2019 International Conference on Computational Intelligence and Knowledge Economy (ICCIKE)

December 11–12, 2019, Amity University Dubai, UAE

Optimized FWM Parameters for FTTH Using

DWDM Network
S Sugumaran Lokesh Sharma
School Of Electrical,Electronics and Communication Engineering Department of Information Technology
Galgotias University Manipal University Jaipur
Greater Noida, India Jaipur, India
s.sugumaran@galgotiasuniversity.edu.in lokesh.sharma@jaipur.manipal.edu

Shilpa Choudhary
Department of Electronics and Communication Engineering
G. L. Bajaj Institute Of Technology & Management
Greater Noida, India
shilpadchoudhary@gmail.com

Abstract—A DWDM System consisting of transmitter, optical the number of wavelengths to be transmitted through a single
span and receiver is designed. The line coding technique NRZ fiber by multiplexing more number of wavelengths through a
(Non Return To Zero) has been used as the modulation schemes. single fiber. This has given rise to nonlinear effects in the fiber.
The variation in the four wave mixing is analyzed with respect to
the designed DWDM (Dense Wavelength Division Multiplexing) The nonlinear effects are SRS (Stimulated Raman Scattering),
system. The DWDM is designed and simulated on Optisystem and SBS (Stimulated Brillouin Scattering) [7], SPM (Self Phase
their BER (Bit Error Rate) is calculated. The DWDM system Modulation), XPM (Cross Phase Modulation) and FWM (Four
is implemented in a FTTH (Fiber To The Home) system and Wave Mixing) [2]. Four Wave Mixing plays a very important
simulated on Optisystem and their BER is calculated. role in the fiber nonlinearities in a DWDM system. FWM has
Index Terms—DWDM, Four Wave Mixing, OptiSystem, Sim-
ulation, Bit Error Rate, FTTH to be reduced so that the system designed becomes efficient
so as to be implemented [5].
I. I NTRODUCTION In this paper, a DWDM system is simulated and the FWM
The expansion and advancements in the field of commu- and Q-factor are analyzed by varying the input power, optical
nication has resulted in the need for an efficient design of gains, number of channels and channel spacing [1]. An effi-
communication systems. The huge amount of data transfers cient system is designed by choosing the optimum parameters
leads to the necessity of a large bandwidth with high efficiency obtained from the analysis and is implemented on an FTTH
without compromising the cost. system and simulated to analyze the FWM and Q-factor. The
Fiber optic communication has changed the world with its paper is organized into three sections. Section I deal with
ability to meet the rising demands for fast internet connection, the introduction to fiber optic communication, FTTH, WDM
video-based multimedia, peer to peer communication, file and DWDM. Section II deal with the block diagrams of the
transfer, HD gaming etc [4]. The fiber technology has played DWDM system as well as the FTTH system. Section III
a vital role in medical field with its reliability, high data rate includes the results obtained from analyzing the parameters
and lower attenuation rates. by varying the input power, optical gains, number of channels
FTTH (Fiber To The Home) or also known as FTTP (Fiber and channel spacing. It also includes the results obtained
To The Premises) is where the communication between the from the analysis of the FTTH system along with the optical
transmitter and receiver takes place with fiber optical cables spectrum and eye diagrams. The paper concludes with the
till the building or premises of the end user [2]. FTTH is result obtained from the analysis of the DWDM system and
capable of delivering digital data, telephony, video etc. at high its implementation in an FTTH system.
data rates. A fiber can carry more than 2.5 million phone
calls simultaneously whereas it is 6 calls in the case of the
conventional coaxial cables.
The concept of WDM (Wavelength Division Multiplexing) II. E XPERIMENTAL A RRANGEMENT
allows data to be multiplexed in to different wavelengths such
that it can be transmitted through a single mode fiber. Dense
Wavelength Division Multiplexing has significantly increased Here the Dense Wavelength Division Multiplexing System
as well as the FTTH system is simulated in OptiSystem and
the simulation results are depicted.

978-1-7281-3778-0/19/$31.00 ©2019 IEEE

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 2019 International Conference on Computational Intelligence and Knowledge Economy (ICCIKE)
December 11–12, 2019, Amity University Dubai, UAE

A. Simulation of Dense Wavelength Division Multiplexing

Experiment
PRBS (Pseudo-Random Bit Sequence) is used to represent
the data transmitted. The data is represent using a NRZ (Non
Return To Zero) coding. A CW (Continuous Wave) laser
operating at 193.1 THz is used as carrier. The PRBS along
with a continuous laser is multiplexed using a Mach-Zehnder
modulator. The PRBS, continuous wave laser and the Mach-
Zehnder modulator represents the transmitter block. Fig. 1
depicts the transmitter block diagram for the NRZ line-coding
technique.

The optical span consists of SMF (Single Mode Fiber), DCF

(Dispersion Compensated Fiber), amplifiers etc. to account for
the losses that occur during the transmission of through the
fiber. The EDFA amplifiers are used; as they do not require
an opto-electric conversion to amplify the signals instead they
Fig. 2. The Block Diagram of a Typical Optical Span
can be done in the optical domain itself. The optical gain is
varied at this point to account for the four wave mixing. A
typical optical span block diagram is represented in Fig. 2. G1 = 10dB The receiver is an optical receiver used at the
end taken from the output of a de-multiplexer. The receiver
is connected to the BER analyzer. Fig. 3 depicts the block
diagram of the receiver.

Fig. 3. Receiver Block Diagram

Fig. 4 depicts the subsystem block diagram of a DWDM

system. The transmitter is made into a subsystem that is
expanded as shown in Fig 1 .
The bitrate for the simulation setup has been fixed at 2.5
Gbps, sequence length of 128 bits and sample per bit 64.
Fig. 1. Transmitter Block diagram of NRZ Line Coding
The input power is varied in the transmitter block for input
SMF stands for single mode fiber [10]. DCF stands for powers 0dBmand − 10dBm. The optical gain has been taken
dispersion compensation fiber [7]. The length of fiber in one as 10dB and 5dB for the first instance and 15dBand6dB for
loop is 50 + 10 = 60km. the DCF length is 10 km. The gain the second instance with a noise figure of 6dB in both the
of EDFA placed after a fiber is such that it compensates the cases. The simulation has been carried on for a 3 channel
losses of the preceding fiber [6] [3]. and an 8-channel DWDM system. A channel spacing of
Let the length of SMF be L km, the attenuation be A dB/km. 100GHzand110GHz has been for the above simulation setup
The Gain of the first EDFA be G1, that of the second be depicted in Fig 4.
G2. The above-mentioned parameters have to be selected such
that the values satisfy the following conditions. The values B. Simulation of Fiber To The Home (FTTH System)
are chosen based on the conditions given below. Gain of first The FTTH system consists of the transmitter, the optical
EDFA G1 = L?A, gain of the second EDFA in the simulation span and the receiver. Fig. 1 represents the transmitter and
G2 = L2 ? A2 and that of the gain of the third EDFA is Fig. 2 represents the optical span.
G3 = L1 ? A1. Fig. 5 represents the receiver block diagram for the FTTH
A sample calculation of the parameters is given below. Let system. The receiver consists of a PIN photo-diode along with
us take L = 10km, A = 0.2dB/km, L2 = 10kmandA2 = a low pass filter with cut off frequency that of 0.75 ? Bitrate.
0.5dB/km . [1] The attenuation due to SMF at 50 km is This setup ensures that the end user gets the signal in the
calculated to be 50 ? 0.2 = 10dB This is neutralized by gain optical domain.

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 2019 International Conference on Computational Intelligence and Knowledge Economy (ICCIKE)
December 11–12, 2019, Amity University Dubai, UAE

Fig. 4. Subsystem layout

Fig. 6. Eye Diagram for 0 dBm input power (8 channel)

Fig. 5. FTTH Receiver Layout

III. RESULT AND ANALYSIS

The eye diagram and optical spectrum has been obtained

to validate the results obtained through simulation Fig. 6 and
7 depicts the eye diagram and optical spectrum respectively
of an 8 channel DWDM system with 0dBm input power,
EDFA amplifier gain of 10dBand5dB respectively with a
Fig. 7. Optical Spectrum Analyzer for 0 dBm input power (8 channel)
noise figure of 6dB and channel spacing of 100 Ghz.
Fig.8 and 9 depict the eye diagram and optical spectrum
respectively of an 8-channel DWDM system obtained by
varying the input power to −10dBm. On comparing the results
obtained by varying the input power from 0dBmto − 10dBm
in the transmitter layout, it is clearly observed that the Q factor
has reduced from 10.5316 to 5.328 as shown in Fig.6 and 8.
The FWM, which was initially observed in -48 dBm in the
optical spectrum analyzer in figure 7, has now come down
towards -68 dBm to -70 dBm ranges.
Fig.10 and 11 depicts the eye diagram and optical spectrum
respectively for the varying the EDFA amplifier gain to 15 dB
and 6 dB with a noise figure of 6 dB,
On comparing the eye diagrams in Fig.6 and 10, on varying
the optical gain from 10 dB to 15 dB for EDFA 1 and 5 dB
to 6 dB for EDFA 2 there occurs a slight increase in the Q
factor from 10.5316 to 12.9877.
The FWM has increased from -48 dBm in Fig. 7 to nearly -40
dBm as shown in Fig. 11. This on increasing the optical gain, Fig. 8. Eye Diagram for -10 dBm input power (8 channel)
the FWM is also found to increase.

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 2019 International Conference on Computational Intelligence and Knowledge Economy (ICCIKE)
December 11–12, 2019, Amity University Dubai, UAE

Fig.12 and 13 depict the eye diagram and optical spectrum

respectively for a 3 channel DWDM system.
On comparing the eye diagrams in Fig.6 and 12, it depicts an
8-channel DWDM system and a 3-channel DWDM system,
as the number of channels varies from 8 to 3, there occurs an
increase in the Q factor from 10.5316 to 12.574.
On analyzing the optical spectrum, it is observed that FWM
has reduced from -48 dBm in Fig.7 to nearly -57 dBm as
shown in Fig.13.
This is supported by the fact that on decreasing the number of
channels eventually reduces the interference of waves resulting
in the further lowering of FWM.

Fig. 9. Optical Spectrum Analyzer for -10 dBm input power (8 channel)

Fig. 12. Eye Diagram for 3 Channel DWDM System

Fig. 10. Eye Diagram for EDFA gain of 15 dB and 6 dB

Fig. 13. Optical Spectrum Analyzer for 3 Channel DWDM System

Fig.14 and 15 depict the eye diagram and optical spectrum

respectively for a channel spacing of 100 GHz.
On comparing the eye diagrams in Fig.6 and 14, it depicts
an 8 channel DWDM system with channel spacing varying
from 100 GHz to 110 GHz, as the channel spacing increases;
there occurs an slight decrease in the Q factor from 10.5316
Fig. 11. Optical Spectrum Analyzer for EDFA gain of 15 dB and 6 dB
to 9.87587.

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 2019 International Conference on Computational Intelligence and Knowledge Economy (ICCIKE)
December 11–12, 2019, Amity University Dubai, UAE

On analyzing the optical spectrum, it is observed that FWM

has reduced from -48 dBm in Fig.7 to nearly -50 dBm as
shown in Fig.15.
This is supported by the fact that on decreasing the channel
spacing eventually gives more space between the channels thus
reducing the interference of waves resulting in the lowering
of FWM.

Fig. 16. Eye Diagram for Efficient FTTH system

Fig. 14. Eye Diagram for Efficient DWDM system

Fig. 17. Optical Spectrum Analyzer for Efficient FTTH system

the same system is implemented in FTTH. It is also observed

from Fig.15 and 16 that the FWM occurs below -68dBm in
the FTTH system whereas it occurs at -40dBm in the DWDM
system. The implemented FTTH system has been optimized
with lower rates of FWM.

Fig. 15. Optical Spectrum Analyzer for Efficient DWDM system

IV. CONCLUSION
The simulation for analysis of FWM by varying input
An Efficient DWDM system is designed by keeping the power, optical gain, number of channels and channel spacing
input power -10db with 100GHz channel spacing and the is analyzed using Optisystem.
optical gain 12dB and 6dB respectively with a noise figure On varying the input power, it is concluded that on reducing
of 6dB each. The above designed system is also implemented the input power the Q factor is lowered drastically but the
in an FTTH system. FWM component has reduced slightly.
Fig.14 and 15 depicts the eye diagram and optical spectrum Increasing the EDFA gains in the optical span for the 6
of the efficient DWDM system while Fig.16 and 17 depicts loops results in slight increase in the Q factor but the FWM
the eye diagram and optical spectrum of the efficient FTTH component has increased with the increase in the optical gain.
system. On analyzing for different number of channels in the
On comparing Fig.14 and 16, it is evident that the Q factor transmitter side, it is found that the Q factor increases and
is higher in case of the DWDM system but slightly less when the FWM components also decreased.

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 2019 International Conference on Computational Intelligence and Knowledge Economy (ICCIKE)
December 11–12, 2019, Amity University Dubai, UAE

On varying the channel spacing the Q factor reduces by

a slight amount as well as the FWM components are also
reduced
The efficient DWDM system has been designed and imple-
mented in FTTH system with reduced FWM.
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