Reversing the history of computer architecture
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From: Paul A. Clayton on 23 Oct 2009 17:49 On Oct 23, 4:38 pm, n...(a)cam.ac.uk wrote: > In article <IpqdnUOUWcd0BnzXnZ2dnUVZ_oydn...(a)bestweb.net>, > Mayan Moudgill <ma...(a)bestweb.net> wrote: > > >Andy "Krazy" Glew wrote: > > >> Go > >> optical, and you have costs, but the long distance costs may be less, > >> encouraging more, simpler, processors. > > >Optical? In a commodity process? For high speed communication? > > > Unless someone has actually managed to get a > >standard-process-compatible laser, not going to happen. Costs are too > >high. I was excited by the iron implant stuff and strained silicon but I > >don't think they ever made it out of the laboratory. Anyone know enough > >to comment? > > Not on that. But the fact that serious money is still going into > research in this area, despite decades of next to no progress, > indicates that the manufacturers are very aware of the potential. > > The last plausible idea I heard was lasers pumping in to silicon > optical switches, but that one seems to have gone awfully quiet. > > Regards, > Nick Maclaren. I am extremely ignorant, but the technology for Light Peak (http://www.eetimes.com/news/latest/showArticle.jhtml? articleID=220400011) seems to indicate that _some_ progress is being made. Paul A. Clayton just a technophile
From: Mayan Moudgill on 23 Oct 2009 18:00 Del Cecchi wrote: > "Mayan Moudgill" <mayan(a)bestweb.net> wrote in message > news:IpqdnUOUWcd0BnzXnZ2dnUVZ_oydnZ2d(a)bestweb.net... > >>Andy "Krazy" Glew wrote: >> >> >>>Go optical, and you have costs, but the long distance costs may be >>>less, encouraging more, simpler, processors. >>> >> >>Optical? In a commodity process? For high speed communication? >> >> Unless someone has actually managed to get a >>standard-process-compatible laser, not going to happen. Costs are >>too high. I was excited by the iron implant stuff and strained >>silicon but I don't think they ever made it out of the laboratory. >>Anyone know enough to comment? >> >>An alternate transport mechanism (when using flip-chip) is to drive >>the signal out to the carrier (specially if it's ceramic) and then >>use that as the high-speed long-haul layer. >> >>[BTW: I'm not sure if its possible to use diodes to do high speed >>optical communication; anyone know?] > > > Not silicon diodes for transmission. > > As for using the ceramic, you are about 30 years late. see TCM for > example. IBM even went to some expense to upgrade the material from > Alumina to Glass Ceramic to improve propagation. > Course I knew that; I was just pointing out that there are alternatives. > Also LEDs are pretty lacking in bandwidth compared to lasers. But > since silicon is indirect band gap the point is moot. Which is why strained silicon and iron-alloys were interesting; they had the potential to convert the indirect bandgap into direct band-gap. Another intriguing possibility is some meta-material/nano-structure property; maybe by creating a correctly dimensioned cavity? > Pipelining wasn't driven by lack of transistors but by frequency. It > didn't come in until transistors got sort of cheap. (cheap is in the > eye of the beholder). > > del > >
From: Mayan Moudgill on 23 Oct 2009 18:02 Paul A. Clayton wrote: > On Oct 23, 4:38 pm, n...(a)cam.ac.uk wrote: > >>In article <IpqdnUOUWcd0BnzXnZ2dnUVZ_oydn...(a)bestweb.net>, >>Mayan Moudgill <ma...(a)bestweb.net> wrote: >> >> >>>Andy "Krazy" Glew wrote: >> >>>>Go >>>>optical, and you have costs, but the long distance costs may be less, >>>>encouraging more, simpler, processors. >> >>>Optical? In a commodity process? For high speed communication? >> >>> Unless someone has actually managed to get a >>>standard-process-compatible laser, not going to happen. Costs are too >>>high. I was excited by the iron implant stuff and strained silicon but I >>>don't think they ever made it out of the laboratory. Anyone know enough >>>to comment? >> >>Not on that. But the fact that serious money is still going into >>research in this area, despite decades of next to no progress, >>indicates that the manufacturers are very aware of the potential. >> >>The last plausible idea I heard was lasers pumping in to silicon >>optical switches, but that one seems to have gone awfully quiet. >> >>Regards, >>Nick Maclaren. > > > I am extremely ignorant, but the technology for Light Peak > (http://www.eetimes.com/news/latest/showArticle.jhtml? > articleID=220400011) > seems to indicate that _some_ progress is being made. > > > Paul A. Clayton > just a technophile SiGe; way $$$ compared to straight Si.
From: Robert Myers on 23 Oct 2009 19:47 On Oct 23, 8:05 am, Mayan Moudgill <ma...(a)bestweb.net> wrote: > Andy "Krazy" Glew wrote: > > Go > > optical, and you have costs, but the long distance costs may be less, > > encouraging more, simpler, processors. > > Optical? In a commodity process? For high speed communication? > http://www.technologyreview.com/infotech/18087/?a=f <quote> "The Intel group has essentially been debunking the myth that silicon isn't good for photonics," says Alan Willner, professor of electrical engineering at the University of Southern California in Los Angeles. And while the silicon laser is important, he says, a fast modulator is crucial. Today's state-of-the-art modulators work at 40 gigabits per second, and for silicon to compete as an optical material, it needs to operate at comparable speeds. Intel's 30-gigabit-per-second silicon modulator is thus "a big deal," he says. </quote> The article also talks about Intel's silicon laser, which I assume is one of the things you are saying hasn't made it out of the laboratory. I don't think devices like this can work with an LED transmitter because they manipulate phase. Robert.
From: Mayan Moudgill on 23 Oct 2009 20:41
Robert Myers wrote: > On Oct 23, 8:05 am, Mayan Moudgill <ma...(a)bestweb.net> wrote: > >>Andy "Krazy" Glew wrote: >> >>>Go >>>optical, and you have costs, but the long distance costs may be less, >>>encouraging more, simpler, processors. >> >>Optical? In a commodity process? For high speed communication? >> > > > http://www.technologyreview.com/infotech/18087/?a=f > > <quote> > > "The Intel group has essentially been debunking the myth that silicon > isn't good for photonics," says Alan Willner, professor of electrical > engineering at the University of Southern California in Los Angeles. > And while the silicon laser is important, he says, a fast modulator is > crucial. Today's state-of-the-art modulators work at 40 gigabits per > second, and for silicon to compete as an optical material, it needs to > operate at comparable speeds. Intel's 30-gigabit-per-second silicon > modulator is thus "a big deal," he says. > > </quote> > > The article also talks about Intel's silicon laser, which I assume is > one of the things you are saying hasn't made it out of the laboratory. > > I don't think devices like this can work with an LED transmitter > because they manipulate phase. > > Robert. Following the links to a prior article http://www.technologyreview.com/read_article.aspx?ch=specialsections&sc=moores&id=17519 its clear that they are using a separately constructed InP emitter which they bond to the silicon. Sorry, doesn't make it cheap. And they're probably using MEMs-like stuff to get a cavity. That stuff's been looked at before. They're bonding a InP emitter onto a Si cavity - the advance may be in the way they're doing the bonding because of the differences in the crystal structures of InP and Si On a similar note, some people were looking at strained SiGe on a fully depleted substrate a while back. IIRC, strained SiGe has a quasi-direct bandgap, and putting SiGe on top of SiO2 causes it to be strained because of the differences in the crystal structure :) Another one of those ideas which hasn't made it out of the lab, AFAIK. |