but I'm less than certain.)
OTOH, a tetrahertz switch doesn't mean a tetrahertz CPU cycle. So I'm not at all sure that you
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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.
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[...] 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.
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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
And ironically enough, we're now at the point where further developments in technology have meant that DC is now superior for high-power transmission over long distances, thanks to lower power losses and the ability to run high-voltage cables underground/underwater (no capacitive coupling losses).
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Also, photons don't have cross-talk. That is a specifically electro-magnetic phenomenon.
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> Also, photons don't have cross-talk. That is a specifically electro-magnetic phenomenon.
Photon, n.: a quantum of electromagnetic radiation
Light has cross-talk, because radio has cross-talk, and when you send a signal down a coax cable, you are basically beaming it down a "radio fiber".
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Where is the "-Not enough Info" moderation when you need it?
I really want to know if photons as quanta don't have crosstalk but this single response on Slashdot has left me begging!
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Quantum mechanics is weird, I guess a photon crosstalks with itself if it feels like it.
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This is jam hot.
Good job.
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First sentence of summary is false. (Score:5, 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.
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Integrated photonics has its place, but it's never going to replace CMOS for computing.
you arent the first to make such a bold assertion. people have said similar things about just about every new technology.
"This 'telephone' has too many shortcomings to be seriously considered as a means of communication. The device is inherently of no value to us." -- Western Union internal memo, 1876.
just sayin
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I'm going to disagree with you, (and agree with smaddox). Light is not good for computation. Simple put, light doesn't like to interact with itself, so making a transistor or switch is difficult. Sure it can be done, but it inevitably takes a lot of power relative to what it takes make a switch with electronics. What light, however, is excellent for is carrying huge amounts of data down a pipe. That's why IBM and INTEL are interested in integrated photonics.
I'm a researcher in this field and have spok
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Never Replacing CMOS (Score:3)
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 inter
No general consensus (Score:1)
"There is a general consensus that ultimately photons will replace electrons running through wires in most of our microelectronic devices."
No there isn't.
We know that for silicon CMOS, Moore's law is starting to slow down and further miniaturisation is becoming much more expensive. We know that if the complexity and efficiency of microelectronics is to continue improving at its current or past pace, we'll probably have to move to something other than silicon. There are multiple possibilities, including carb
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"There is a general consensus that ultimately photons will replace electrons running through wires in most of our microelectronic devices."
No there isn't.
We know that for silicon CMOS, Moore's law is starting to slow down and further miniaturisation is becoming much more expensive. We know that if the complexity and efficiency of microelectronics is to continue improving at its current or past pace, we'll probably have to move to something other than silicon. There are multiple possibilities, including carbon (graphene or nanotubes), semiconductors other than silicon, titanium dioxide memristors and other more exotic things. Maybe one of these technologies will enable us to push computing closer to its physical limits. Maybe more than one. Maybe none of them will, and eventually we'll just have to be satisfied with gradually refining and optimising silicon CMOS techniques even further. Optical computing has attracted some criticism about its prospects: http://www.nature.com/nphoton/... [nature.com] (sorry for the paywall).
There is no consensus at this point that any particular technology, optical or otherwise, is one of the next major steps in microelectronics.
I think the point that was being made is that optical will eventually replace all electrical connections. It was not saying the only jump to be from Silicon -> Optical, but rather will ultimately be replaced by Optical as a faster medium just like the advances we saw by deploying Fiber Optic cables (and the more recent push for optical-based network switches to replace existing electrical). Realistically the full Optical transition is still years away and you are likely correct that we will move to on
"nanoparticles of vanadium dioxide" (Score:2)
You mean nanoparticles of a substance called "vanadium dioxide" [slashdot.org] , don't you?