Nonlinear plasmonics 描述光子在奈米尺度下和奈米結構交互作用下的非線性現象，
在打造 Nonlinear plasmonic devices 中扮演著重要的角色。以 Third Harmonic Generation(THG)來說，因為所有的物質皆展現三階非線性效應，因此其非線性的來源、產生的機制與形式並不十分明確。為了設計出 Third harmonic plasmon-based devices，更進一步的探討是必要的。 以 Shaped slit 作為探討的結構， 我們探討在不同形狀 Slit 下產生出的基頻電漿子波在平面介面上傳遞所產生的三倍頻之機制、及其所建構出來的 Third harmonic pattern 跟 Slit 形狀、入射光偏振態的關係。此外，我們還透過計算Local nonlinear polarization 以證明 THG 主要 Gold 來產生，並指出即使 THG 有 bulk response，但整個過程是由 surface response 主導。

Nonlinear plasmonics describes the nonlinear interaction between photon and the nanostructures, playing a vital role in the design of the nonlinear plasmonic devices. However, the
exact nonlinear source of THG and the working mechanisms are still under debate due to non-vanish third order susceptibility in all materials. To develop the third-harmonic plasmon-based devices, the deep understanding to the THG mechanisms in plasmonic structures is necessary. In this paper, we experimentally find out that the mechanisms of THG, which is generated by the fundamental harmonic surface plasmon polaritons in the shaped surface plasmon slit. Meanwhile, we also find that how the third-harmonic patterns relate to the shape of the slit and incident polarization. Despite THG is involved with bulk response, we show that the third order nonlinear process is dominated by the surface of the gold by calculating the local nonlinear polarization.

摘要---------------------------------------------------------------------------------------------------------------------------------I
Abstract--------------------------------------------------------------------------------------------------------------------- -------II
誌謝-------------------------------------------------------------------------------------------------------------------------- -----III
第一章 序論---------------------------------------------------------------------------------------------------- ----------------1
1-1 Nonlinear Optics-------------------------------------------------------------------------------------------------------3
1-1-1 Wave Picture of Nonlinear Interaction------------------------------------------------------------------------3
1-1-2 Phase Mismatching----------------------------------------------------------------------------------------------5
1-2 Nano-Optics------------------------------------------------------------------------------------------------------------8
1-2-1 Plasmonics--------------------------------------------------------------------------------------------------------9
第二章 模擬與理論預測---------------------------------------------------------------------------------------------------11
2-1 THG 產生之機制----------------------------------------------------------------------------------------------------11
2-2 Local Nonlinear Polarization Calculation-------------------------------------------------------------------------12
2-2-1 Third Order Susceptibility-------------------------------------------------------------------------------------12
2-2-2 Nonlinear Polarization on Planar Interface------------------------------------------------------------------13
2-2-3 Nonlinear Polarization of Slit---------------------------------------------------------------------------------15
2-3 偏振光和 Slit 的交互作用-----------------------------------------------------------------------------------------16
2-4 Third-Harmonic Pattern---------------------------------------------------------------------------------------------18
第三章 實驗結果與分析---------------------------------------------------------------------------------------------------21
3-1 實驗架設--------------------------------------------------------------------------------------------------------------21
3-2 實驗結果--------------------------------------------------------------------------------------------------------------22
3-2-1 Power Relation--------------------------------------------------------------------------------------------------22
3-2-2 Third-Harmonic Emission (機制二) ------------------------------------------------------------------------24
3-2-3 Third-Harmonic SPPs (機制一、三) -----------------------------------------------------------------------28
3-3 結果分析與討論-----------------------------------------------------------------------------------------------------31
3-3-1 Third-Harmonic SPPs 的來源 -------------------------------------------------------------------------------31
3-3-2 造成 Third-Harmonic pattern 分布不均勻的原因--------------------------------------------------------32
第四章
4-1 結論--------------------------------------------------------------------------------------------------------------------33
4-2 未來與展望-----------------------------------------------------------------------------------------------------------34
參考文獻------------------------------------------------------------------------------------------------------------------------35

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