光纖通訊網路系統輔助了這個世界不斷增長的網路需求,在前一個世紀,人們認為光的帶寬是無限的,事實上,現在我們幾乎已利用所有頻寬,所以在光纖中更有效率的運用可用帶寬,增加頻譜效率是必須而且重要的.

一般的調變方式使用的是高斯脈衝格式，它在頻域和時域具有相同的形狀。但這個特性會使頻譜帶寬變寬。在波分波多工(WDM)系統中，這個特性會造成相鄰信號通道之間的串擾(cross talk)。為了提升頻譜效率 ,矩形頻譜能夠降低相鄰信號通道之間的保護區間，這個方法使得提高系統的頻譜效率成為可能。

本碩士論文的擬將利用SINC波形於相干WDM系統以提升頻譜效率，利用調變PRBS（偽隨機二進制序列）來包裝信息於奈奎斯特帶寬之時域波形的SINC，實現在頻域上的矩形頻譜。

The optical fiber communication system has been supporting the growing demand of the internet traffic in the world. In the last century, people believed that the optical fiber bandwidth was infinite, but in fact, it is almost fully utilized at this moment. So, a more efficient utilization of the available bandwidth in the optical fibers is required, and the increased spectral efficiency is necessary.
Conventional modulation scheme uses Gaussian pulse, and it has the same shape in the frequency domain and the time domain. It‘s spectral skirts broaden the spectral bandwidth. In WDM systems, that can cause the crosstalk between the neighboring channels unless there is large guard band. As the rectangular spectrum enables to reduce the guard band between neighboring channels, it makes possible to enhance the spectral efficiency of the system. This master thesis is focusing on utilizing the coherent WDM system based on the SINC waveform to improve the spectral efficiency, SINC waveform in the time domain modulated with some data can pack the information in the Nyquist bandwidth, and realize the rectangular spectrum in the frequency domain.

中文論文審定書 i
致謝 ii
中文摘要 iii
Abstract iv
Content v
圖次 vii

Chapter 1 Introduction 1
1.1 Background 1
1.2 Motivation 3
1.3 Structure of this Thesis 5
References 6

Chapter 2 Technologies of the Nyquist WDM System 7
2.1 Introduction 7
2.2 Nyquist WDM 8
2.3 SINC-based Waveform in Time domain 11
2.3.1 Fundamental Concept 11
2.3.2 Time domain signal based on SINC 13
2.3.3 Calculation Results 16
2.3.4 Arccosine compensation 18
2.4 Homodyne Detection 19
2.4.1 Coherent detection 19
2.4.2 Homodyne detection 21
2.5 Phase Shift Keying Modulation 23
2.5.1 Binary Phase Shift Keying Modulation 23
2.5.2 Mach-Zehnder Modulator 26
References 27

Chapter 3 Experimental Investigation of BPSK Nyquist WDM Coherent System Based on SINC Waveform 28

3.1 Introduction 28
3.2 Experimental Setup 29
3.2.1 NRZ SINC Signal for Experiment 29
3.2.2 Experimental Setup 31
3.2.3 Performance Measurement Setup 36
3.2.4 Phase Estimation Algorithm and differential decoding
38
3.2.4-1 Phase Estimation 38
3.2.4-2 Differential decoding 43
3.3 Results and discussions 44
References 53

Chapter 4 Summery 54
List of Abbreviations 55

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