當電子束垂直入射金屬表面，能激發寬頻的表面電漿(Surface Plasmons)及轉移輻射(Transition Radiation)。我們利用模擬軟體Lumerical和光柵耦合公式(Grating Coupling)來模擬和設計金屬表面光柵，並分析寬頻表面電漿經由光柵耦合後的輻射角度。根據結果特性設計同心環光柵、兩等分同心環光柵以及四等分同心環光柵，使耦合光在空間中形成如甜甜圈形狀的環形光束(annular beam)、聚焦光點(convergent beam)和隨時間在不同區域依序出現光波的特性。以上的結果我們可以運用在STEM的depletion beam、光子操控、光學成像、光束波長的調控和密碼學等光學領域中。

When the electron beam is perpendicularly incident on the metal surface, it can excite wide-band surface plasmons and transition radiation. We designed the metal surface grating using the simulation software Lumerical and grating coupling, then analyzed the radiation angle of the broadband surface plasmons coupled via the grating. According to the result characteristics, we designed concentric ring gratings, two-part concentric ring gratings and four-part concentric ring gratings, so that the coupling light forms an annular beam like a doughnut shape in space, convergent beam and sequentially appearing light in different regions with time.
The above results can be used in the optical field of STEM depletion beam, photon manipulation, optical imaging and cryptography.

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