Simulation of IR Waveguide Amplifiers Using FDTD-Based Overlapping Integral-RK Method

A novel algorithm, calling FDTD-based overlapping integral-RK method, is proposed to analyze Er-Yb co-doped phosphate glass IR waveguide amplifiers. This new method is derived from the combination of Finite-Difference Time-Domain(FDTD), overlapping integral and RK method. First the normalized eigen-fields of signal and pump lights in Er-Yb co-doped phosphate glass waveguide are calculated by FDTD algorithm, and then the overlapping integrals between light fields and the distribution of Er³⁺(Yb³⁺) concentrations are obtained, finally the distributions of powers of signal and pump along waveguide are calculated by RK method. Gain performance of IR waveguide amplifiers is obtained from calculated signal power. Comparison of the simulation result with an experiment is given, it demonstrates that this new algorithm is valid and shows good agreement with experimental results.