Beta
×

Welcome to the Slashdot Beta site -- learn more here. Use the link in the footer or click here to return to the Classic version of Slashdot.

Thank you!

Before you choose to head back to the Classic look of the site, we'd appreciate it if you share your thoughts on the Beta; your feedback is what drives our ongoing development.

Beta is different and we value you taking the time to try it out. Please take a look at the changes we've made in Beta and  learn more about it. Thanks for reading, and for making the site better!

Nano-Scale Optical Co-Axial Cables Announced

ScuttleMonkey posted more than 7 years ago | from the hairy-logic dept.

Communications 157

toybuilder writes "Reuters reports that scientists have published their work on nano-scale optical coax in the most recent issue of Applied Physics Letters. The coax cable is only about 300nm wide, and is able to transmit optical signals using a carbon center conductor, transmitting light at about 90% the speed of light."

Sorry! There are no comments related to the filter you selected.

I have problems with regular coax... (4, Funny)

ArcherB (796902) | more than 7 years ago | (#17514390)

The coax cable is only about 300nm wide,...

How do you plug it in?

Re:I have problems with regular coax... (4, Funny)

0racle (667029) | more than 7 years ago | (#17514590)

Carefully

Very carefully (1)

symbolset (646467) | more than 7 years ago | (#17514592)

With really tiny tweezers.

Re: How do you plug it in? (0, Redundant)

noidentity (188756) | more than 7 years ago | (#17514748)

Very carefully.

Re:I have problems with regular coax... (4, Funny)

kfg (145172) | more than 7 years ago | (#17515034)

Doesn't matter, some kid with a Tonka backhoe is just going to end up dyking off the network anyway.

KFG

Re:I have problems with regular coax... (0)

Anonymous Coward | more than 7 years ago | (#17515330)

It's not the size, mate. It's how you use it!

Re:I have problems with regular coax... (1)

Ferzerp (83619) | more than 7 years ago | (#17516000)

coax?

do we really have problem with interference in fiber where we have to use coaxial cable???

Editors please!

btw: http://en.wikipedia.org/wiki/Coaxial_cable [wikipedia.org]

Re:I have problems with regular coax... (4, Informative)

halftrack (454203) | more than 7 years ago | (#17516430)

do we really have problem with interference in fiber where we have to use coaxial cable???

Most (all?) fiber optical cables have a co-axial design. Simplified; there is a core and a cladding, with the cladding having a lower refractive index than the core; thus creating total reflection (multimode fibers.) Now the cladding could be the air surrounding the cable, but it's probably not, thus as you see the co-axial design is a reasonable one. (Though you could probably get a away with some off axis designs, at least for multimode fibers.)

Wikipedia on fiber optics [wikipedia.org]

As for the GP, he might be joking but that is actually a serious concern. To get the correct electromagnetic modes in the fiber you need to align your fiber with your source carefully. obviously this isn't easy when for instance connecting this 300 nm fiber to some chip ... probably mostly useful for integrated stuff. (NIDNRTFA)

Re:I have problems with regular coax... (1)

Ferzerp (83619) | more than 7 years ago | (#17517292)

but that's not coaxial cable....

Mixed up with Seinfeld: (1)

norminator (784674) | more than 7 years ago | (#17516062)

Kramer: Why, I've plugged in cables so small I couldn't even see them!
Elaine: How did you know you plugged them in?
Kramer: ... Well... I guess I just assumed...!

Re:I have problems with regular coax... (0)

Anonymous Coward | more than 7 years ago | (#17516100)

How do you plug it in?

It gets worse...
a cable that thin, properly anchored, would slice through your hand like a hot knife through butter.

Re:I have problems with regular coax... (2, Funny)

Random Destruction (866027) | more than 7 years ago | (#17517100)

Er. you know, or your hand will slice through it like a giant piece of bipedal monkey through a tiny cable.

huh? (5, Funny)

macadamia_harold (947445) | more than 7 years ago | (#17514406)

The coax cable is only about 300nm wide, and is able to transmit optical signals using a carbon center conductor, transmitting light at about 90% the speed of light.

methinks the speed of light is whatever speed the light travels at.

Re:huh? (3, Informative)

mandelbr0t (1015855) | more than 7 years ago | (#17514440)

The physics constant c refers to the speed of light in a vacuum. Read here [rpi.edu] to find out why this statement isn't stupid.

mandelbr0t

Re:huh? (2, Funny)

kfg (145172) | more than 7 years ago | (#17514918)

the speed of light in a vacuum.

Appears to be zero. Now if you'll excuse me I have to go blow my nose and take a shower.

KFG

Re:huh? (0)

Anonymous Coward | more than 7 years ago | (#17515006)

Uhm.. so if you transmit to the air, you can transmit really close to the speed of light in the vacuum, and it's wireless! Faster, no wires! Way better! (And you don't have to have hard times plugging in the thin wire!).

Re:huh? (5, Insightful)

Incongruity (70416) | more than 7 years ago | (#17515654)

Hardly -- the statement is a little stupid because it doesn't mention the constant c nor "the speed of light in a vacuum", it simply says "the speed of light" -- most people will recognize the error, but it's still an error.

Re:huh? (0)

Anonymous Coward | more than 7 years ago | (#17517052)

The error would be if it said "the speed of THE light"
It just said "the speed of light", leaving it an open question as to which light is being spoken of.
So, not an error.

Re:huh? (5, Insightful)

Anonymous Coward | more than 7 years ago | (#17514458)

Light always travels at 100% of the speed of light. However, in this cable, light travels at about 90% of the speed of light in a vacuum.

Re:huh? (0)

Anonymous Coward | more than 7 years ago | (#17514560)

Methinks they are wanting to mean 90% the speed of light in a vacuum (the famously constant quantity.

Re:huh? (-1, Offtopic)

Anonymous Coward | more than 7 years ago | (#17515246)

Actually, do due general relativity, the speed of light does not equal the speed of light. Ignoring all the complex maths, theories, proofs, and whatever else, ill instead put all of this into layman's terms so you can understand.

This is quit simple really, the Furtssenvrietig equations (derived from from Einstein's and Maxwell's equations) states that light (donated by c), travels at ct=((S^s-2*n)/cos(0.1947295))^(c*km-3)+lsc clearly, if you look over the equation, you shall see that the speed at which light travels, is not the speed at which light travels. The equation clearly defines that as light travels, it bends and twists in a fashion not unlike Shakira's hips. You could say light dances across the sky. These motions by light make it so that at any point in time, light doesn't know how fast it travels, and in fact can even travel back and forth really fast (rather then only moving forward). The light wave then travels at different speeds in different areas of space, according to Einsteins general relativity equations.

To put it simply: light doesn't travel at the speed of light, because its constant fluctuations within space-time make it impossible to know how fast it travels (and indeed, light can even skip around, further making it impossible to know where, when, or how fast its traveling, even if you know every other possible variable).

Re:huh? (1)

polar red (215081) | more than 7 years ago | (#17515342)

so "be very careful with that laser little johnny" ?

I fart into your general direction (1)

ArsenneLupin (766289) | more than 7 years ago | (#17516472)

Furtssenvrietig

Yeah, right. And the glass spere does know nuthink about that guy. <big silent but smelly one>

Re:huh? (1)

stigin (729188) | more than 7 years ago | (#17515312)

Well you are right in some sense... the individual photons always travel at the speed of light. The phase velocity however can be slower (and in fact also be faster) tha the speed of light. It is the later al these articles refer to since this is the classically measured propagation of a coherent bunch of photons aka a beam of light.

Re:huh? (1)

tmosley (996283) | more than 7 years ago | (#17515512)

Unfortunately, the material is so heavy that each pound weighs over ten thousand pounds.

pounds? (0, Offtopic)

tepples (727027) | more than 7 years ago | (#17517400)

Unfortunately, the material is so heavy that each pound weighs over ten thousand pounds.

What material costs $1.93 [google.com] for five tons?

Re:huh? (1)

A beautiful mind (821714) | more than 7 years ago | (#17515720)

methinks it is like a weasel

Re:huh? (1)

Gordonjcp (186804) | more than 7 years ago | (#17516248)

What happens is that it gets gradually slower as each photon realises "Oh, I should be going 90% slower" with every Planck length that passes. Thus the speed of light through this fibre asymptotically tends to zero. It's actually pretty damn clever stuff. For a practical application, see "The Light of Other Days", by Arthur C. Clarke.

fp (-1, Offtopic)

Anonymous Coward | more than 7 years ago | (#17514410)

muh diKKK

90% of the speed of light.... (-1, Redundant)

DeathKoil (413307) | more than 7 years ago | (#17514430)

Honest question here, I thought the speed of light was absolute. So why then does this cable allow allow the light to travel at 90% of the speed of light? What is causing this slow down?

Re:90% of the speed of light.... (1)

ERJ (600451) | more than 7 years ago | (#17514482)

The "absolute" speed of light is measured in a vacuum. As soon as light travels through any material it slows down to less then the absolute speed of light.

Re:90% of the speed of light.... (1)

PhysicsPhil (880677) | more than 7 years ago | (#17514606)

The "absolute" speed of light is measured in a vacuum. As soon as light travels through any material it slows down to less then the absolute speed of light.

If you really want to be pedantic, the speed of light in a vacuum is not measured but rather defined to be 299,792,458 m/s.

Re:90% of the speed of light.... (1)

CrimsonAvenger (580665) | more than 7 years ago | (#17515910)

If you really want to be pedantic, the speed of light in a vacuum is not measured but rather defined to be 299,792,458 m/s.

Of course, if you REALLY want to be pedantic, the speed of light in a vacuum is measured, and the meter is defined as being the distance light travels in 1/299792458th of a second.

Re:90% of the speed of light.... (2, Informative)

PhysicsPhil (880677) | more than 7 years ago | (#17517424)

Of course, if you REALLY want to be pedantic, the speed of light in a vacuum is measured, and the meter is defined as being the distance light travels in 1/299792458th of a second.

While this is Slashdot, we still encourage pedantic comments to be correct. :)

Your definition of the metre is correct, but you may notice that it fixes the speed of light at precisely 299792458 m/s, with no room for measurement. What you actually do in modern science is measure a second with a very precise clock, and calibrate your meter bar appropriately. Any errors you make are in the length of the metre, not the speed of light.

It didn't always used to be this way; for about eighty years the meter was defined in terms of atomic transition lines, so that the speed of light was the measured value. In 1983, however, timekeeping was accurate enough that the definition of the metre changed over so that the metre was a derived quantity.

Re:90% of the speed of light.... (1)

medge_42 (173874) | more than 7 years ago | (#17514500)

No, apparently not.
One university in the US (New Hampshire I think) had it down to 60km/h.

Re:90% of the speed of light.... (2, Informative)

medge_42 (173874) | more than 7 years ago | (#17514546)

I should mention that that was going through a block of sodium at -272C (near absolute zero)

Re:90% of the speed of light.... (1)

COMON$ (806135) | more than 7 years ago | (#17514812)

just curious, how do you cool something that well?

Re:90% of the speed of light.... (1)

imsabbel (611519) | more than 7 years ago | (#17515060)

Liquid helium, under reduced pressure.
If you want to go even lower, than you can use adiabatic demagnetisation (put stuff into magnetic field->Spin orientation reduces entropy->remove heat->shut off magnetic field->the new degree of freedom reduces temperture).
Alternatively, you can try laser cooling (the closesed thing to a maxwell daemon we have), or diffusion cooling (with helium 3 and 4).

Re:90% of the speed of light.... (1)

tool462 (677306) | more than 7 years ago | (#17515412)

There's also evaporative cooling in a magnetic field. The atoms you are cooling are placed in a magnetic trap, and the more energetic ones "boil" off, leaving the remaining atoms cooler. This combined with the laser cooling is what was used to create the Bose-Einstein condensate that Eric A. Cornell, Wolfgang Ketterle and Carl E. Wieman won the Nobel Prize for back in 2001. link [nobelprize.org]

Re:90% of the speed of light.... (1)

medge_42 (173874) | more than 7 years ago | (#17515130)

You put in in an Aston Martin DB9.

Physicists in Helsinki have managed to get temperatures to 1 billionth of a degree above absolute zero.
I am more curious as to how you measure something that cold.

Re:90% of the speed of light.... (1, Funny)

Anonymous Coward | more than 7 years ago | (#17514700)

That's nothing. I had it down to zero, using nothing but a block of wood.

Re:90% of the speed of light.... (0)

Anonymous Coward | more than 7 years ago | (#17515804)

while walking uphill!

Re:90% of the speed of light.... (1)

kitsunewarlock (971818) | more than 7 years ago | (#17514898)

If time travel occurs beyond the speed of light, I've seen it at 88 miles per hour. And the earth once was spun backwards at that rotational velocity in Superman 1.
But seriously, when will we create a material that doesn't have light bounce off of it, but is reflected and bounces off of light?
Wait...Physists worked on this project. I thought they were too busy explaining Shrodinger to Peta.

Light travels at the speed of light, not 90% of it (-1, Redundant)

Anonymous Coward | more than 7 years ago | (#17514434)

Although light might at 90% of the speed of light vacuum when passing through some other substance...

WTF? (-1)

MarkusQ (450076) | more than 7 years ago | (#17514464)

Coax for light?

Why?

Did they also discover some new physics that replaces Maxwell's equations with some bazaaro world version where light causes inductance?

--MarkusQ

Re:WTF? (3, Funny)

MustardMan (52102) | more than 7 years ago | (#17514626)

Right, because the slashdot poster definitely understands the details of the physics publication in a peer-reviewed physics journal, written by experts in the field, and can clearly question its validity in the three seconds it takes to read a slashdot summary.

Here's an idea, instead of immediately trying to show how smart you are by posting minutes after an article goes up just to say "this is dumb", have a little faith in the scientific publication process and actually read the (original, peer-reviewed) article before you jump to conclusions.

Re:WTF? (1)

kfg (145172) | more than 7 years ago | (#17514980)

. . .have a little faith in the scientific publication process . . .

Well, maybe he hasn't had half his brain sucked out yet?

KFG

Re:WTF? (2, Informative)

Anonymous Coward | more than 7 years ago | (#17514986)

You have faith in the peer reviewed physics journal? You must not know any of the peers, or have any insight into the review process. Trust me, its a mess. Although I am not a physicist myself, my friends who are complain to no end at the state of affairs with the journals. Its not that everything published is wrong, its just most of it is very, very difficult to review and very very little of it is worth reading. Its never wrong to ask stupid questions, or compare new discoveries to existing models of thought on a discussion forum. Of course, in this case it answers the question in the article, but it should have been in the summary.

Re:WTF? (5, Informative)

MustardMan (52102) | more than 7 years ago | (#17515772)

Yes, I DO have faith in the peer review process. It's far from perfect, but it's not as bad as you make it out to be. The thing you need to know is, a lot of physicists, and scientists in general (myself included) can be really anally retentive bastards. I one got blasted for fifteen minutes over my use of the phrase "high reynolds number" when the colleague in question believed "moderate" was the appropriate adjective and "high" was misleading. These are the types of errors that get physicists steaming, and with good reason - physics is perhaps the most rigorous of the sciences, and you have to be damn careful about how you word things. People will complain, loudly, about very minor issues. Many scientists strive for absolute perfection, and fixate on the negatives in an attempt to make the process better. There's nothing wrong with this, but it's useful to keep in mind when you form opinions about the peer review process based on your friends' complaints.

When people bitch about physics journals, in my experience it's been mainly for two common reasons:
1.) Drawing large, over-arching conclusions without enough evidence to support it. This is in no way saying the bulk of the work is invalid, just that the authors got a little greedy when writing the conclusions.
2.) Disagreement with the underlying assumptions that make up the paper. This one is trickier, but again it doesn't immediately invalidate the work, just questions how relevant the results are.

In either case, the peer review process, by people well-versed in the field, is a whole HELL of a lot more trustworthy than the slashdot peanut-gallery. The OP was full of crap, and others have gone into great detail to explain why he/she is full of crap. I was merely pointing out that the knee-jerk slashdot "post early, post often" karma whoring competitions lead to a whole lot of dumbass assertions without any firm understanding of the actual facts of the discussion.

Re:WTF? (2, Insightful)

Bill, Shooter of Bul (629286) | more than 7 years ago | (#17517636)

I was merely pointing out that the knee-jerk slashdot "post early, post often" karma whoring competitions lead to a whole lot of dumbass assertions without any firm understanding of the actual facts of the discussion.

But thats what slashdot is. Its a discussion forum. It wasn't a stupid question, as you can see it was asked in other places in this subject.Its about the exchange of ideas and is what makes slashdot a *good* place. Its like instant wikipedia that has people pooling their collective areas of expertise together. Just reading a summary, I can usually guess the topics that are going to be raised and discussed because people feel free to express their knee jerk reactions. It makes the discussion richer in the end. It helps me get a sence of what other people are thinking and why they think that way. I don't want people to self sensor themselves, (thats what the mods are for (no, seriously .. stop laughing, the mod system works ... usually).

Re:WTF? (0)

Anonymous Coward | more than 7 years ago | (#17515186)

I have to admit, that I've read LOTS of published articles in well known journals and conferences, that give me the creeps, I mean... I don't know how do those papers could ever be published! (Perhaps as an example of "How not to"). So, I'll give a little credit to the skeptical people that questions everything!

However, I rather think on something else: If it is coaxial, the axis is shared with? I mean, you only have one fiber inside the cable, and I don't expect that fiber to be covered by a cylindrical planar fiber. So, is it correct the use of "coax" in this cable? or on the other hand... it is "always" coax?

Re:WTF? (5, Informative)

kebes (861706) | more than 7 years ago | (#17515190)

Well put. The original scientific article in question is this one:

Rybczynski, J.; Kempa, K.; Herczynski, A.; Wang, Y.; Naughton, M. J.; Ren, Z. F.; Huang, Z. P.; Cai, D.; Giersig, M. "Subwavelength waveguide for visible light" Applied Physics Letters 2007, 90, (2), 021104. (doi: 10.1063/1.2430400).

The paper is here [aip.org] , although only subscribers can read the fulltext. The abstract says this:

The authors demonstrate transmission of visible light through metallic coaxial nanostructures many wavelengths in length, with coaxial electrode spacing much less than a wavelength. Since the light frequency is well below the plasma resonance in the metal of the electrodes, the propagating mode reduces to the well-known transverse electromagnetic mode of a coaxial waveguide. They have thus achieved a faithful analog of the conventional coaxial cable for visible light. ©2007 American Institute of Physics
These are extremely small structures and this leads to an interaction between the light (which is an electromagnetic wave of course) that is essentially identical to when radiofrequency EM radiation propagates down a normal (macroscopic) coax cable. Specifically, in the introduction they say:

In this work, we show experimentally that a nanoscopic analog of the conventional coaxial cable, with properly chosen metals for the electrodes and proper electrode dimensions, indeed retains approximately all of the above properties of its conventional macroscale cousin.
Then they go through the details. Their device uses a multiwall carbon-nanotube (MWCNT) as the center conductor (it is a 'metallic' CNT). The MWCNT is embedded in aluminum oxide, which acts as the optically transparent 'dielectric'. The outer wrapping electrode is made of chromium.

The mere creation of these nano-sized devices is quite an accomplishment. The fact that they've demonstrated successful transmission of light through these sub-wavelength sized devices is even more impressive. I can imagine a wide range of applications in nano-scale imaging (imagine a massive array of NSOMs [wikipedia.org] ), lithography, or even optical computing.

Re:WTF? (1)

Steve525 (236741) | more than 7 years ago | (#17515788)

While I'll agree with your assesment that this is really cool work, (the first demonstration of a coaxial cable at optical frequencies), I'm not sure if any of the applications you list are likely.

NSOM: You really want something that's much smaller than the wavelength. This isn't.
Lithography: Optically lithography works well because you project trillions of pixels at once. Something like this could only approach maybe a million or so. And like NSOM, you want something smaller than this will ever be.
Optical computing: Maybe, but there are already plenty of ways to guide light using strictly dielectrics. If the materials could do interesting things, then maybe it could be useful.

Re:WTF? (1)

A beautiful mind (821714) | more than 7 years ago | (#17515298)

You must be new here, right?

First of all, if you thought the OP was the only thing he will post, then you're wrong.

5 people will point out where exactly is the original paper mistaken, then
4 people will write a post about how dare those 5 people challenge a peer reviewed journal,
the original 5 plus 15 new people will point out the flaws in that argument,
10 people will post "in soviet russia you suck vacuum" jokes, of which the first 6 will be modded redundant and the last 4 modded up to anything between +2 and +5 funny,
2 people will play grammar nazi and correct mistakes while making much bigger errors in their post and subsequently 7 others will invoke Godwin,
6 people will be actually people with physics jobs commenting with informative posts, but they'll be reduced to oblivion by 34 people in well written but totally clueless posts that will get modded up to +5,
24 other people will post only loosely connected nonsense to the topic,
1 person (me) admits that he only included the previous item to taunt grammar nazis with a proper use for loosely,
and finally 2 trolls will post the best posts, in a tie, in the entire discussion by complete accident

Re:WTF? (1)

EvolvedHumanoid (181646) | more than 7 years ago | (#17515602)

10 people will post "in soviet russia you suck vacuum" jokes, of which the first 6 will be modded redundant and the last 4 modded up to anything between +2 and +5 funny,
I think you meant: "In Soviet Russia, vacuum sucks you".

Also might add the following:

1 person finally succeeds in combining a "in soviet russia" post with grammar nazi tactics.

Neologism (0)

Anonymous Coward | more than 7 years ago | (#17515790)

10 people will post "in soviet russia you suck vacuum" jokes, of which the first 6 will be modded redundant and the last 4 modded up to anything between +2 and +5 funny,

I think you meant: "In Soviet Russia, vacuum sucks you".

Also might add the following:

1 person finally succeeds in combining a "in soviet russia" post with grammar nazi tactics.


I think you meant "One person invents the grammar commie."

Re:WTF? (1)

j00r0m4nc3r (959816) | more than 7 years ago | (#17514708)

From TFA:

"This enables the cable to carry electromagnetic signals with wavelengths bigger than its own diameter."

Re:WTF? (1)

silentounce (1004459) | more than 7 years ago | (#17514736)

co = two
axial = "being or situated in line with an axis" or "around or about an axis (a link between two or more places)" or "along, or parallel to, the main axis; lengthwise, longitudinal"

The term coax has nothing to do "spefically" with conveying electric current. That just happens to be its most common use. Etymology is your friend.

Re:WTF? (1)

silentounce (1004459) | more than 7 years ago | (#17514852)

And before anyone says anything... I should have said, co = Together; joint; jointly; mutually.

Re:WTF? (1)

ArcherB (796902) | more than 7 years ago | (#17514744)

Coax for light?

Why?


Think processors that produce less heat, but don't look at them directly without eye protection. As speeds ramp up, heat sincs will be replaced with tinted shields.

Re:WTF? (0)

Anonymous Coward | more than 7 years ago | (#17514856)

Could these cables be used to space to perhaps reach something that would normally not be reachable?

And what happens to a piece of string or yarn in space? Since there is no wind, would it stick straight out or would it move freely?

Re:WTF? (1)

wass (72082) | more than 7 years ago | (#17515198)

In the simplest sense, light here refers to light 'waves', which are the propogating electric/magnetic fields which are solutions to Maxwell's equations given the proper boundary conditions of the coaxial cable.

Of course this particular case involves a tiny coax, so if the wavelength of light is of order or larger than the size of the coax (I'm too lazy to read the article to see what wavelengths are used), then one would probably need to consider quantum mechanics and QED, to get the full behavior of the dynamics of these propagating waves.

But anyway, even in the classical sense there's no bizarro-world phsyics going on at all, any AC signal sent down a coaxial cable is actually sending 'light'. You might not think of a measly 10 MHz signal as being 'light', but it really is, it's propagating EM waves. That's why you need to properly terminate your coax, otherwise you can get electronic reflections and signal degradation, which is the exact analog to getting reflections at an interface between optical components where indexes of refraction are mismatched (glass/air for example).

And regarding your inductance of light phenomena, look up characteristic impedance [wikipedia.org] in a decent E&M text, you might want to check out what the impedance of free space is.

I just skimmed the article (1)

wass (72082) | more than 7 years ago | (#17515352)

They transmitted visible light through the coax, which basically means it's like a typical coaxial cable transmission line [wikipedia.org] we're used to, but due to the small geometry they can still send TEM waves up to the frequencies of visible light.


In other words, this nano-coax-cable has the proper physical characteristcs such that optical frequencies of EM radiation (ie, visible light) can be transmitted without significant dissipation [wikipedia.org] or dispersion [wikipedia.org] .

Re:WTF? (0)

Anonymous Coward | more than 7 years ago | (#17515626)

Did they also discover some new physics that replaces Maxwell's equations with some bazaaro world version where light causes inductance?

Not bizarre at all. Light is nothing but RF radiation. Perfectly capable of TEM propagation in a coaxial transmission line of the appropriate size and characteristic impedance.

Re:WTF? (1)

Eternauta3k (680157) | more than 7 years ago | (#17516710)

Did they also discover some new physics that replaces Maxwell's equations with some bazaaro world version where light causes inductance?
I really don't understand your post. It didn't say light causes inductance. It just said the disposition of its layers is coaxial.

won't work (-1)

Anonymous Coward | more than 7 years ago | (#17514810)

transmitting light at about 90% the speed of light

Well, clearly there's a flaw in their design. Any entity that keeps going 90% of the speed of itself is quickly going to come to a complete stop.

Re:won't work (1)

dotgain (630123) | more than 7 years ago | (#17517360)

You're wrong. In fact, it never will.
17,16,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1

Impressive Indices (1)

overshoot (39700) | more than 7 years ago | (#17514868)

Wowsers. An index of refraction of only 1.1 is damned impressive.

The fibers are k3w1, but what I really want to know is how they got the silly things to be so much less of a "drag" than teflon. If they can extend that, it has a lot more immediate applications as a low- material than as a fast lightpipe.

Quite fast (1)

swale44 (630395) | more than 7 years ago | (#17517406)

Good glass I've used in fiber optics only allow about 0.6C, a much higher index of refraction. If it works like fiber optics the cladding would have a index of refraction of near 1.09. I guess they would be nano-dot calbes. Triaxial micro-dot cables were bad enough. john

Comments so far about 'speed of light' (1)

Meccanica (980734) | more than 7 years ago | (#17514902)

As soon as I read that, it occurred to me that half of the comments were going to focus on that one sentence. And what do you know? I was right.

Nostradamus, are you not. (1)

ichigo 2.0 (900288) | more than 7 years ago | (#17516072)

You might want to cancel the pointy wizard hat you just ordered from theprophetshop.com, the summary is only two sentences long so half of the comments focusing on the second sentence isn't particularly odd. ;)

Sorry to be picky but (-1, Redundant)

syousef (465911) | more than 7 years ago | (#17514972)

Sorry to be picky but the following statement sounds like the author hasn't graduated high school: "transmitting light at about 90% the speed of light". Try "transmitting light at about 90% the speed of light IN A VACUUM" or "transmitting DATA at about 90% the speed of light IN A VACUUM" instead. Light always travels at the speed of light. In fact most things I know of travel at their own speed.

Re:Sorry to be picky but (0, Flamebait)

EnderGT (916132) | more than 7 years ago | (#17515096)

Congratulations, you only missed being first to point this out by 30 minutes! You missed second or 3rd 28 minutes, 4th by 10 minutes, and 5th by 5 minutes.

Sorry about your impending Redundant moderation.

Re:Sorry to be picky but (1)

funwithBSD (245349) | more than 7 years ago | (#17515730)

Sorry, fresh out of mod points...

Re:Sorry to be picky but (1)

badboy_tw2002 (524611) | more than 7 years ago | (#17515916)

Redundant? Redundant? How could someone with an ALL YOUR BASE signature be redundant?!? That's so fresh and hip that the poster in question had a really good shot of posting something worth while to the conversation, like pointing out something everyone else glossed over and understood to be a mistake to make himself look smarter.

Re:Sorry to be picky but (1)

syousef (465911) | more than 7 years ago | (#17516426)

I view at +4 and didn't have time to check. You have all the time in the world though I see. Too much time.

Re:Sorry to be picky but (0)

Anonymous Coward | more than 7 years ago | (#17515168)

Thank you for pointing that out. The world is a better place because of pedants like you.

Re:Sorry to be picky but (1)

MustardMan (52102) | more than 7 years ago | (#17515960)

No, it doesn't sound like the author didn't graduate high school at all. The constant c is almost universally referred to as "the speed of light". Only rarely is the "in a vacuum" tacked onto the end. It's perfectly understood that when you refer to "the speed of light" that it means "the speed of light in a vacuum". Your nit-picking is pointless and goes against the convention used in thousands of published books, papers, articles, ad nauseum.

Re:Sorry to be picky but (1)

syousef (465911) | more than 7 years ago | (#17517420)

Yes and speed and velocity are used interchangeably, but if you're talking physics and do that you're a twit.

The nit picking as you put it isn't pointless. The point is that if you're talking science and don't get the jargon right you become much more ambiguous and it's a bad habit to form. Yes in this case it was obvious what he meant but that doesn't make it a good story submission.

Re:Sorry to be picky but (2, Informative)

Cyrom (984413) | more than 7 years ago | (#17516452)

When not qualified the term "speed of light", to the majority of the population (except maybe a few who think they are clever for pointing out the lack of said qualification), means the speed of light in a vacuum. When one is referring to the speed of light through some other medium it is usually stated as such.

Re:Sorry to be picky but (1)

Bloater (12932) | more than 7 years ago | (#17517572)

That is not correct. Read up on QED, the most accurate description of the interaction of light and electrons ever devised (Quantum Electro-Dynamics).

Light travels at a variety of speeds in the face of interactions or when travelling through free space. What is constant is the number of times the little arrow spins in a given vector length through spacetime (watch the Feynman lectures to get this "little arrow" reference at http://www.vega.org.uk/video/subseries/8 [vega.org.uk] )

Thosands of times faster than electronics? (5, Informative)

JesseL (107722) | more than 7 years ago | (#17515000)

From TFA:
"It's not quite the speed of light, but it's probably 90 percent the speed of light. That's still thousands of times faster than electronics," Naughton said in an interview.


It was my understanding that electric fields propagate through copper at about 1/3 C.

Re:Thosands of times faster than electronics? (1)

Cutie Pi (588366) | more than 7 years ago | (#17515258)

It's actually about 2/3 the speed of light (depending on the dielectric constant). The TFA might be referring to the drift velocity of electrons in the wire (on the order of a centimeter/s), which is not a particulary useful comparison.

Re:Thosands of times faster than electronics? (4, Informative)

KokorHekkus (986906) | more than 7 years ago | (#17515388)

I thought it was a bit higher than that (still not 90% though). Did some digging and wikipedia came up with that the velocity of propagation was about .79 for a coax cable according to it. Checked a supplier of coax cables and they quoted velocity of propagation at .66 C to .84 C (latter for 1.13 mm copper KTV cable with PE insulation)

Source: http://en.wikipedia.org/wiki/Velocity_of_propagati on [wikipedia.org]

Re:Thosands of times faster than electronics? (1)

leighklotz (192300) | more than 7 years ago | (#17516852)

90%+ is possible for waveguides, and for open-wire feedline, but is usually lower for coaxial feedline.
VF is 1/sqrt(dielectric constant). Interestingly, the velocity itself is VF*c=1/sqrt(L*C) where c=speed of light in a vacuum, and L and C are the series inductance and shunt capacitance of the feedline, so those values are directly related to the velocity factor. Finally, given L and C we can calculate the characteristic impedance Z=sqrt(L/C).

The characteristic impedance of the coax is important to achieve maximum power transfer.

Another interesting thing nobody mentioned from the paper is that they say you can create an antenna by extending the center line out of the coax; presumably this is done with a 1/4 wavelength, though they specifically refer to this as matching to the impedance of free space, which we all know is 120*pi = ~377 Ohms. This number again is calculated by the sqrt(L/C) formula, but using L/m (magnetic permeability) and C/m (permittivity) which are both constants, so it's a little unfair.

You can do other fascinating calculations using transmission line equations [wikipedia.org] . In fact, the paper says that the experimenters verified some of their findings by using larger scale components and microwave experiments.

So, if you're interested in the math behind, you can do it at home using standard coax and RF yourself, and get a flavor. Now that there's no more morse code test involved for getting a ham radio, it would be a good time to check out getting your ham license [arrl.org] with just written tests of knowledge, and start doing experiments with practical results.

thickness is the key issue (3, Informative)

rjdegraaf (712353) | more than 7 years ago | (#17515004)

The 300nm wide fiber is the key issue.


The thinner the fiber, the less the digital light pulses are spread (due to reflections on the fiber shell) per unit distance, the more information can be sent through per unit time.

Thinner means more bandwidth.

Re:thickness is the key issue (1)

cdogg228 (1048648) | more than 7 years ago | (#17515520)

The spreading of digital pulses as the light travels down the fiber is known as "chromatic dispersion". This phenomenon degrades the signal more and more as the signal travels further and further down the fiber. Consequently, dispersion only affects the link length, not the bandwidth. More bandwidth is realized by using different light sources of different "colors" in a wavelength division multiplexing (WDM) scheme.

Re:thickness is the key issue (2, Funny)

sexybomber (740588) | more than 7 years ago | (#17515726)

I guess "fat pipes" is a misnomer, then.

Re:thickness is the key issue (1)

GeorgeS069 (956679) | more than 7 years ago | (#17516420)

A "super fast rad kool" connection like the one described would be termed a "phat pipe"

Re:thickness is the key issue (0)

Anonymous Coward | more than 7 years ago | (#17516748)

Dispersion matters in waveguides. Coax lines are not wave guides. There is no reflection as there is in waveguides, so you do not get the same sorts of dispersion.

The advantage to these coax lines, it seems to me, is their ability to be smaller in diameter than optical fiber and yet carry the same EM signal. This is because the size of a waveguide is related to the wavelength that you are attempting to send down it, whereas coax cables do not have this limitation. For example, it is common to send AM (550 - 1600kHz) radio signals, with wavelengths in the hundreds of meters, down a coax cable which is 1cm in diameter. Try making a waveguide for those frequencies!

Re:thickness is the key issue (1)

cycoj (1010923) | more than 7 years ago | (#17517598)

How can anyone label this as informative?! It is utter bullshit. If it's a joke it might be labeled funny. The area of the fiber as almost nothing to do the amount of information it can transmit (disregard multimode singlemode etc.). Light inside a waveguide (and a fiber is one) does not spread in the directions perpendicular to the propagation direction, that's why it is a _waveguide_, it guides light by total internal reflection. Now the spreading which limits the amount of information is caused by chromatic dispersion, light pulses spread in the temporal domain when propagating. Thus at some point pulses will overlap and we can't distinguish the ones and zeros anymore.

The bottum line... (1)

Maliron (1026708) | more than 7 years ago | (#17515126)

I think the thing we need to think about is when this may be useful to us. Right now it has to cost around elevenity billion dollars to make just enough to test... I think I will stick with the current speed of light through fiber.

Re:The bottum line... (1)

Rod Beauvex (832040) | more than 7 years ago | (#17515648)

Thank you for your comments, Numbah 2. ;)

Yawn.. (1)

djcatnip (551428) | more than 7 years ago | (#17515222)

Wake me up when they announce nano-scale HDMI.

uh, say again? (0, Redundant)

adrenalinerush (518023) | more than 7 years ago | (#17515284)

transmitting light at about 90% the speed of light

Was I the only one who did a double-take at that?

Yes, yes, I know that light travels at different speeds through different materials.

Didn't seem problematic to me (1)

Dachannien (617929) | more than 7 years ago | (#17517036)

I mean, each pound of dark matter weighs over ten thousand pounds, so light moving at 90% of the speed of light seems pretty reasonable to me.

Coax is silly for optical (2, Interesting)

smellsofbikes (890263) | more than 7 years ago | (#17516224)

Will someone tell me *why* they did this? Yes, it's very cool. But the whole and only point of coax, as they talk about in TFA, is that it minimizes electrical influence.
If you're using light, there *isn't* any electrical interference, either as a transmitter or a receiver. That's one of the major benefits of using light.
So it's kind of pointless to make a coax, unless you really want a two-channel transmitter where one's a funny ring-shape. In which case, why not make optical ribbon cable?
Which brings up a wholly separate question: one reason industry has moved from parallel to very-high-speed serial is that you don't have to worry about timing and synchronicity, which are primarily due to impurities in copper. Is this an issue with optical? Coz the engineering is generally easier to run ten existing lines in parallel than to make one line ten times faster, if you don't have to worry about synchronizing them.

Re:Coax is silly for optical (2, Informative)

fluffy99 (870997) | more than 7 years ago | (#17517056)

You obviously didn't read the entire article. The whole point is that they are shoving something with a wavelength of 375 nm down a 300 nm pipe. They explained that this is the exact same issue with shoving RF down a coax (ie 1-meter wavelengths down a 1/4" coax).

Re:Coax is silly for optical (1)

StikyPad (445176) | more than 7 years ago | (#17517388)

"Coax," short for coaxial, is defined as "having or mounted on a common axis." In cables, it is any design in which a central conductor is surrounded by a shielded cladding -- they both encircle a common "axis" or center. All fiber cables are coax, except those used in toys and art. Most have multiple levels of shielding to protect against energy loss/insertion, physical stresses and environmental hazards, in order from inner to outer.

Monster Cable: take note. (0, Flamebait)

Hamster Lover (558288) | more than 7 years ago | (#17517562)

Hey motherfuckers at Monster Cable: bigger isn't always better. Those assholes have driven up the price of HDMI and DVI cables to ridiculous levels thanks to arrangements with major electronics retailers to carry or feature their cables exclusively.

Anyway, suck it.
Load More Comments
Slashdot Login

Need an Account?

Forgot your password?