介质覆层下金属周期结构变化对TE波异常透射特性的影响

根据金属光栅结构变化对TE波异常透射特性影响的研究需要,建立了相应的模型。应用时域有限差分(FDTD)方法分别计算了单缝结构、多缝结构、不同宽度和不同周期等结构下的透射分布特征。研究发现添加凹槽会对金属表面能量的传递起阻碍作用。透射频域宽度随薄膜宽度增加而增加。随着狭缝宽度的增加,透射率分布曲线包络线趋于平坦,主透射峰短波长侧透射曲线分布基本不变,而主透射峰及其长波长侧的透射曲线分布变宽。这说明宽度的变化影响了表面共振模式,从而影响透射的分布。单个狭缝的透射与多周期结构相比,透射率曲线几乎重合,表明狭缝对表面模式没有调制作用,各狭缝的透射相对独立。

Effect on Extraordinary Transmission of TE Wave from Different Metallic Periodic Structure Covered with Dielectric Layer

Metal grating models are designed to correspond the extraordinary transmission, structures with single slit and periodic slits and structures with different widths and different periods are calculated by finite difference time domain (FDTD) method. It is found that grooves on a metal grating play a negative role to energy transfer on the metal surface. Frequency domain of transmission becomes wider in pace with the width of the film; with the increasing of the width of the slit, the distribution envelope tends to flat, the side of shorter wavelength of the main transmission peak is essentially the same, while the distribution curve of the main transmission peaks and the side of longer wavelength of it become wider. It indicates that the width of the slits impacts the resonance modes of surface and the distribution of transmission. The transmission of single slit compared to the periodic structure′s, we found that transmittance curves almost coincide. It shows that the surface modes do not depend on the slits and there is no interaction between them.