以往对于超短脉冲与二能级原子系统的研究大多基于一些近似方法(慢变包络近似和旋转波近似等), 从而求得解析的近似解。但是, 由于忽略掉一些有用的光场中的信息, 就会造成光场导数项所产生的非线性性质的缺失。本文基于FDTD算法和预测-校正法相结合, 建立了预测-校正FDTD算法, 用于研究超短脉冲与二能级原子系统的相互作用, 以准确地描述光场与原子系统相互作用的特征, 验证了面积定理的部分规律；进一步构建了能够实现完全反转原子系统上下能级粒子的短脉冲。相关研究可为目标的特征分析提供参考。

Since the previous studies on ultrashort pulses and two-level atom systems are mainly based on slow-variable envelope approximations and rotational wave approximations, the nonlinear properties of the derivative terms in these studies cannot be well described. In this paper, FDTD algorithm and prediction-correction method are combined to establish a predictive-corrected FDTD algorithm for the study of the interaction between ultrashort pulses and two-level atom system. It can clearly characterize the time derivative of the electric field at the upper and lower levels of the system. At the same time, a pulse excitation source that can completely invert two-level particles is well established. Our method can be used as a numerical tool for target recognition.