An efficient beam-propagation method for pulse propagation modelling of photonic crystal MMI devices

A finite difference ADIM-based TD-BPM technique with the Pade (1, 1) approximation is investigated and programmed for the purpose of designing and realizing the novel devices based on the photonic crystal multimode interference waveguides. Compared with the conventional numerical method, the present method can achieve the accuracy in the same order but with much coarser mesh sizes, which means the faster in computation speed and less in memory requirements. The propagation properties of a photonic crystal transmission line and two power splitters are successfully simulated, which validates the correctness and effectiveness of our newly-developed programs and shows its promising potentials in the design of the compact and low-loss filters, directional couplers and power dividers in sub-millimeter and Terahertz regimes.