在1310 nm 波段直調式的光纖類比視訊傳輸系統中(50∼750 MHz)，傳輸品質主要是受到雷射本身線性度所影響，其會造成系統合成二次拍差(CSO)與合成三次拍差(CTB)的劣化。雖然現今類比式半導體雷射的線性度在製程時已設法提高，然在經多頻道、高深度調變與長距離傳輸後，仍造成載波雜訊比(CNR)、CSO與CTB的劣化而導致訊號之失真。因此，我們採取電路補償方式，以改善雷射經傳輸所產生的非線性失真，希望能增加訊號傳輸時的性能與距離。在本論文中我們提出一種新的電路架構，利用阻抗不匹配的枝狀(Branch)線路來產生所需的二次和三次預失真訊號，並經實驗驗證其效能。在未作失真補償時，系統的CNR / CSO / CTB 分別為 51.6 dB / 62 dBc / 70 dBc。經新的電路架構補償後，CNR / CSO / CTB分別為51.5 dB / 70 dBc / 71 dBc；其中 CSO 改善了8 dB。由實驗結果可知，此電路架構可有效改善雷射線性度。本研究結果將可提供直調式類比視訊光發射機的預失真補償技術設計參考。最後，期此新電路的設計與開發，能對爾後光發射機之研製能有所幫助。

Direct RF modulation on semiconductor lasers of wavelength 1310 nm has been widely applied to amplitude modulation vestigial side-band(AM-VSB)lightwave cable television (CATV) systems. The channel capacity is limited mainly by the nonlinear distortion of laser diode, which induces system performance degradation of composite second order (CSO) and composite triple beats (CTB). Though the linearity of laser diode has been improved during the fabrication process, carrier to noise ratio (CNR), CSO, and CTB were still degraded by increasing either RF output power level or the channel loading. Thus, some linearization techniques were proposed to extend the channel capacity. The predistortion approach is the simplest and the lowest cost one among the techniques. This paper describes a distortion compensation method with an electrical “branch” circuit configuration, which is designed to reduce the nonlinear distortion induced by the laser diode. In this architecture, we utilize the method of impedance non-matching and the reflection of signals. According to the experiment results, we have found that before predistortion compensation, CNR / CSO / CTB are 51.6 dB / 62 dBc / 70 dBc, respectively. After compensation, CNR / CSO / CTB are 51.5 dB / 70 dBc / 71 dBc, respectively. Comparing with and without the distortion compensation, we found that CSO has an improvement with 8 dB, which reveals that the predistorion circuit improves the linearity of laser obviously. This study may give a guideline of predistortion technique and help to design optical transmitter.

致謝......................................................Ⅰ
中文摘要……………………………………………………….……….Ⅱ
英文摘要………………………………………………………………..Ⅲ
內容目錄………………………………………………………………..Ⅳ
圖表目錄………………………………………………………………..Ⅵ

第一章 簡介
1-1 前言……………………………………………………………....1
1-2 研究動機及背景簡介………………………………………....…1
1-3 論文架構……………………………………………………..2

第二章 光發射機的介紹
2-1 有線電視系統光纜架構………………………………………....3
2-1.1 1310 系統架構………………………………………........3
2-1.2 1550 系統架構……………………………………......…..4
2-1.3 1310 與 1550 系統特性比較……………………......…..4
2-2 1310 系統用之直調式光發射機……………………………....5
2-2.1 振幅直接調變…………………………...……………......6
2-2.2 雷射二極體(Laser Diode)…………………………….....…7
2-2.3 雷射模組控制電路……………………………………........8
2-3 雷射二極體的非線性失真…………………………………...….9
2-4 預失真補償電路…………………………………………….....10
2-4.1 典型預失真電路………………………………………...11

第三章 雷射控制電路的設計與製作
3-1 自動功率控制電路……………………...……………………..13
3-1.1 電路設計原理……………………………………….......…13
3-2 自動溫度控制電路…………..………………………………...14
3-2.1 電路設計原理………………………………………….......15
3-3 電路製作與性能測試….…………………………………..…..15
3-3.1 雷射控制電路性能測試……………………………….......16

第四章 預失真電路的設計與製作
4-1 預失真電路的發展與設計………………………………….....19
4-2 預失真電路的架構與分析………………………………….....20
4-2.1 CSO 補償電路………………………………………........20
4-2.2 CTB 補償電路……………………………………….........22
4-2.3 阻抗匹配……………………………………………….......24
4-3 軟體 MircroWave 模擬…………………………………….....25
4-3.1 模擬理論分析………………………………………….......25
4-3.2 模擬結果……………………………………………….......26

第五章 系統性能實驗
5-1系統架構…………………….……………………………….....30
5-2 預失真電路特性測試……………………..…………………...32
5-2.1預失真補償前的性能…………………………………........32
5-2.2預失真補償後的性能…………………………………........34
5-2.3經12.5公里光纖傳輸後的系統性能……….………….......35
5-2.4 多顆雷射測試………………………………………….......37
5-2.5 經長距離25公里單模光纖傳輸…………………….........37
5-2.6 增加 RF 輸入準位以提升 CNR 值………………..........38
5-3 比較與討論………………………………………………….....40

第六章 結論…………………………………………………………..43

參考文獻……………………………………………………………….44

附錄
附錄A……………………………………………………………….46
附錄B……………………………………………………………….47
附錄C……………………………………………………………….51

1. W. Huang, “Increases optical node output power using predistortion,” 1999 Digest of the LEOS Summer Topical Meetings, 1999.
2. H. T. Lin, and Y. H. Kao, “Nonlinear distortion and compensations of DFB laser diode in AM-VSB lightwave CATV applications,” J. Lightwave Technol., vol. 14, no. 11, pp. 2567-2574, 1996.
3. W. I. Way, “Broadband Hybrid Fiber/Coax. Access Systems Technology,” Academic Press, San Diego, 1999.
4. H. Blauvelt and H. L. Loboda, “Predistorter for linearization of electronic and optical signals,” U. S. Patent Number 4,992,754, 1991.
5. C. Y. Kuo, “Second order distortion and electronic compensation in analog links containing fiber amplifier,” J. Lightwave Technol., vol. 11, pp. 1751-1759, 1992.
6. V. B. Gorfinkel, “Fundamental limits for linearity of CATV lasers,” J. Lightwave Technol., vol. 13, no. 2, pp. 252-260, 1995.
7. N. Imai, “Novel linearizer using balanced circulators and its application to multilevel digital radio systems,” IEEE Trans. Microwave Theory and Tech., vol. 37, no. 8, pp. 1237-1243, 1989.
8. H. Yonetani, “Transmission characteristics of DFB laser modules for analog applications,” J. Lightwave Technol., vol. 11, no. 1, pp. 147-153, 1993.
9. S. Y. Huang, “Frequency-dependent distortions of composite triple beat in lightwave CATV transmission systems,” IEEE J. Select. Areas in Commun., vol. 8, no. 7, pp. 1365-1368, 1990.
10. J. Lipson, “High-fidelity lighwave transmission of multiple AM-VSB NTSC signals,” IEEE Trans. Microwave Theory and Tech., vol. 38, no. 5, pp. 483-493, 1990.
11. G. Wilson, “Predistortion techniques for lineaization of external modulators,” 1999 Digest of the LEOS Summer Topical Meetings, pp. 39-40, 1999.
12. H. M. Salgado, “Experimental validation of Volterra series nonlinear modeling for microwave subcarrier systems,” IEE Proc–Optoelectron, vol. 143, no. 4, pp. 209-213, 1996.
13. L. Zhang, “Second order and Third-Order Harmonic Distortion in DFB Lasers,” IEEE J. Quantum Electron., vol. 31, no. 11, pp. 253-256, 1995.
14. H. Gysel, “Electrical predistortion to compensation for combined effect of laser chirp and fiber dispersion,” Electron. Lett., vol. 27, no. 5, pp. 421-423, 1991.
15. M. S. Lin, “Measurements and modeling of the harmonic distortion in InGaAsP distributed feedback lasers,” IEEE J. Quantum Electron., vol. 26, no. 6, pp. 653-658, 1990.
16. C. J. Chuang, “Practical TV channel capacity of lighwave multichannel AM SCM systems limited by the threshold nonlinearity of laser diode,” IEEE Photon. Technol. Lett., vol. 4, no. 3, pp. 289-292, 1992.
17. K. Morrris and P. Kenington, “Power amplifier linearisation using presdistortion techniques,” RF and Microwave Components for Communication Systems, IEE Colloquium on, pp. 6/1-6/6, 1997.