Modeling of stimulated Brillouin scattering in optical fibers with arbitrary radial index profile

Stimulated Brillouin scattering (SBS) is an impairment seen in narrowband transmission over optical telecommunications fiber at high laser power. Accurate modeling is necessary to predict the strength of this phenomenon. One method of SBS control is the optimal design of the fiber radial index of refraction profile. Previous work has been limited to modeling optical fibers with one or more radial step changes in index. Here, the author derives and solves a general set of differential equations that allow the numerical solution of SBS spectral gain for an arbitrary radial index profile. Simulated and measured spectra are compared for several fibers with GeO₂-doped cores. It is found that radial material displacement plays a significant role in the SBS interaction in fibers with a complex radial index profile.