我們結合了傳統長周期光纖光柵感測器與稜鏡式表面電漿共振感測器的優點，提出一個新型的光纖光柵表面電漿共振感測器。新型的光纖光柵表面電漿共振感測器利用適當的長周期光纖光柵之周期設計，使核心模態耦合至激發表面電漿波的纖核模態，並且在固定波長上監測核心模態功率傳輸後的衰減，來觀察待測物折射率的變動，進而推算其濃度。
本論文中還包含針對此新型表面電漿感測器的分析及研究，包含：存在於具四層結構表面電漿共振感測器的傳輸模態色散關係、非共軛形式的模態耦合方程式之推導；為了大量增加分析的效率，提出積分形式耦合係數之簡化；針對結構相關參數之分析；基本實驗架構以及光罩遇到的問題解決。而從數值模擬運算的結果來看，可以證明此新型、簡單的架構能作為高靈敏度的感測器。
為了更了解本篇論文使用到的特殊規格長週期光纖光柵，針對光柵週期與耦合模態的關係作模擬以及初步探討，從兩者來討論固定其中一項變數，觀察另一變數的趨勢來繪製模態與週期的分佈曲線圖，並且與理論比較；不難發現越短的週期需要越高的模態來耦合，但是高階模態可能只是存在於數學與物理公式計算出來的結果中，要在現實生活中來控制高階模態是有一定難度的，建議是盡量不要利用難以控制與觀察且能量微弱的高階模態耦合現象將光柵之週期設計在特殊長度處。

As for the application on optical fiber sensor, we combine the advantages of traditional LPG sensor and present prism coupler surface plasmon resonance (SPR) sensor. Now we further propose a novel type of optical fiber SPR sensor. It simply employs a long-period fiber grating with proper period to couple a core mode to the co-propagating cladding mode that can excite surface plasmon wave (SPW) and monitors the change of the transmitted core mode power, which is operating at a fixed wavelength, to determine the variation of the refractive index of analyte.
As far as the excitation of SPW, the model of numerical simulation, and the complexity of measurement equipment are concerned. In this dissertation, we derive the dispersion relation of guiding modes in this four-layer optical-fiber SPR sensor, and the unconjugated form of coupled-mode equations. In order to increase greatly the efficiency on analyzing this new SPR sensor, further simplifications on the integration form of coupling constants are proposed. In addition, we also do some basic experiment to confirm its application.
In order to understanding more about our specific period, we also discuss about the relationship between mode order and period of LPG by simulating. We calculate from two aspects which are period fixed and cladding mode order fixed to inspect the affect between each other. From the results of simulation, we can plot diagrams of the cladding mode order against grating period and effective refractive index in cladding mode against the period of grating for resonant wavelength at 1550 nm. In aspects of mathematics and physics, all cladding modes exist possibly by solving the structure of fiber through arithmetic equations. But to be concerned with practicality, it is impossible to control the cladding modes independently and accurately.

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