4 ms·

Quick aside: I'm one of the team that built this. If you've got any questions, shout!

Kenji 12y ago
I have a question. How do you connect two optical cables as opposed to copper wires? Can you melt the glass together or do you have to put a repeater inbetween? I have no clue how you can repair glass fibers.
- K2h 12y ago
  single mode splice is not so bad. multi mode takes a bit more work to get complex index of refraction in the fiber correct. http://www.thefoa.org/tech/ref/termination/fusion.html http://www.thefoa.org/tech/ref/termination/fusion.html
- dfox 12y ago
  You melt the glass in controlled manner and let it to fuse together. As far as the process goes it is mostly similar to how lab technicians in chemistry labs build custom glassware, but with much smaller dimensions and better control In practical terms you use ridiculously expensive computer controlled portable machine that just does it without much of manual intervention. It is done by such automatic splicers almost since fiber optics are used for practical applications. There were manual (mostly mechanical) splicers that are not too hard to use (it certainly requires less skill than above mentioned laboratory glassware), but it's more economical to just automate the task. The problem is that even almost perfect splice incurs significant additional signal loss, so for long cable runs you do want to do smallest number of splices (and connectors, which are orders of magnitude worse) as possible.
  - onnoonno 12y ago
    Does that machine have to correct for the rocking of the ship? Edit: To be more specific - do you have a quiet/stabilized optical platform onboard to perform this?
    - dfox 12y ago
      The whole mechanism tends to be mounted inside the case on some kind of damping, but I would assume that has more to do with overall ruggedness than with vibrations in operation (it's precision micro mechanics that are quite rigid, flexing of the fiber itself does not seem like much of an issue to me).
      - onnoonno 12y ago
        Ah, I see. Interesting. Thanks for the explanation! If a public tour is ever offered on such a repair ship, I'll check it out, it sounds like awesome technology.
- tomkinstinch 12y ago
  While melting the glass is standard for permanent splices like those used in joining sections of fiber, it is not required for a tap. Fiber bending and evanescent coupling are two methods that do not modify the source fiber[1][2][3][4]. Across undersea long hauls, optical amplifiers exist (think repeaters, but without any introduction of delay). They get their energy from being pumped by a wavelength of light different from those used for data transmission[5]. 1. http://www.idquantique.com/images/stories/PDF/network-encryption/white-paper-optical-fibers.pdf http://www.idquantique.com/images/stories/PDF/network-encryp... 2. http://en.m.wikipedia.org/wiki/Evanescent_wave#Evanescent-wave_coupling http://en.m.wikipedia.org/wiki/Evanescent_wave#Evanescent-wa... 3. http://131.238.119.245/asarangan/courses/542/student_projects/evanescent-coupler.pdf http://131.238.119.245/asarangan/courses/542/student_project... 4. http://www.rootsecure.net/content/downloads/pdf/fiber_optic_taps.pdf http://www.rootsecure.net/content/downloads/pdf/fiber_optic_... 5. http://en.wikipedia.org/wiki/Optical_amplifier#Doped_fibre_amplifiers http://en.wikipedia.org/wiki/Optical_amplifier#Doped_fibre_a...
dm2 12y ago
Great article and a fascinating topic. Here is a picture of the device used during Operation Ivy Bells, it's in the KGB museum in Moscow. http://www.therebreathersite.nl/11_Closed%20Circuit%20Rebreathers/images/GE%20MK10/UnderseaEspionage.jpg http://www.therebreathersite.nl/11_Closed%20Circuit%20Rebrea... It might be interesting to readers some more information about these underwater taps. The devices are built to detach when the cable is raised to prevent detection. How long they store data? This one was 1-2 weeks before it had to be collected via submarine and new drives put in or the drives wiped. Later devices such as the nuclear powered ones developed by Bell Labs and buoy tethered devices. Also, here is a great cable map that has been around a couple years, it shows who owns each cable. http://www.submarinecablemap.com/ http://www.submarinecablemap.com/ Facebook and Google have their own underwater fiber lines across the Pacific and possibly the Atlantic, http://www.wired.com/2012/07/facebook-submarine/ http://www.wired.com/2012/07/facebook-submarine/ This is a good article too: http://motherboard.vice.com/blog/undersea-cable-surveillance-is-easy-its-just-a-matter-of-money http://motherboard.vice.com/blog/undersea-cable-surveillance...

Kenji 12y ago

I have a question. How do you connect two optical cables as opposed to copper wires? Can you melt the glass together or do you have to put a repeater inbetween? I have no clue how you can repair glass fibers.

K2h 12y ago
single mode splice is not so bad. multi mode takes a bit more work to get complex index of refraction in the fiber correct. http://www.thefoa.org/tech/ref/termination/fusion.html http://www.thefoa.org/tech/ref/termination/fusion.html
dfox 12y ago
You melt the glass in controlled manner and let it to fuse together. As far as the process goes it is mostly similar to how lab technicians in chemistry labs build custom glassware, but with much smaller dimensions and better control In practical terms you use ridiculously expensive computer controlled portable machine that just does it without much of manual intervention. It is done by such automatic splicers almost since fiber optics are used for practical applications. There were manual (mostly mechanical) splicers that are not too hard to use (it certainly requires less skill than above mentioned laboratory glassware), but it's more economical to just automate the task. The problem is that even almost perfect splice incurs significant additional signal loss, so for long cable runs you do want to do smallest number of splices (and connectors, which are orders of magnitude worse) as possible.
- onnoonno 12y ago
  Does that machine have to correct for the rocking of the ship? Edit: To be more specific - do you have a quiet/stabilized optical platform onboard to perform this?
  - dfox 12y ago
    The whole mechanism tends to be mounted inside the case on some kind of damping, but I would assume that has more to do with overall ruggedness than with vibrations in operation (it's precision micro mechanics that are quite rigid, flexing of the fiber itself does not seem like much of an issue to me).
    - onnoonno 12y ago
      Ah, I see. Interesting. Thanks for the explanation! If a public tour is ever offered on such a repair ship, I'll check it out, it sounds like awesome technology.
tomkinstinch 12y ago
While melting the glass is standard for permanent splices like those used in joining sections of fiber, it is not required for a tap. Fiber bending and evanescent coupling are two methods that do not modify the source fiber[1][2][3][4]. Across undersea long hauls, optical amplifiers exist (think repeaters, but without any introduction of delay). They get their energy from being pumped by a wavelength of light different from those used for data transmission[5]. 1. http://www.idquantique.com/images/stories/PDF/network-encryption/white-paper-optical-fibers.pdf http://www.idquantique.com/images/stories/PDF/network-encryp... 2. http://en.m.wikipedia.org/wiki/Evanescent_wave#Evanescent-wave_coupling http://en.m.wikipedia.org/wiki/Evanescent_wave#Evanescent-wa... 3. http://131.238.119.245/asarangan/courses/542/student_projects/evanescent-coupler.pdf http://131.238.119.245/asarangan/courses/542/student_project... 4. http://www.rootsecure.net/content/downloads/pdf/fiber_optic_taps.pdf http://www.rootsecure.net/content/downloads/pdf/fiber_optic_... 5. http://en.wikipedia.org/wiki/Optical_amplifier#Doped_fibre_amplifiers http://en.wikipedia.org/wiki/Optical_amplifier#Doped_fibre_a...

dm2 12y ago

Great article and a fascinating topic. Here is a picture of the device used during Operation Ivy Bells, it's in the KGB museum in Moscow. http://www.therebreathersite.nl/11_Closed%20Circuit%20Rebreathers/images/GE%20MK10/UnderseaEspionage.jpg http://www.therebreathersite.nl/11_Closed%20Circuit%20Rebrea... It might be interesting to readers some more information about these underwater taps. The devices are built to detach when the cable is raised to prevent detection. How long they store data? This one was 1-2 weeks before it had to be collected via submarine and new drives put in or the drives wiped. Later devices such as the nuclear powered ones developed by Bell Labs and buoy tethered devices. Also, here is a great cable map that has been around a couple years, it shows who owns each cable. http://www.submarinecablemap.com/ http://www.submarinecablemap.com/ Facebook and Google have their own underwater fiber lines across the Pacific and possibly the Atlantic, http://www.wired.com/2012/07/facebook-submarine/ http://www.wired.com/2012/07/facebook-submarine/ This is a good article too: http://motherboard.vice.com/blog/undersea-cable-surveillance-is-easy-its-just-a-matter-of-money http://motherboard.vice.com/blog/undersea-cable-surveillance...