- 學位論文
一維與二維結構中消逝波之表面電漿子耦合行為及其在感測器上之應用
Surface Plasmon Coupling Behaviors of Evanescent Waves in One- and Two-dimensional Structures and Their Sensor Applications
摘要
本論文探討了消逝波與表面電漿子耦合在感測器上的應用，其中包含了兩個部份，第一部份是利用二維六角狀排列的光子晶體， 第二部份則是使用一維平面波導與奈米金球的複合結構來作分析。 在第一部份中，一個由週期性孔洞六角狀排列的二維光子晶體被利用來作為感測器。二維光子晶體在空間中將光束繞射到不同的角度，利用位於滿足相位匹配條件與成為消逝波之間的臨界波長來作為判斷施加在感測器表面介質的折射率。根據這樣的量測機制，我們使用了葡萄糖溶液作為待測物，展示了這樣的感測器具有高敏感度與低量測極限。同時，我們也使用了第四型人類皰疹病毒抗體作為待測物，觀測這樣的量測系統在感測抗體抗原等微小生物分子時的表現。由於生物分子表面功能化的因素，一層金薄膜加入了二維光子晶體表面，消逝波與金薄膜表面電漿極化子的耦合帶來了相位匹配條件的改變，進而對感測器表面的微小生物分子有著良好的感測性。為了進一步瞭解兩者耦合的特性，我們藉由光學模擬來觀測近場分布及對應的繞射頻譜，此外，不同晶格方向的量測結果也會在這一部份中探討。 在第二部份中，一個一維平面波導結構與表面沉積的奈米金球被利用來作為感測器。藉由光學模擬，研究來自波導模態的消逝波與來自奈米金球的局域表面電漿共振之耦合對表面電場的增強以及對量測結果的影響。使用葡萄糖溶液作為待測物，我們展示了在不同入射光角度下，其吸收頻譜變化與近場分布，探討這樣的耦合強弱對感測器表面介質折射率的改變有何關係。同時，實驗結果也被拿來作為驗證模擬數據，其結果表明這樣的耦合能局域地增強奈米金球表面電場，帶來相當程度的靈敏度提升。
並列摘要
This dissertation discusses sensor applications of evanescent wave and surface plasmon coupling, which contains two parts. The first part is discussed by using a two-dimensional (2D) hexagonal photonic crystal (PhC), whereas a hybrid structure composed of one-dimensional (1D) planar waveguide and gold nanoparticles (AuNPs) is applied in the second part. In the first part, a 2D periodic nanoholes array hexagonal PhC is used as a sensor. The PhC can diffract optical beams to various angles in the azimuthal space. The critical wavelength that satisfies the phase matching condition or becomes evanescent is employed to benchmark the refractive index of the material applied on the sensor surface. According to this sensing mechanism, glucose solution is used as the analyte, and it is demonstrated that our sensor has high sensitivity and low limits of detection (LOD). Furthermore, to investigate the performance of the sensor for detecting small biomolecules such as antigens and antibodies, Epstein-Barr nuclear antigen-1 (EBNA-1) antibody is also employed as the analyte in this research. Since the functionalization for biosensing, a thin gold film is deposited on the sensor surface. The coupling between the evanescent wave and surface plasmon polariton (SPP) changes the phase matching condition and enables the sensor sensitive to small biomolecules. To further understand the properties of the coupling, simulation of near-field distribution and the corresponding diffraction spectrum are analyzed. In addition, the sensing results of different lattice orientations are also discussed in this part. In the second part, a 1D planar waveguide with deposition of AuNPs is used as a sensor. The enhancement of electric field intensity in the vicinity of AuNPs from the coupling between the evanescent wave of the guided mode and the localized surface plasmon resonance (LSPR) and their sensing results are analyzed by simulations. Using glucose solution as the analyte, we demonstrate the wavelength shift in the absorption spectrum and near-field distribution at various incident angles and discuss the relation between the sensing results and the strong or weak coupling. Also, an experiment is employed to verify the simulation results. The results show that the coupling can locally enhance the electric field in the vicinity of AuNPs and improve the sensitivity of the sensor.
參考文獻
延伸閱讀
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