近年來，隨著現代網際網路的迅速發展，人類對網路需求的提升，許多不同的多媒體應用相繼發展，如何在短時間內傳送大量資料成了技術發展的重要課題。然而，現階段唯有光通訊所支援的傳輸速率最符合期待，且較同軸電纜相比提供了低能量耗損與傳輸距離上的優勢。

為了因應快速成長的網路需求，我們需要高容量的調變格式，而近年來正交分頻多工 (orthogonal frequency division multiplexing, OFDM) 因為其具備較高的頻譜使用效益，所以不論在有線或是無線通訊上都受到大量的矚目。雖然正交分頻多工具備較高的頻譜使用效益，但是使用具成本效益的傳輸系統仍能使得傳輸速率最佳化，因此便宜且簡單的強度調變與直接偵測 (intensity modulation/direct detection, IM/DD) 系統是一個很好的選擇，然而 IM/DD-OFDM訊號會受到色散所造成的功率衰減和非線性失真的問題。非線性失真的部分過去皆是以電致吸收調變雷射(electro-absorption modulated laser, EML)為主去做討論，對於直調雷射 (directly modulated lasers, DML)的非線性失真僅在於理論上。在功率衰減的問題上，過去我們使用負啁啾去改善功率衰減的問題，但是為了從根本上解決功率衰減的問題，所以我們選擇使用單邊帶訊號。

在本篇論文中，我們在實驗上實現了直調雷射的非線性補償，在100公里下增進11.25-Gbps，最後在100公里下達到30-Gbps的訊號傳輸。我們也提出了一個新穎的單邊帶 OFDM訊號調變方法，使用單一的串聯式電致吸收調變雷射去產生單邊帶訊號，在不使用隨距離改變的位元分配下達到0~200公里的13.5-Gbps IM/DD-OFDM訊號傳輸。

With exponentially increasing needs for internet traffic, many different multimedia applications have been developed. Higher bit rates, lower power consumption and reaching longer distance with the deploy standard are main feature of all optical networks.
In order to meet these requirements, we need high capacity modulation technique and cost-effect transmission systems. OFDM attracted attention in recent years. Bandwidths can be effectively used in OFDM transmission scheme. The IM/DD scheme is simple and cost-effect, but there will be two problems in IM/DD-OFDM transmission scheme. One is nonlinear distortion, and the other is RF power fading. Two problems will be discussed in this thesis.
In this thesis, we experimentally realize the nonlinear compensation in DML-based OFDM transmission system, and improve data rate by 11.25-Gbps over 100 km. Finally, we achieve the 30-Gbps DML-based OFDM transmission. We also propose a novel single sideband OFDM signal modulation scheme using a single cascaded EAM, and achieve the 13.5-Gbps SSB OFDM transmission with bit error rate (BER) of < 3.8×10-3 over 0~200 km fiber transmission without adaptive bit-loading.

論文審定書 iii
論文公開授權書 iv
Acknowledgements v
中文摘要 vi
Abstract vii
List of Figure viii
Contents ix
Chapter 1 Introduction 1
1.1 Development of Optical Network 1
1.2 Thesis Motivation 2
Chapter 2 Optical IM/DD OFDM System 3
2.1 Introduction of OFDM 3
2.1.1 What is OFDM 4
2.1.2 Benefit of OFDM System 7
2.1.3 Disadvantage of OFDM System 9
2.2 Challenges of IM/DD-OFDM System 11
2.2.1 Subcarrier to Subcarrier Intermixing Interference 12
2.2.2 RF Power Fading 13
Chapter 3 Previous Works 15
3.1 Subcarrier to Subcarrier Intermixing Interference 15
3.1.1 SSII theory 15
3.1.2 Nonlinear Compensation 17
3.1.3 Directly Modulated Laser SSII 18
3.2 RF Power Fading 20
3.2.1 Negative-Chirp for EML 21
3.2.2 Integrated EAM-SOA 22
3.2.3 Single-Sideband Modulation Scheme 23
Chapter 4 Experiment Demonstration of Nonlinear Compensation and DML-based OFDM Transmission System 26
4.1 Experimental Setup 26
4.2 Measurement Results and Discussions 28
Chapter 5 Experiment Demonstration of Dispersion-Tolerant Single-Sideband OFDM Transmission 32
5.1 Experimental Setup 32
5.2 Measurement Results and Discussions 35
Chapter 6 Conclusion 40
6.1 Summary of Works 40
Reference 42

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