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周期性金属阵列结构的太赫兹透射光谱特性研究
【作者】 王洋；
【导师】 赵国忠；
【作者基本信息】 首都师范大学 ， 光学， 2008， 硕士
【摘要】 本论文利用太赫兹时域光谱技术(THz-TDS),研究了周期性金属小孔阵列结构的太赫兹透射光谱特性,并对影响共振透射的因素进行了细致的探讨。本论文主要研究了周期性金属阵列结构中的小孔形状、排列方式、阵列周期、小孔尺寸这几个因素对太赫兹透射特性的影响,探究了太赫兹波段透射增强现象的物理本质。本论文所做的主要工作包括:(1)研究了太赫兹波段周期性金属小孔阵列结构的透射增强现象,证实了这些结构的透射光谱具有明显的频率选择性。(2)研究了金属铜箔上周期性矩形孔阵列结构的太赫兹透射特性及小孔形状对太赫兹透射特性的影响。实验结果表明:孔的形状对透射峰的幅值和共振透射峰的频率位置有较大的影响,当矩形孔的长宽比增大时,透射峰的幅值会随着变大且共振透射峰的位置会向低频方向移动。(3)研究了矩形孔阵列结构对太赫兹的偏振依赖性。对于具有对称性结构的样品来说,样品的太赫兹透射光谱不依赖于入射太赫兹波的偏振方向,对于具有非对称性结构的样品来说,样品的太赫兹透射光谱依赖于入射太赫兹波的偏振方向。(4)研究了金属铜箔上周期性矩形孔斑图结构的太赫兹透射特性及排列方式对太赫兹透射特性的影响。(5)研究了硅衬底上亚波长周期性金属阵列结构的小孔尺寸和阵列周期对太赫兹透射光谱特性的影响。在进行实验研究的同时,本文还利用时域有限差分方法(FDTD)进行模拟来验证和分析了实验结果,进一步探讨了在太赫兹波段金属周期性结构透射增强现象的物理本质,为以后的工作提供了参考。总之,本论文主要从影响周期性金属阵列结构的太赫兹透射光谱特性的几个方面探讨了透射增强现象的本质,为太赫兹波段光学器件的发展提供了一定的参考。
【Abstract】 In this thesis, the terahertz transmission characteristic of metallic periodic hole arrays are investigated by means of the terahertz time-domain spectroscopy (THz-TDS). The factors affected THz transmission properties are analyzed one by one. The main work of this thesis is focused on the relationship between the THz transmission properties and the hole shape, the array alignment, the period, the hole diameter of the periodic array of sub-wavelength holes. In order to understand the influence of these factors to the terahertz transmission properties, and to further understand the physical mechanism of the enhanced transmission in terahertz range. The main work in this thesis include as follows:Then we fabricated the periodic arrays of rectangular holes with different alignment in the copper foil. The influence of the array alignment to their terahertz transmission properties is studied. Finally, we fabricated the periodic arrays with the different aperture diameters and the different periods of apertures of the Au film on silicon substrate. The influence of the diameter and the period of apertures to their terahertz transmission properties are studied in detail.(1) The enhanced transmission phenomenon of the periodic arrays of holes is investigated in the terahertz range. The frequency selective properties of THz transmission of the metallic periodic array of holes are confirmed.(2) We fabricated the periodic arrays of rectangular holes and studied their THz transmission properties. These holes in the copper foils have the same areas but the different shape, the influence of the shape of holes to their terahertz transmission properties is studied. The shapes of holes strongly affect the amplitude and frequency position of the resonance transmission peak. Keeping the polarization angle of THz field and the incidence angle fixed, the positions of transmission peak shift towards lower frequencies and the maximum of transmission will be increased with the length-to-width ratio of the rectangular holes. (3) The polarization dependence of THz transmission of the periodic array of rectangular holes is studied. For the symmetrical samples, THz transmission characteristic of these samples independence of the polarization of incidence THz wave. For the nonsymmetrical samples, THz transmission characteristic of these samples depend on the polarization of incidence THz wave.(4) THz transmissions of the pattern array of rectangular holes are studied.(5) THz transmissions of metallic aperture array on the silicon substrate are studied. The dependence of THz transmission on the hole size and array period are investigated in detail. At the same time, we investigate the physical mechanism of the enhanced THz transmission by means of The Finite-Difference Time-Domain (FDTD) Method. The calculated results are compared with the experimental one.In summary, the mechanism of the enhanced THz transmission of the metallic periodic array of holes is studied from several aspects of the hole shape, the hole size, the alignment of holes, and the period of array. This work will provide a significant reference for investigating the photonic devices in the terahertz frequency range.