Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/6150
標題: 非等距通道置放之分波多工光纖系統
WDM Lightwave Systems Employing Unequal-Spaced Channel-Allocation
作者: 張耿端
Chang, Keng-Duan
關鍵字: Wavelength Division Multiplexing;分波多工;dispersion-shifted fiber;four wave mixing;散佈偏移光纖;四波混合信號
出版社: 電機工程學系
摘要: 
分波多工技術在現今光纖通訊系統中日益受到重視。藉由在光纖上之不同波段同時傳送資料在不同之通道,分波多工技術可傳送大量之高速資料,因此可有效的利用光纖系統之大量頻寬。而藉由使用散佈偏移光纖減少色散偏移效應,分波多工技術可提供光纖系統遠距離之傳送。但是在現今工業界所使用之散佈偏移光纖將會產生四波混合信號,造成系統傳輸效率降低。在所有的干擾中,以四波混合信號對分波多工光纖系統影響最為嚴重。因此如何有效的分析分波多工光纖系統中之四波混合信號,並配合系統其他雜訊之分析,成為系統設計之重要考量。四波混合信號的強弱與分波多工光纖系統之通道間距以及光纖偏移有關。四波混合信號不能單純藉由增加通道間距來解決,此外增加通道間距將會減少分波多工光纖系統可用之通道數。
在本篇論文中,我們提出兩種演算法分別對非等距通道置放分波多工系統中位於使用頻帶之四波混合信號總數及個別通道之四波混合信號數目作有系統的分析。藉由這兩個結果,可對最小通道間距等系統參數作調整,以平衡四波混合信號和通道間干擾,並避免通道置放的頻段受到嚴重之影響。同時比較所提出的演算法和直接計算兩種方法的複雜度,並推導出在非等距通道置放分波多工系統中使用頻帶上四波混合信號數目的上限。最後分析四波混合信號對四種使用不同調變與解調方法系統的影響。

Wavelength-division multiplexing (WDM) technique is recently receiving substantial attention for fiber-optic communication systems. WDM, which allows information at various channels being transmitted in form of different wavelengths, achieves high data-rate transmission and hence fully exploits the vast bandwidth provided by optical fiber. To allow high-data rate transmission over long distances, dispersion-shifted fiber (DSF) is deployed to reduce the chromatic dispersion. However, the commercially available DSF increases the efficiency of four-wave mixing (FWM), resulting in system degradation. Among the optical nonlinearities, FWM is the most serious one to the WDM fiber-optic systems. Therefore, to analyze the performance of the system with the effects of FWM and other optical nonlinearities is important to the design of the WDM system. The efficiency of FWM depends on both channel spacing and fiber dispersion. FWM cannot be reduced by only increasing the channel spacing. Furthermore, wider channel separations result in the less number of channels in a fixed operating bandwidth.
In this thesis, we develop two algorithms, using frequency difference triangles and frequency difference squares, that can systematically determine the total numbers of FWM signals falling onto the operating band and each channel, respectively, of unequal-spaced WDM systems. By knowing these two numbers, one can adjust the system parameters, such as minimum channel spacing, to keep a good balance on the adverse effects of FWM crosstalk and interchannel interference, or avoid the assignment of channels at locations with the most severe crosstalk. The order of computational complexity of the frequency difference square algorithm and direct computation method is compared. An upper bound on the total number of FWM signals falling onto the operating band of an unequal-spaced WDM system are also developed. Finally, the system degradations due to FWM crosstalk with four different kinds of modulation/demodulation schemes are analyzed.
URI: http://hdl.handle.net/11455/6150
Appears in Collections:電機工程學系所

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