本論文在實驗及模擬上探討基頻入射訊號在波導裡面所傳遞的模態種類、不同入射偏振態對於產生二倍頻效應的影響，並藉由觀察樣本表面的電場傅立葉影像強度來分析不同入射偏振態所激發的二倍頻差異，最後利用有限差分時域法來模擬雙傳輸線中藉由奈米電漿子產生的二倍頻訊號。
本論文中的樣品皆是透過聚焦離子束將結構刻在金上，並透過兩套共焦成像系統來分別分析基頻訊號及非線性訊號。本系統所使用的基頻雷射半高寬為56飛秒且中心頻率為1560奈米，透過一百倍物鏡聚焦並耦合進目標雙傳輸線。觀察在第一套共焦系統中其反射光的激發亮點位置及能量強度，並於第二套共焦系統中觀測穿透的非線性訊號。
實驗結果中，入射基頻的偏振方向不論平行或是垂直於雙傳輸線，其所激發的二倍頻模態方向依然會與平行於雙傳輸線所激發的基頻 模態方向相同，透過分析二倍頻訊號的電場空間傅立葉轉換強度並與模擬比對，我們可以得出激發的二倍頻皆為同一模態。

We observed two kinds of the fundamental surface plasmon polariton modes in the Two-Wire Transmission-Line (TWTL) and the excited second harmonic generation (SHG) signal both numerically and experimentally. Analyzing the intensity distribution of the spatial Fourier transform of the electric field on TWTL, we tell the difference between the SHG signal excited by two fundamental modes. We use Finite-Difference Time-Domain (FDTD) method in simulation.
TWTL is fabricated by focused ion beam on a gold layer deposited on a glass substrate. We use dual-confocal setup to analyze near-infrared (NIR) regime and visible regime (also SHG regime) separately. The laser pulse duration we used as source is 56-fs and the center wavelength is located at 1560-nm. Focused by a 100x objective lens, the laser coupled into the TWTL and reflect back to the NIR confocal system while the transmission wave goes into the visible confocal system.
As the results, no matter which polarization we used as source, perpendicular (TE) or parallel (TM) to the TWTL, the excited the SHG signal will always be parallel to the transmission line. Comparing the intensity distribution of the spatial Fourier transform of the electric field on TWTL with the simulation. We ensure that the excited mode by TE or TM modes is exactly TM.

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