當電子束通過光柵結構時會使表面電漿輻射，且改變光柵的週期會使輻射角度改變。利用這個機制，我們設計週期性光柵沿著圓排列，以具有電子迴旋運動的電子束在結構下方通過，使其輻射出軌道角動量光束。通過固定電子束能量來改變光柵的個數和固定光柵個數來改變電子束的能量能得到不同拓撲電荷的軌道角動量光束，並觀察其相位分布。
本篇論文主要討論產生軌道角動量的新方法，由於其獨特的相位型態和物理特性，在光學鑷子、光通訊系統、量子通訊等領域得到廣泛應用。

When the electron beam passes through the grating structure, the surface plasma is radiated, and changing the period of the grating changes the radiation angle. Using this mechanism, we designed periodic gratings to be arranged along a circle, with an electron beam with electron cyclotron motion passing under the structure to radiate an orbital angular momentum beam. By fixing the electron beam energy to change the number of gratings and the number of fixed gratings to change the energy of the electron beam, orbital angular momentum beams with different topological charges can be obtained, and the phase distribution can be observed.
This paper mainly discusses a new method for generating orbital angular momentum. Due to its unique phase pattern and physical properties, it is widely used in optical tweezers, optical communication systems, and quantum communication.

[1] Alison M. Yao, Miles J. Padgett, “Orbital angular momentum: origins,behavior and applications”, Advances in Optics and Photonics, Vol. 3, Issue 2, pp. 161-204, 2011.
[2] Miles Padgett, Johannes Courtial, Les Allen, “Light’s Orbital Angular Momentum”, Physics Today, 57, 5, 35, 2004.
[3] M. J. Padgett, L. Allen, “The angular momentum of light: optical spanners and the rotational frequency shift”, Optical and Quantum Electronics, Volume 31, Issue 1, pp 1–12, 1999.
[4] Sonja Franke-Arnold, Neal Radwell, “Light Served with a Twist”, Optics & Photonics News, Volume 28, June 2017
[5] Robert C. Devlin, Antonio Ambrosio, Noah A. Rubin, J. P. Balthasar Mueller, Federico Capasso, “Arbitrary spin-to–orbital angular momentum conversion of light”, Science, Vol. 358, Issue 6365, pp. 896-901, 2017.
[6] Xinlun Cai1, Jianwei Wang, Michael J. Strain, Benjamin Johnson-Morris, Jiangbo Zhu, Marc Sorel, Jeremy L. O’Brien, Mark G. Thompson, Siyuan Yu, “Integrated Compact Optical Vortex Beam Emitters”, Science, Vol. 338, Issue 6105, pp. 363-366, 2012.
[7] H. A. Atwater, “The promise of plasmonics”, Sci Am. Apr;296(4):56-63, 2007.
[8] 邱國斌, 蔡定平, ”金屬表面電漿簡介”, 物理雙月刊, 28卷, 2期, pp. 472-482, 2006.
[9] 吳民耀, 劉威志, “表面電漿子理論與模擬”, 物理雙月刊, 28卷, 2期, pp. 486-496, 2006.
[10] Stefan A. Maier, “Plasmonics: Fundamentals and Applications”, Springer Science+Business Media, 2007.
[10]邱國斌, 蔡定平, “金屬表面電漿簡介”, 物理雙月刊, 28卷, 2期, pp. 472-483, 2006.
[11] Sen Gong, Min Hu, Renbin Zhong, Xiaoxing Chen, Ping Zhang, Tao Zhao, and Shenggang Liu, “Electron beam excitation of surface plasmon polaritons”, Optics Express, Vol. 22, Issue 16, pp. 19252-19261, 2014.
[12] Kane S. Yee, “Numerical Solution of Initial Boundary Value Problems Involving Maxwell’s Equations in Isotropic Media”, IEEE Trans. Antennas Propagation, vol.14, No.3, pp.302-307, May 1966.
[13]藍永強, 邱行偉, “電漿模擬”, 物雙月刊,28卷,2期, pp.498, 2006.
[14] A. Taflove, “Computation Electrodynamics: The Finite-Difference Time-Domain Method”, Boston, MA: Artech House, 1995.
[15]J. P. Berenger, “Perfectly Matched Layer for the Absorption of Electro-magnetic Wave”, Academic press, 0021-9991/94, 1994