近年來，由於網路頻寬的需求快速增加，都會光纖網路已經漸漸被重視並且視為解決頻寬不足的辦法。在這種需求下，光倍二位元的調變方式因為具有較窄信號頻寬與較強的抗色散能力，在10 Gbps的系統中能將訊號傳輸200公里以上而不需要任何色散補償，是一種相當具有潛力的傳輸系統。除此之外，系統的接收端與一般的單極不歸零信號完全相同，只需要在傳送端加上一個差分編碼器和一個低通濾波器即可將傳統的光單極不歸零傳輸系統轉換成光倍二位元傳輸系統。在此篇論文的第一個部份，我們觀察到100%的驅動電壓搭配2.5 GHz低通濾波器並非是系統最佳化的條件，如果使用頻寬較寬的低通濾波器則需要較低的驅動電壓來使系統最佳化。在實際的實驗當中，我們使用了3.0 GHz低通濾波器搭配88%的驅動電壓得到了最佳化的結果。和一般倍二位元系統比較，在傳輸了245公里的單模光纖後，我們得到了2.5 dB信號靈敏度的改善。
在此篇論文的第二部份中，我們提出了一個長距離、多波長的光纖光柵感測系統。此系統中採用環狀光纖雷射的架構來得到較高的訊號雜訊比，並且使用一個混合式的光放大器做為系統中的增益媒介。這個混合式的光放大器由一個摻鉺光波導放大器串接一個半導體光放大器而成，它提供了較高的放大自發光輻射、高增益以及同時多波長雷射的能力，使得此一架構適合於長距離或大範圍的感測系統。實驗結果顯示，在二十五公里的距離下，我們得到了一個高功率、穩定以及多波長的輸出。此多波長輸出具有50 dB以上訊雜比且功率擾動在十分鐘的觀察下小於0.56 dB，證明了此系統的可行性。

We numerically and experimentally demonstrated that 100% driving voltage doesn’t necessarily yield optimal results in optical duobinary systems. LPFs with larger bandwidth require lower driving voltage to be optimized. Compared with conventional condition, a 2.5 dB sensitivity improvement is obtained following 240 km of standard single mode fiber (SSMF) transmission by using 3 GHz LPFs with optimum voltage.
In part 2 of this thesis, a fiber Bragg grating (FBG) sensor system using a fiber ring laser with a hybrid amplifier is proposed and demonstrated. The hybrid amplifier comprises an erbium doped waveguide amplifier and a semiconductor optical amplifier. The experiment shows that such the hybrid amplifier has a high amplifier spontaneous emission power and gain spectrum. Moreover, this fiber ring laser can provide a stable multiwavelength output with an optical signal-to-noise ratio over 50 dB even if the FBGs are located at a 25 km remote sensing position.

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