衍射微柱透镜聚集特性的严格电磁分析

利用时域有限差分(FDTD)方法作为严格电磁计算模式,分析了有限口径衍射微柱透镜衍射效率与透镜F数的关系.严格分析比较了在不同入射极化波(TE极化和TM极化)情况下,具有不同面型分布(连续面型和8台阶、2台阶量化面型)的微柱透镜衍射效率随透镜F数的变化,并且与传统标量理论进行了比较.结果表明,随着F数的减小,标量理论和严格矢量理论得到的透镜衍射效率之差逐渐加大;在大F数情况,TM极化波入射时微柱透镜的衍射效率要略高于TE极化波入射的情况.

Analysis of Diffractive Micro-cylindrical Lenses Based on Rigorous Electromag-netic Model

The rigorous analysis of finite aperture diffractive micro-cylindrical lenses was presented by using a rigorous electromagnetic computational model- the two-dimensional finite-difference time-domain(FDTD) method.Compared with the conventional scalar diffractive theory,the relationship between diffractive efficiency and F-numbers of lenses was analyzed and compared for different incidence polarization waves (TE polarization and TM polarization) and for different profile structures (continuous profiles,8-level profile and 2-level profile).The results show that diffractive efficiency increases with an increasing number of F-numbers and with an increasing number of phase levels,and that the differences between scalar and electromagnetic theory increases with an reducing number of F-number.When F-number is large,diffractive efficiency for TM polarization is a litter larger than that of TE polarization.We believe that these results will be useful to actual applications and academic analysis of diffractive lenses.