Absorbing waveguides cladding

A description of propagation on absorbing waveguides or fibers was given in Chapter 11. When absorption is slight, we can treat the absorbing fiber as a perturbation of the nonabsorbing fiber. Here we consider clad fibers of arbitrary cross-section on which... 

Fig. 6-2 Squiggly lines denote the fraction T of ray power lost to the absorbing cladding from a bound ray at (a) the reflection points on a step-profile waveguide and (b) the turning points of a graded-profile waveguide.

If the core and cladding materials of the waveguide are slightly absorbing, the ray power attenuation coefficient of Eq. (6-3) is identical to the modal power attenuation coefficient of Table 11-2, page 232, provided the lateral shift is included. Details are presented in Section 36-10. 

The delineation applies both to leaky rays and to bound rays on waveguides with an absorbing cladding. 

In this section we compare the attenuation of modal power due to slightly absorbing media with the corresponding attenuation of ray power. For simplicity we consider a step-profile planar waveguide of core width 2p, and, if superscripts r and i denote real and imaginary parts, the core and cladding refractive indices are = njj, + ini and ci = "cl "ci> respectively, where The modal propagation constant... 

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