Terahertz Microporous Array Transmission Phenomenon Theory And Time Domain Spectral Analysis

The extraordinary transmission in the sub-wavelength holes array has been attracted a lot of attention in recent years. In this thesis, the extraordinary transmission characteristics of metallic periodic holes array are investigated in terahertz regime. The main work of this thesis is focused on theoretical study, 3-D computer simulation and experimental study with terahertz time-domain spectroscopy system (THz-TDS). In order to understand the physical mechanism of the terahertz extraordinary transmission properties, the relationship between the THz transmission properties and the hole shape, the surface plasmons, the surface wave and the polarization of incident wace has been studied. The main work in this thesis include as follows:1. The dispersion relations of surface plasmon mode in single coaxial and rectangular metallic microhole have been studied. The analysis of the surface plasmon wave conditions and the relation between surface plasmon and the size of the hole are investigated.2. Detailed theoretical investigation and computer calculations on the surface wave in the 2-D holes array are carried out, and it can be found that the shapes of holes strongly affect the cutoff frequency of the surface wave.3. Detailed theoretical investigation on the extraordinary transmission in the sub-wavelength holes array is presented. The Eigenfunction expansion is applied to ananlyze the physical mechanism. And the coupled equations which govern extraordinary transmission can be obtained.4. 3-D computer simulation of the inclined incidence and perpendicular incidence are presented, from the results we can find the relation between the transmission and reflection field.5. We fabricated the periodic arrays of rectangular holes and studied their THz transmission properties by applying THz-TDS system.The experimental study on the polarization dependence of THz transmission of the periodic array of rectangular holes and the size of the holes has been carried out.From the studied stated above, we can conclude that the extraordinary transmission in THz regime may not mainly caused by the surface wave in the array but the mode coupling in the hole.