- 學位論文
銀-二氧化矽-銀奈米三明治薄膜之研製與負折射率光學特性量測
An Ag-SiO2-Ag Nanosandwich Film with Negative Refractive Index:Fabrication and Optical Measurement
摘要
本研究利用電子束蒸鍍系統與斜向角度沉積技術(GLAD)，並搭配基板方位角旋轉來依序沉積出銀-二氧化矽-銀奈米三明治薄膜，進而分析與比較在不同薄膜厚度下所造成不同奈米三明治直徑之尺寸分佈，其相對於光學常數之關係。由於上下兩層銀奈米柱中的反相電偶極共振而造成反向磁場之現象，使其等效相對導磁係數的實部為負值。在光學量測上，利用分離式(Walk-off)干涉儀與偏極式(Polarization)干涉儀來量測銀-二氧化矽-銀奈米三明治薄膜在可見光波段下之透射係數與反射係數，進一步得到此薄膜之四個等效光學常數：等效折射率、相對本質阻抗、相對介電係數與相對導磁係數，進而分析不同的各層厚度與直徑尺寸分布造成其光學特性之變化關係，結果驗證此結構為全可見光譜負折射率的光學薄膜。
並列摘要
In this work, the silver (Ag) / silicon-dioxide (SiO2) / silver (Ag) nanosandwich films are deposited using glancing angle deposition technique with continuous azimuthal rotation during electron beam evaporation. The transmission and the reflection coefficients of the Ag-SiO2-Ag nanosandwich films for p-polarization and s-polarization are measured by walk-off and polarization interferometers. Accordingly, the equivalent electromagnetic parameters of each film are derived from the two coefficients. The measured results indicate that films exhibit negative refractive indices over the visible regime. Furthermore, we analyze the optical properties caused by the variation of the different thicknesses of layers and the distribution of nanosandwich sizes. It is demonstrated that the induced reversal magnetic dipole moment leads to the negative real part of the equivalent relative permeability.