Intel Demos Optical Data Transfer For Servers 71
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."
Re:but (Score:5, Informative)
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.
Re:but (Score:1, Informative)
It is not the speed but the bandwidth that is used. Light wavelengths don't cause interference like electronics do.
Re:but (Score:5, Informative)
Speed of electromagnetic waves on copper are close to the speed of light (95 - 97%). http://en.wikipedia.org/wiki/Speed_of_electricity [wikipedia.org]
Speed of light in optical fibre is approx 2/3 the speed of light http://en.wikipedia.org/wiki/Optical_fiber [wikipedia.org]
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]
Re:but (Score:5, Informative)
> 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.
Re:but (Score:3, Informative)
Re:but (Score:5, Informative)
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.