Comparison of a few transparent boundary conditions for finite-difference optical mode-solvers

Various transparent boundary conditions are investigated for finite difference mode solvers, beyond the classical condition of a uniform exponential decrease for the field. A simple but efficient improvement is proposed with no extra numerical cost. High-order transparent boundary conditions (TBCs) also exist, that lead to even better results but at the cost of more numerical difficulties. Results are given within both the method of lines (MoL) and a two-dimensional (2-D) finite difference technique.