光瞳工程應用於表面電漿之研究

Abstract

根據觀測材料的特性與尺度的大小，繞射理論可以分成將電磁場視為純量之繞射理論或滿足電磁波之邊界條件，計算上較為複雜的向量繞射理論。在傳統低數值孔徑的架構下，採用純量繞射即可達到相當接近的近似解；然而，在現代科技的進步下，高數值孔徑的架構對於某些應用是不可或缺的，純量繞射理論得到的近似解已經無法適用於高數值孔徑的架構下，必須以向量繞射的理論去解釋、估算才能得到精確的解。除了入射光瞳之振幅、相位以外，在向量繞射理論中，我們還必須將入射光瞳的極化的影響納入考量，藉此估算出較為精確的三維點擴散函數。 在這篇論文中，首先將探討入射光瞳對於點擴散函數的影響，並在第二章介紹不同的入射光罩與一些基本應用。接著討論不同的極化光在高數值孔徑的系統下會出現何種聚焦場型。並利用徑向極化光能在一金屬-絕緣層的介面中激發表面電漿的性質，達到超解析的效果。再提出一個新的方法創造出多波長非均勻極化的光束，用以激發多波長表面電漿。最後提出一金屬-絕緣層-金屬的結構，增強此系統對於折射率變化的偵測範圍與敏感度。

In the diffraction theory, scalar diffraction theory is based on specific conditions such as low numerical aperture. The electromagnetic fields are treated as the scalar components to obtain a good approximation by relatively simple mathematics formula. However, it is necessary to use high numerical aperture in many optical systems while the technology was fast developed. Meanwhile, the approximation of scalar diffraction is so unsuitable that we have to use the vector diffraction theory. The Three Dimensional Point Spread Function (3D PSF) is not only dominated by amplitude and phase but polarization of pupil function in vector diffraction theory. In this thesis, we first study the relationship between pupil function and point spread function. Different kinds of pupil mask will be introduced in chapter 2. Then we discuss different polarized fields and use radial polarization to excite Surface Plasma Resonance (SPR). A new method is proposed to generate a spatially inhomogeneous polarized beam so that a chromatic SPR can be excited in the objective-based setup. Finally, we add a metal-insulator-metal coupler to enhance the performance of this chromatic SPR sensor.