Page 147 - Fiber Bragg Gratings
P. 147
124 Chapter 4 Theory of Fiber Bragg Gratings
and the corresponding fields in the cladding are
where the following normalized parameters have been used in Eqs.
(4.1.17M4.1.20):
and
where n eff is the effective index of the mode and
Finally, assuming only a single polarization, the .y-polarized mode,
The choice of the cosine or the sine term for the modes is somewhat
arbitrary for perfectly circular nonbirefringent fibers. These sets of modes
become degenerate. Since the power carried in the mode in watts is
2
|A M| , from the Poynting's vector relationship of Eq. (4.1.15), the normal-
ization constant C^ can be expressed as
