Specialty Optical Fibers Handbook

2.3.5 Finite Element Analysis for Waveguide

Calculations

Index profiles for real fibers may be much more complex than the idealized

step-index waveguide of Fig. 2.1. Even matched clad fibers that are step index in

principle will depart from an idealized step in various ways, depending on the

details of the particular manufacturing process. More complex fiber designs may

comprise grading of the refractive index, as well as multiple index layers, includ-

ing those with index below that of the (nominally) pure silica cladding. The field

solutions and propagation constants for LP modes of complex fiber designs,

such as those described in Chapter 5, are