Analytical solution for the dynamic behavior of erbium-doped fiber amplifiers with constant population inversion along the fiber

We present an analytical solution for the coupled rate and propagation equations for a dynamic two-level homogeneously broadened system interacting with radiation and with constant population inversion along the longitudinal axis of the fiber, z. We derive an analytical solution for the z dependence of these equations, which greatly simplifies the numerical solution for the output powers’ time dependence. Amplified spontaneous emission and background loss influences are considered in the model, in contrast to the previous analytical solution presented by Y. Sun et al. The solution is derived, and the importance of each term for the dynamic modeling of typical erbium-doped fiber amplifiers is analyzed.