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Negative Refractivity for Optical Computing
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.
isn't the negative index of refraction called reflection?
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?
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what this means is that u can bend the light BEYOND the normal. it is NOT reflecting off the surface of the material, but rather entering the material and reversing direction within it. (iMHO)
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I must have been out of the negative refractivity thread of modern physics, but I love this word...
"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"
http://pcblues.com - Digits and Wood
wouldn't that mean you would have to FORCE electrons through the material? that seems like a bad consequence.
BSD is for people who love UNIX. Linux is for those who hate Microsoft.
Sounds like this technology could drastically improve implementing Quantum Cryptography. Imagine, long distance completely secure connections , that are provably unbreakable. Lets see Carnivore tackle that.
Thinking is good, I think.
It doesn't mean the velocity is faster than 'c'. It only means the light beam is deflected towards the opposite direction ( angle of refraction > 90 deg )
Nobody has given the least thought to what they are going to do with all this peculiar junk after it gets to the end of its useful life. Just dig a big hole like any good primate and throw it in, right?
Dr. Frankenstein lives on.
Hic iacet Arthurus, rex quondam rexque futurus.
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.
ok, so how long until Law Enforcement agencies decide that optical computation needs to be regulated because of the unbreakable nature of quantum cryptography? yay another clipper debacle
I found this post more insightful when Kha0S posted it. I thought you were a different kind of troll than this Physics! *sniff*
Didn't we have a story about how skeptical scientists were about these results.
I'm still waiting for the next big breakthrough in quantum computing, but this new optical technology will give way to some really fast stuff. Just imagine having a quantum computer cpu with optical connections to a solid-state hard drive. At least there is something to look forward to in computing nowadays.
A computer is a valuable tool, so use it and stop whining.
No.
Light travelling faster than c would imply an index of refraction less than 1.
(not less than 0 as implied above)
If they could build optical circuits with this stuff, could they replace my silly blue wire? Sure optical is here, but could this bring it to my house?
Hmmmm....
Negative refractive index does not mean light is moving faster than C. According to Snell's law the refractive index of any material with respect to vacuum = velocity of light in vacuum / velocity of light in material.
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
the story from CNN is here:
http://www.cnn.com/2000/TECH/space/07/20/speed.of. light.ap/
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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.
Is it just me or does "surface plasmon polaritons" sound like somebody left the StarTrek technobabble generator on overnight?
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..."
I'm sorry it's not > 90 deg., it's 0 deg.
I forgot the conventions of defining the angle of incidence/refraction during a braino.
How stable is all this going to be? I have to believe this is only working in vacuum conditions at the moment. I doubt it's going to be hitting the inside of anyone's computer in the near future. As the article says, the first applications will probably be high power microscopes. Not too much else seems feasible in the near term.
You can only be young once, but you can be immature forever.
I thought the index of refraction was defined as:
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
-- Hello_World.c: 17 Errors, 31 Warnings
those are good points. However, I'd like to point out that ``c'' (constant) is the speed of light in a vacuum. If we're not in a vacuum, we can alter other conditions (packing density, refractivity index, EM raditiaon interference, etc) to increase or decrease the speed of light. Becknull's law covers the quantum variability of isotope determination, which has Snell-law implications.
Any *normal* material has R.I. 1.
thanks to
KhaOS for the subject line.
Negative refractive index would mean that light a slab of material from a vacuum bends away from the normal. In conventional (positive refractive) materials, light bends towards the normal.
Negative refractive indices are known at other wavelengths (e.g. microwave and X-ray), but what is new is discovering this phenomenon in the optical regime.
Any *normal* material has R.I. < 1. Light travelling faster than 'c' implies R.I. > 1.
/. & forgot 'Plain Old Text' implies HTML.
err. I am new to
indx1*sin(a) = indx2*sin(b)
Where a is the angle of the incident ray, b is the angle of the refracted ray, indx1 is the optical density of the first medium and indx2 is the optical density of the second medium.
These are perfectly legal solutions of Maxwell's equation and only occur on the surface (hence the name) of metals.
karma police: arrest this man, he talks in maths; he buzzes like a fridge, he's like a detuned radio. [radiohead]
is given by sqrt(permittivity * permeability). If they're both negative, the negative signs cancel. I think what people are trying to say is that if the index of refraction drops below 1, then the speed of light will be faster than in a vacuum. Although this has been demonstrated in optical fibers in areas of anomalous dispersion , this article is not talking about that...
Gheesh. I thought we had enought problems recycling our old CRT's. I wonder what kind of issues these materials are gonna have if they make it mainstream?
I wonder what country we're gonna pollute this time. Oh! Bad American!
This signature is a waste of 42 characters
You mean 0 deg?
This is simply astounding, folks. If this were possible, computers would be so fast that there really wouldn't be a need to build a quantum computer.
Ha! New words to play with. Let's see here...
;-)
'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?
Bruce Lane, KC7GR,
Blue Feather Technologies
Light moves "away" from normal even for materials with positive refractive index (but refractive index less than 1). Light moves "towards" the normal for materials with refractive index greater than 1. Moving "away" from normal does not imply negative refractive index. For example as the post above said, light moving from a glass to air moves away from the normal - doesnt mean air (or glass) has negative refractive index. For a material to have a refractive index less than 0, the sine of the refracted angle should be greater than 180 degrees (and ofcourse less than 360 degreees).
Go Boilers!!!
Sorry, had to say it, its my alma mater
And yes! its off topic!
All you are creating in your example is a convex water lense contained in a glass block. Your example dosen't really work.
one example, the speed of light might be faster than in vacuum.
No, the speed of light in the medium need only be faster than the speed of light in the surrounding medium--e.g. air.
120 characters isn't enough to explain it.
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?
There is nothing so silly as other peoples traditions, and nothing so sacred as our own.
If they can fiddle with light and directly manipulate it, does this mean they could possibly simulate some form of "invisibility". E.g. bending light completely around an object, so that the object no longer refracts light itself, but is essentially hidden within a sphere of redirected light?
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-
What I find particularly absurd is the reliance on the existence of so-called "negative numbers." Puh-leez.
Banach-Tarski Overdrive
It doesn't mean the velocity is faster than 'c'.
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.
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.
C'mon, moderators. Anyone who mentions FTL speeds regarding negative refractive index either didn't read the article or hasn't understood physics beyond a few college courses. This is hardcore solid-state optical physics and stands up to peer-reviewed scrutiny. Sheesh.
Stefan
The most important aspect is the ability to focus light to a point finer than it's wavelength. The article discusses using visible light to image individual molecules. Up until now the only way to do such a thing with visible light was with the near field effect.
Another interesting application would be telescopes. Maybe we won't have to wait
for the space interferometers to see all
the cool stuff out there.
Retard. of course it works, I've done similar things many times.
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.
Negative refraction could definitely alllow you to have at least some sort of invisibility. If not the ability to make anything disappear like with some sort of "cloaking device", you could make materials that are completely invisible. They would be constructed of this material with negative refraction along with some other material, like fused quartz or something, so that you would have a composite material with a total index of refraction of zero.
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?
Today on slashdot, we have a nanomaterial that focuses light backwards, and also a nanomaterial that can attach to a flat, clean, dry surface well enough to support 200 lbs with a few square inches (using forces thought to only have effects at microscopic scales). The former is found only in labs and is brand new, and the latter is found in gardens and is older than humanity.
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.
plasmonic nanomaterials
Heck, that even sounds cool.
Envy my 5 digit Slashdot User ID!
03/2001 photonics.com article
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...then it's exactly what you need in order to make this work. [Stop- HAMR time.]
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Quoth the intro: "we hope to directly manipulate light, guide it around corners with no losses"
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.
-Billco, Fnarg.com
been reading the original negative index of refraction paper from 2000 the following preposterous claim may actually be true. 1) a lens (actually just a flat slab) of negative index of refraction n=-1 would perfectly focus an incident wave IN THE FAR FIELD more tightly than the diffraction limit of light (i.e. to much less than its wavelength). (note I said IN THE FAR FIELD, we all know about nearfield stuff) add to this the recent fabrication of negative index materials and it gets more interesting. first the easy to understand part: n=-1 slab acts a lot like a phase conjugate mirror, except instead of being a mirror it does not reflect the light but rather refocuses it downstream. THE KEY POINT: BUT as we also know they must obey a diffraction limit on how well they can refocus the beam Why cant they do better? well the diffraction limit comes from the fact that not all the fourier components are there. where did they go? well one place they went was the aperature cut off. But suppose we built the worlds largest perfect lens so that the aperature cut-off did not matter. We still could not focus light below the size of wavelength Why? Well there is one other place we lost fourier compontents. imagine the following you have a light source that is smaller than the wavelength of light (e.g. a molecule! or maybe a nearfield light source). what happens? well the small size means there are fourier terms that have k-vercots so large that for any given wavelength they cannot propagate. that is they are evenescant near field light that quickly dies away. the K-vectors that can propagate, the small ones, cant be refocused to an object as small as the source. Thus you supposedly cant ever refocus light in the farfield to smaller than a wavelength of light. But wait! those evanescent waves die exponentially so they do reach the far field, just they are really really weak. suppose you were to selectively amplify them up and then refocus the light with out phase conjugate mirror? well then you could focus light to smaller than a wavelength. Now here is where it gets REALLY SPOOKY!, if you do the math a negative one index of refraction does exactly that, it conjugates the phase and it AMPLIFIES ANY IMAGINARY K-VECTORS!!!!!!!!! that is it AMPLIFIES evenescent waves. But wait "CONSERVATION OF ENERGY YOU SCREAM !!!!". Nope! not a problem, because evanescent waves dont carry energy. "Baloney" you say. well okay, imagine an evenescent wave propagating, where does its energy go? is it absorbed by the air? put it in vacuum and it would still be evenascent. No the poynting vectors conspire to recouple the energy back to the source of the wave. THe author claims this means one can amplify these waves at no energy cost.
The claims of this news story were already disproven here: http://www.utexas.edu/research/cemd/nim/NIM1.html
In short:
K.L.M. (a physicist)
Is that an optical CPU core in your pocket, or are you just happy to see me?
My deviantArt site
The key word is tunable. Canon et al. could make some seriously cool lenses from this stuff.
Looks like Pink Floyd were waaaaaay ahead of their time. Check out:
m oo n.html
http://www.superseventies.com/ac19darksideofthe
A Negative reftactive index prism clearly demonstrated way back in the 70s.
The sine of the angle must be -ve & the angle must be < 0 deg, not > 180 deg
-ve R.I. doesn't mean -ve velocity.
The angle is actually between -90deg and 0deg (or if you like it this way, 270deg & 360 deg).
It's like this:
\
_|
\ air
-------------
/ medium
|_
/
For those who don't know why, it's because ST shows use terminology like 'plasmonic' as buzzwords.
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