Peeking At The Future: "Perfect Mirror" Cables

sonofpan writes: "About 18 months ago I heard about a few guys at MIT who developed a process for creating a (near) perfect mirror that could reflect many different frequencies at any angle with almost no loss of strength (something that was said to be theoretically impossible). Apparently, they have finally gotten their patents and used the technology to create a dielectric coaxial cable that can transmit light across vast distances and around tight turns with virtually no loss of signal. Read about it at: http://web.mit.edu/newsoffice/ nr/2000/waveguide.html and the company they started at: http://www.omni-guide.com. And the original link that described the process and the huge possibilities for its uses is a very interesting read as well: http://web.mit.edu/newsoffi ce/tt/1998/dec09/mirror.html."

Comments

Mirror site :-)

[Robin Hood]

What with all the hits their page is getting, do you think they're going to need a mirror site?

(Sorry, couldn't resist.)
-----
The real meaning of the GNU GPL:

some additional info...

[freedman]

Also of interest, might be the following web-page concerning the research group of one of the principal investigators (John Joannopoulos of MIT): ab-initio.mit.edu.

Actually, when I was at MIT, I took one of Joannopoulos's graduate courses in solid-state physics and can vouch for his teaching abilities in addition to his well-known reputation within the field of electronic structure calculations.

Also of interest might be the webpage of Prof. Tomas Arias at Cornell (whom I work for now), who was a collaborator of John's at MIT up till last year: www.ccmr.cornell.edu/~muchomas.

For a little more background:

Many of the computational calculations that are used by these investigators, in situations like the one where the perfect mirror was postulated, fall into the category of "ab-initio electronic structure calculations". The "ab-initio" part, latin for "from first principles", denotes that the calculations attempt to simulate actual resultant macroscopic behavior from the much more fundamental precepts of the quantum mechanical interactions between the atoms and electrons in the material under investigation. This has some very interesting advantages, not the least of which is that the resulting calculations do not have to justify higher level assumptions, whose applicability might be less assured. That's not to imply that no assumptions are used in this process (if NO assumptions were used, even most modern supercomputers would be unable to calculate the resultant quantities of interest for any more than 4 or so atoms). As it is, typical experiments generally are able to consider 100-150 atoms, which is usually sufficient to determine many properties of interest. The main approximations that are still necessary are the free electron approximation (which mandates that atomic nuclei and core non-valence electrons are immobile compared to the much lighter valence electrons which are important for conduction) and the independent electron approximation (which stipulate that the potential felt by a valence electron is not specifically dependent on the impact of every other electron [as it would be ideally], but is instead affected by a sort-of mean-field approximation of all the other electrons' potentials). However, this independent electron approximation necessitates that the resulting Hamiltonians (energies of the system) must be found by iterative self-consistent methods, whereby each successive output is computationally fed into the algorithm as input until the result converges within certain error limits. The independent electron approximation is usually implemented in terms of either the Hartree or Hartree-Fock theories (in case you want to search for more info).

Anyway, that's all I have the energy to write about, but the websites I spoke of above, probably give links to lots more material. They also have some amazing photos of the ab-initio simulations.

-Daniel

Re:some additional info...

[MattEvans]

Daniel,

Actually, although Joannopoulos does do a lot of electronic structure stuff (and is quite good at it), the research which lead to this mirror breakthrough comes from the other half of his group. He also does research on "photonics", which is essentially the study of light propagation through materials with varying dielectric constant. The scale is well beyond that of ab-initio electronic structure; visible light wavelengths are an order of magnitude larger than lattice constants/interatomic spacings, which are of course the relevant length scales for (valence) electrons. Photonics is done more-or-less macroscopically; everything is derived from good old Maxwell's equations.

That being said, what Joannopoulos' photonics group does is essentially very similar to band structure calculations. Assuming there's a periodicity in the dielectric constant in the material (just like a periodic potential in a crystal!), then Maxwell's equations can be recast in a form which bears a striking resemblance to the Schrodinger equation for an electron in a solid. What they get out of that is a "band structure" for light. Certain frequencies are allowed, some are forbidden. Thus it becomes possible to make a perfectly selective waveguide. Just design a material which has "band gaps" at the frequencies you want to filter, shine the light through, and let nature (Bragg reflections? :) ) take its course. Of course, you can also do other cool stuff, like introducing defects, which create localized states just like in solids. This is a source of little "light boxes". There are a lot more similarities; Joannopoulos et al. have written a really good book on the subject called "Photonic Crystals". It's short and quite easy to read, but a few years out of date . Also, if you know how to make the analogies, it makes an excellent introduction to concepts of electronic band theory.

The above explanation might be incorrect in its details. I read the book pretty quickly and superficially on the subway when I was visiting MIT this spring (opposite of you: I was a physics undergrad at Cornell, and will be going to MIT this fall). I encourage you (or anyone) to look into photonics more closely. It's really fascinating.

Matt

Forget fiber optics; other uses of Perfect Mirror

[2nd Post!]

Doesn't this really mean that we now have a plastic mirror, where before one needed metal like aluminum or silver or stuff to make mirrors?

So now we can have microwaveable plastic containers that are shiny, if IR is allowed through? That we can create a film to place on windows that reflect all the light without using metals such as copper and gold? That we could build LCD displays with this material to provide brighter, thinner, lighter displays?

It isn't just fibers and cables; it really is a mirror, isn't it?

Bye!

Implications

[Chairboy]

Hey, I just realized what this means. If it's reflective on such a wide range of frequencies, that means that the amount of multiplexing data compression you can do is huge.

One of these fibers might be able to carry a hundred times more data then any current fiber, for instance, just by having sub-bands that use different light frequencies. Each band would think they had exclusive use of the superfiber, so they could all be running at max datarate.

Re:Implications

[MAXOMENOS]

Hey, I just realized what this means. If it's reflective on such a wide range of frequencies, that means that the amount of multiplexing data compression you can do is huge. One of these fibers might be able to carry a hundred times more data then any current fiber, for instance, just by having sub-bands that use different light frequencies. Each band would think they had exclusive use of the superfiber, so they could all be running at max datarate.

Just what we need. Another 50,000 channels of cable TV.

The Tyrrany Begins....

Faster Data Transfer?

[PHr0D]

..I could use that to download that 100k animated gif on the company website..
--------------------------------------

Oh yeah! Bionic soldier, here I come!

[Chairboy]

This is exactly what I've been waiting for. Now, I can get that 100 watt CO^2 laser and RTG power source implanted in my midriff and run one of these cables through my arm and to my fingers so I can fire laser beams from my hands!

No need to invest in handguns, spare keys, or window defrosters, I'll just take a finger laser, thank you!

The reason I haven't done this before, of course, is the heat problem with fiberoptics cooking all the musclemeat between the laser and the aperature.

Oh, that and I don't have the millions it'd take to buy the hardware and surgeons needed. But that's hardly the important issue here, is it?

Re:Screw networking

[Shoeboy]

Can you imagine a sheet of this stuff on your ceiling?
And wake up every morning thinking a naked fat guy was about to land on top of me? No thanks.
--Shoeboy

double-A photon batteries...

[Sebastopol]

This is from one of the links off of the article:

Trapping light invites all sorts of intriguing questions, Fink points out. For instance, if you light a candle in a room lined with perfect mirrors, would the room stay illuminated even after the flame is extinguished?

It seems there wouldn't be any way to test to see if the light was trapped inside the room. If you looked inside, some light would escape, and if any energy was exiting the box as a result of the light, then it wouldn't be trapped in the room.

Maybe I'm confusing light & energy here, but if you burned a candle in a box made of this perfect mirror: 1) all of the heat energy from the chemical reaction during burning the candle is released in photons via radiation; which means 2) all of the chemical energy would be converted to photons bouncing around in the box; therefore 3) the box/room would now be a type of battery storing the energy in photons.

So could one create little boxes-o'-light that would have pracitcal uses like a common battery?

I think I'll stop now that I've grossly misused a good number of physics concepts...


---

Re:double-A photon batteries...

[mindstrm]

Yes, the idea woudl be somewhat correct.

All 'heat' energy is not released as light. A more proper analysis woudl be that the energy released by the burning candle is released in the form of a) EM radiation (light) and b) chemical changes. Most of the 'heat' detected comes from conduction/convection by the hot gasses given off in the reaction. So.. some of the 'energy' given off of the exothermic reaction that is a burning candle is kinetic, some is EM, and some goes into chemical changes themselves.

Yes, with a perfectly reflecting surface *and nothing inside to absorb the light*, you would have a 'photonic battery... but it wouldn't work with a candle in the middle.

I suppose, given the right reflective surface, we would be able to put immense amounts of light into a small enough container and use it as a battery.. however, perfect reflection has it's limits. Enough energy in the form of photons would cause the mirror to stop working.. remember how a mirror works. It doesnt' 'reflect' photons, it 're-emits' them. There is a limit to what it can reflect; a laser with enough juice can still destroy a mirror.

Real World Implications

[rockwall]

If anyone is interested in the real world implications of this breakthrough, I suggest you check out Mother Earth, Mother Board. Written by Neal Stephenson, it is a rather lengthy article about the difficult process of laying undersea fiber. Part of that difficult is because of the imperfections of today's fiber and the need for signal amplification.

Technology such as this could eliminate the need for periodic repeaters and signal amplifiers, and quite possibly make cable-laying a less complicated proposition.

Who knows, one day soon, our only worries in accessing a trans-Pacific might be the latency inherent in the speed of light! yours,
john

This may make Quantum Cryptography a reality

[Pontiphex]

One of the biggest things holding back quantum cryptography is the fact that you can't go but 30km before you lose the signal. In traditional communications you can just use a booster/repeater....but when we are talking about measuring the spins of photons we run into the heisenburg wall. (can't measure something without disturbing it)

Since repeaters would need to measure a photon to recreate it as a stronger signal, this has always been out of the question. But now if we have this cable that can go great distances without repeaters, then we are one giant step closer to quantum crypto.

If you want more info on the subject, I suggest the book "Minds, Machines, and the Multiverse"

--b

Question

[tealover]

If you break the mirrors will you get 7 regular years of bad luck or 7 internet years of bad luck?

Screw networking

[Shoeboy]

If you've got a perfect mirror, give 2 of em to me so I can glue em to the tops of my shoes.
--Shoeboy