基于Lalanne经验法与Gtz法向矢量法的傅里叶因式分解过程,给出了傅里叶模态层吸收法的一个快速收敛方案.通过求解解析边界轮廓函数的梯度矢量,简化了Gtz法向矢量法的傅里叶因式分解过程,使其单波长点计算时间降低两个量级.通过距离反比权重法构造4个典型方向的法向矢量场,降低了法向矢量法在傅里叶因式分解过程中的不确定性.根据这4个典型法向矢量场与Lalanne经验法,提供了5个傅里叶模态层吸收法的收敛性改进矩阵.预先对5个收敛性改进矩阵优选分析,选择一个最优矩阵进行傅里叶模态层吸收法的衍射模拟计算,可以实现快速收敛.计算结果表明,对于硅材料简单结构,优选的改进矩阵相比于非优选矩阵收敛性提高2阶左右,能有效提高衍射场计算速度.该方案可提高光栅设计和集成电路结构分析/测试的效率.

Based on the Fourier factorization process in Lalanne′s empirical method and Gtz normal vector method,a fast convergence solution was proposed for Fourier modal slice absorption method.The gradient vectors of analytic boundary function were used to simplify the Fourier factorization process in Gtz normal vector method,which made the caclation time for a single wavelength point reduced by 2 orders of magnitude.4 typical types of normal vector fields were built by inverse distance weighting algorithm,and the degrees of freedom in normal vector method was reduced.According to these 4 normal vector fields and the Lalanne′s method,5 types of convergence improved matrice were finally presented.By pre-selection among the 5 matrice,an optimal matix could be implemented in the caculation of Fourier modal slice absorption method to guarantee fast convergence.Calculation results demonstate that for a simple silicone structure the optimal matrix has 2 diffraction oders improved compared with the un-preferred slected matrix,and effectively improves the simulation rate of diffraction.The proposed fast convergence solution is expected to improve the efficiency for grating design and analysis/testing of integrated circuit.