22 - Analysis of Chromatic Dispersion Compensation in Fiber Optic Communication Systems

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Analysis of Chromatic Dispersion Compensation in Fiber Optic 
Communication Systems 
Fabrício Pinho da Luz1 
Fabio Barros de Sousa1 
Jorge Everaldo de Oliveira1,2 
Marcos Benedito Caldas Costa1,3 
 
 
Keywords: Chromatic Dispersion, Q-Factor, BER 
 
1. INTRODUCTION 
The dispersion consists of a temporal enlargement in the form of the wrist during the 
propagation in an optical fiber. Because due to propagation of signals occur at different speeds, 
resulting in delays, which consequently leads to distortion of the signals transmitted by the 
system performance. One of the ways to solve this problem is the use of a Dispersion 
Compensation Fiber (DCF) in the optical link, since this type of fiber has negative dispersion 
coefficient, in the range of -70 to -90 ps/nm.km [1], so they can be used to compensate for the 
positive dispersion of the Standard Single-Mode Fiber (SSMF), in addition it reduces Kerr non-
linearity and Accumulated Spontaneous Emission (ASE) accumulation resulting from 
amplification of the Doped Fiber Amplifier Erbium (EDFA) [2]. 
In this work we propose the dispersion compensation through OptiSystem 15.0 software 
in three basic configurations [3]: Post-compensatio, Pre-compensation and Mix-compensation. 
The discussions and comparisons of the data were based on Bit Error Rate (BER), maximum 
Q-factor and OSNR as a function of Input Power. These methodologies are discussed here to 
compare them and know which offers the best performance. The paper is organized as follows: 
In Section 2, the block diagrams of the three configurations and also the simulation parameters 
are defined. In Section 3 the results of the comparison between the three compensation methods 
were reported and finally in Section 4, the conclusions and finally the thanks and references. 
2. MATERIAL AND METHODS 
The design consists of a single-mode system in which the transmitter is composed of a 
CW laser operating at  equal to 1552.5 nm, a Mach-Zehnder modulator, a RZ pulse generator 
and a Pseudo-Random bit sequence generator with a bit rate of 10 Gb/s. A SMF as the main 
link with chromatic dispersion DSMF equal to 17.8 ps/nm.km, length LSMF equal to 100 km, 
attenuation coefficient  equal todB/km, effective area Aeff equal to 80 m
2 and 
dispersion slope S equal to 0.075 ps/nm2/km. And a DCF with DDCF equal to -80 ps/nm.km, 
 
1Programa de Pós-Graduação em Engenharia Elétrica do Instituto de Tecnologia da Universidade Federal do 
Pará, Belém. (e-mails: {fabriciopluz, fabiobarros.s85}@gmail.com, joeveraldo@unifesspa.edu.br, 
marcosta@ufpa.br 
2Faculdade de Física do Instituto de Ciências Exatas da Universidade Federal do Sul e Sudeste do Pará, Marabá. 
3Faculdade de Engenharia de Materiais da Universidade Federal do Pará, Campus Ananindeua. 
mailto:marcosta@ufpa.br
 
 
LDCF equal to 22 km,  equal to dB/km, Aeff equal to 30 m
2, S equal to 0.075 ps/nm2/km 
and PMD equal to 0.5 ps/km1/2. EDFAs with gains equal to 20 dB and 13 dB, both with Noise 
Figure NF equal to 4 dB. The receiver is composed of a PIN photodetector, a Bessel low pass 
filter, which is responsible for removing noise from the electrical signal and finally a BER 
analyzer. 
A more detailed description of the three dispersion compensation processes presented 
in this paper will be presented below. All simulation parameters were entered according to 
Optisystem references and standard. 
 
2.1 The Three Dispersion Compensation Methodologies 
 
The dispersion compensation can be performed through three methodologies: The Post-
Compensation Pre-Compensation and Mix Compensation. In the post-compensation 
methodology the signal initially passes through an SMF which is then amplified by the EDFA 
and at the end of the link the signal dispersion is compensated by a DCF. In pre-compesation 
the signal is negatively scattered by the DCF which is then amplified by the EDFA with a gain 
and at the end of the link the SMF will compensate positively for signal scattering. 
And as shown in figure 1 in the Mix-compensation the signal is compensated negatively by the 
DCF then it is amplified by the EDFA with gain of 13 dB, it passes through a pair of SMF again 
is amplified by two EDFAs both with gains of 20 dB and finally the dispersion of the signal is 
compensated by another DCF. This configuration is also called symmetric scatter 
compensation, ie it consists of the combination of the post-compensation and pre-compensation 
method. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3. RESULTS AND DISCUSSION 
For the analysis of the results a power variation of 0 to 25 dBm was made linearly in 
steps of 0.5 dBm in 50 scanning interactions. 
Figure 1. Mix-compensation block diagram. 
 
 
For the analysis of the performance of the three dispersion compensation systems, the 
values of the Q-factor and the MIN BER were used for the input power of 0 dBm. For the 
analysis of the performance of the three dispersion compensation systems, the values of the Q-
factor and the MIN BER were used for the input power of 0 dBm. 
It can be seen in figure 2 that the value of the Q-factor for the pre-compensation system 
was equal to 24.4, and for the post-compensation the value of 24.5 was obtained. While for the 
mix-compensation it was 31.8. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
In figure 3 the BER log charts show that for the mix-compensation system the MIN 
BER equal to 4x10-222, which is the lowest bit error rate compared to the pre-compensation with 
MIN BER equal to 3x10-132 and the post-compensation with MIN BER equal to 7x10-133. 
Therefore, the mix-compensation system offered a higher quality factor and a lower bit error 
rate, thus, it presented better performance than the pre and post-compensation systems. 
Figure 4 shows the result of the maximum Q-factor as a function of the input power of 
the simulation of the three dispersion compensation systems. It can be seen from Figure 4 that 
the maximum Q-factor equal to 90 and OSNR equal to 36 dB were achieved by the mix-
compensation system at an input power of 10.5 dBm. For the pre-compensation system, the 
maximum Q-factor equals 34.5 and OSNR equal to 28 dB and for post-compensation the 
maximum Q-factor equals 73.5 and OSNR equal to 34 for an 8.5 dB input power. 
Figure 2. Performance of the Three Q-Factor Dispersion Compensation Systems. 
Figure 3. BER charts for the Three Dispersion Compensation Systems. 
 
 
The Q-factor values decrease for all three dispersion compensation systems shortly after 
reaching the maximum level reaching 0 for the pre-compensation and mix-compensation 
system when the power tends to 25 dBm. This occurred because, as the power level increased, 
the OSNR value decreased. Thus the signal was degraded by the effect of selph-phase 
modulation resulting in high of bit errors rates. 
 
 
 
 
 
 
 
 
 
4. CONCLUSION 
In this work three dispersion compaction systems were studied, where a DCF bond was 
used for this purpose. The Q factor and BER values were compared and analyzed at a 
transmission rate of 10 Gb/s. It was verified that the factor Q and the OSNR for the mix-
compensation system were the largest, so it was considered the best dispersion compensation 
scheme among the three presented here. 
 
 
ACKNOWLEDGMENTS 
 
This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de 
Nível Superior - Brasil (CAPES) - Finance Code 001. 
REFERENCES 
[1] SINGH, Narinder; GOEL, Ashok K. Analysis of Four Wave Mixing Effect at Different 
Channel Spacing in DWDM Systems Using EDFA with Single Pump Source. An 
International Journal of Engineering Sciences, January, v. 17, p. 382-389, 2016. 
[2] DEHGHANI, Fatemeh; EMAMI, Farzin. Suppression of Four wave mixing based on the 
pairing combinations of differently linear-polarized optical signals in
WDM 
system. Journal of Optoelectronical Nanostructures, v. 1, n. 1, p. 1-8, 2016. 
[3] P. Sharma, Mr. B. Koushal, S. Jain. “Performance Analysis Of Dispersion Compensation 
Of Optical Fiber Using EDFA”. International Journal of Engineering Research & 
Technology. e-ISSN: 2278-0181, p. 2559-2566. Vol.2 - Issue 7, July - 2013. 
 
Figure 4. Input Power Vs Max. Q-Factor.