在長距離光纖通訊中,隨著國家到國家或者是國家到洲之間對於資訊傳輸量的需求,傳輸速度的增加是不可或缺的.但隨著速度的提升,傳輸時發生在光纖中的非線性效應,足以影響系統傳輸的表現.因此,許多克服非線性效應的方法被提出來改善系統表現,包括不同的調變方法、色散圖、以及改變中繼器的距離等.本篇論文中,在分波多工(WDM)的技術下,我們選擇對於非線性效應具有高抵抗性的零碼差分相移鍵調變( RZ-DPSK )的調變方式來改善系統的傳輸表現.

在分波多工的技術下,零碼差分相移鍵調變(RZ-DPSK)系統在常使用的重複區域型色散架構圖中傳輸,其傳輸表現是跟波段相關的,尤其是當著重在是否包含自我相位調變(SPM)效應的情況下,其差異更為顯著.因此,探討此種非線性效應的影響是極其重要的.而本篇論文著重在零碼差分相移鍵調變( RZ-DPSK )調變方式在傳統色散圖中傳輸之後,系統表現之於交叉相位調變(XPM)與自我相位調變(SPM)效應之差異的比較.

本篇論文中,著重於實驗與理論模擬的研究.在模擬部分,與零色散波長相關的系統表現是探討的主軸.零碼差分相移鍵調變( RZ-DPSK )系統在傳統色散圖中傳輸之後,我們可以很清楚的得到較好的系統表現,當我們把系統的零色散波長移到分波多工(WDM)頻帶之外.在實驗部分,我們以量化的數據來探討,交叉相位調變(XPM)與自我相位調變(SPM)效應對於長距離光纖通訊系統傳輸表現的影響.在交叉相位調變(XPM)的實驗中,當比較包含與移除此效應其系統行為差異僅僅只有0.1dB;然而在自我相位調變(SPM)實驗中,其系統表現值高達1.3dB的差異.而從理論模擬與實驗結果得知,倆倆互相得證.

With the essence of robustness toward fiber nonlinearity owing to the increasingly required high-speed data rate from the country to country or country to the state, many useful methods are proposed upon the long-haul optical fiber transmission, such as modulation format, dispersion map and repeater spacing, etc. Return-to-zero differential phase shift keying (RZ-DPSK) format was chosen in this master thesis because of its high tolerance toward nonlinear effect in the wavelength-division multiplexing (WDM) system transmission.

It has been realized that the system performance is wavelength-dependent by the combination of the WDM technology and the RZ-DPSK system with the commonly used block-type dispersion map, especially for the significant performance difference between including or excluding the self-phase-modulation (SPM) effect. Therefore, it is quite significant to investigate the unwanted fiber nonlinearity. In this master thesis, the influence relating to the cross-phase modulation (XPM) effect and the SPM effect with the conventional dispersion map after long distance transmission is the mainly concerned issue to be discussed.

In this master thesis, both experiment and theoretical simulation are investigated. On the theoretical simulation part, the Q-factor of the system zero dispersion wavelength at 1543.8nm, 1550nm, 1556.2nm were degraded and their value were less than 10dB. The Q-factor was around 1.5dB less than the averaged value. However, the performance of the long-haul RZ-DPSK system based on the block-type dispersion map shows no significant performance by shifting the system zero dispersion wavelength out of the WDM signal wavelength band. On the experimental part, the impact of the XPM effect and the SPM effect on the long-haul optical fiber communication system is investigated quantitatively. For the XPM experiment, the system performance was just only 0.1 dB difference after 6000km transmission. On the contrary, for the SPM experiment, the Q-factor between best and worst performance was up to 1.3dB difference. At last, the experiment and the simulation support each other successfully in this master thesis.

◎致謝 I
◎中文摘要 II
◎Abstract III
◎List of Contents IV
Chapter 1 Introduction
1.1 Introduction of long-haul optical fiber communication 1
1.2 Motivation 2
1.3 Structure of this Thesis 3

Chapter 2 Theoretical Study of the Effect of Different System Zero-Dispersion Wavelength upon Long-haul RZ-DPSK Transmission System
2.1. Digital data format 5
2.1.1 NRZ format 5
2.1.2 RZ format 5
2.2 DPSK modulation format 6
2.3 Nonlinear phase effect 7
2.3.1 Kerr effect and Gordon-Mollenauer effect 7
2.3.2 SPM effect 8
2.3.3 XPM effect 9
2.4 Numerical simulations 10
2.4.1 Split-step Fourier method 11
2.4.2 Simulation model 13
2.4.3 Results and Discussion 14
2.5 Conclusion 20
Chapter 3 Experimental Study of SPM and XPM effect upon Long-haul RZ-DPSK Transmission System
3.1 Introduction 23
3.2 Experimental setup 23
3.2.1 Transmitter 24
3.2.2 Transmission line 25
3.2.3 Recirculating loop 27
3.2.4 OSNR 29
3.2.5 Receiver 29
3.3 Results and discussions 30
3.3.1 Impact of the XPM effect 31
3.3.2 Impact of the SPM effect 35
3.4 Conclusion 42

Chapter 4 Conclusion 46

List of Abbreviation 48

[1] http://www.ripe.net/projects/reports/2008cable-cut/index.html
[2] A. H. Gnauck, G. Raybon, S. Chandrasekhar, J. Leuthold, C. Doerr, L.Stulz, A. Agarwal, S. Banerjee, D. Grosz, S. Hunsche, A. Kung, A.Marhelyuk, D. Maywar, M. Movassaghi, X. Liu, C. Xu, X. Wei, and D. M. Gill, “2.5 Tb/s (64 x 42.7 Gb/s) transmission over 40 x 100km NZDSF using RZ-DPSK format and all-Raman-amplified spans,” in OFC 2002, Anaheim, California, March 2002, paper PD-FC2.
[3] G. Charlet, E. Corbe, J. Lazaro, A. Klekamp, R. Dischler, P. Tran, W. Idler, H. Mardoyan, A. Konczykowska, F. Jorge, and S. Bigo, “WDM transmission at 6 Tbit/s capacity over transatlantic distance, using 42.7Gb/s differential phase-shift keying without pulse carver,” in OFC 2004, Los Angeles, California, February 2004, post-deadline paper PDP36.
[4] B. Zhu, L. E. Nelson, S. Stulz, A. H. Gnauck, C. Doerr, J. Leuthold, L. Gruner-Nielsen, M. O. Pedersen, J. Kim, and R. L. Lingle, “High spectral density long-haul 40-Gb/s transmission using CSRZ-DPSK format,” Journal of Lightwave Technology, vol. 22, pp. 208–214, January 2004.
[5] J.-X. Cai, D. G. Foursa, L. Liu, C. R. Davidson, Y. Cai, W.W. Patterson, A. J. Lucero, B. Bakhshi, G. Mohs, P. C. Corbett, V. Gupta, W. Anderson, M. Vaa, G. Domagala, M. Mazurczyk, H. Li, S. Jiang, M. Nissov, A. N. Pilipetskii, and N. S. Bergano, “RZ-DPSK field trial over 13 100 km of installed non slope-matched submarine fibers,” in OFC 2004, Los Angeles, California, February 2004, post-deadline paper PDP34.
[6] T. Mizuochi, K. Ishida, T. Kobayashi, J. Abe, K. Kinjo, K. Motoshima, and K. Kasahara, “A comparative study of DPSK and OOK WDM transmission over transoceanic distances and their performance degradations due to nonlinear phase noise,” Journal of Lightwave Technology, vol. 21, pp. 1933–1943, September 2003.
[7] H. Taga, S. -S. Shu, J. -Y. Wu, and W. -T. Shih, "A theoretical study of the effect of zero-crossing points within the dispersion map upon a long-haul RZ-DPSK system," Optics Express, vol. 16, pp. 6163-6169, April 2008.
[8] C. Xu, X. Liu, L. F. Mollenauer, and X. Wei, “Comparison of return-to-zero differential phase shift keying and on-off keying in long haul dispersion managed transmission,” IEEE Photon. Technology Letter, vol. 15, pp. 617–619, April 2003.
[9] http://en.wikipedia.org/wiki/Kerr_effect
[10] http://en.wikipedia.org/wiki/Self-phase_modulation
[11] H. Taga, S. -S. Shu, J. -Y. Wu, and W. -T. Shih, "A theoretical study of the effect of zero-crossing points within the dispersion map upon a long-haul RZ-DPSK system," Optics Express, vol. 16, pp. 6163-6169, April 2008.
[12] J. X. Cai, D. G. Foursa, C. R. Davidson, Y. Cai, G. Domagala, H. Li, L. Liu, W. W. Patterson, A. N. Pilipetskii, M. Nissov, and N. S. Bergano, “A DWDM Demonstration of 3.73 Tb/s over11,000 km Using 373 RZ-DPSK Channels at 10 Gb/s”, in OFC 2003, Atlanta, Georgia, March 2003, post-deadline paper PD 22.
[13] C. Xu, X. Liu, and L. Mollenauer, “Comparison of Return-To-Zero Phase Shift Keying and On-Off Keying in Long Haul Dispersion Managed Transmissions”, in OFC 2003, Atlanta, Georgia, March 2003, paper ThE3.
[14] G. P. Agrawal, Lightwave Technology: Telecommunication Systems (Wiley, Hoboken, NJ, 2005).
[15] G. P. Agrawal, Nonlinear Fiber Optics, 4th ed. (Academic Press, Boston, MA, 2007).