Analysis of Waveguide Discontinuities by a Fourth-Order Finite-Difference Reflective Scheme

A highly accurate reflective scheme is developed for analysis of two-dimensional (2-D) waveguide discontinuities by using the fourth-order finite-difference (FD) formula. It is demonstrated that the new method achieves a significantly higher accuracy/computation cost ratio in comparison with the conventional FD method. Furthermore, the advantage of the new method is more pronounced for the case of high-index-contrast structures with small feature sizes