臺灣博碩士論文加值系統

本研究是利用電弧加熱熔拉的方式製作熔拉光纖(taper fiber)，並應用於光纖式液面感測器，且探討其感測架構與量測方式。熔拉光纖干涉儀具有高靈敏度，當外界施與此光纖元件微小應變參數時，其干涉光譜的尖峰功率及尖峰波長也隨之產生高變化量，因此非常適合作為微小環境變化的感測器。
本研究利用熔拉光纖設計了兩種不同干涉方式的熔拉光纖干涉儀－反射式的單錐形Michelson干涉儀(RTFMI)和透射式的雙錐形Mach-Zehnder干涉儀(DTFMZI)。並針對兩種干涉元件進行探討，比較其靈敏度之優劣與元件製作之難易。
為了瞭解光在經過熔拉光纖時的變化情況，利於各種現象的分析、理解，我們先用光路模擬軟體進行模擬，再動手製作熔拉光纖、感測結構，進行實際量測。實驗中發現彈性基板的長度和熔拉光纖的干涉長度與錐腰直徑等參數，對光譜變化的靈敏度有很大的關聯。所以將這些參數之改變對干涉光譜的影響作了一系列的比較，並進行合理的理論探討。
最後，再以不同密度的液體進行液面感測的實驗。發現微小的密度差異都有顯著相異的光譜，再次驗證熔拉光纖干涉儀優異的靈敏度表現。

In this thesis, the taper fibers, which can be fabricated by a commercial fusion splicer, are used to achieve liquid level sensors. Moreover, we investigate the sensor structure and measurement approaches. The interferometer based on a taper fiber is quite sensitive. For the interference spectra, the power and wavelength of the peak are varied intensely as the taper fiber senses a slight variation from external environment. Therefore, the taper fiber is suitable for a sensor to sense a slight variation in the surroundings.
In the work, by using the taper fiber, we have designed two kinds of taper fiber interferometer with different interference scheme. They are reflection tapered fiber Michelson interferometer (RTFMI) and dual- tapered fiber Mach–Zehnder interferometer (DTFMZI). In this thesis, we will probe into these two kinds of interferometer, and compare the sensitivity and the degree of difficulty in fabrication between these two kinds of device.
To understand the variation of light while it passes through the taper fiber and facilitate the analysis, we simulated the taper fibers by using a simulation tool firstly, and then tapered a single mode fiber, set up the measurement structure. Finally, the experimental results have been measured. The experimental results reveal that the length of the elastic- plastic and the taper fiber and the diameter of the taper waist relate to the sensitivity of spectral variation greatly. Therefore, a series of comparisons for the interference spectra affected by these parameters are made, and the reasonable explanations are brought up.
Ultimately, the experiments of liquid level sensing are made by using different density of liquids. The experimental results show that the difference between the interference spectra of the liquids with very little density-difference is quite obvious. These results verify that the taper fiber interferometer has an outstanding sensitivity again.

致謝 I
摘要 II
Abstract IV
目錄 VI
圖目錄 VIII
第一章 緒論
1.1. 研究背景 1
1.2. 研究動機 1
1.3. 文獻回顧 2
1.4. 研究方向 5
1.5. 研究方法 6
第二章 錐形光纖
2.1. 單模光纖 7
2.2. 錐形光纖結構與製作 9
2.3. 錐形光纖特性及應用 15
2.4. 錐形光纖光場分佈 17

第三章 錐形光纖干涉儀
3.1. Fabry–Pérot干涉儀 23
3.2. Michelson干涉儀 25
3.3. 光纖式Mach-Zehnder干涉儀 28
第四章 感測元件製作
4.1. 反射式錐形光纖Michelson干涉(RTFMI)元件製作 32
4.2. 雙錐形光纖Mach-Zehnder干涉(DTFMZI)之元件製作 39
第五章 元件應力量測
5.1. 反射式錐形元件 42
5.2. 錐形區彎曲變化 43
第六章 液面感測設計與光譜分析
6.1. 浮力原理 47
6.2. Au-RTFMI元件液面量測 49
6.3. DTFMZI元件液面量測 53
第七章 結果與討論
7.1. 實驗結果 62
7.2. 研究結論 63
參考文獻 64

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