同調系統在近幾十年來因為接收訊號的靈敏度比 強度調變/直接接收 系
統好還可利用分波多工(WDM)來提高光譜的使用效率。同調系統有強度調變
(ASK)、相位調變(PSK)、頻率調變(FSK)。而同調接收系統可分為Homodyne
接收與Heterodyne 接收，兩者在接收端皆需要一個光源(Local oscillator
light)。在上一屆學長王俊儒的論文中, 利用QPSK 調變系統傳輸27-1 的假
隨機訊號(PRBS)達51 公里已經被探討了，且此系統用了 pilot carrier 的
技術來達到Homodyne 接收。使用pilot carrier 技術的優點是不需要額外
的光源在接收端。在本篇論文中使用了QPSK 調變系統傳輸215-1 的假隨機訊
號(PRBS)達500 公里，也是使用了 pilot carrier 的技術。我們也同時利用
了相同的實驗概念架構一個分波多工(WDM)系統來增加頻寬的使用效率。此實
驗用了MATLAB 來計算誤碼率(BER)。本實驗中分別量測了QPSK 調變系統傳
輸20G bit/s 的訊號達500 公里時在單一個通訊頻道和多個通訊頻道下的效
能

The coherent system has been extensively studied in recent years. The reasons
are that receiver sensitivity is better than Intensity Modulation with Direct
Detection (IM/DD) and the spectral efficiency of wavelength division
multiplexing (WDM) is increased. The modulation formats of the coherent system
are Amplitude shift keying (ASK), Phase shift keying (PSK), and Frequency shift
keying (FSK). The detection techniques are Homodyne detection and Heterodyne
detection, both of them need a laser light source in the receiver called as the Local
oscillator (LO).
In the previous study, the Quadrature phase shift keying (QPSK) modulation
format with Pseudo Random Binary Sequence (PRBS) 27-1 to transmit 51km was
investigated, and the pilot carrier method realized the Homodyne Detection. The
merit of the pilot carrier is that the LO is not necessary in the receiver. In this
master thesis, the optical signal of the QPSK modulation format with PRBS 215-1
is transmitted over 500km using the pilot carrier method. A WDM system
demonstration is also conducted to increase the system capacity. The Bit error rate
(BER) is calculated by the MATLAB program.
The BER performance of 20G bit/s, 500 km transmission system using the
QPSK with single channel and multiplexed channels were measured.

致謝 I
中文摘要 II
Abstract III
Contents V
1 Introduction 1
1.1 The coherent System . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.3 The Structure of this Thesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2 Theoretical Study of QPSK coherent Transmission 6
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2 Homodyne Detection . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2.1 Coherent System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2.2 Homodyne Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.3 Quadrature Phase Shift Keying Modulation. . . . . . . . . . . . . . . . . . . . . . 10
2.4 90 Degree Hybrid and the Balanced receiver. . . . . . . . . . . . . . . . . . . . . 12
2.5WDM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3 Experimental Study of QPSK WDM System with Coherent Detection 18
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
3.2 Experimental Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.2.1 The Transmitter.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.2.2 The transmission line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
3.2.3 The Receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
VI
3.3 Results and discussions . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . 31
3.4 Conclusion 35
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
4 Summary 37
List of abbreviations VII

[1] P. Boffi, L. Marazzi, L. Paradiso, P. Parolari, A. Righetti, R. Siano, P. Franco,
R. Cigliutti, D. Mottarella, and M. Martinelli, “Experimental comparison of
RZ-IMDD and RZ-DQPSK performance in a standard 2000-km DWDM
system,” Proceedings of CLEO 2004, paper CThBB5, May 2004.
[2] G. Bosco, and P. Poggiolini, “The impact of receiver imperfections on the
performance of optical direct-detection DPSK,” Journal of Lightwave
Technology, cal.23, no.2, pp. 842-848, February 2005.
[3] Jiun-Ru Wang, “The Performance of Using Different Modulation Formats in
Digital Coherent System”, National Sun Yat-sen University Kaohsiung,
Taiwan, R.O.C.
[4] Tetsuya Miyazaki and F. Kubota, “PSK self-homodyne detection using a
pilot carrier for multi-bit/symbol transmission with inverse-RZ signal,”
IEEE Photon.
[5] Govind P. Agrawal, Fiber-optic communication systems, third edition.
[6] Photoline Technologies, “Low Loss Dual Parallel Mach Zehnder Modulator”,
http://www.photline.com/MXIQ-LN-40.pdf
[7] Queensleed University of Technology, School of Engineering Systems,
“ENB346 Digital Communications Lecture 5 pi/4-QPSK and Eye Diagram”,
http://campspublic3.ihmc.us/rid=1224197201492_276366100_5982/L5.pdf
[8] Optoplex Corporation, “Optical Hybrid Enables Next-Generation Optical
Communication”
http://www.optoplex.com/download/coherent_detection_and_optical_hybrid
.pdf
[9] Michael G. Taylor, Member, IEEE, “Phase Estimation Methods for Optical
Coherent Detection Using Digital Signal Processing”, Journal of Lightwave
Technology, vol. 27, NO. 7, APRIL 1, 2009
[10] Govind P. Agrawal, “Fiber-Optic Communication Systems”, third edition.
[11] Gerd Keiser, “Optical Fiber Communication”, fourth edition.
[12] National Semiconductor Application Note 236, January 1980, “An introduction
to the sampling theorem”,
http://www.national.com/an/AN/AN-236.pdf
[13] Jiun-Ru Wang, “The Performance of Using Different Modulation Formats in
Digital Coherent System”, National Sun Yat-sen University Kaohsiung, Taiwan,
R.O.C.