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fibre optic cladding by saralk on 03-18-2006 at 12:47 PM

In fibre-optics, they have cladding, which is a boundry outside the core that has a lower refractive index than the core itself, so the useful range of the core is reduced and the pulsese don't overlap and scrambling doesn't happen.

Can someone who knows a lot about this, tell me: if the light defracts into the cladding, what stops is totally internally reflecting on the edge of the cladding and then reflecting back into the core and causing scrambling?

RE: fibre optic cladding by TReKiE on 03-18-2006 at 10:33 PM

quote:
Originally posted by saralk
In fibre-optics, they have cladding, which is a boundry outside the core that has a lower refractive index than the core itself, so the useful range of the core is reduced and the pulsese don't overlap and scrambling doesn't happen.

Can someone who knows a lot about this, tell me: if the light defracts into the cladding, what stops is totally internally reflecting on the edge of the cladding and then reflecting back into the core and causing scrambling?
I'm definitely no expert in this topic, but since no one else was replying, I thought I would.

I believe that since the light wave has been refracted into the cladding, it's simply "lost" as you already know.  I guess your real question is, why is it lost?  The answer is since it has a lower reflective index (if you Google, you'll get the equations), it cannot reflect the light thats been refracted into it and therefore it can't reflect back.
RE: fibre optic cladding by rav0 on 03-18-2006 at 10:40 PM

I kinda know about this, but I don't understand what your question is. Could rephrase it please?

RE: fibre optic cladding by saralk on 03-21-2006 at 08:37 PM

well you have the cladding, and the point of the cladding is to get rid of any light which has an angle outside the tolerance cone thing.

[Image: Optical-fibre.png]

As you can see, some of the light goes into the cladding, and the idea is that it can't get back in. BUT, what happens if it totally internally reflects on the edge of the cladding, and goes back into the core. TIR can't happen between the core edge and the cladding edge because it is going from a lower to a higher refractive index, so it can just go back into the cable and not work.

RE: fibre optic cladding by Wabz on 03-22-2006 at 12:56 PM

quote:
Originally posted by saralk
As you can see, some of the light goes into the cladding, and the idea is that it can't get back in. BUT, what happens if it totally internally reflects on the edge of the cladding, and goes back into the core. TIR can't happen between the core edge and the cladding edge because it is going from a lower to a higher refractive index, so it can just go back into the cable and not work.

Well from what you've said there I gather that it would cause a data error.  Which brings you to the TCP/IP protocol and whats called the 3 way handshake which is the way TCP error checks :), in essence the dodgy light would cause an error and the computer recieving would send a message saying "Send me that again it wasn't correct"