Dense wavelength-division-multiplexed passive network (DWDM-PON) has been acknowledged as an appealing solution for the NGN optical access networks. Due to of its large capacity, network security, channel-independence and per-user-based enhancement flexibility it offers unique characteristics for broadband optical access services. In DWDM-PON system each customer is allocated a discrete “color” (wavelength). Major Nonlinear effects occurring in DWDM Passive Optical Networks need to be analyzed for better quality of service. Parameters which are responsible for the generation of FWM are simulated, discussed and compared their results to reduce the impact of FWM and Optisystem is operated to demonstrate the solution feasibility.

Keywords: DWDM, PON, Four Wave Mixing, Optisystem, Access Network, Quality of Service.

Abstract

Objectives

Typical Diagram of DWDM PON

Methodology

Effect of Range

Results CONCLUSION

Four wave mixing effect is analyzed in a DWDM PON system while varying five parameters (i.e. Range, Spacing, Input Power, data rate, number of channels). It has been observed that increase in link range also increases the efficiency of FWM components as interaction between light pulses increases with distance. FWM effect increases with decrease in spacing between adjacent channels. Therefore, lower spacing yields more FWM components. Input power is having substantial effect on the DWDM system because FWM is generated as a result of nonlinear dependence of refractive index on power. Increase in input power results in increment in FWM sidebands. Results can be improved by using low input power but it will result in low SNR. Previous literature review depicts that effect of FWM is not significant on data rate. Lastly, increasing number of channels, increases FWM effect due to increase in number of interacting pulses.

FWM suppression is done using rectangular filter before De-Mux. Rectangular filter removes all the FWM components and doesn’t add any distortion to the original signals.

References

Wason, Amit, and R. S. Kaler. "Investigation of four wave mixing effect with different number of input channels at various channel spacing." Optik-International Journal for Light and Electron Optics 124.20 (2013): 4227-4230.

Kaur, Gurmeet, and M. L. Singh. "Effect of four-wave mixing in WDM optical fibre systems." Optik-International Journal for Light and Electron Optics 120.6 (2009): 268-273.

El-Halafawy, F. Z., M. H. Aly, and M. A. A. EI-Bary. "Four-Wave Mixing Crosstalk in DWDM Optical Fiber Systems." Radio Science Conference, 2006. NRSC 2006. Proceedings of the Twenty Third National. IEEE, 2006.

Rasheed, Iftikhar, et al. "Analyzing the non-linear effects at various power levels and channel counts on the performance of DWDM based optical fiber communication system." Emerging Technologies (ICET), 2012 International Conference on. IEEE, 2012.

Meena, D., et al. "A Novel Analytical Study of Different Channel Allocations and FWM Efficiencies in Optical WDM Systems." (2012).

Ahmed, Jameel, et al. "Parametric analysis of four wave mixing in DWDM systems." Optik-International Journal for Light and Electron Optics 125.7 (2014): 1853-1859.

Acknowledgments

All thanks and praise to the Allah almighty who blessed us with health, intellect and certain resources to complete our work in time. Secondly, the life of our Holy Prophet (SAW) is a role model for us to excel in every field of our life. Thirdly, this whole work will not be possible as it is done without the guidance of our respected supervisor.

Lastly, the sincere prayers of our parents and never ending support of our fellows is also appreciable in every manner.

Design Approach

Major Nonlinear effects occurring in DWDM Passive Optical Networks need to be analyzed for better quality of service.

Design of a DWDM PON while enabling all the major non-linear factors.

Evaluation of certain parameters under the influence of Four Wave Mixing

Suppression of Four Wave Mixing

First of all, DWDM passive optical network is designed and simulated using Optisystem.

Nonlinear effects are introduced to evaluate FWM. Certain parameters (i.e. Range, Spacing, Input Power, data

rate, number of channels) are analyzed using iterations. Results are generated using spectrum analyzer and BER

analyzer in Optisystem. FWM suppression is performed using rectangular filter.

Department of Telecommunication EngineeringNauman Hameed, Usman Mushtaq

Study of Four Wave Mixing in a DWDM PON

Four Wave Mixing

When two or more light pulses are propagating in a WDM or DWDM optical system, these pulses tend to interact with each other producing new pulses in the neighboring spectrum of the signal.

Figure 1(a): Signal spectrum after Mux before transmission. (b) Signal spectrum after propagation through optical fiber.

Let λi, λj and λk are three different wavelengths of different channels, travelling along in a single medium (SMF). These pulses tend to overlap and generate new frequencies. If the newly produced pulses lie on any of the designated wavelength then crosstalk is induced in the system, which is termed as FWM.

Effect of Spacing

Effect of Input Power

• Define Problem

• Literature Review

Phase-1

• Design of DWDM

PON using Optisystem

• Introducing Non-Linear

effects• Parameters

Evaluation using

Simulative Analysis

Phase-2

• Detailed Results

• Conclusion• Report

Phase-3

Proposed System

Effect of number of channels

FWM suppression using Rectangular Filter

Rectangular Filter