使用電漿子狹縫之超穎介面產生非常態光偏折

在這篇論文中，我們藉由刻在金薄膜上的V型狹縫陣列來產生非常態光偏折現象。在數值模擬的部分，我們使用有限時域差分法來得到較為精確的結果。當我們使用水平方向偏振的光垂直入射打到V型狹縫陣列的結構上時，除了產生一樣為水平方向偏振的穿透光之外，還會產生出偏振方向為垂直方向的偏折光，我們可以用廣義上的斯乃爾定律來解釋角度的偏折，藉由數值模擬的方式來找出適當的重複週期，我們就使用這個週期大小來做進一步的分析以及實際上用來進行實驗量測的樣品大小。　　而在實驗所使用的樣品上，我們在玻璃基板上用熱蒸鍍的方式鋪上一層金薄膜，再使用聚焦離子束的方式在金膜上刻出V型狹縫的陣列。實驗的架構上是使用架設出來的成像系統並用近紅外光的相機來收光。因光打在樣品後會產生出穿透光以及折射光，當我們觀察樣品下方的不同平面時，會觀察到兩個光點隨著觀察面的位置不同而有不同的間距，根據這些數值就可以計算出其折射角。最後藉由不同波長的光源以不同的入射角進行實驗，得到的結果亦可以很好的符合理論上的數值。

關鍵字

電漿子；超穎介面

並列摘要

In this work, we demonstrate cross-polarization anomalous light refraction using V-shaped air slits array fabricated on a thin gold film. We use finite-difference time domain (FDTD) method to perform our simulation work. When the x-polarization light normally incident onto the slits array, there would be an x-polarized transmission light as well as an angle-bent y-polarized field. We can explain the bent light by the generalized Snell’s and find out the appropriate dimension. Thus the selected dimension could be used in further analysis and experiment measurement. Our experiment sample is fabricated by focus ion beam (FIB) on thermally evaporated gold film with glass substrate. We use a simple imaging system with a near infrared(NIR) camera as our experimental setup. We collect the images at different positions under the sample stage to get different separation between transmission light and refraction light and thus count out the refraction angle. Furthermore, we use different wavelengths as our light source and find that the result angles match well to theoretical values.

並列關鍵字

Plasmonic ； Metasurface

參考文獻

[1] Wood, R. W. "On a remarkable case of uneven distribution of light in a diffraction grating spectrum." Philosophical Magazine 4(19-24): 396-402. (1902).

[2] Fano, U. "Some theoretical considerations on anomalous diffraction gratings." Physical Review 50(6): 573-573. (1936).

[3] Fano, U. "On the anomalous diffraction gratings II." Physical Review 51(4): 288-288. (1937).

[5] Fano, U. "The theory of anomalous diffraction gratings and of quasi-stationary waves on metallic surfaces (Sommerfeld's waves)." Journal of the Optical Society of America 31(3): 213-222. (1941).

[6] Ritchie, R. H. "PLASMA LOSSES BY FAST ELECTRONS IN THIN FILMS." Physical Review 106(5): 874-881. (1957).

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使用電漿子狹縫之超穎介面產生非常態光偏折

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