利用電漿子光學天線產生頻率轉換之探討

本論文利用有限時域差分法以數值模擬的方式設計電漿子光學天線，得到單一對雙線天線總長600nm~640nm時對於紅外光波段1560nm的光學響應達到最佳化，利用侷限性表面電漿的場強化特性來產生光學的非線性轉換。樣品製成利用電子束微影技術，在石英玻璃基板上製作金的奈米天線陣列，單一種尺寸的天線陣列大小達到100um×100um。在測量上，激發光利用聚焦透鏡將平均功率約110mW，重複率80MHz，脈衝寬約60飛秒的脈衝雷射聚焦至樣品區域，收光端利用自組光學顯微鏡架構將訊號呈現於camera及spectrometer上。最後對於實驗數據的非線性頻譜、偏振態及能量關係作分析，與模擬結果做比對。利用偏振態相關性和與入射能量關係圖，驗證三倍頻訊號是否由天線陣列產生。

關鍵字

非線性電漿子；光學天線；三倍頻

並列摘要

In this work, we used finite-difference time-domain (FDTD) numerical analyses to find the optimized dimensions of plasmonics gap antenna arrays for near-infrared femtosecond laser which center wavelength is 1560nm. Total length of each gap antenna pair is designed for largest field enhancement at 1560nm. We find total length around 600nm to 640nm had best optical response for localized surface plasmon (LSP) field enhancement. High field enhancement caused by LSP give our large potential to induce nonlinear effect from our device. We used e-beam lithography (EBL) to fabricate the antenna. Each antenna array with different parameters covered 100um×100um area. Femtosecond pulse laser was used in experiment whose average power was 110mW, pulse duration was about 60 fs and with repetition rate 80MHz. Measurement data was recorded by camera and spectrometer in optical microscopy system. Finally, we compared experimental data with simulation to give our good promise for nonlinear effect generation by plasmonic gap antenna array.

並列關鍵字

nonlinear plasmonics ； optical antenna ； third harmonic generation

參考文獻

1. Wood, R.W., XLII. On a remarkable case of uneven distribution of light in a diffraction grating spectrum. Philosophical Magazine Series 6, 1902. 4(21): p. 396-402.

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

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

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, 1941. 31(3): p. 213-222.

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

國際替代計量

利用電漿子光學天線產生頻率轉換之探討

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