Influence of initial dopant distribution in fiber core on refractive index distribution of thermally expanded core fibers

We investigate the process of dopant diffusion of a thermally expanded core fiber by solving the corresponding diffusion equation using the explicit finite-difference method. We compare our numerical solution with analytical solution of diffusion equation for two different initial dopant concentrations in the core. The conclusions reached provide a guideline for the accurate modeling of dopant diffusion of thermally expanded core fibers, which is important for the prediction of the mode field enlargement.