建立了熔石英后表面3维横向划痕模型, 并采用3维时域有限差分方法对熔石英亚表面划痕周围的电场强度进行了数值模拟, 分析了划痕宽度、深度、长度以及划痕倾斜角度对入射光场的调制作用, 结果表明：随划痕深度和划痕长度的增加, 熔石英内的最大电场强度增大, 且当划痕长度达到1 μm以上时, 最大电场强度趋于稳定；划痕结构因子在1～2之间的划痕较容易引起熔石英损伤；而入射激光在划痕界面和后表面之间发生内全反射时, 后表面上的光强增强效果更加明显, 因此减少角度范围在20.9°～45°之内的划痕能大幅提高熔石英的损伤阈值。

The three-dimensional transverse defect model on exit surface of fused silica was established. Three-dimensional finite-difference time-domain method was used to simulate the electric field intensity distribution in the vicinity of transverse cracks on fused silica subsurface. The modulation of incident light field caused by the width, depth, length and gradient angle of the cracks was analyzed. The results show that the maximal electric field intensity in fused silica will be enhanced as the depth and length increase. The maximal electric field intensity tends to be a constant when the length exceeds 1 μm. The fused silica is more fragile while the crack configuration factor is 1～2. The effect of light intensity enhancement on the rear surface is more obvious when total internal reflection occurs at the transverse crack and the rear surface. Therefore, reducing cracks whose angles are between 20.9° and 45.0° could increase the damage threshold of fused silica substantially.