發展平行化三維有限差分時域數值模型以研究漁網結構超穎材料與金屬奈米顆粒

Abstract

本篇論文中，我們用C++程式語言發展了一個平行化的三維有限差分時域模擬器架構以計算漁網結構超穎材料以及金屬奈米顆粒的總散色截面。我們計算了不同參數的磁共振器和漁網結構的穿透/反射頻譜以及直角三角形稜鏡的光學性質。另外在表面電漿領域，我們計算，入射波正面射時奈米金屬方塊的總散射截面，並且發現當波長在總吸收截面的峰值時，近場的振幅會有較大的值。另外我們計算了三種入射和偏振方式的兩顆球的總散射截面，並且和譜方法結果做比較。最後對於奈米金屬平行板的情況，我們計算了當入射波正面入射在板平面上時的總散射截面，並且發現在平行入射電場方向的板子長度和總散射截面的峰值的頻譜位置有強烈相關的現象。

In this thesis, a parallelized three-dimensional (3D) finite-difference time-domain (FDTD) method numerical simulator is developed by using the message passing interface (MPI) library coded in C++ language. The capabilities of the simulator are than demonstrated by studying two topics in metamaterials and plasmonics, respectively. The transmission/reflection spectra of metamaterial magnetic resonators with different parameters are calculated and a right-angled triangular prism is numerically designed to observe the negative-refractive-index properties of fishnet structure. For plasmonics, the spectra of total cross sections and the near fields of silver nano particles of different shapes including cubes, sphere-pairs, and nano plates, are investigated. It is shown that the phasor amplitude is larger when the wavelength is at the absorption-cross-section peak rather than the scattering-cross-section peak for the case of cubes. The FDTD obtained results are compared with those based on the pseudospectral time-domain (PSTD) method calculation. For the nano-plates, plate length along the incident electric polarization direction is found to be strongly correlated with the resonant wavelength for waves normally incident on the parallel plates.