本論文旨在優化一基於布里淵散射之分佈式光纖感測系統，主要優化項目包括空間解析度、量測距離，並探討比較布里淵相關域分析法以及布里淵光時域分析法。首先介紹分佈式光纖感測系統量測原理並歸納重要參數，透過選取參考頻率，以及分析探測光單邊頻帶調制改善空間解析度。在參考頻率選擇5、1、0.5和0.125MHz中，發現當參考頻率設為0.5或0.125 MHz，才能進行準確的資料解析，在一樣的實驗條件下0.125 MHz作為後續實驗參數。
在未購入單邊頻帶調制器前，利用實驗室自製光纖光柵設計出反射型架構進行單邊頻帶調制，達到約20 dB的抑制效果，調制效果有相當的限制；在使用”單邊頻帶調制器搭配布拉格光纖光柵”架構能達到最佳的調制效果，達到約30 dB的抑制效果；原架構中，於鎖相放大器前使用FFP-可調式電濾波器，預防光功率太高，透由調整適當鎖相放大器的靈敏度，可不使用FFP-可調式電濾波器，就能正確讀取資料，優化輸入訊號品質；更換新的DFB-LD，有更好的輸出功率與更窄的雷射線寬利於單邊頻帶調制，且較窄的線寬使相關峰值更窄，類似有更窄的探測頭，助於系統性能提升；將訊號產生器1更換成效能佳的，在掃頻上的運作時間更快，且其針對調變振幅選取由原本的的100 mV為單位小至1 mV，在調變深度的選取能更準確。原先掃頻速度11.66 point/min，更換後掃頻速度24.07 point/min，速度提升2倍以上，大幅改善量測效率，透由參數的設定與架構的改良，最後量測距離提升到313公尺並有3公尺之空間解析度；分析BOCDA與BOTDA兩大系統，BOCDA系統具有高解析度與快速的資料分析，適合應用於動態應變與高精度應變的監測上，但是受到感測距離的限制，尚未有商業化的產品；而BOTDA最大的優勢就在長距離的感測，已經有商業化的產品產出，利用對BOTDA系統的了解，設法利用現有儀器設計出BOTDA系統。

The aim of this thesis is to improve a distributed fiber sensing system based on Stimulated Brillouin scattering (SBS) effect while the improved characteristics include spatial resolution and sensing range. What’s more, we compare the differences between Brillouin optical correlation domain analysis and Brillouin optical time domain analysis. In the experiment, we introduced the measuring principle of distributed fiber sensing system and defined the importance of parameters. While the spatial resolution was affected by the reference frequency and the sideband component suppressed in the probe. Among choosing the reference frequency from 0.125MHz to 5 MHz, we found that the accurate data could be obtained when the reference frequency was set at 0.125 MHz. Therefore, we set the reference frequency of 0.125 MHz as a parameter in this study.
Before we purchased the single sideband modulator, the homemade tunable fiber Bragg grating using for obtaining single sideband modulation was discussed. At first, we design and investigate the reflection type (R-type) setups for SSB to improve the data. However, it was not good enough because the difference of optical power between the upper sideband (USB) and lower sideband (LSB) was only about 20 dB by using R-type setup. Finally, the suppression ratio of the other frequency components in the probe was more than 30 dB by combining a single side band modulator (SSBM) with a tunable fiber Bragg grating (FBG).
In the original experimental setup, the fiber Fabry-Perot (FFP) tunable filter was used before the lock-in amplifier (LIA) in order to prevent the power from getting too high. We also adjusted the sensitivity of the lock-in amplifier so we could read the data correctly without FFP-tunable filter and optimize the input signal quality.
Afterward, we replace the new DFB-LD with better output power and narrower linewidth because it was useful for single side band modulation. The narrow linewidth not only improved the system performance but also made the correlation peak narrower; that is, it was similar to a narrower sensing point. Moreover, by replacing the signal generator, the operation time on the frequency sweep would be faster; while the speed increased more than two times from 11.66 points/min to 24.07 points/min. As for the modulation amplitude, it was selected from the original 100 mV unit as small as 1 mV so the modulation depth of the selection could be more accurate. Finally, we successfully achieved the measurement range to 313 m with 3 m spatial resolution.
Finally, we also analyze BOCDA and BOTDA, BOCDA is suitable for the sensing system with dynamic strain measurement and high precision strain measurement because of the high spatial resolution and fast data acquisition. There has been a challenge to achieve commercial products in BOCDA because the measurement range is not long enough. On the other hand, BOTDA is good at measuring long range so there are commercial products based on BOTDA. To understand the BOTDA system, the future researchers may try to use the existing equipment to design BOTDA system.

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