基于非稳态场的相干理论，对部分空间相干部分光谱相干二维厄米高斯脉冲电磁光束在自由空间传输时的偏振特性做了详细的数值研究。结果表明，脉冲电磁光束的偏振度分布由光束阶数、光束的空间相关长度、时间相干长度和场点位置等因素共同决定。研究表明，当空间相关长度趋于零或无穷大时，轴上点偏振度趋于一固定值，与光束阶数和场点位置无关。光束阶数较大或传输距离较远时，轴上点偏振度随时间相干长度的增大而增大，随脉冲宽度的增大而减小。光束阶数越大，横截面上偏振度P=0出现的次数越多。

Based on the coherence theory of non-stationary fields, the spectral degree of polarization of two-dimensional spatially and spectrally partially coherent electromagnetic Hermite-Gaussian pulsed beams propagating in free space is studied and analyzed numerically. It is shown that the spectral degree of polarization of electromagnetic Hermite-Gaussian pulsed beams depends on the beam order, spatial correlation length, temporal coherence length and the position of the field point. The on-axis spectral degree of polarization, which is independent of the beam order and the position of the field point, tends to a fixed value when the spatial correlation length tends to zero or infinite. The on-axis spectral degree of polarization increases with the increase of temporal coherence length, and decreases with the increase of pulse duration when the beam order is large or the propagation distance is long. The larger the beam order is, the more times the spectral degree of polarization P=0 appears on cross section.