1550 nm 直調式光纖有線電視長距離傳輸系統 ;Long-Distance Transmission of Directly Modulated 1550 nm Fiber Optical CATV Transmission Systems

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题名:	1550 nm 直調式光纖有線電視長距離傳輸系統;Long-Distance Transmission of Directly Modulated 1550 nm Fiber Optical CATV Transmission Systems
作者:	呂海涵;Hai-Han Lu
贡献者:	光電科學研究所
关键词:	直調式光發射機;半頻多工;分波多工;Directly Modulated Transmitter;Half-Split-Band;Wavelength-Division-Multiplexing
日期:	2000-07-13
上传时间:	2009-09-22 10:23:46 (UTC+8)
出版者:	國立中央大學圖書館
摘要:	本論文中，主要研究目的在於探討利用分頻、分波多工及光放大器串接技術所架構之長距離傳送直調式光纖有線電視系統。系統性能參數載波二次合成拍差比獲得大幅改善，同時載波雜訊比及載波三次合成拍差比參數性能亦有不錯的表現。首先我們利用半頻及分波多工技術搭配串接之兩級光放大器架構長距離傳送直調式光纖有線電視系統，光信號經由80公里單模光纖傳送後，系統參數性能相較於傳統外調式光纖有線電視系統而言，載波雜訊比、載波二次合成拍差比及載波三次合成拍差比都可以得到相當好的值。接著我們以高功率類比DFB雷射二極體、推挽式前置放大器、半頻多工技術、光放大器串接及分波多工技術架構直調式光纖有線電視系統。光信號傳送距離由80公里延伸至110公里，系統參數性能載波二次合成拍差比及載波三次合成拍差比比起之前的架構更進一步獲得改善。同時整體而言載波雜訊比、載波二次合成拍差比及載波三次合成拍差比都有相當不錯的特性。再則研究以FP雷射二極體、光隔離器及光纖光柵的組合來取代傳統DFB雷射二極體，同樣利用分頻、分波多工及光放大器串接技術架構直調式光纖有線電視長距離傳輸系統。光信號經由100公里單模光纖傳送後，系統參數性能載波雜訊比、載波二次合成拍差比及載波三次合成拍差比可以測得不錯的結果。更進一步的以5個不同的波長建構混合式有線電視及多媒體分波多工系統架構。系統之中其中2個波長用來傳送半頻多工直調式光纖有線電視系統、2個波長用來傳送64-QAM數位信號、最後1個波長則用來傳送OC-48數位基頻信號。主要研究目的在於探討利用5台直調式光發射機所構成之分波多工系統，光放大器串接三級、光信號經由110公里標準單模光纖傳送後之系統參數性能。最後，我們提出一個在訂戶終端量測迴影比率基頻參數的新方法。從理論上的推演及實驗上的驗證，可以發現迴影比率及單一波道頻率響應平坦度特性兩參數之間有相關聯的特性。在量測單一波道頻率響應平坦度特性時，亦可同時量測迴影比率參數特性。這種新的迴影比率參數量測方法相較於傳統的量測方法而言，不但在技術層次上更為簡易、且在經濟效應上更具競爭優勢。 In this dissertation, we study the directly modulated NTSC 80-channel erbium-doped fiber amplifier (EDFA)-repeated system using split-band and wavelength-division-multiplexing (WDM) techniques to improve the composite second order (CSO) degradation accompanied by better carrier-to-noise ratio (CNR) and qualified composite triple beat (CTB) performances. First, an architecture of a directly modulated NTSC 80-channel EDFA-repeated system using half-split-band and WDM techniques is proposed. As compared with the conventional externally modulated lightwave AM-VSB CATV transmission system, good CNR, CSO and CTB performances are obtained in our proposed system after 80 km standard single mode fiber (SMF) transmission. We also build a directly modulated NTSC AM-VSB 80-channel system using high power analog distributed feedback (DFB) laser diodes, push-pull preamplifier, half-split-band, in-line EDFA's and 2-optical channel WDM techniques. The transmission distance is extended from 80 km to 110 km, and the CSO and CTB performances are improved in this system. In addition, good CNR, CSO and CTB performances are also obtained in this proposed system. And we propose and experimentally demonstrate a directly modulated 1550 nm NTSC 80-channel EDFA amplified system using split-band and WDM techniques, as well as a combination of a Fabry-Perot (FP) laser diode, an optical isolator and a fiber Bragg grating (FBG) to replace the conventional DFB laser diode. By replacing the DFB laser diode with the combination of an FP laser diode, an optical isolator and a FBG, good performances of CNR, CSO and CTB are obtained after 100 km standard SMF transmission. Furthermore, we demonstrate a hybrid dense-wavelength-division-multiplexing (DWDM) system for CATV and multimedia trunking, using a 5-wavelength system as an example. The system uses two wavelengths for AM-VSB video signal, two wavelengths for 64-QAM digital signals and one wavelength for OC-48 baseband digital signal. We investigate the performance of this lightwave system employing five 1550 nm directly modulated DFB laser transmitters and three cascaded stages of broadband in-line EDFA's. Transmission over 110 km of a standard SMF is studied. Finally, we present a novel measurement method to measure the echo rating baseband parameter at the subscriber. From both theoretical derivations and experimental results, a relation between the echo rating and the in-channel frequency response has been found. We use the in-channel frequency response RF parameter to simultaneously indicate the echo rating performance. This proposed novel echo rating measurement method is simpler and more cost-effective than the conventional measurement method.
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