金纳米圆孔阵列异常光学透射模拟研究

Simulation study of extraordinary optical transmission of gold nano-size circular hole arrays

利用COMSOL Multiphysics对金纳米圆孔阵列的物理场进行模拟,分析不同金属膜厚度、孔径、周期下阵列的光谱和电场分布,探究异常光学透射(extraordinary optical transmission,EOT)的成因.通过分析发现透射峰主要有3个成因:一是材料本身的带间跃迁特性会导致透射峰;二是金属阵列产生的表面波会激发金属膜背侧的局域表面等离激元,通过散射形成透射峰;三是耦合的表面等离激元转化成波导模式,沿着圆孔传输造成透射峰,该透射峰的频率低于表面等离激元的频率.

The physical field of gold nano-size circular hole arrays is simulated by using COMSOL Multiphysics.The spectra and the electric field distribution of arrays with different metal film thicknesses,hole diameters and periods are analyzed to identify the causes of extraordinary optical transmission(EOT).It is found that transmission peaks are mainly caused by three reasons.First,a transmission peak featured by the inter-band transition characteristics of the material itself is identified;Second,the surface waves generated by the metal arrays excite the local surface plasmon polariton on the other side of the metal film,forming the transmission peak by scattering.Third,the coupled surface plasmon polariton is converted into waveguide mode which propagates along the circular hole and results in a transmission peak at a frequency lower than that of the surface plasmon polariton.