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Intel: Advances in silicon photonics can break the I/O “power wall”
- oneplane 6y agoThis is where they can start thinking about 'optronics' as a marketing name, isn't it.
- neogodless 6y agoNo, this branch of semiconductor engineering is un-optane-able.
- CoastalCoder 6y agoI'm curious about the relative latency of photonics vs. electronics, when connecting e.g. two chiplets in the same package. My (possibly wrong) understanding is that the E-O and O-E conversion adds a non-trivial amount of latency in a situation like that.
- adgjlsfhk1 6y agoHas there been much research on making cpus that are fully light based? It seems like if that were possible, it would make a lot of this much easier.
- moistbar 6y agoI remember hearing about one back in the early 2000's, but I'm unable to find the article I read way back then. I recall it making some extremely lofty claims regarding clock speed, somewhere on the order of 300 GHz IIRC, but it never saw the inside of a production machine as far as I know.
- amelius 6y agoI guess the main problem is that Maxwell's equations are linear, and thus you need some optical non-linear effect to make a logic gate. And you need some way to prevent attenuation of your signals.
- N1H1L 6y agoI think one of the problems would be miniaturization. Visible light is hundreds of nanometers, and X-ray photonics are still in it's infancy
- entropicdrifter 6y agoYou aren't limited by the wavelength in terms of pure transmission and reception. Bass frequency sound waves are multiple feet long, yet earbuds transfer those frequencies just fine.
- derefr 6y agoA wave of sound is a wave of pressure — i.e. density. Sound waves are one-dimensional. You can have a material one atom thick in a vacuum, and it’ll transmit sound just fine, as long as that material has some elasticity to it. Light waves, on the other hand, are two- [linearly-polarized] or three- [circularly-polarized] -dimensional. They’re heading in one direction, and also wiggling side-to-side as they go. If light didn’t have a “thickness” — that is, if light could “sneak through” gaps narrower than its “diameter” — then 1. “Optical” fibre would be capable of acting as a waveguide for all frequencies, not just optical ones; and 2. the Faraday cage around a microwave wouldn’t prevent the microwaves from escaping. (You might think we’d also get universal antennas out of that, but no, antennas are a quantum thing—it’s not about squeezing through a gap, but about exciting an AC electric field in the material, so letting the whole wavelength hit the antenna actually causes the induced field to destructively interfere with itself. Think of an antenna as absorbing the wave “head-on”, rather than “side-on.” Your antenna needs to catch half the wave — node to anode to node — to get the highest-power signal out. But you don’t miss the wave entirely if you catch less. You just get a less powerful signal — it’s still possible to do useful work [like power an optical receiver, or decode an AM radio signal] with just a 1/Nth slice of each cycle of the wave.)
- entropicdrifter 6y agoTIL, thanks!
- CoastalCoder 6y agoLightmatter [0] is doing something along those lines. But IIUC they're only attempting optical computing for certain mathematical ops (FMA and/or convolution?) [0] https://lightmatter.co/ https://lightmatter.co/
- mmmBacon 6y agoMatrix multiplication. They use a cascaded Mach-Zhender MEMs array as their systolic matrix multiplier. These types of schemes are limited to the amount of loss that they have. Additionally since these are analog components they have a certain physical size which is difficult to reduce. In my view this type of architecture does not scale very well.
- magicalhippo 6y agoAFAIK yes. Of course you need some actual non-light hardware to guide the light and such though. https://en.wikipedia.org/wiki/Optical_computing https://en.wikipedia.org/wiki/Optical_computing https://www.eetimes.com/how-does-optical-computing-work/ https://www.eetimes.com/how-does-optical-computing-work/
- musingsole 6y agoMost projects I've read focus on specific components (mainly ALUs). I'm aware of a photonics flip-flop equivalent design, but I'm unaware of equivalents for dense memory. I imagine DRAM would remain mundane electronics even if the CPU were fully migrated to the tech.
- jl2718 6y agoYou can calculate it as the RC constant of the PN junction. The issue is that the photon wavelength makes a fairly large area. This may be solvable with plasmonics.
- mmmBacon 6y agoThe latency at this scale of the device is largely irrelevant as it would be dominated by FEC. The PN junctions themselves have BW of about 25GHz, well above anything compute is doing.
- annoyingnoob 6y agoWhile this could allow you to put more distance between components, I'm not convinced that this is a good thing in practice.
- FourHand451 6y agoWhy do you think it might not be a good thing in practice?
- annoyingnoob 6y ago> That could look like pools of compute, memory, and peripheral functionality distributed throughout the system; connected over long distances with optical links, software-defined infrastructure, and high-speed networking. Latency comes to mind. But also how many people does it take to troubleshoot a system where the compute, memory, and storage are all in different physical locations? Building a distributed system seems fragile.
- sumtechguy 6y agoVery much so. It also creates some interesting possibilities. Such as a memory unit that can be shared between a few computers and then reconfigured as needed. This would be useful in such things as VMs and docker units and dynamic scaling. They probably would not be located in different buildings. But probably in the same rack or adjacent. You can see some of this sort of thing with software defined networks and storage pools.
- deburo 6y agoUnrelated to photonics, but this: >memory unit that can be shared between a few computers and then reconfigured as needed It reminds me of reading recently about Compute Express Link, when Micron announced they were moving away from 3D Xpoint and would focus on CXL. https://blocksandfiles.com/2021/03/25/cxl-and-the-developing-memory-hierarchy/ https://blocksandfiles.com/2021/03/25/cxl-and-the-developing...
- pjc50 6y ago> the company hopes to scale its silicon photonics platform up to 1 Tb/s per fiber at 1pJ of energy consumed per bit, reaching distances of up to 1 km. Astonishing numbers. 1pJ is tiny. And yet that's still cooking away at a whole watt of TX power.
- ksec 6y agoYes. I wonder if this will be the future of Intel. They seems to be quite far ahead in Silicon Photonics than every one else. And I dont see an end for our need for more bandwidth in the near future, at least not in the next 10 years.
- rektide 6y agoif we believe their press releases, they seem like they've been in the lead for the last 10 years[1]. they had one of their very first demonstrations a year ago[2]. it's promising as heck. and I dont mind that it's taking a while. but it is also an area I have, after the many years, learned to keep tempered expectations on. [1] https://arstechnica.com/gadgets/2010/07/the-future-of-electronics-is-frickin-hybrid-silicon-lasers/ https://arstechnica.com/gadgets/2010/07/the-future-of-electr... [2] https://www.servethehome.com/hands-on-with-the-intel-co-packaged-optics-and-silicon-photonics-switch/ https://www.servethehome.com/hands-on-with-the-intel-co-pack...
- mmmBacon 6y agoMany others have been shipping SiP in higher density for much longer. Acacia and Luxtera (both acquired by Cisco) for example.
- cogman10 6y agoBandwidth isn't the reason photonics matter (IMO). The reason they matter is because they eliminate cross talk. That can mean more densely packed transistors and less data lines.
- bullen 6y agoCopper allready transports electromagnetic waves at the speed of light. You should probably view this as a desperate attempt to keep the status quo of eternal growth. The real reason for all the news you see today, and that you will see until the end of times is caused by peak dead trees. Or atleast until the sun has powered enough trees, which BTW is the best solar panel AND battery; to make the same amount of coal, oil and gas we had in the early 1900.
- jcranmer 6y agoThe speed of light in copper cable is not the same as the speed of light in a vacuum. Light will propagate faster through optical cables than it will in copper cable.
- akvadrako 6y agoThey are almost the same. Speed of electrical signals in copper cable and speed of light in optical cables is about 2.0e8 m/s. Though you are technically correct that Light will propagate faster through optical cables than it will in copper cable.
- musingsole 6y agoDo photonics based components have similar potential for complex calculations as quantum computing? We use binary because it was an improvement on analog, and it beat out ternary or higher orders. However, light can have a number of effectively binary attributes. I wonder if you could use polarity in addition to the light's presence for smuggling more data into a "bit"
- mmmBacon 6y agoIn theory yes. For example, certain optical elements perform Fourier transforms. However optical computing as we know it today is really a type of analog computer. Today’s optical devices are relatively large compared to transistors so difficult to make an optical computer scale very well. Also given that each optical computing stage involves optical power loss, there’s a limit to how many stages one can cascade before having to regenerate via an OEO conversion.
- fanf2 6y agoWho remembers Intel Light Peak from 2009? They switched from silicon photonics to copper and it became Thunderbolt in 2011. https://en.wikipedia.org/wiki/Thunderbolt_(interface)#Introduction https://en.wikipedia.org/wiki/Thunderbolt_(interface)#Introd...
- m463 6y agoI think displayport does optical right now. all the dp 8k cables are fiber.
- dogma1138 6y agoThere are some active cables for DisplayPort that are optical the port itself is still electrical it’s basically like a fiber SPF module. The benefit is that you get a long, thin and flexible cable, the downside is that these cost and arm and a leg (£400 in the UK for 15m cables).