長距離次載波/分波多工光纖系統與混合光纖同軸擷取網路

Abstract

在本論文中，我們研究將單頻帶/次載波（SSB/SCM）技術結合分波多工（DWDM）架構應用於都會型光網（Metropolitan Optical Network）的可行性。都會型光網不同一般長距離光纖通訊網路的特點在於：它要求高頻寬效益、高容量、高適應性（也就是說，每個次載波頻道裡的資料，彼此間是與通訊協定或資料速率無關的。）、且低成本。為了了解此系統在傳輸上的限制，我們在論文中推導出，由於（1）Mach-Zehnder 光調變器與（2）光纖色散所導致的二階和三階拍差失真（CSO、CTB）的理論公式。另為了與分波多工的架構相結合，我們也同時推導在分波多工的架構下，由於光纖非線性所導致之物理現象（Cross-Phase Modulation）因而產生的光波長間干擾（Crosstalk）的理論與數值分析上的結果。此理論與數值分析並不受限於光波長間距的寬窄、每波長入射光的功率大小、調變訊號頻率的高低乃至光訊號的調變方式。以上所有的理論與數值分析結果都經由電腦模擬予以一一驗證。我們亦實際討論了兩個SSB/SCM/DWDM的系統以了解它們各自的基本限制與未來衍生的研究方向。 在本論文中，為了提供窄頻服務到用戶端，我們也提出了一個全新的，具有漸進式演化發展特性的混合光纖與同軸（HFC）擷取網路的架構，並以實驗驗證了它的可行性。此架構在演化的最初期並不要求一開始就舖設昂貴的分波多工的許多主被動元件，例如ITU規格的雷射、分波多工器與解分波多工器等等。雖然如此，然而當每個光節點用戶的頻寬要求持續增加時，它卻也可以逐漸升等為多波長的分波多工架構。此外，此架構的特點是每個波長均可載多個次載波頻道以滿足節點用戶高容量的要求。

In this dissertation, we investigate the applicability of single-sideband subcarrier-multiplexed (SSB/SCM) technology combined with dense wavelength-division-multiplexing (DWDM) scheme in the metropolitan optical network, which requires significantly more bandwidth-efficiency and high capacity with high granularity (protocol-and rate-independent at the same time) at low cost. To understand the transmission limitation of the SSB/SCM signals, we present a close-form analysis to predict the Mach-Zehnder intensity (MZI) modulator-induced composite triple beat (CTB), and linear-fiber-dispersion-induced composite second-order (CSO) and CTB distortions. To combine SSB/SCM with DWDM systems, analytical and numerical tools, which are not constrained by any wavelength spacing and modulation frequencies, are used to analyze cross-phase modulation (XPM) -induced crosstalk. All the analytical and numerical results are verified by computer simulations. Several multichannel SSB/SCM/DWDM systems with transport capacities of 10 or 20 Gb/s per wavelength, with a wavelength spacing of 25,50,100 GHz, are also studied in this dissertation to understand the fundamental transmission limitations.

We also proposed an evolutionary hybrid-fiber-coax (HFC) network architecture, which does not require DWDM in the beginning stage of adding narrowcast services, yet can be eventually upgraded using multiple DWDM wavelengths with a large channel loading per wavelength, is proposed and experimentally verified.