MODIFIED FINITE-DIFFERENCE BEAM-PROPAGATION METHOD BASED ON THE DOUGLAS SCHEME

A modified finite-difference beam-propagation method (FD-BPM) based on the Douglas scheme is presented. The truncation error in the modified FD-BPM is reduced to o(DELTAx)4 in the transverse direction, whereas the error in the conventional FD-BPM is typically o(DELTAx)2. With trivial programming changes, the accuracy can be improved without the introduction of additional computation time. Numerical results obtained for a slab optical waveguide and a directional coupler illustrate the advantage of this method.