Modal amplitudes bound

Table 11-1 Properties of bound modes. Summary of bound-mode properties, dropping the subscript j when only one mode is involved. A nonabsorbing waveguide is assumed so that e, h, can be taken to be real and e, are then imaginary. The modal amplitude coefficient, a, is defined by Eq. (11-2).

Table 13-2 Properties of bound inodes on weakly guiding waveguides. Parameters are defined inside the back cover. The modal amplitude a depends on the source of illumination, and A o is the core cross-section. We assume e, and F are real on nonabsorbing... 

The current sources in Fig. 21-1 launch power into bound modes, and thus specify the modal amplitudes. Expressions for these amplitudes are derived from Maxwell s equations in Chapter 31. We find from Eqs. (31-35) and... 

As we now have orthogonality relations and normalization expressions for leaky modes, results which were derived for bound modes in earlier chapters can simply be extended to apply to leaky modes. These include the perturbation expressions of Chapter 18, the modal amplitudes due to illumination in Chapter 20, and the excitation and scattering effects of current sources in Chapters 21 to 23. We give an example of leaky-mode excitation by a source in Section 24—23. 

Given a source of excitation, either at the waveguide endface or within the waveguide, the modal amplitudes aj Q) of radiation modes are found by analogy with the bound-mode amplitudes aj. 

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