金属膜圆孔阵列异常透射特性的波导机制  

Waveguide Mechanism of Extraordinary Transmission Characteristics of Circular Hole Array on Metal Film

作　　者：薛润玉 王正宇 王正岭[1] Xue Runyu;Wang Zhengyu;Wang Zhengling(School of Physics and Electronic Engineering,Jiangsu University,Zhenjiang,Jiangsu 212013,China)

机构地区：[1]江苏大学物理与电子工程学院,江苏镇江212013

出　　处：《光学学报》2022年第4期220-228,共9页Acta Optica Sinica

基　　金：江苏省自然科学基金(BK20161342);江苏省“六大人才高峰”高层次人才项目(GDZB-018);江苏省高校自然科学研究重大基金(15KJA140001)。

摘　　要：对线偏振平面波垂直入射到亚微米金属膜圆孔阵列的透射谱进行了研究,优化结构参数后得到的最大透射率可达0.896,远大于圆孔阵列的孔填充比,突破了传统理论的预期。对金属膜圆孔阵列的电场分布、波导模式、相位特征及色散关系等进行了分析,研究了基于金属膜圆孔波导的异常透射机制。研究发现,表面Bloch波的存在使得金属膜圆孔阵列的上方形成了一套二维周期性的光晶格,并且光晶格的电场分布中心正好在金属膜圆孔部分的上方。当光晶格的电场模式与圆孔中的横向本征电场模式匹配时,将导致较大的耦合效率。如果电场模式沿着圆孔传播时满足相位匹配条件,就能保证圆孔中的光能从圆孔中有效地耦合出来,进而形成较大的透射率。该机制不但可以解释较厚的二维金属膜圆孔阵列的光频段异常透射现象,而且适用于太赫兹波段。如果在圆孔中填充大折射率介质,还可以实现波长远大于孔半径情况下的较大透射率。The transmission spectrum regarding the vertical incidence of a linearly polarized plane wave on the circular hole array on a submicron metal film is investigated.The maximum transmittance after the optimization of structural parameters is up to 0.896,which is much higher than the hole-filling ratio of the circular hole array,breaking through the expectation of traditional theories.After the analysis of the electric field distribution,waveguide mode,phase characteristics and dispersion relationship of the circular hole array on the metal film,the extraordinary transmission mechanism based on the circular hole waveguide on the metal film is investigated.A two-dimensional(2 D)periodic optical lattice is formed above the circular hole array on the metal film due to the surface Bloch wave,and the electric field distribution center of the optical lattice is just above the circular hole part of the metal film.When the electric field mode of the optical lattice matches the transverse intrinsic electric field mode in the circular hole,the coupling efficiency will be large.If the phase matching condition is satisfied when the electric field mode propagates along the circular hole,the light in the circular hole can be effectively coupled from the circular hole,which thus generates a large transmittance.This mechanism can not only explain the extraordinary transmission phenomenon of a thick 2 D circular hole array on a metal film but also be applicable to terahertz bands.If the circular holes are filled with a medium having a large refractive index,a large transmittance can be achieved when the wavelength is much larger than the hole radius.

关 键 词：薄膜 圆孔阵列 透射机制 模式特性 圆孔波导 

分 类 号：O436[机械工程—光学工程]