講演情報
[10a-N203-3]Thickness Dependence Resonance Characteristics of Meta-Atoms Excited by a Point Terahertz Source
〇Yixin Zhao1, Kazunori Serita1 (1.Waseda Univ.)
キーワード：
skin-depth、point terahertz source、metamaterials
Terahertz (THz) metamaterials have attracted attention for their unique ability to control and manipulate THz waves, enabling the development of novel THz devices. For applications to various fields such as integrated circuits and biochips, compact THz metamaterial sensors with high sensitivity are essential. To overcome the diffraction limit of THz waves and realize more compact device, we have developed a point THz source technique, in which THz waves are locally generated via optical rectification in a nonlinear optical crystal at the focal spot of a femtosecond pulse laser beam, which is on a sub-wavelength scale. This enables resonance excitation in just a few arrays of meta-atoms while maintaining high sensitivity. To further improve compactness and sensitivity, it is necessary to optimize parameters such as structure, array numbers, and metallic thickness. The skin depth effect suggests that resonance becomes significant near a critical sub-skin-depth value under the far-field THz excitation. However, the influence of the metallic thickness on the resonance characteristics under the point THz source excitation has not yet been explored. Therefore, in this study, we investigated the variation in resonance characteristics with respect to metallic thickness. The study shows even meta-atoms with thickness below the skin depth exhibit remarkable resonance under the point THz source excitation. This finding contributes to the development of more efficient meta-atom sensors. A detailed analysis of surface current distributions is also presented to provide further insight into optimization strategies under point THz source excitation.