旋转体时域有限差分法对轴对称亚波长衍射光学元件的分析

采用旋转体时域有限差分法对轴对称亚波长衍射光学元件进行严格的矢量分析.推导了旋转体时域有限差分法的基本计算公式;给出了入射波的设置方法;采用了完全匹配层吸收边界条件;改进了平面波谱传播算法,大大简化了计算过程并提高了计算速度.对多台阶微透镜和二元亚波长微透镜进行分析给出了它们焦平面的电场强度分布.数值计算结果表明,本文的算法可以准确且高效地分析轴对称亚波长衍射光学元件.

Body-of-revolution Finite-difference Time-domain Method for the Analysis of Axially Symmetric Subwavelength Diffractive Optical Elements

Body-of-revolution finite-difference time-domain (BOR FDTD) method was used to analyze axially symmetric subwavelength diffractive optical elements (SWDOEs).Total-Field/Scatter-Fixed technique was employed to induce incident wave and perfectly matched layer (PML) boundary conditions were used to absorb outgoing wave.The basic finite-difference equations for computing the field components in FDTD meshes were presented.The formulations that can directly use the output data of electrical components in the FDTD meshes without Fourier transformations to obtain the focal plane diffractive pattern were also presented,which deduced from vector-based plane wave spectrum (VPWS) propagation method.The algorithm including above aspects was applied to the analysis of both multilevel and binary subwavelength microlenses.Only 15 minutes were taken on 1500 MHz PC to obtain focal plane diffractive pattern of a large microlenses with 150 μm,25 zones and 8 levels by use of the Matlab code of above algorithm.The numerical results showed that the algorithm is robust and efficiency for analysis of axially symmetric SWDOEs.