- 學位論文
利用色散補償機制改善有線電視傳輸系統的性能
Improved Performance of Fiber-Optic CATV Transport System by Using Dispersion Compensation Scheme
摘要
在本篇論文中，我們提出並驗證一建構於分頻多工技術及使用色散補償元件作訊號補償的光纖有線電視傳輸系統，系統性能參數載波雜訊比，同時對於載波二次合成拍差比與載波三次合成拍差比也有不錯的表現。 首先，建構一使用負色散光纖之光纖有線電視傳輸系統。我們提出一外調式NTSC滿載77 頻道，經長距離( 100 km)負色散光纖後，藉由負色散光纖所存在的負色散特性，來克服頭端所產生的擾頻效應，最後能測量出最佳的傳輸品質。 再則，於系統接收端使用單旁波帶濾波器對色散做補償。藉由光纖光柵的窄通帶特性來產生光單旁波形式的光信號。希望可以利用最簡單元件去除因系統長距離傳輸所引起光譜線寬變寬的現象，藉以改善訊號經由系統傳輸後所產生的非線性失真。 最後，我們利用分頻多工技術與短距離的光子晶體光纖 (3.6 km) 進行色散與色散斜率的補償，可以有效應用於多波長的傳輸系統。光信號在經由100 公里標準單模光纖傳送後，系統可獲得良好的光纖有線電視參數性能。
並列摘要
In this thesis, we study the NTSC 77-channel erbium-doped fiber amplifier (EDFA)-repeated system using split-band technique and optical compensation device to improve composite second order (CSO) and composite triple beat (CTB) performances. First of all, an architecture of an externally modulated AM-VSB CATV transport system in the 1550nm region using negative dispersion fiber (NDF) as the transmission fiber is proposed. To the best of our knowledge, it is the first transmit externally modulated CATV signals maximum up to 80 km NDF without dispersion compensation. This negative dispersion property overcomes the positive frequency chirp and results in system with better transmission performance. Second, an externally modulated NTSC 77-channel erbium-doped fiber amplifier (EDFA)-repeated system employing fiber Bragg grating (FBG) in combination with an optical circulatior (OC) as an optical SSB filter at the receiving site. The function of the FBG filter is to replace the head-end optical SSB transmitter, not only to simplify the technique, but also to overcome the fiber chromatic dispersion. Finally, we demonstrate directly-modulated national television system employing split-band technique and photonic crystal fiber (PCF) as a broadband dispersion compensation device. Good performance of CNR, CSO, and CTB were obtained over a combination of 100-km single-mode fiber and 3.6 km PCF.