電子束經過週期金屬結構時表面會激發出Smith-Purcell輻射，而Smith-Purcell輻射應用領域十分廣泛，如同調光輻射光源，粒子探測與奈米微影技術，且能做可見光、兆赫波等輻射光源，所以本篇論文著重在討論Smith-Purcell輻射。但目前Smith-Purcell輻射的問題在於功率太小，所以利用鎖定頻率來提高功率作為調控方式。
本篇論文利用meep模擬探討三種增強輻射機制，分別為表面電漿效應(Surface plasmon polarition)、共振腔模態(cavity mode)與邊界模態(edge mode)。我們研究的Smith-Purcell輻射位於可見光波段，並且比較單一變因對於整體結構的表面電漿輻射變化，包括電子束能量、光柵週期、光柵長度與光柵高度，進行分析與探討，並且驗證了電子束與平面波都可達到激發dipole 輻射的表現。

When electron beam passes through periodic metal structure, surface will stimulate Smith-Purcell radiation, and Smith-Purcell radiation have wide range application, such as coherent radiation source, particle detection, etc. But the current problem of Smith-Purcell radiation is power too small, so try to use locked frequency to increase power. This paper uses meep to explore three enhanced radiation mechanisms, namely surface plasma, cavity mode and edge mode, and changed electron energy, grating period, length, height, and verify electron beam and plane wave are achieve the performance of exciting dipole mode.

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