LAUSR

Sources are important in the finite-difference time domain (FDTD) method. There are several types of sources, such as the hard source (applied field), the transparent current source (impressed current), the total field/scattered field (TF/SF) source, and the transparent field source. These sources have certain drawbacks in the simulation of waveguide structures. A novel positive–negative (P–N) source is proposed in this letter. It is transparent and can excite the same field as the hard source. For no auxiliary FDTD calculation is required, the P–N source is more efficient than the transparent current source and the transparent field source in the simulation of waveguide structures.