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'Optical Fiber' Made Out of Thin Air
Dave Knott writes: Scientists from the University of Maryland say they have turned thin air into an "optical fiber" that can transmit and amplify light signals without the need for any cables. As described in the research, this was accomplished by generating a laser with its light split into a ring of multiple beams forming a pipe. Very short and powerful pulses from the laser are used to heat the air molecules along the beam extremely quickly. Such rapid heating produces sound waves that take about a microsecond to converge to the center of the pipe, creating a high-density area surrounded by a low-density area left behind in the wake of the laser beams. The lower density region of air surrounding the center of the air waveguide has a lower refractive index, keeping the light focused, and allowing the higher-density region (with its correspondingly higher index of refraction) to act like an optical fiber. The findings, reported in the journal Optica, have applications in long range laser communications, high-resolution topographic mapping, air pollution and climate change research, and could also be used by the military to make laser weapons.
On top of a shark's head.
and the only ones that looked remotely practical was the laser weapon and remote sensing requiring high power high focus.
Using lasers for freespac communications is already very practical and well solved, just look at this example
http://esc.gsfc.nasa.gov/267/2... (BTW definitely one of the better uses of NASA's budget. )
All the other mentioned applications also have off the shelf solutions that perform exceptionally well. The weapons and high power remote sensing however while listed last seem to have the most to gain. Being able to generate a waveguide in either case solves their two big problems atmospheric distortion and the need to focus large amounts of laser energy on a small point.
I see you stopped your music education in kindergarten.
Here's a link to the press release from UMD with some links to the professor's web site.
http://cmns.umd.edu/news-events/features/2356
When reading the description of a bundle of laser beams guiding a central one, I can't help but think of a ladder evolving in the game of Go... http://en.wikipedia.org/wiki/L...
One of the chief benefit of optical fiber is that it doesn't require LOS. All they've done here is demonstrate the capability to mimic the loss-less advantages of optical fiber without actually having a fiber ... once they can do this around corners... then maybe they've "created optical fiber out of thin air" until then not so much.
But, does it bend? After all, that's the point behind fiberoptics, to be able to snake a light beam around corners and through tight spaces so that we don't have to maintain perfect optical alignment over a distance. So, what's the point of this setup? Does it keep moths away by burning them on the outer beams?
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I'm puzzled as to what this does or what it's good for, exactly.
... they have turned thin air into an "optical fiber" that can transmit and amplify light signals without the need for any cables.
1. Air already transmits light signals. It's transparent.
2. They haven't mentioned anything about amplifying light signals. This would be hard.
So, they are creating a "pipe" that can transmit light... but it doesn't stop beam spread (since the beams that make up the "pipe" still have diffraction-limited beam spread), and it can't bend light around corners. So, they now have a pipe that will funnel a laser beam along the path made by other laser beams, which take it exactly the same path that the beam would go without the pipe...
http://www.geoffreylandis.com
Sounds prohibitively expensive.
Pretty well actually
http://www.fastlinks-wireless....
http://etherealmind.com/free-s...
They are currently in widespread use
The real question is just how much improvement would you get with the new system under inclement conditions. The other big question is how they fare against microwave links.
Why not just use the first laser to transmit the data you need in the first place?
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Stay tuned for some shock and awe coming right up after this messages!
no, IR remotes and handheld lasers have not been using refractive channels made out of air as a waveguide to transmit pulses of light with as little noise as possible for decades.
So if I understand this correctly, the beams that form the "psudofiber" have to be intense enough to heat the surrounding air in less than a microsecond... and the signal will be pushed down the center of the pipe... so all those hoards of unholy photons that created the pipe in the first place are going to arrive at the destination a microsecond before the signal does, and they should still be nicely focused and searching for a nice electronic sensor to deposit all that energy into... Or did I miss something?
Which has more power: the hammer, or the anvil?
Baby on board, oh how I adored...
Science advances one funeral at a time- Max Planck
But can it vaporize a human target from space?
This would be good for performing measurements on objects you wouldn't want to get that close to. Like nuclear reactors.
Would be like the 'End' sequence in Ender's game where they use the drones to protect the gunship (or in our case the actual laser signal)
Read: http://www.ars-nova.com/Theory...
Silence is a state of mime.
Predicted the 1960's (Kerr-induced self-focusing: http://journals.aps.org/prl/ab... ), and it was a big part of SDI: http://www.ncbi.nlm.nih.gov/pu... and was again applied to space-to-ground weapons systems in 2009: http://journals.aps.org/prl/ab...
It was ale demonstrated at LLNL in 2009: http://www.researchgate.net/pu... and 2010: http://www.researchgate.net/pu...
What's new about this one is that they've renamed the tunnel as the desired artifact, rather than describing it in beams going down the tunnel.
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so.... A laser tube to conduct a laser signal? To protect the internal laser?
-no sig today-
air is not transparent
To the extent that air is not transparent, this doesn't work.
and does cause beam scattering.
This does not address beam scattering. If the air is scattering the laser beam, it still scatters the beam.
by creating a refractive channel like this they absolutely will reduce beam dispersion.
It would reduce beam spread... except that the beams that create the channel are not themselves channeled.
obviously it doesn't eliminate beam spread
on this we agree
but even a fiber channel perfectly designed for a single mode will have some diffusion so whats your point?
My point is that from a surface-level analysis, it doesn't do anything useful.
they may be able to increase snr by 10^4 over current technologies at 100 m. that's a serious improvement that shouldn't simply be dismissed so thoughtlessly.
Let me repeat. The beams that create the channel are not themselves channeled. So the channel itself... has the diffraction, scattering, and beam spread of an unchanneled beam. The net result can't be better than an unchanneled beam, because it is made out of an unchanneled beam.
http://www.geoffreylandis.com
I was not trying to kill him, I was simply sending him a large amount of high speed data.
Do not look at laser with remaining good eye.
Perhaps if you'd read more than the headline you'd see that this is not what IR remotes and lasers have been doing for ages, at all.
Seriously, saying "fiber optic cables from thin air" is an idiotic statement.
It's actually a pretty good summation of a very clever bit of engineering. What's your beef?
systemd is Roko's Basilisk.
Let me repeat. The beams that create the channel are not themselves channeled. So the channel itself... has the diffraction, scattering, and beam spread of an unchanneled beam. The net result can't be better than an unchanneled beam, because it is made out of an unchanneled beam.
Not necessarily. Since the surrounding laser pulses should spread in a more or less uniform way, the central channel of denser air should still occur as distance from the emitter increases and remain centralized in the channel. It sounds like it will make air work a little like graded index multimode fiber. The difference in density between the central channel and the surrounding air will likely fall off with distance, making the air channel less efficient, but still present out to some distance. It's not like this would allow perfect single-mode propagation to infinity in a coherent beam, but it could improve bandwidth and/or distance capability for point-to-point laser communications.
Granted, I'm just another /.-er who never RTFAs, but I do have some experience w/ FO comms and free-air transmitters (of one wavelength or another).
So consider: the channeling lasers may disperse, but they carry no information beyond the existence of the channel and possibly the source and destination. The transmitted data packets do not disperse, so what you've got is the equivalent of a phased-array transmitter with zero sidelobes.
https://app.box.com/WitthoftResume Code: https://github.com/cellocgw
Nice sig, man!
So the channel itself... has the diffraction, scattering, and beam spread of an unchanneled beam.
The beams making the channel are channeled by themselves, they create filaments that self-focus the beam. Self-focusing beams in air have been pretty well established at this point and will go quite far if you have enough power because of the attenuation involved.
So, what you just said is that the beams self-channel anyway.
So, if beams self-channel, this innovation does nothing, right? It's a complicated system of multiple beams to make the beam channel, which is to say, self-focus. But you just told me "self-focusing beams in air have been pretty well established at this point."
http://www.geoffreylandis.com