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Intel Demos Optical Data Transfer For Servers
angry tapir writes "Intel is taking the first steps to implement thin fiber optics that will use lasers and light as a faster way to move data inside computers, replacing the older and slower electrical wiring technology found in most computers today. Intel's silicon photonics technology will be implemented at the motherboard and rack levels and use light to move data between storage, networking and computing resources. The new rack architecture with silicon photonics is a result of more than a decade of research in Intel's laboratories, Intel CTO Justin Rattner said. It could enable communication at speeds of 100Gbps and transfer data at high speeds while using less power than copper cables. The technology could also consolidate power supplies and fans in a data center, reducing component costs."
Is this "good-bye OEM motherboards"?
Questions raise, answers kill. Raise questions to stay alive.
copper wires cause electromagnetic interference. Every single copper wire at those frequencies start to act as an antenna which causes problems. Light does not have this problem hence you can work with way much higher frequencies.
First of all, speed of light in one medium differs from speed of light in another. So yeah, probably there is some immeasurably small difference in speed of signal in copper and glass. But of course main difference comes from interference and heating - you can pack more channels of information running much higher frequencies in the same space. Plus there may be some speed gain from changing electronic elements with optronic ones (standard transistor can change its state only this fast - maybe optronic equivalent can do it faster?), but I don't have real numbers on my hands right now and too lazy to search and compare them.
Absence of proof != proof of absence.
Speed of electromagnetic waves on copper are close to the speed of light (95 - 97%). http://en.wikipedia.org/wiki/Speed_of_electricity
Speed of light in optical fibre is approx 2/3 the speed of light http://en.wikipedia.org/wiki/Optical_fiber
Propagation speed is affected by insulation, so that in an unshielded copper conductor ranges 95 to 97% that of the speed of light, while in a typical coaxial cable it is about 66% of the speed of light.[1]
relevant wikipedia:
http://en.wikipedia.org/wiki/Photonic_computing
A claimed advantage of optics is that it can reduce power consumption, but an optical communication system will typically use more power over short distances than an electronic one. This is because the shot noise of an optical communication channel is greater than the thermal noise of an electrical channel which, from information theory, means that more signal power is required to achieve the same data capacity. However, over longer distances and at greater data rates, the loss in electrical lines is sufficiently large that optical communications will comparatively use a lower amount of power. As communication data rates rise, this distance becomes longer and so the prospect of using optics in computing systems becomes more practical.
and a more interesting article from 2010.
http://phys.org/news199470370.html
Today computer components are connected to each other using copper cables or traces on circuit boards. Due to the signal degradation that comes with using metals such as copper to transmit data, these cables have a limited maximum length. This limits the design of computers, forcing processors, memory and other components to be placed just inches from each other. Today's research achievement is another step toward replacing these connections with extremely thin and light optical fibers that can transfer much more data over far longer distances, radically changing the way computers of the future are designed and altering the way the datacenter of tomorrow is architected.
we are talk about the nanoseconds it takes a memory access requests to cross your motherboard and the answer to return. and the many CPU clock cycles spend idle while wait for it.
Just long enough so that you won't be upset about having to upgrade.
"Here Lies Philip J. Fry, named for his uncle, to carry on his spirit"
> Don't electrical pulses along a copper wire go at the speed of light already?
That's not the problem, it's propagation effects and timing issues. As someone else here pointed out, these high-frequency signals are essentially radio waves and behave like radio waves. You have interference issues from other, nearby signals. The copper traces on your current motherboard must be carefully routed and kept at equal lengths (because they're essentially transmission lines), or you'll have some bits arriving later than others. Chaos. Using optical eliminates that problem.
(This is also why, if you've ever tried to repair a damaged motherboard, you probably weren't successful. Even if you could successfully identify all the damaged traces -- not easy, what with the "sandwich" layered design -- when you use little jumper wires to bridge the gaps, it just won't work reliably.)
By the way, these propagation effects are the reason why (counter intuitively) SATA and USB can more easily be made faster than older-style parallel connections. Once you get into the 100 megabit range, interference and the precise arrival time of the parallel bits becomes very hard to control. If it's a bit stream, even though it's several orders of magnitude faster, it's just easier to predict and control.
Cogito, igitur comedam pizza.
AC steps in with a complete misunderstanding of the concepts.
Good job quoting Wikipedia though.
You'll find that electrons will need a whole lot of time to 'travel from power supply to the motherboard'. As per http://en.wikipedia.org/wiki/Speed_of_electricity : "These speeds are on the order of millimeters per hour." It's the pulse (wave) that electron movement creates that is close to lightspeed, not the speed of electrons themselves.
So are pulses of light in a fiber medium.
If you do the math, copper is actually around 10-25% lower transit latency. As has been pointed out, fiber wins because it suffers less interference and can go longer distances; that means fewer hops, higher frequencies, etc.
in waveguides the speed is slower, and that includes twisted pair and coax. Typical twisted pair impulse propagation is 45 - 65 % speed of light. Bare copper conductor over ground plane (what you quoted) is not relevant here.