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MIT Researchers Make Advance Toward Photonic Circuits
MrSeb writes with this excerpt from an article in Extreme Tech: "Light-emitting diodes are a cornerstone of consumer tech. They make thin-and-light TVs and smartphones possible, provide efficient household, handheld, and automobile illumination, and, of course, without LEDs your router would not have blinkenlights. Thanks to some engineers from MIT, though, a new diode looks set to steal the humble LED's thunder. Dubbed a diode for light, and crafted using standard silicon chip fabrication techniques, this is a key discovery that will pave the path to photonic (as opposed to electronic) pathways on computer chips and circuit boards. The diode for light — which is made from a thin layer of garnet — is transparent in one direction, but opaque in the other. Garnet is usually hard to deposit on a silicon wafer, but the MIT researchers found a way to do it."
New we need a real one way mirror.
The summary (taken from the first article) implies that these new diodes are going to supersede LEDs, but they have completely different purposes. LEDs make lights, these things don't.
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The whole system could be made using standard microchip manufacturing machinery, Ross says. “It simplifies making an all-optical chip,” she says. The design of the circuit can be produced “just like an integrated-circuit person can design a whole microprocessor. Now, you can do an integrated optical circuit.” That could make it much easier to commercialize than a system based on different materials, Ross says. “A silicon platform is what you want to use,” she says, because “there’s a huge infrastructure for silicon processing. Everyone knows how to process silicon. That means they can set about developing the chip without having to worry about new fabrication techniques.”
It is good to see someone is coming up with an innovation that can "actually" be introduced. Seems like I read about new innovations every day on slashdot that never get off the ground because completely new manufacturing processes need to be created. Hopefully this will actually make it because it requires fewer changes by manufacturers (which can be significant barriers to innovation).
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Does this mean a light transistor is coming soon?
I am wondering if there is any material that acts as a mirror and can be switched from reflective to transparent electronically? I assume there is not or you wouldn't have devices like MEMS displays. I'm thinking if you had such a material it would be essentially a light transistor.
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Could someone with expertise in the topic tell me:
Assuming you don't `leak' light like you do with electricity thought a traditional transistor gate when scaling way down this technology could provide a method of continued packing of high speed transistor like elements. The next interesting question would be how hot the chips would actually run, considering we're really no longer resisting, resulting in high temperatures.
Wake me up when they create neutrinoic circuits.
It doesn't go off and start talking about LEDs and WDM which just confuses the issue.
http://www.mit.edu/newsoffice/2011/optical-computing-diode-1123.html
Just because you can use it to store data doesn't mean it will make a good processor any time soon.
how long does it take to switch states. That's why flash ram is not used in primary memory.
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When are we going to start driving on it? Sadly, progress is not made in academia. It's made in the market. Until there is a photonic device on the market they are simply blowing smoke. Frankly, I'm getting tired of hearing how photonic devices are "almost here" and yet they never seem to materialize. Wake me up when they have actually got something on the market.
...what kind of circuit board or processors we'll have in the future.
Every day there is a new break-through that "may" change the world of _________ (micro chips, LEDs, circuits, cars,etc.)
The new diodes seem to be a small achievement in an MIT lab.
"this is a key discovery that will pave the path to photonic (as opposed to electronic) pathways on computer chips and circuit boards"
Yeah? When?
I need news that are relevant to me, if I wanted to be on the cutting edge of science and read about every. Single. Experiment. I'd read arXiv.
Things don't work that way in the real world, kid. Have a lollipop.
The work at MIT built on the breakthroughs in garnet depositition and ion lithography made by Hieronymous Dosch and his team at the University of Southern North Dakota at Hoople. It was only three years ago that they made the famous "Dosch Garnet".
So if I make a 'photonic circuit'... doesn't some kind of electrical impulse have to modulate the light pathways, i.e. turning them on and off to allow light through, in order to create logic structure? i.e... doesn't this still require transistors? Or does this material actually *change* like a transistor gate when subjected to light, and change back when the light is taken away... Now that I could see making logic gates with.
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We get at least one of these overhyped materials science articles each month. This time, someone has figured out how to deposit a garnet layer in a wafer fab. This is blown up into "photonic computing real soon now". It's not.
There's a lot of work in progress (PowerPoint) on optical on-chip interconnects. This is not "photonic computing". It's clusters of CPUs with a network of optical interconnects, all on one IC. The CPUs are still made of transistors. IBM has a very active research program in this area. But it's a long way from working. There are optical switching elements that work experimentally, but nothing ready for volume manufacturing yet. The optical interconnects themselves aren't considered to be the big problem.
So far, most of the proposed approaches involve un-buffered circuit switched networks. An optical connection is set up from CPU 1 to CPU 2 by electrical means, and then data is blasted across it. Circuit setup time is long compared to the data rate. So this is for long messages within a cluster, not cache synchronization. Think (inevitably) Beowulf cluster on a chip, not thousand-CPU shared memory microprocessors. The technology may also be useful as a network optical switch.
Short version: when this all works, servers get more densely packed.
This mentality is a big part of our national decline. Nobody wants to make the investments or do the hard work. They just want to swoop in when the technology is ripe for commercialization and reap all the profit from others' years of investment. Individuals and big companies act this out in different ways, but it boils down to, "just wake me up when I can get it on sale at Walmart."
Can they do it in lin? :0)
The purpose of existence is to make money.
This could be great for long term, non volatile data storage, I suppose, but unless they develop an efficient method of changing the state (i.e., which direction is opaque), I can't see this being much use for processing in general.
On the plus side, maybe we'll finally get to see those data cubes/crystals that popular SF books are always referring to...:-)
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I agree with "Nobody wants to make the investments or do the hard work....just wake me up when I can get it on sale at Walmart." Remember that even 'normal transistors' were ideas conceived and realized in 'research labs' and definitely not the market. And there are companies which (search for infinera) are doing things like 'photonic integrated circuits' (the signal processing is in electronics and transmission is optical); and they're better off than blowing smoke.
My reading of the summary says that they claim that is opaque in one direction and transparent in the other.
Consider the following thought experiment:
Assume that this material works the same way for far-infrared as it does for visible light.
In a well insulated cylinder place a sheet of this material across the interior of the cylinder so that light can pass to the left, but not to the right.
Now the material in the right end of the cylinder is emmitting infra-red radiation. It can pass through the material. This warms up the left side, and cools off the right side.
Now we have a temperature difference, so we can run a heat engine. Voila! perpetual motion.
Now if the material doesn't do this with room temperature radiation, then we have to put it in a red hot environment. Will the material still work at those temps?
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I beg to differ. The market gets things done. The market demands results and promotes competition. In academia their is little to no incentive to actually make something useful. If it were actually useful they would market it. Until then, they're just full of hot air. Academia is all about writing grants, getting money, and providing the appearance of actually progress, when, in reality, nobody in academia wants to do the hard work they know they have to do. Academia has turned into a money making scheme. They just steal from the poor students and give to the rich faculty. Academia hasn't made any practical scientific advancements in over 20 years. And, no, it is not true that progress is made incrementally. That is an excuse for the time wasted in between real advancements. Academia needs to make several changes. First, academia needs to be made more much challenging, so they can weed out the bad students. This does *not* mean professors should give insufficient material for learning, be completely inaccessible to students, and give lots of trick questions on tests. It means they need to *extend* test length and time, thoroughly teach *all* of the material they are testing on (yes, this IS possible if professors aren't lazy, or too busy with research), and make problems more challenging. But, professors don't want to do this, because its "too much work for them". It comes down to the fact that they are lazy and have no real passion for their area of research (because they weren't weeded out at the beginning of the process). Yes, I said it. Its the truth. Deal with it.
Yes, actually, that's exactly how they work. Academia hypes lots of claims of what they can do, and its not until a business develops and markets them do they actually materialize or have any impact on humanity whatsoever. Most of the time numerous obstacles must be overcome before an actual product can be made, and none of that work is done by academia. I may be exaggerating slightly, but that's basically how it is. Oh, and lollipops are a creation of the market (nobody even knows who actually invented them, they just emerged from the invisible hand of the market), so maybe you should have one, kid.