Improved wide-angle finite-difference beam propagation method for the analysis of nonlinear optical waveguides

An improved wide-angle finite-difference beam propagation method (WA-FD-BPM) formulated in terms of complex Pade approximants is proposed to investigate nonlinear optical waveguides. The formalism utilizes the Crank-Nicholson scheme. An adaptive update of the reference index and an iterative algorithm in every propagation step are utilized to accelerate convergence. Stability problems relative to high-order approximants are also addressed in this work.