Accurate generation of a Gaussian beam in the HIE-FDTD method

In this paper, we present a method for accurately integrating a tightly focused Gaussian beam into the hybrid implicit-explicit finite-difference time-domain (HIE-FDTD) method. Compared to the conventional FDTD, the proposed method significantly enhances computational efficiency. By introducing both electric and magnetic current sources, unidirectional beam propagation is successfully achieved. The accuracy and efficiency of the method are validated through numerical simulations and comparisons with FDTD results, analytical solutions, and plane wave expansion methods.