Efficient and accurate FDTD algorithm for the treatment of curved material boundaries

The application of finite-difference time-domain methods to the analysis of structures having curved boundaries is a long-standing problem. Traditionally, either the staircasing approximation which is simple but inaccurate, or the generalised nonorthogonal grids which are accurate but complex have been used. In this article a novel approach is presented which combines the efficiency of the Cartesian mesh with the accuracy of the conformal grid. Results are presented for some example structures which are in good agreement with other methods