# Weakly Guiding Approximation

I was reading a chapter on Fiber Optics and I encountered Weakly Guiding Approximation. I am reading John M. Senior and it says Optical fibers used in communication purposes follow weakly guiding approximation where the relative refractive index (delta) is much less than 1.I tried searching different sources but with no success. Kindly help me understand it. Thanks.

-
Hi Mozart, welcome to Physics.SE. What exactly do you want to know about it? After a tiny Google search, it seems like it's a fairly well researched topic. It would help if you were more specific about what your confusion is, then you'll get better and more specific answers as well. :) –  Kitchi Mar 6 '13 at 20:06
The issue is more particularly with Weakly Guiding Approximation. I don't know what that is. –  mozart Mar 6 '13 at 20:23