Analysis of cylindrical subwavelength diffractive optical elements by an approximate vectorial diffraction method

摘要

Vectorial diffraction methods provide accurate analysis of subwavelength diffractive optical elements, but they usually consume a lot of computing time and computer memory. On the other hand, scalar diffraction methods have simpler physical models and cost much less computer resources at the expense of a large numerical error. Therefore, an approximate method is highly required, which can substantially relieve the computational burden and possess a high accuracy. We firstly propose such an approximate vectorial method, i.e., the improved first Rayleigh-Sommerfeld method (IRSM1), and apply it to analysis of two-dimensional (2-D) cylindrical microlenses and metallic cylindrical focusing micromirrors. The IRSM1 is clearly proved to be much more accurate than the scalar diffraction method. In addition, compared with the vectorial boundary element method, the IRSM1 consumes much less computing time and computer memory. Besides of the above, the IRSM1 is expected to be used in optical designs of subwavelength diffractive optical elements by incorporating with the simulated annealing method or the Yang-Gu algorithm.