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Refraction and fiber optic cable diameter

  1. Dec 16, 2009 #1
    Hello there,
    I'm wondering if there is any restricting reason why fiber optic cables are not made thicker. Regardless of the practical applications, is there any reason you can't make a fiber optic cable that is only 2m long but 2cm thick (compared to the normal 0.0125 cm thick)?
    Does width of the high index core make a difference, and does the width of the low index coating make a difference in regard to total internal reflection?

    To sum it up, is there any physical reason why fiber optic cables can't be made thicker?

    Thanks for reading,
    Last edited: Dec 16, 2009
  2. jcsd
  3. Dec 16, 2009 #2


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    Welcome to the PF. Are you aware of the differences between single-mode and multi-mode fiberoptics?


    And are you aware of the concept of "dispersion", where the path lengths for multi-mode fibers (especially as wide as you are asking about) indroduce different delays for different ray traces? What effect would dispersion have on high-bandwidth optical signals?
  4. Dec 16, 2009 #3
    Thanks for answering and good points berkeman,
    I am not particularly concerned with transmitting data or signals, and so I believe that dispersion wouldn't play a bad role as long as the light was a guided ray the whole time. You could say that I want to be able to use the fiber optic cable like a snake light, where you could put light in one end of the cable and receive light out of the other end, like an extension cord for a flash light. I believe the thickness would require multi-mode, it would allow more light sources can be used.
  5. Dec 16, 2009 #4

    Andy Resnick

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    Light pipes are different than fibers. Fibers are (usually) significantly longer- many kilometers- for one thing.
  6. Dec 16, 2009 #5


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    If you want a thicker fiber optic, just bundle up a bunch of smaller ones.
  7. Dec 16, 2009 #6
    That could possibly work. A light pipe (Thank you Andy Resnick) is what I believe the term is what I am looking for.
    Last edited: Dec 16, 2009
  8. Dec 16, 2009 #7

    Andy Resnick

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    It depends on the application- do you need it to be flexible? Are you trying to image?

    Liquid light guides have diameters up to 8 mm. I've seen rigid light guides with diameters over 2 inches, but I don't recall who made them.
  9. Dec 16, 2009 #8
    I'm not trying to image, just pass light from a flashlight into one end and out the other to be used for light to see. Rigid works, flexible is better. Light guides are the closest I've seen so far. I can adapt from the light guide concept and go from there.
    Thanks for pointing me in the right direction Andy.

    This is what I was looking for.
    http://www.lumatec.de/e_superlite/e_superlite.htm [Broken]
    Last edited by a moderator: May 4, 2017
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