# Optical Fibres

Discussion in 'Physics' started by aliashar86, Jan 25, 2007.

1. ### aliashar86 Thread Starter Active Member

Nov 23, 2006
71
0
plz explain in simple n few words the concept of optical fibres in connection with total internal reflection.

2. ### aliashar86 Thread Starter Active Member

Nov 23, 2006
71
0
How is the "Index of refraction of material through Prism" determined by the relation :

nm = [Sin (A+Dm)/2]
--------------
[Sin (A/2)]

3. ### aliashar86 Thread Starter Active Member

Nov 23, 2006
71
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Why Dm i.e., minimum angle of deviation is taken here why not <D.

4. ### Papabravo Expert

Feb 24, 2006
10,340
1,850
At the boundry between two materials (glass and air) a beam of light can do one of two things. It can be reflected at the boundry with the angle of reflection equal to the angle of incidence. It can also pass through the boundry and be refracted (bent) as it does so.

In total internal reflection the amount of light which escapes from the fiber is idealy zero.

5. ### thingmaker3 Retired Moderator

May 16, 2005
5,072
6
Are these schoolwork questions? If so, we can move this thread to the appropriate forum. If they're just musings or such, please ignore my post.

Mar 5, 2007
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May 16, 2005
5,072
6
8. ### DrNick Active Member

Dec 13, 2006
110
2
Optical fibiers are just dielectric waveguides. Since the intrinsic impedance of the medium (the fiber) is higher than that of air, total internal reflection confines the wave (ie light) in the fiber. Outside of the fiber evenescent waves propagate, giving an exponentially decaying solution that is determined from the boundry conditions.

9. ### thingmaker3 Retired Moderator

May 16, 2005
5,072
6
At least until you kink that sucker real good!

10. ### alitex Active Member

Mar 5, 2007
122
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dear waht do u mean about "404 dude"?????

Mar 5, 2007
122
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12. ### Dave Retired Moderator

Nov 17, 2003
6,960
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HTTP 404 error

Dave

13. ### DrNick Active Member

Dec 13, 2006
110
2
The link produces a 404 error (document does not exist)..

14. ### Ashraf Ali New Member

Nov 2, 2007
6
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optical fibers are jus wave guides, basically they have a core (the actual guide) and a cladding surrounding it, the fiber uses Total Internal Reflection (TIR) as its principle for transmission of the intensity, TIR will occur if the refractive index of the cladding is lower than the core, the angle of incidence is greater than the critical angle (minimun angle below which TIR will not occur), and the incident intensity must be well with in the acceptance cone of the fibre. when these parameters are met TIR occurs and the wave is propogated through.