臺灣博碩士論文加值系統

本篇論文提出一種新型的光調變技術，此種調變技術可以傳輸向量訊號並具有倍頻效果。利用單一驅動的光調變器產生載子抑制調變，驅動信號為10-GHz的正弦信號組合在5-GHz的1.25-Gb/s的開關鍵控，二相移相鍵控或四相移相鍵控信號，在光偵測器接受後，產生在15-GHz的倍頻微波信號。傳輸五十公里的單一模態光纖後，三種不同的信號靈敏度下降小於0.2dB，四相移相鍵控較開關鍵控擁有兩倍的頻譜效益而且將近提升2dB的靈敏度。並且我們展示正交分頻多工調變的下傳信號與波段再利用得到的上傳信號，系統的上傳信號為5-Gb/s的16QAM正交分頻多工調變信號與透過反射半導體光放大器傳送1.25-Gb/s的OOK下傳信號。

This investigation presents a novel modulation approach for generating optical vector signals using frequency multiplication based on double sideband with carrier suppression. A single-electrode Mach-Zehnder modulator (MZM) is biased at null point with a driving signal consists of a 10-GHz sinusoidal signal and a 5-GHz sinusoidal signal modulated with 1.25-Gb/s on-off keying (OOK), 1.25-Gb/s binary phase shift keying (BPSK) data or 625-MSym/s quadruple phase shift keying (QPSK) data. After square-law photo detection, 1.25-Gb/s RF signal at a sum frequency of 15 GHz is generated. After transmission over 50-km single mode fiber (SMF), the power penalty of all three modulation formats is under 0.2 dB. QPSK format has twice the spectral efficiency and approximately 2 dB better receiving sensitivity than OOK format. And we also demonstrate OFDM signal with wavelength reuse for uplink signal. The 5-Gb/s 16QAM OFDM signal for ROF downstream link and 1.25-Gb/s OOK signal via RSOA for upstream link are demonstrated.

Acknowledgements.............................................................................................i
Chinese Abstract............................................................................................... ii
English Abstract.............................................................................................. iii
Contents............................................................................................................ iv
List of Figures...................................................................................................vi
List of Tables......................................................................................................x
Chapter 1 Introduction 1
1.1 Review of Radio-over-fiber system 1
1.2 Basic modulation schemes 2
1.3 Motivation 4
Chapter 2 The Concept of New Optical Modulation System 5
2.1 Preface 5
2.2 Mach-Zehnder Modulator (MZM) 5
2.3 Single-drive Mach-Zehnder modulator 6
2.4 The architecture of ROF system 6
2.4.1 Optical transmitter 6
2.4.2 Optical signal generations based on LiNbO3 MZM 7
2.4.3 Communication channel 9
2.4.4 Demodulation of optical millimeter-wave signal 10
2.5 The new proposed model of optical modulation system 12
Chapter 3 The theoretical calculations of Proposed system 15
3.1 Introduce MZM 15
3.2 Theoretical calculation of single drive MZM 18
3.2.1 Bias at maximum transmission point 18
3.2.2 Bias at quadrature point 19
3.2.3 Bias at null point 20
3.3 Theoretical calculations and simulation results 20
3.3.1 The generated optical signal 20
3.3.2 The generated electrical signal 26
3.3.3 Consider dispersion effect 30
3.4 The generated optical signal using optical filtering 35
3.4.1 Analysis of the generated signal 35
3.4.2 The effects of fiber dispersion 40
3.5 The optimal optical power ratio condition 45
3.5.1 Signal without optical filtering 45
3.5.2 When the LSB2 or LSB1 is filter out 48
Chapter 4 Experimental Demonstration of Proposed System 50
4.1 preface 50
4.2 Experimental results for optical signal without optical filtering 51
4.2.1 Experiment setup 51
4.3.2 Optimal condition for RF signal 53
4.3.3 Transmission results 60
4.4 Experimental setup for optical signal with optical filtering 62
4.4.1 Experiment setup 62
4.4.2 RF signals at sum frequency 63
4.4.4 RF signal at different modulation index 69
Chapter 5 Experimental Demonstration of OFDM Signal Generation 73
5.1 Introduction OFDM generation system 73
5.2 Experimental Concept and Setup 74
5.3 Experimental Results and Discussions 79
Chapter 6 Conclusion 84

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