Negative Refractivity for Optical Computing 125
zero_offset writes "This article in EE Times details Purdue's efforts to create a material with negative refractivity. One of the important results would be the ability to create optical computers due to the effect's tendency to amplify and focus light at wavelengths larger than the thickness of the nanowires used in the transmission system. Purdue's School of Electrical and Computer Engineering's Vladimir Shalaev says, "Using these plasmonic nanomaterials, we hope to directly manipulate light, guide it around corners with no losses and basically do all the fundamental operations we do with electronic circuits today, but with photons instead." Nanowires, surface plasmon polaritons, optical computers, nanoscale metamaterials, unnatural refractivity -- what's not to like?" We did a story on the first material known to have a negative index of refraction last year.
not at all (Score:2, Insightful)
Re:not at all (Score:1)
Moore's Law (Score:1, Troll)
I guess it has a bit of life left in it, but with the article talking about 'single molecule' focal points. I geuss we are about to run into a little wall if these ever actually make it to market.
Of course, with the computational power that will come of this, maybe we will be satisfied for a while. Somebody once said "Nobody will need more than 640 k of RAM" Right?
Re:Moore's Law (Score:2)
Moore's Law [intel.com] describes an increase in transistor counts.
I hope you are referring to the idea that traditional microprocessor design would be obsolteted by 'optical computing' thus halting the advancement of traditional microelectronics, thus stopping the advancement of transistor counts as opposed to somehow having transistors being used in 'optical computing.'
Re:Moore's Law (Score:1)
I hope you are referring to the idea that traditional microprocessor design would be obsolteted .....
Well, yes.
The role transistors play will not always be performed by transistors. Just like vacume tube technology halted in the 70's and buggy-whip disigns have been stagnate (for the most part) since the 1920's.
But I think you missed part of my point. That being: weather of not you are talking about a transistor, once a single molecule is used as the focal point of a device, the count will not be rising much from there.
Don't read too much into this. I am in my early 30's and for IT people my age, Moore's Law has been darned-near the only constant in our professional lives. I was just "thinking out loud" about the possibility if it now being obsolteted.
kind of a bummer: But at least it will be around for at least a bit longer.
Re:Moore's Law (Score:2)
(vacuum, designs, stagnant, "whether or" "of it" obsolete)
Re:Moore's Law (Score:1)
OK I get it ... and yes I did miss your point at first. Thank you.
Re:Moore's Law (Score:2)
I'm not saying that more power wouldn't have many uses, but it always bothers me when people quote the "640K" line about modern computers. Imagine if Bill Gates, living in three bedroom house, had said "Nobody needs more than three bedrooms." And then now, living in a forty bedroom house, he says "Nobody needs more than forty bedrooms."
The latter, I think, rings a lot more true than the former. In most endeavors, diminishing returns can kick in after a while. It's the same reason we can't get away from the x86 architecture: There are more important issues than raw performance.
Re:Moore's Law (Score:1)
Re:Moore's Law (Score:1)
yeah... sure it is.... if I had ever said something so monumentally stupid there's no way in hell that I would admit to it... you honestly think that captain doublespeak himself is any different???
Re:Moore's Law (Score:2)
Computers are now fast enough to do the easy problems comfortably, even on quite large datasets. These are the ones people have in mind when they say computers are "fast enough."
But computers are no where near fast enough to solve large problems of the second kind, and it doesn't seem that they ever will be in the forseeable future. A problem of this type might be, "what lossless compression/decompression algorithm under 1000K in length has the highest average compression on a given sample dataset?" It's easy to write a program to solve this problem, but awfully hard to wait for it to finish.
I think we're falling into the gap between easy and hard problems. We can do easy problems easily, but have no feasible way to approach the hard problems.
Learnt a new word.... (Score:3, Funny)
"They had free drinks that night. Trevor was absolutely PLASMONIC. I mean... shit, man! he almost had a negative refractive index. Lucky we got him in a taxi when we did"
Re:Learnt a new word.... (Score:1)
dont you mean
"they had free drinks that night. Afterwards, Trevor was absolutely PLASMONIC, when he 'drove' me out of this world (in the back of the taxi)...."
ahem.
Re:Learnt a new word.... (Score:1)
I mean, that is some clever PLASMONIC GOYVIN!
Quantum Cryptology (Score:1)
Re:Quantum Cryptology (Score:2)
Bend light=invisible? (Score:2, Interesting)
I suppose the current theory applies only to light within some conduit of sorts, like fibre optics, but it would be cool if it had other such uses
I'm not a physacists, so feel free to critisize, but it's just a thought... direct manipulation of light could be a powerful thing.
-Quote-
"Using these plasmonic nanomaterials, we hope to directly manipulate light, guide it around corners with no losses and basically do all the fundamental operations we do with electronic circuits today, but with photons instead," said Shalaev.
-EndQuote-
Re:Bend light=invisible? (Score:1)
Some Claims are absurd (Score:3, Informative)
the ways one can escape these limits in a semantic sense is that you can change the index of refration of the media so the wavelength is shorter than in vaccum, but that's not really accomnlishing the goal. Alternatively, near field or or ther diffraction effects can confine a light field to a region smaller the wavelength, but it cant propagate in vacuum/air that way.
likewise the claim you could make a perfecly flat focusing lens by combining poistive and negative materials is pretty hilarious too. You can do that right now with conventional positive only materials. (example take two plano confave lenses of high index material, and fill the space between them with water. voila!).
on the other hand you could do a lot of really interesting stuff with negative index materials that is harder to put in laymans terms. one example, the speed of light might be faster than in vacuum.
Stealth materials (Score:1)
Re:Stealth materials (Score:2, Interesting)
now how would that work anyway... if you painted a basketball with "zero reflectivity" paint, you would no longer see the ball, because no light would bounce from it to your eyes, but you would also not be able to see anything behind it... so what would you see.. .or perceive??
Re:Stealth materials (Score:1)
Re:Stealth materials (Score:1)
It'd look like a perfect black circle was photoshopped into the world. No light comes from it: it's black, only absolute black.
Re:Stealth materials (Score:1)
Re:About that "flat" lense (Score:1)
Re:Some Claims are absurd (Score:1)
No, the speed of light in the medium need only be faster than the speed of light in the surrounding medium--e.g. air.
Re:Some Claims are absurd (Score:1)
Re:Obvious Troll: Some Claims are absurd (Score:1)
Who said anything about FTL travel? (Score:2, Informative)
but in regards to the article, the final comment was sheer speculation. THe existence of a negative index suggests that it might be possible to create a composte substance with an index less than one yielding an electomagnetic propagation media with a speed faster than vacuum.
I recant: it is not absurd afterall (Score:1)
Negative R.I. for sure? (Score:1, Interesting)
Quantum / Optical computers (Score:1)
Plasmonic Nanomaterials (Score:2)
Plasmonic nanomaterials
Plasmonic nanomaterials
Plasmonic nanomaterials
Now I'm sorry I went into software. I really, really wish I could tell people that I was into plasmonic nanomaterials.
Wurdz... (Score:1)
Actually way kuel stuff, SciAm had an article at length about this a few months back, and it was an awesome read... one of the other cool effects of this technology is optical microscopes that are orders of magnitude higher in resolution... visual systems that will let people look at things in optical frequecies that were limited to electron microscopy in the past (means we can see things way up close, that are still alive and kicking... or nanoscopic...)
"The future's so bright you need shades..."
This all sounds great on paper but.... (Score:1)
Meaning? (Score:2)
n = (speed of light in vacuum)/(speed of light in medium),
or n = c/cmed
Now, convenctional wisdom and all modern science says c is always the bigger value, so n is always >= 1, but positive. How the heck does one get a negative refractivity? Niether of these quantities should be signed, let alone oppositely signed, right? What is meant by negative refractivity?
Tim
Re:Meaning? (Score:2)
cmed < 0
Re:Meaning? (Score:2)
Re:Meaning? (Score:3, Informative)
n = (speed of light in vacuum)/(speed of light in medium),
another definition, IIRC, is c/sqrt(mu*epsilon)
mu = permeability
epsilon = permittivity
both are coeeficients of the linear response of meterials to the EM field.
now, if the linear response of a material to EM fields is complex, I guess you can have negative (or imaginary) n.
imaginary means exponential decay or growth, BTW, but of course in the case of growth the material stops responding linearly at some point, thus changing the dependance.
IIAC, negative n does not really mean the speed of light reverses
Now, convenctional wisdom and all modern science says c is always the bigger value, so n is always >= 1
AFAIK you're right in saying c is always the bigger value, however there exist superluminal photons [cerncourier.com] , which have phase velocity higher than c.
This is not, again AFAIK, related to the response medium but to other quantum phenomenas.
The universe can do some weird, convoluted vodoo
Re:Meaning? (Score:2)
If n=c/sqrt(mu * epsilon) as you suggest, then negative n would simply result from the negative roots of the sqrt. No fancy gymnastics with complex roots necessary.
Re:Meaning? (Score:2, Informative)
Your definitions are correct, but incomplete. The speed of light, c, (and cmed for that matter) are defined as c^2 = e*u (electric permittivity of the substance times the magnetic permeability of the substance). In other words, the speed of light is determined by how well the substance it is travelling through can be influenced by electric and magnetic fields.
To complete the definition:
n^2 = c^2/cmed^2 = (e0 * u0)/(e * u).
(The zeroes indicate that they are in free space.)
Now to the questions: Negative refractivity should be impossible. Both e and u are positive quantities, and if they weren't, the square would make them at the minimum postive imaginary numbers. The problem is that e and u are only scalars if you are working with the prefered direction of the substance. Otherwise, they are 2nd order tensors (3x3 matrices). (e0 and u0 are always scalars.) I am not sure how this would influence the outcome w/o doing the math. But, it may allow for this type of effect.
Re:Meaning? (Score:2)
And when we're done.... (Score:1)
I wonder what country we're gonna pollute this time. Oh! Bad American!
Re:And when we're done.... (Score:2)
Re:And when we're done.... (Score:1)
And these things don't occur in nature, much like potato chips.
Oh, goody! (Score:3, Funny)
'Surface plasmonic polaritrons...' Nah, too long. Let's condense it down to something like this...
"Give your laundry that FRESH, SPARKLING, NEGATIVE REFRACTIVE INDEX with Maytag's NEW SURFACE PLASMONITRON!! Yes, you too can have your clothes looking like they got lost in a physics lab for a month, AND REVERSE THEIR POLARITY, all in three easy cycles!!!"
(Read all warning labels before use. Not recommended for cashmere, poodle fur, or llama wool. Batteries most definitely NOT included, minor assembly and Ph.d required. This product is not available in Pakistan).
Ok... who else wants to contribute?
Re:Oh, goody! (Score:1)
Not me.
So what exactly do you get (Score:2)
Is it faster? Cheaper? Less heat? More Compact? Some of these but not all of these? What do you lose by switching to photon?
It does sound like good stuff, but what exactly is the good?
Re:So what exactly do you get (Score:1)
Re:So what exactly do you get (Score:1)
Re:So what exactly do you get (Score:1)
Re:So what exactly do you get (Score:1)
Higher switching speed: true
But optics work on a scale much larger than electrons. Index of refraction requires a medium larger than a few molecules. Microscopic optics would run into size problems long before electronics, requiring whole conduits limited by wavelength considerations. Electronics are approaching the realm of molecular switches. 100 million transistors (typical CPU) would fill a small room with even the smallist optical transistors. Propagation speed advantage of 50% to 100% would pale next to propagation distances of 1000 times more.
Optical will always be more expensive, you can't lay down optics with lithography or other large pattern duplication techniques. It requires every path to be a fiber.
So optics have lots of uses, data transmission being the biggy. But logic is not likely to be one of them. I was hoping someone had a good idea of some overriding advantage, but all i get are trolls.
Flame away. If you know anything it'll show. If you don't, that'll show too.
Re:So what exactly do you get (Score:1)
Fibres can be grown in place... so where standard lithography fails, we've still got the power to make a crystalline fibre grow where and when we want. Labs are already making self-building chips. Currently, optics DO work on a larger scale than electrons. Much larger. We send billions of photons for every bit sent down a fiber line. I'm talking about optics that work on single photons.
So even as we are developing monomolecular transistors after decades of improvement, we're still only figuring out how to build optical logic components right; I don't think the comparisson is quite fair. An electron is much more massive (on a handful of orders of magnitude, IIRC) than a photon, and requires more energy to toss around. This implies to me that there is much more room for improvement. And optical doesn't necissarily mean visible. We can (in theory) build optical circuits that work with X-rays with a wavelength under 1nm. Doing a search for molecular transistors, I find that the smallest we've made is still larger than 1nm. IIRC, the optical components have to be around 2nm for them to work on 1nm light. Double the frequency, halve the feature size. Electrons don't "shrink" like that.
If you want a single electric-circuit-killing uber-feature of optics, you won't find one. Optics is still a very young technology. Think about your statement, "100 million transistors (typical CPU) would fill a small room with even the smallist optical transistors." I seem to recall using a room-sized computer not so many years ago. It ran on electrical transistors.
New words a boon to Star Trek writers! (Score:2)
Stefan
Re:New words a boon to Star Trek writers! (Score:2)
Brilliant!
Invisibility? (Score:1)
I have thought about this subject before, and I did some research about different materials. Just think of glass. The only reason that pure glass reflects anything is that it has a different index of refraction as the air or vacuum or water that contacts it. If you notice clear ice that is in water, it is almost invisible since the index of refraction of ice is very close to that of liquid water.
There are many applications of this type of material. Does anybody have any ideas of some applications for a zero-refraction material? Perfectly clear windows? Practical jokes?
Re:Invisibility? (Score:1)
And that will only work with some forms of radiation.
I could imagine that you could construct something so that no photons escaped your body. Then you'd be unrecognisable but people would still know that you were there. A low-tech implementation is a stocking mask!
"unnatural" materials? (Score:2)
It's sort of interesting that the article refers to the negative refraction materials as "unnatural". Nature has been doing nanotech for millions of years now. It's pretty likely that, if these materials turn out to be good for anything that occurs in nature, they can be found there.
Retro Sci Fi (Score:2)
Heck, that even sounds cool.
What negative refraction means (Score:3, Informative)
03/2001 photonics.com article [photonics.com]
If this works as they claim... (Score:1)
Put this bitch into reverse! Beep Beep! (Score:1)
Stupid scientists, always reinventing the wrong wheel. Rather than blow billion$ and years of research trying to make light turn corners, just get a fricking ruler and make those pathways straight! Do dragstrips run around in circles ? No, they're straight. Straight = fast. I don't care if my optical CPU core is 20 inches long and 2mm thick with a big protective slab of iron wrapped around it, as long as it puts out 20ghz of pixel-twaddling goodness.
Re:Put this bitch into reverse! Beep Beep! (Score:2)
Sounds familiar... (Score:1)
For those who don't know why, it's because ST shows use terminology like 'plasmonic' as buzzwords.
Re:Remember your physics (Score:2, Interesting)
Re:Remember your physics (Score:1)
These are perfectly legal solutions of Maxwell's equation and only occur on the surface (hence the name) of metals.
Re:Remember your physics (Score:2, Interesting)
Re:Remember your physics (Score:1)
That's how it's negative...Thank you. I'd been beating myself around on this one. Trying how to figure out how to get a negative IR. An IR less than 1 would be big news... Oh, wait. It already was [cnn.com].
So when it enters the material, it is going back out of the material? Ok, I think these guys have simply discovered reflection. If, at the interface from medium A to medium B, it reverses direction, it never entered medium B. If it did enter medium B, then it is moving in the positive direction in medium B, which this article says it isn't. Either medium B is non-homogenous, and is using a gradient of IR to bend the light back out the surface, it is reflection, or they're playing silly symantic games concerning the direction of time.
Re:Remember your physics (Score:2, Informative)
So for dense thingies refractive index greater than 1. Eg glass. Now the refractive index of material A with respect to material B is Vel in B / Vel in A. So light travelling from Inside a glass slab to outside would think it encountered refractive index less than 1.
Now negative refractive index mean negative velocity ?? I dunno. Refractive index can also be calculated from Sine (incidence angle) / Sine (refracted angle). The only way to get negative refractive index is if Refracted angle greater than 180. (Remember high school trigonometry. Sine is negative only in the third and fourth quadrant). Now refracted angle greater than 180 would mean that light has suffered total internal reflection. So a negative refractive index material would behave like a mirror and not a lens. (hence giving negative velocity - velocity is a vector, has magnitude as well as direction). I smell a rat in the article.
-Dracken
Re:Remember your physics (Score:1)
the story from CNN is here:
http://www.cnn.com/2000/TECH/space/07/20/speed.of. light.ap/