在現今資訊爆發的年代，對於資訊傳輸的速率與容量的需求越來越大。所以光纖通訊的高傳輸與高容量就正好符合上述需求，所以去了解光纖通訊這項技術來改善傳輸的效能是一個非常重要的課題。以目前科技來說，色散平坦光纖(DFF)以及歸零碼差分向一鍵調變(RZ-DPSK)，都兼具了有效改善傳輸效能的特色，所以把這兩種技術作結合將會是一門改善系統傳輸效能的重要技術。
並且在目前的長距離傳輸光纖通訊系統中色散圖是一項相當重要的技術，並且已經廣泛使用在長距離光纖通訊系統中，並且之前的研究曾經證明blockless type與block type之比較，其結果證明blockless type色散圖有較好的系統效能，所以致力於改善block type之系統效能為目前課題。先前研究使用位移色散圖法(Shifting dispersion map)與傾斜色散圖法(Tilting dispersion map)去減少零色散點，但是位移色散圖法(Shifting dispersion map)方法是較無效的，其傾斜色散圖法(Tilting dispersion map)是較有效。
所以在這篇論文中，我們藉由數直模擬的方法發現到，延續色散圖之研究使用分階位移色散圖法(Split shifting dispersion map)與分階傾斜色散圖法(Split tilting dispersion map)，並且使用不同的光纖色散補償機制也可以決定系統傳輸效能好壞，所以我嘗試著去設計更理想化的色散圖，以期能在傳輸效能上有所改進。
並且將探討DFF光纖的有效面積，因為影響光纖傳輸系統的效能其有效面積也是重要因素。

Long-haul optical fiber communication system is an important technology to support the latest broadband communication in the world, and there is strong competition in optical long-haul transmission to achieve high channel bit rates and large transmission capacity. Therefore, it is important to study a technology to improve the performance of such system. As we have already known, return-to-zero differential phase shift keying (RZ-DPSK) is an attractive solution to improve the long distance transmission system performance compared to the conventional on-off keying (OOK) in a 10-Gb/s system, because it has a high nonlinear tolerance.
The dispersion flattened fiber (DFF) is attractive for its ability to improve the system performance. Therefore, it is possible to improve the transmission performance by a combination of the RZ-DPSK and the DFF, and one important technology of the current long-haul optical fiber communication system is the dispersion map. And it is widely deployed for already installed undersea optical fiber communication system in the world.
A previous study reported that the blockless type dispersion map showed a superior performance than the block type dispersion map, and some efforts to improve the transmission performance of the block type map were conducted. Fundamental idea to improve the transmission performance of the block type map is to reduce the zero crossing points, and one idea is to shift the map toward the positive or the negative cumulative dispersion to reduce the zero crossing points within the map, but it was not so successful. The other idea is to tilt the dispersion map and it was more successful but not good enough.
In this master thesis, I continued the study to improve the long-haul RZ-DPSK system performance using the block type dispersion map. One new idea of the dispersion map shifting, the split shifting, was tried, and another new idea of the dispersion map tilting, the split tilting, was examined. The performance with different repeater output power and different compensation scheme within the dispersion map was simulated by a numerical simulator .The goal is, following previous research, to clarify improved dispersion map design of the long-haul RZ-DPSK based transmission and find the effective method to improve the transmission performance.
In addition, I also investigate tolerance of the effective area of the transmission fiber theoretically for the long-haul RZ-DPSK system based on the DFF.

◎ 致謝 ..................vii

◎ Abstract...............viii

◎ 中文摘要...............x

Chapter1 Introduction
1.1 Background of long-haul optical fiber communication system.....1
1.2 Motivation of this study.......................................3
1.3 Structure of this thesis.......................................5
References in this chapter.........................................6

Chapter2 Theoretical and technical background of this study
2.1 Theoretical background.......................7
2.1.1 Nonlinear Schrödinger equation..........12
2.1.2 Split-step Fourier method...............13
2.2 Technical background.........................16
2.2.1 Dispersion map..........................16
2.2.2 Dispersion flattened fiber..............18
References in this chapter.......................21

Chapter3 Explanation of the simulation model.....22
References in this chapter.......................25

Chapter 4 Efforts to improve the transmission performance of the block-type dispersion map
4.1 Explanation of the basic ideas...............26
4.1.1 Dispersion map split shifting...............27
4.1.2 Dispersion map split tilting...............29

4.2 Results of the dispersion map split shifting.......31
4.2.1 Detail of the dispersion map..................31
4.2.2 Results and discussions..........................36

4.3 Results of the dispersion map split tilting........38
4.3.1 Detail of the dispersion map..................38
Part 1 : SLA:IDF=64:36.................................38
Part 2 : SLA:IDF=63:37.................................41
Part 3 : SLA:IDF=62:38.................................43
Part 4 : SLA:IDF=61:39.................................45
Part 5 : SLA:IDF=60:40.................................47
4.3.2 Results and discussions.......................49
References in this chapter.............................53

Chapter 5 Tolerance of the fiber effective area
5.1.1 Fiber effective area studied for the simulation..54
5.1.2 Results and discussions..........................55

Chapter 6 Conclusion...................................58

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