10 ms·
After 50 years of effort, researchers made silicon emit light
- jonplackett 7y agoOn a scale of zero to really big deal. How much of a big deal is this?
- deleted 7y ago[deleted]
- keyle 7y ago42
- artemonster 7y agoTwo bananas
- jka 7y ago"Integrating photonic circuits on conventional electronic chips would enable faster data transfer and lower energy consumption without raising the chip’s temperature, which could make it particularly useful for data-intensive applications like machine learning." Sounds potentially like a big deal :)
- perlgeek 7y agoIt's an incremental step in a good direction.
- The_rationalist 7y agoPhotonic can only be up to 20% faster... And I'm talking about a fully photonic cpu, not an hybrid one that has a light/electricity translation cost.
- andromeduck 7y agoI don't think the win here will be speed, particularly chip level as much as enabling lower power and higher throughout architectures at the system level. As in this is mote likely to be used for medium range links where infiniband/pcie/nvlink are used today.
- gridlockd 7y ago> Photonic can only be up to 20% faster... How did you come up with that number? The speed of travel? That's not really the main bottleneck in current computer architectures, at least not yet. Using photons would enable quite different architectures that we haven't even conceived of yet.
- The_rationalist 7y agoHow did you come up with that number? Honestly I can't find it :/ I had read this number either in the wiki page of photonic but it's not there anymore (or never was?) Or maybe it was how much faster was light in solids vs electricity speed? At least I could find back However, optoelectronic devices lose 30% of their energy converting electronic energy into photons and back; this conversion also slows the transmission of messages. All-optical computers eliminate the need for optical-electrical-optical (OEO) conversions, thus lessening the need for electrical power. So maybe that this number is wrong but has the research really been too mediocre to calculate the real maximum potential speed gain from light alone (and not new way of computing)? Or did they calculate it and decided to not make it visible online because otherwise they would loose funding?
- knolax 7y ago> Modern transistors, which function as a computer’s brain cells Who's the target audience for this analogy? If you understand what a brain cell is then you probably know what a transistor is too. I would bet that more people know what a transistor is than what a brain cell is.
- artemonster 7y agoThe whole article is like this (facepalm)
- dang 7y agoMaybe so, but could you please stop posting unsubstantive comments to Hacker News?
- capableweb 7y agoYou don't need to know the details of a brain cell to get the analogy. If I say "transistor" to my mom, she wouldn't be able to tell me what it is. If I say "It's like the brain cells for the computer", she would probably understand that "Ah, so a computer has many transistors that helps it think", which seems good enough for an article with a broad audience. > I would bet that more people know what a transistor is than what a brain cell is I'm happy to take you up on that bet, but it depends on what bubble you ask. In San Francisco/Silicon Valley, that's probably true, but outside any high-tech bubbles, more people know that we have brain cells in our heads, than we have transistors in our computers, I'm fairly sure.
- Someone 7y agoI would take that bet, too. If you say “transistor” to non-technical people over 50 or so, they more likely would think of small portable radios (https://en.m.wikipedia.org/wiki/Transistor_radio https://en.m.wikipedia.org/wiki/Transistor_radio). To them, and many others, computers don’t have transistors, they have chips. They _might_ know the transistor replaced vacuum tubes, but I doubt many would be able to tell what function either had, or be able to point out the transistors inside such a radio.
- xt00 7y agoSuper cool -- one challenge will be that in order to live on the hot processors of today, these emitters will need to still work at around 400K -- the good news is that these appear to still work well at around 300K -- but it sounds like these go to nearly no bandgap at higher temperatures and shift into the infrafred. But yea, pretty awesome stuff..
- 01100011 7y agoWouldn't infrared be acceptable for data transmission?
- GordonS 7y agoNot sure how applicable it is, but the IrDA (Infrared Data Association) protocol tops out at only 16Mbps.
- layoutIfNeeded 7y agoFalse. >GigaIR: 512 Mbit/s – 1 Gbit/s, NRZI, 2-ASK, 4-ASK, 8b/10b https://en.wikipedia.org/wiki/Infrared_Data_Association https://en.wikipedia.org/wiki/Infrared_Data_Association
- raverbashing 7y agoThat's like asking the GoKart association how fast you can take a Formula 1 car ;) IrDA has its uses but it seems they don't deal with fiber comms.
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- cybert00th 7y agoReally impressed they stuck at it, by the sounds of it there's still a lot of work to do. Hopefully it won't be another 50 years before we see it adopted at scale.
- armada651 7y agoIt's kind of fitting that this was done in Eindhoven, a city that formed around the Philips light bulb factory. It's a place that celebrates a history of making stuff glow.
- donnellycc 7y agoI graduated from TU/e and in my experience their applied physics department, specifically nanomaterials like this are very well funded and attract a lot of international talent. Eindhoven likes light! And....making bridges out of beer crates: https://www.ed.nl/default/tu-e-studenten-vestigen-nieuw-record-met-bierkrattenbrug-video-foto-s~a0720318/ https://www.ed.nl/default/tu-e-studenten-vestigen-nieuw-reco...
- deleted 7y ago[deleted]
- RaoulP 7y agoIs the breakthrough here about emission or transmission? Or is the physics for these two connected? It's not clear to me, between the title and the article. Secondly, could using a "photonic" memory bus bring RAM access speeds close to cache speeds, or is the transmission distance/time not the main issue there?
- BostonEnginerd 7y agoThey were able to measure a strong photoluminescence signal from the silicon germanium nanowires. Photoluminescence is a good proxy for how efficiently it will light up - carriers are generated optically with a light source more energetic than the bandgap of the material. This is much easier than fabricating a full device with electrical contacts. Silicon is typically a really lousy photon emitter because it’s an indirect bandgap material. Turning an electron/hole pair into a photon requires an interaction with a phonon. It seems by getting the silicon to grow in a hexagonal orientation, it becomes a direct bandgap material leading to much higher emission efficiency.
- RaoulP 7y agoThank you. There is a lot here I need to read more about.
- Sheppy96 7y agoTransmission time isn’t really the main issue, it’s more about the work required to get a memory request through the levels of the hierarchy to DRAM and back. Probing each level of cache, propagating through the miss queues, translation (maybe with TLB miss), waiting for the DRAM controller, etc.
- RaoulP 7y agoInteresting - if that's the case I would imagine it make sense for some systems to feature an architecture which skips the idea of multilevel cache entirely and has only RAM connected over a photonic bus. No probing, no cache misses.
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- anthk 7y agoGood. This means less heat, and a much faster transmission.
- baybal2 7y agoSilicon photodiodes and LEDs are in the infrared range, so they still can be considered light emitting
- wffurr 7y agoHow long until isolinear optical chips, then? https://memory-alpha.fandom.com/wiki/Isolinear_chip https://memory-alpha.fandom.com/wiki/Isolinear_chip
- ctack 7y agoReally not sure this is the correct way to think about it, but if the silicon is now transparent and parts of it are emitting light, how is the focus limited / controlled ie. how does a receiver know from emitter it should be receiving from?
- datenwolf 7y agoGaaah, please stop advertising optical computers as the technology that will overcome Moore's law. It makes no effing sense. Wavelength of the light emitted by these devices: ~4000nm Latest generation commodity CPU transistor structure size: 7nm Add to that that photons really don't like being trapped; you essentially need a delay line and optical amplifier to hold them indefinitely (that's essentially the core technology my whole PhD thesis centers around), it makes them a really impractical thing to store bits with. Things with a rest mass can be stored easily, though. Things like, say, electrons!
- dr_dshiv 7y agoI like to think that comments like this make me smarter with 10x efficiency. In this case, the pattern is: 1. Identify and refute common conception 2. Compare easily understood numbers 3. Assert basis of knowledge 4. Introduce a clear, tangible model for alternative thinking 5. Appropriate use of emotional resonance to capture and maintain attention
- karkisuni 7y agoFive Easy Steps to Becoming a 10x Commenter!
- kevin_thibedeau 7y agoThere's no profit in taking five steps.
- deleted 7y ago[deleted]
- dannypgh 7y agoIt's definitely not a continuation of Moore's law as it has nothing to do with transistor density, but it may mean that the performance people expect from computers - which is why people are usually talking about Moore's law - may continue increasing. I don't see how the wavelength is comparable to transistor size because as you switch to the optical realm, the benefit of information propagation at speeds near c (or c, if you're pulling a vacuum) means physical size doesn't matter as much. At 4Ghz you can move information 7.5cm in one cycle, and that's a pretty large distance compared to any integrated circuit I've ever seen. Why is storage necessary? If you can move bits to optical gates and get a result back it seems to me like you can work around the fact that, in an electrical system, capacitance and heat (due to density achieved in the quest for minimizing capacitance) start to limit the computation you can do.
- mattjoyce 7y agoTitle : "After 50 Years of Effort".... 1st Para : "NEARLY FIFTY YEARS ago, Gordon Moore..."
- thatguy27 7y agoAnybody else annoyed by this being written up as if the research was just published?
- pieterk 7y agoIf anyone is interested in how this new material is made: it’s literally grown from scratch. Imagine a 3D printer at atom scale. But because the scale is so small, the nozzle has to deposit a gas. The magic is in making the individual gas molecules get to the right place. Layer by layer, to what theory predicted would be a light emitting configuration. Incredible achievement. https://www.nature.com/articles/s41586-020-2150-y/figures/6 https://www.nature.com/articles/s41586-020-2150-y/figures/6
- jpmattia 7y agoMOVPE is more of a self-assembly process than 3D printing, and it has been around for decades. BTW It is worth noting from your link that the silicon is being grown on a GaAs substrate, so to be useful they would have to figure out how to grow the silicon wire on a silicon substrate. (GaAs already has many options for optical devices.)
- jpmattia 7y ago> Modern transistors, which function as a computer’s brain cells, are only a few atoms long. If they are packed too tightly, that can cause all sorts of problems: electron traffic jams, overheating, and strange quantum effects. One solution is to replace some electronic circuits with optical connections that use photons instead of electrons to carry data around a chip. Journalists need to be educated: Transmission lines are photonic, so silicon already has connections carrying data around using photons. As you would expect, those photons are traveling at the speed of light in the material. If I were king, I would demand that every optical-silicon publication explicitly describe why their optical photons are more desirable than microwave photons that are already in widespread use.
- jl2718 7y agoSo bad, had to stop reading. >> cubic crystal lattice that allows electrons to move within the lattice under certain voltage conditions. But it doesn’t allow similar movement for photons, and that’s why light can’t move through silicon easily. Uhhh.. not really. I’ll try to explain (forgive my ad-lib MatSci from 20 years ago). Efficient light generation is a matter of direct or indirect bandgap. A direct transition is one where the electron wave number is unchanged in dropping from the high to low energy state, so it can be completed with a single photon (light). An indirect transition fails conservation of energy and momentum with one photon, so it requires phonon (heat) interactions. Semiconductors have an energy gap between the highest few occupied state and the lowest few unoccupied states, and these are the only states that can exchange energy. Direct transitions generate mostly photons, so even if it gets absorbed, it will get re-emitted intact until it leaves the material. Indirect transitions means that phonons remove energy each time, so it all becomes heat. In normal conditions, Indirect materials are more transparent, although direct materials can become transparent by population inversion, which is when there are more electrons in the high-energy states then the low-energy states for the bandwidth of the photons being generated. Then any photon generated is more likely to generate more photons on its way out (stimulated emission) than to be absorbed. This is what you want. Okay I’ll stop now, but there are tricks that you can use to get this behavior in silicon, an indirect-bandgap material, which is the topic of the article.
- econcon 7y agoYou can get light out of anything. All you need to do is shoot it with a photon bean, and the when material can no longer absorb the photons you send at it, it will begin releasing them as reflection. But the one you are shooting in aren't the same ones that are coming out.