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'Optical Fiber' Made Out of Thin Air 115

Posted by Soulskill
from the sufficiently-advanced-technology dept.
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.
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'Optical Fiber' Made Out of Thin Air

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  • by Anonymous Coward on Wednesday July 23, 2014 @02:54PM (#47517331)

    On top of a shark's head.

  • by Crashmarik (635988) on Wednesday July 23, 2014 @03:07PM (#47517421)

    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... [nasa.gov] (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 can't be the only one getting a squee moment from the fact that we might finally have a chance to create practical laser weapons.

    • by jmichaelg (148257)

      How well do freespace laser communication fare in foggy environments?

    • by Anonymous Coward

      says this technique can increase the SNR by 10^4, which means you can use less reliable forms of modulation to increase your channel bandwidth. this absolutely is in no way limited to only weaponry. and what is most freespac communication if not remote sensing requiring high power high focus.

    • by timeOday (582209)
      And you will note at the end of the paper:

      Acknowledgments

      This research was supported by the Air Force Office of Scientific Research, the Defense Threat Reduction Agency, and the National Science Foundation.

    • The paper makes it clear that this is about remote sensing, and more about getting the response back from the remote location than getting the probe beam to it.

      The list of other potential uses seems to have been added by the linked article's author, who does not seem to have asked himself why, if you are sending guide beams to the destination, can't you just modulate them?

      The word 'weapon' does not appear in the paper, and the researchers do not seem to have attempted to guide powerful beams by this method.

  • UMD Link (Score:5, Informative)

    by bosef1 (208943) on Wednesday July 23, 2014 @03:10PM (#47517443)

    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 [umd.edu]

  • 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... [wikipedia.org]
  • by MondoGordo (2277808) on Wednesday July 23, 2014 @03:14PM (#47517469)
    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.
    • by wiggles (30088) on Wednesday July 23, 2014 @03:19PM (#47517507)

      Not necessarily - there are lots of situations where it's not practical to run a cable. Secure connectivity between naval vessels is a prime example, others would be for use in the space program, or cheaper data communication between buildings in a campus. Residential broadband internet would be simpler - put an optical transceiver on the roof and point it at a tower - no more digging up the garden to provide fttp.

      • by Dynedain (141758)

        Optical is already used in those scenarios for line-of-sight networking. How does engineering a wind tunnel around a laser improve the effectiveness in any of those scenarios?

      • Not necessarily - there are lots of situations where it's not practical to run a cable. Secure connectivity between naval vessels is a prime example, others would be for use in the space program, or cheaper data communication between buildings in a campus. Residential broadband internet would be simpler - put an optical transceiver on the roof and point it at a tower - no more digging up the garden to provide fttp.

        It would work... until it rains.

        • Just increase the energy on the surrounding laser beams to evaporate any water in it's path. That way it can also double as a security measure.

    • 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 l

      • by mrego (912393)
        Yes, but it can kill stray birds and insects...
        • by RH434 (3637461)
          Agreed. Just ask the windmill power generation companies how they fared in this area.
      • by Anonymous Coward on Wednesday July 23, 2014 @03:55PM (#47517775)

        air is not transparent and does cause beam scattering. by creating a refractive channel like this they absolutely will reduce beam dispersion. obviously it doesn't eliminate beam spread but even a fiber channel perfectly designed for a single mode will have some diffusion so whats your point?

        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.

        • 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

          • 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 n

        • by mehemiah (971799)
          the point is that it doesn't bend. While it makes an improvement over laser communication, it's hardly as useful as an optic fiber. This is still cool.
      • by sFurbo (1361249)
        What about to get the reflected beam back to the starting point (thus "remote sensing", being able to do e.g. a Raman spectrum at a long distance)? Here, you have light scattering in all directions. The optical fiber will make sure that more of it gets back the way the original laser beam came. That could be phrased as "amplification", though I think another word would be more correct.
    • by sFurbo (1361249)
      That would be in the same way that it would be silly to call gold a metal, because it is too soft to replace steel?

      This does more or less what an optical fiber does: It keeps light on the right path by using differences in refractive index (though I imagine the exact process is different: Optical fibers use total internal reflection, this probably just uses refraction). An optical fiber has the additional advantage of being able to go around corners, but that is not what makes it an optical fiber; the re
      • nice straw-man you built there ... a single shared property does not the same thing make ... a platypus and a duck are not the same species just because they have "duck bills"

        The refractive index profile is what makes it "optical" ..agreed. The part that makes it a "fiber" is it's nature of being a long fine continuous thread or filament..(which gives it the ability ti bend around corners. )

        I never said it wasn't an optical channel ... I said calling it an optical fiber made of air was silly ... they

        • by sFurbo (1361249)

          nice straw-man you built there

          It's not a straw man, as I did not indicate that you meant that gold was not a metal. It is an analogy, and possibly a bad analogy, like your platypus-duck one.

          they should have said something like "optical fiber effect replicated in thin air" ...

          If only there was some way to indicate that a phrase wasn't used literally, they could have used that in the title, and then people wouldn't be think they had made air solid and made a fiber out of it.

  • But... (Score:4, Insightful)

    by camperdave (969942) on Wednesday July 23, 2014 @03:20PM (#47517515) Journal
    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?
    • Re:But... (Score:5, Funny)

      by gstoddart (321705) on Wednesday July 23, 2014 @03:26PM (#47517567) Homepage

      Our new Monster Cable Air ionizes the air around the signal ensuring maximal defrobulation of the signal flux and maximal polarization in the near infra-red spectrum, guaranteeing a smooth, minty taste.

      When connect to your tube amplifier, this provides a sound which is spunkier and enhanced in the pink spectrum, causing women to swoon. Achieve smooth bass response like never before.

      For only eleventy zillion dollars, you too can get the most out of your sound system. :-P

      Either this stuff is real, with real benefits, or it's hype. Either way, someone will use it for marketing complete crap.

    • by johnsie (1158363)
      I don't care if it bends. Does it blend? That is the question.
    • Nice sig, man!
  • It's the stuff they made the Emperor's clothes with.
  • My phone does this, it's called "Speaker mode"

    Seriously, saying "fiber optic cables from thin air" is an idiotic statement. IR remotes have been doing this for decades, and using lasers to do so has also been done for ages.

    • by Anonymous Coward

      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.

    • 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?

  • Sounds prohibitively expensive.
  • Why not just use the first laser to transmit the data you need in the first place?

  • 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 someth

    • HP ink jet printer heads heat the ink up to temperatures 7 times hotter than the the sun. It doesn't end up burning a hole in the earth's crust though, since it only lasts 2 microseconds.
      http://h20423.www2.hp.com/prog... [hp.com]

      It doesn't take a lot of energy to heat something up really fast as long as it's really low mass, like air.
      In fact, the quicker you heat something up the less energy is required, since there is less time for the heat to dissipate during the heating process.

      • "hoards of unholy photons" didn't tip you to the fact that I was being somewhat less than scientific about my analysis?

  • But can it vaporize a human target from space?
  • by Scottingham (2036128) on Wednesday July 23, 2014 @04:35PM (#47518105)
    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)

  • Yawn (Score:3, Informative)

    by tlambert (566799) on Wednesday July 23, 2014 @04:56PM (#47518243)

    Predicted the 1960's (Kerr-induced self-focusing: http://journals.aps.org/prl/ab... [aps.org] ), and it was a big part of SDI: http://www.ncbi.nlm.nih.gov/pu... [nih.gov] and was again applied to space-to-ground weapons systems in 2009: http://journals.aps.org/prl/ab... [aps.org]

    It was ale demonstrated at LLNL in 2009: http://www.researchgate.net/pu... [researchgate.net] and 2010: http://www.researchgate.net/pu... [researchgate.net]

    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.

    • by Anonymous Coward
      Wow, you cite a bunch of theory and numeric papers, and label them as "demonstrated". You could at least find an experimental paper, e.g. demonstrating some of the effects in 2008 [umd.edu] by experiment... oh, but that is the same group as here. To be fair though, experimental work goes back to the mid 90s, and this group has been involved in that work for 15 years now. There has been considerable improvement in the work since the original theory predictions and early experiment work in the 90s, where now using m
    • by sFurbo (1361249)
      Doesn't all of your citations only have one laser, that then focuses itself (hence "self-focusing")? Wheres this has two lasers, where one focus the other?
  • A million pigeons cried out in terror and were suddenly silenced.

  • so.... A laser tube to conduct a laser signal? To protect the internal laser?
  • I was not trying to kill him, I was simply sending him a large amount of high speed data.

  • 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.

Air is water with holes in it.

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