Improvement of CATV/ROF Transport Systems by Using External Light Injection/Optoelectronic Feedback Techniques and Photonic Crystal Fiber

• Main Authors: Yao-Wei Chuang, 莊耀瑋
• Other Authors: 呂海涵
• Format: Others
• Language: en_US
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/ev37v5

碩士 === 國立臺北科技大學 === 光電工程系研究所 === 95 === In the thesis, we propose and demonstrate variously fiber optical cable television (CATV) and radio-on-fiber (ROF) transport system, which include architectures of bidirectional system, wavelength-division-multiplexing (WDM) techniques, full-duplex ring network and hybrid signals transmission as well as employing external light injection, optoelectronic feedback techniques and photonic crystal fiber (PCF) to overcome limitation factors of long distance transmission. In the first architecture, we study a bidirectional radio-on-dense-WDM (DWDM) transport system based on vertical-cavity surface-emitting lasers (VCSELs) external light injection and optoelectronic feedback techniques. Using injection-locked and optoelectronic feedback techniques not merely to increase large laser frequency response but reduce laser threshold current as well, leading to an improvement in systems’ overall performances. Good parameters of bit error rate (BER), error vector magnitude (EVM), and intermodulation distortion to carrier ratio (IMD/C) were obtained; consequently, to inter-operate satisfyingly with broadband ROF distribution networks. In the second architecture, we build a two-wavelength WDM CATV externally modulated transport system employing PCF as a dispersion compensation device to compensate the fiber dispersion and to reduce the cross-phase modulation (XPM)-induced crosstalk. The PCF could efficiently suppress fiber dispersion to be almost zero. In comparison a two-wavelength WDM externally modulated transport system without using PCF, good performances of composite second order (CSO) and composite triple beat (CTB) were achieved accompanied by acceptable carrier-to-noise ratio (CNR) due to the power loss of the PCF in the our proposed WDM CATV system over a combination of 100-km single-mode fiber (SMF) and 3.6-km PCF. In the third architecture, we also use PCF in a full-duplex ROF transport system based on WDM and optical add-drop multiplexing techniques. RF power degradation owing to the fiber chromatic dispersion was overcome by employing proper length of PCF for the first time, low third order intermodulation distortion to carrier ratio (IMD3/C) and BER values were obtained in the full-duplex radio-on-PCF ring network; moreover, to be suitable for the long-haul microwave optical links. Finally architecture, we propose a hybrid signals transport system, combining a directly modulated CATV and ROF transmission using simultaneously external light injection, optoelectronic feedback techniques, and PCF to improve signal quality. As result of the experiment, excellent performances of CNR, CSO and CTB were obtained for CATV band; as well as BER and IMD3/C values were achieved for ROF band. This demonstrated that such a CATV/ROF transport system is very attractive for the fiber backbone applications.