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研究生:林燈財
論文名稱:光脈衝寬度變化對有色散管理光通信系統品質的影響
論文名稱(外文):Effect of pulse width swing on the performance of dispersion mangement optical communication system
指導教授:溫盛發
學位類別:碩士
校院名稱:中華大學
系所名稱:電機工程學系碩士班
學門:工程學門
學類:電資工程學類
論文種類:學術論文
論文出版年:2001
畢業學年度:89
語文別:中文
中文關鍵詞:色散波長多工脈衝寬度變化率
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由於光纖通訊的應用越普及,在技術上的要求是朝著越高速、長距離、高品質來努力。然而光纖的非線性效應卻會造成光信號的變形,使品質變差。
在本論文中,為解決非線性效應的問題,我們採用了不完全色散補償的方式,提供一個過多補償或少補償的量 (d),以減少信號及雜訊的四波混合的累積,並希望找到一個夠大的 d,能提供波長多工系統的參考。我們發現當色散參數 D >0,d >0 時,波形擴張,d <0時波形先壓縮再擴張。在傳輸過程當中,我們可將色散補償分為三部分。第一部份是在每補償週期50 km的前端及末端加色散補償;第二部份是在傳輸距離9000 km末端與接收器之間加一根後置補償光纖,對信號波形作個修整;第三部份,就是本論文研究的重點,在傳輸距離當中,根據脈衝寬度的變化情形,適時加入補償。
光纖通訊系統中,因為有自相位調變,會增強脈衝寬度的變化。在本文中使用信號傳輸率是10 Gbit/s,信號格式是NRZ,每週期末端使用放大器及濾波器,並在沒有雜訊的情況下對脈波寬度設定上限值 (0.2, 0.4, 0.5, 0.7, 0.9, 1.2 )及下限值 (-0.1, -0.2 ),如果傳輸當中脈波先變寬的,只要到達上限,我們就加色散補償光纖,予以壓縮到下限;反之,先壓縮的波形,只要達到下限,我們就加色散補償光纖予以擴張到上限;如此繼續,週而復始,到9000 km。然後我們由信號錯誤率(bit error rate ,BER)與品質因數Q的關係,在含有雜訊的情況下算出Q值。我們得到脈波先擴張的情況比脈波先壓縮的,有較好的Q值,而色散參數D從1 ps/km-nm至11 ps/km-nm之間作比較,以4 ps / km-nm~6 ps / km-nm間的Q值最大;若對同一個色散參數D時,脈波寬度變化率越大時,所能容許 d 值較小。 若色散參數D=1ps / km-nm或4ps / km-nm,未完全補償量d =1,脈波寬度變化率在-0.1~0.2間時,均能維持品質因數Q在9以上,但脈波寬度變化率在-0.1~0.9時,Q將降到6以下。也就是說脈衝寬度的變化會影響品質因數Q,而且是與未完全補償量 d 及色散參數D有關。

Because fiber communication application is more popularize, the technology is to impove the hgih speed and long distance. On the other hand, fiber nonlinearities deteriorate signal pulse.
In this thesis, to tailor the problem of fiber nonlinearities, we used the incomplete dispersion compensation to provide too much compensation quantity or too less compensation quantity (d). It reduced the accumulate of signal-noise four wave mixing (FWM). We hope to find a bigger d to provide WDM system. It is found that when dispersion parameter D>0, d>0, the pulse shape is broadened. When d<0, the pulse shape is compressed and then is broadened. During transmission, we can separate dispersion compensation for 3 sections. The first section is add dispersion compensation in front and in end for every compensation 50km. The second section is add one dispersion compensation fiber (DCF) between transmission distance 9000km and receiver. A DCF is used to tailor the pulse shape after signal transmission. The third section is add compensation at the right moment during transmission distance and this section is the research key point of this thesis.
It will cause the pulse width make change when self-phase modulation (SPM) during fiber communication system. The considered signal transmission rate and signal format is 10 Gbit/s and NRZ. We used amplifier and wave filter for every end of compensation period and set the pulse width maximun (0.2, 0.4, 0.5, 0.7, 0.9, 1.2 ) and minimun (-0.1, -0.2) under no noise situation. During transmission, when the pulse shape is broadened and arrived to the maximun, we will add dispersion compensation fiber to compress to minimum. On the other hand, when the pulse shape is compressed and arrived to the minimum, we will add DCF to broaden until it arrived to maximun. We are continuous to do it until 9000km. We can obtained the Q factor including noise from the relationship of bit error rate and quality factor Q. It is found that the Q factor is better when the pulse shape broadening first. The maximun Q is the dispersion parameter between 4-6ps/km-nm. When the change ratio of pulse width bigger, the d will smaller under the same dispersion parameter D. If d >0, the change ratio of pulse width is between 0.2 and –0.1, the dispersion parameter D=1ps/km-nm or 4ps/km-nm, or d=1, it will maintain the Q above 9. It means the change ratio of pulse width is related with d and dispersion parameter.

目錄
摘要………………………….………………………………….….…i
Abstract……………………………………………………………..iii
誌謝………………………………………………………….………v
目錄……………………………………………..……………………v
圖目錄……………………………………….….…………………. vii
第一章 概論………………………………………….………………1
第二章 理論背景………………………………………………………
2.1 光纖傳輸波動方程式……………………………….………...4
2.2光纖損失…………………………..………………….………...6
2.3光纖色散…………………………….…………………………8
2.4 信號錯務率及系統傳輸品質的評估………………………..
第三章 系統架構……………………………………………..……17
3.1 光發射器………………….……………….………….. 17
3.2 傳輸光纖………………………..…………………17
3.3 色散補償元件……………………………..……………20
3.4 光放大器…………………………………………………
3-5 濾波器……………………………………………………
第四章 均方根脈衝寬度的近似公式推導……………………….
4-1 傳輸過程中均方根脈衝寬度的公式推導……………….
4-2 加上後置色散補償光纖的均方根脈衝寬度…………….
4-3 在傳輸過程中,適時加入色散補償光纖……………….
第五章 結果與討論 ..…………………………………………..29
5.1 脈衝寬度變化率....…………………………….……….29
5.2 不完全補償與色散參數D 之關係…………………………..
5.3 不完全補償量………………………………………….…..30
第六章 結論……………………………….…………...………..34
參考文獻…………………………………………………….………62

[1] S. Wen, “Bi-end Dispersion Compensation for Ultralong Optical Communication System,” IEEE J. Lightwave Technol., vol. 17,pp. 792-798, 1999.
[2] G. P. Agrawal, Nonlinear Fiber Optics, 2nd ed.New York: Wiley, 1995.
[3] N. Henmi,T.Saito, and S.Nakaya, ”An arrangement of transmission fiber dispersions for increasing the spacing between optical amplifiers in lumped repeater systems,” IEEE Photon. Technol.
Lett., vol. 5, pp. 1337-1340, 1993.
[4] C. J. Anderson and J. A. Lyle, ”Technique for evaluating system performance using Q factor in numerical simulations exhibiting inter symbol interference,” Electron. Lett., vol. 30, p. 71, 1994.
[5] F. Metera and M. Settembre, “Comparison of the performance of optically amplified transmission systems,” IEEE J. Lightwave Technol., vol. 14, pp. 1-12, 1996.
[6] S. Watanabe, T. Naito, and T. Chikama, “Compensation of chromatic dispersion in a single-mode fiber by optical phase conjugation, ” IEEE Photon. Technol. Lett., vol. 5, p. 92, 1993.
[7] C. D. Anderson and J. A. Lyle,”Technique for evaluating sustem performance using Q factor in numerical simulations exhibiting inter sysmbol interference,” Elecctron. Lett., vol.30,p. 71-72, 1994.
[8] C. R. Giles and E. Desurvire, “Modeling erbium-doped fiber amplifier,” IEEE J. Lightwave Technol., vol. 9, p. 271, 1991.
[9] S. Wen and T.Lin, “Ultralong Lightwave System with Incomplete Dispersion Compensations,” IEEE J. Lightwave Technol., vol.19, p. 471-479, 2001.

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