本論文主旨為研究光纖液體參數感測系統，主要感測的參數為液體折射率、溫度及深度。首先介紹本論文所使用的兩種光纖光柵—長週期光纖光柵與布拉格光纖光柵，詳細說明其原理、特性與製作過程，並介紹摻鉺光纖放大器作為感測用的寬頻譜光源。實驗部分使用長週期光纖光柵進行液體折射率與溫度感測，液體折射率感測以鹽水為樣本，折射率感測範圍1.335-1.375，長週期光纖光柵對於外在液體折射率變化約為-62.667 nm/n，線性度R^2約為0.997；液體溫度感測以水為樣本，感測範圍15-75℃，長週期光纖光柵對於外在液體溫度變化約為-0.3369 nm/℃，線性度R^2約為0.9952。另外，使用布拉格光纖光柵設計成光纖雷射感測液體深度，液體深度感測一樣以水為樣本，感測範圍從0公分至200公分水深。將布拉格光纖光柵黏貼於兩種不同的碳纖維複合材料上，再將複材黏貼於設計的感測頭上，雙層複材之感測頭其水位靈敏度約為-1.4 pm/cm，線性度R^2約為0.975；單層複材之感測頭其水位靈敏度約為-11.4 pm/cm，線性度R^2約為0.9989。最後，將長週期光纖光柵與布拉格光纖雷射整合於同一條光路裡，並分別感測液體折射率、溫度及深度對於此兩個感測體的變化。當液體折射率為感測參數時，長週期光纖光柵靈敏度約為-36.96 nm/n，線性度R^2約為0.9955，而布拉格光纖雷射不會因為外在折射率的改變而改變其輸出波長；當水溫為感測參數時，長週期光纖光柵靈敏度約為-0.36 nm/℃，線性度R^2約為0.9964，而布拉格光纖雷射中心波長對水溫稍有些許變化，靈敏度約0.0086 nm/℃；當水位為感測參數時，布拉格光纖雷射靈敏度約為-10.6 pm/cm，線性度R^2約為0.9987，而長週期光纖光柵對應水位變化其中心波長一直保持不變，並不會因為水位深淺而改變其輸出波長。

The aim of this thesis is to develop the fiber optic sensing systems for liquid-parameter measurement. The parameters include liquid refractive index, liquid temperature and liquid level. Here, the long period fiber grating (LPFG) and regular fiber Bragg grating (FBG) are utilized. Their principles, characteristics and the fabrication are introduced. In addition, an erbium-doped fiber amplifier (EDFA) as sensing broadband light source is included in the thesis.
The LPFGs are used to sense the change of liquid refractive index and temperature. Saline liquid, ranging from 1.335 to 1.375, is the sample liquid for refractive index measurement. The sensitivity and the linearity R^2 of refractive index sensor are -62.667 nm /n and 0.997, respectively; the sample liquid for temperature sensing is water with temperature ranging from 15 to 75℃. The sensitivity of temperature sensor is -0.3369 nm /℃ and the linearity R^2 is 0.9952, respectively.
Besides, a FBG-based linear cavity fiber laser is also proposed for the liquid level sensing. The sample liquid for level sensing is water with sensing height is from 0 to 200 cm. FBGs are pasted on two different carbon fiber reinforced plastics (CFRPs) to sense the water level, corresponding to water pressure. The variation of the sensor made by two-layer CFRP is -1.4 pm/cm and the linearity R^2 is 0.975; the variation of the sensor made by single-layer CFRP is -11.4 pm/cm and the linearity R^2 is 0.9989.
For simultaneously liquid solution refractive index/temperature and liquid level sensing, the LPFG and regular FBG are cascaded in the fiber path. When the sensing parameter is refractive index, the LPFG sensitivity is -36.96 nm/n and the linearity R^2 is 0.9955, with negligible change of central wavelength of the fiber laser under various liquid refractive index. When the sensing parameter is temperature, the LPFG sensitivity is -0.36 nm/℃ and the linearity R^2 is 0.9964, while central wavelength of the fiber laser varies a little under different temperature values. Finally, when the sensing parameter is water level, the sensitivity of fiber laser is -10.6 pm/cm and the linearity R^2 is 0.9987, nevertheless, the central wavelength of LPG is not changed under different water levels.

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