231
3C Tecnología. Glosas de innovación aplicadas a la pyme. ISSN: 2254 – 4143 Edición Especial Special Issue
Noviembre 2021
CROSSTALK MEASURE OF THE FM – EDFA IN MDM
TRANSMISSION USING PM-QPSK
T. Senthil
Ph.D., Kalasalingam University. B.E and M.E degree, M.K university, India.
Associate Professor, department of ECE, Kalasalingam University,
Krishnankoil, Tamilnadu, (India).
E-mail: t.senthil@klu.ac.in
ORCID: https://orcid.org/0000-0002-0044-5371
Recepción:
11/11/2019
Aceptación:
28/10/2020
Publicación:
30/11/2021
Citación sugerida:
Senthil, T. (2021). Crosstalk measure of the FM – EDFA in MDM Transmission using PM-QPSK. 3C
Tecnología. Glosas de innovación aplicadas a la pyme, Edición Especial, (noviembre, 2021), 231-241. https://
doi.org/10.17993/3ctecno.2021.specialissue8.231-241
232
https://doi.org/10.17993/3ctecno.2021.specialissue8.231-241
3C Tecnología. Glosas de innovación aplicadas a la pyme. ISSN: 2254 – 4143 Edición Especial Special Issue
Noviembre 2021
ABSTRACT
In optical ber communications, Mode –Division Multiplexing in combination with
Wavelength Division Multiplexing and advanced modulation formats like QPSK n-QAM
are utilized to deliver more amounts of data through a single ber. For amplifying the
signals in the long haul optical bres link Few –Mode Erbium –Doped Fiber Amplier is
employed to equally and eciently amplify both modes and respective wavelengths over
the telecommunication C-band frequency range. In this paper A Dual-Carrier PM-QPSK
transmission system is proposed for enhancing data rate with reduced bit error due to the
cross section generated by the optical bre non-linear properties. The spectrally ecient
high bitrate transmission has generated in coherent systems. Using two PM-OPSK carriers,
one can reduce transmitter bandwidth requirement to half compared to standard single
carrier PM-QPSK while still supporting the same total bitrate. The total bitrate for this
layout is given as 40Gbps. The 100-Km of bre is modelled via a loss element and the ber
dispersion is modelled by an FBG model. Low transmitted power values in coherent systems
typically give lower nonlinearity. Each sub-carrier is modulated by 21.4Gbps including FEC
overheads. That means each polarization of a carrier is modulated by 10.7Gbps implying
the symbol rate of 5.35 GHz. In order to minimize the crosstalk between the two carrier,
the separation between them is kept half the symbol rate. As a result, when one carrier is
at maximum, the other is at its minimum. The proposed scheme is utilized for both linear
and non-linear ber.
KEYWORDS
DC-PM- QPSK, Forward Error Correction, Fibre Bragg Grating.
233
https://doi.org/10.17993/3ctecno.2021.specialissue8.231-241
3C Tecnología. Glosas de innovación aplicadas a la pyme. ISSN: 2254 – 4143 Edición Especial Special Issue
Noviembre 2021
1. INTRODUCTION
In electronics and telecommunication, modulation is the process of varying one or
more properties of a periodic waveform, called the carrier signal, with a modulating
signalthat typically contains information. The optical communication is one of the fastest
communication methods. Ave-mode erbium doped amplier is described, and the spectral
and modal gain distribution is characterized using PDM-QPSK (Askarov & Kahn, 2012).
However, the combination of polarization division multiplexing (PDM)or in phase/
quadrature phase modulation formats with (WDM) wavelength division multiplexing
in single mode ber leads to the Shannon limit (Ip, 2012). 41.6 Tbit/s C-band signal is
transmitted using 12 spatial & polarization modes over 74.17Km (Genevaux et al., 2016).
Multiplexing and De-multiplexing of each spatial mode is needed which causes loss and
need several ampliers, to amplify all the modes at the same time MDM is an economical
benet (Essiambre et al., 2015). General approach to describe and predict the amplifying
properties of FM-EDFA – (Few Mode) (Essiambre et al., 2015). The combination of some
erbium doped properties with adapted pump has investigated to develop a FM-EDFA
model based on the vector modes (Ryf et al., 2012). In this paper we describe the Dual-
Carrier transmission using PM-QPSK modulation and describes the need for PM-QPSK
in section II. Then the result analysis and tabulation are shown in section III. This paper
concludes in section IV.
2. MATERIALS AND METHODS
In this paper the Dual-Carrier transmission is generated using coherent system like PM-
QPSK. The total bitrate for the layout is 40 Gbps. The system consists of three parts rst
is the transmission part in which pseudo random bit sequence (PRBS) is used as the data
transmission which is modulated using the LASER. Then the modulated data is transmitted
through the ber which the second part is, it consists of the combiner and splitter. The
ber used here is EDFA with 100-Km. Then at the third part receiver is placed which will
measure the crosstalk between the two carrier. The process is subjected to both linear and
non-linearities of the ber.
234
https://doi.org/10.17993/3ctecno.2021.specialissue8.231-241
3C Tecnología. Glosas de innovación aplicadas a la pyme. ISSN: 2254 – 4143 Edición Especial Special Issue
Noviembre 2021
A. MODULATION TECHNIQUE
Modulation is the process of combining the information signal with the carrier signal. Here
we use PM-QPSK to achieve the spectrally ecient transmission. Using two PM-QPSK the
transmitter bandwidth can be reduced half as compared to single carrier. Each subcarrier
is modulated by 21.4Gbps. This will improve the bandwidth eciency of the transmission
system eectively. The block diagram of PM-QPSK is given below (Figure 2).
B. OPTICAL AMPLIFIER
EDFA is an Erbium Doped Fiber Amplier which amplies the signal is also called as the
optical amplier. EDFA is used to avoid the repeaters / regenerators in long distance optical
bre transmission. If we use regeneratorsmeans, there will be high noise introduced by
them. To avoid this, we go for EDFA system. However, the cost of this ber will be high.
Even though EDFA amplies the modulated signal, it needs an external laser pump signal.
The EDFA amplier block is given below (Figure 3).
C. CROSS TALK MINIMIZATION
To minimize the crosstalk between the two carriers the separation between them is kept as
half the symbol rate that is when one carrier has the maximum symbol rate means other
will be at the minimum. The local frequency is set to the transmitted carrier frequency
in single PM-QPSK and so the real and imaginary part of the received electromagnetic
is a baseband signal. This drastically reduces the possibility of cross talk occurring by
introducing orthogonal property in the modulated signal.
3. RESULTS
The separation between the two carrier signals is kept as half the symbol rate. The gure
shows the orthogonal nature of the signal so that the maximum point of the one signal
coincides with the minimum point of another signal thus reducing the crosstalk nature
eectively. The dual polarization itself send the two-information signal thus forming one
form of multiplexing.The spectrum of the transmitted dual-carrier PM-QPSK is given
below. The bandwidth of the carrier signal is determined by the symbol rate of the baseband
signal. Thus, by selecting the appropriate Band Pass Filter in the input section the symbol
235
https://doi.org/10.17993/3ctecno.2021.specialissue8.231-241
3C Tecnología. Glosas de innovación aplicadas a la pyme. ISSN: 2254 – 4143 Edición Especial Special Issue
Noviembre 2021
rate can be decided for the required isolation in between two signals thus avoiding the cross
talk between the signals.
The BER versus for the various symbol rate data from each carrier is analysed and the
equalizer is used in the transmitter part to compensate for all transmission anomalies. The
data is received with error free is given below. The BER increases with the increased symbol
rate and the crosstalk signal strength i.e. overlapped signal spectrum of the two signals also
increases with the symbol rate of the baseband signal. The Mode division multiplexed
(MDM) system increases the channel capacity imposed by the non – linear properties of the
single mode bre communication system.
In simulation the dual carrier PM –QPSK is designed and then the bre is set with the
optimized non-linear properties so that the eect of the non – linear nature varying the
spectral response of the transmitting bre. The optical signal and spectrum view is given in
the Figure 7. The maximum value of the spectrum coincides with the minimum attenuation
windows of the single mode bre. Then the bit error rate range is given in the Figure 8,
for both the modulation end. At the receiver side Fibre Bragg Grating (FBG) is used to
compensate the bit error rate. The gain value is calculated which is used to minimize the
bit error rate due to the dual carrier nature. The range of gain is 6- 6.5db in our simulation
generated. By applying non-linearity of the bre channel, the resultant bit error rate will be
approximately nil for the dual carrier system.
Figure 1. Dual Carrier PM-QPSK system.
Source: own elaboration.
237
https://doi.org/10.17993/3ctecno.2021.specialissue8.231-241
3C Tecnología. Glosas de innovación aplicadas a la pyme. ISSN: 2254 – 4143 Edición Especial Special Issue
Noviembre 2021
Figure 4. Half the symbol EDFA Working.
Source: own elaboration.
Figure 5. DC-PM-QPSK spectrum at the transmitter.
Source: own elaboration.
238
https://doi.org/10.17993/3ctecno.2021.specialissue8.231-241
3C Tecnología. Glosas de innovación aplicadas a la pyme. ISSN: 2254 – 4143 Edición Especial Special Issue
Noviembre 2021
Figure 6. BER for each carrier.
Source: own elaboration.
Figure 7. Optical signal and spectrum at the transmitted end.
Source: own elaboration.
239
https://doi.org/10.17993/3ctecno.2021.specialissue8.231-241
3C Tecnología. Glosas de innovación aplicadas a la pyme. ISSN: 2254 – 4143 Edición Especial Special Issue
Noviembre 2021
Errors bit 1 = 51
Errors bit 2 = 66
Errors bit 3 = 40
Errors bit 4 = 44
BER bit 1 = 0.7782576E-03
BER bit 2 = 0.1007157E-02
BER bit 3 = 0.6103981E-03
BER bit 4 = 0.6714379E-03
Errors bit 1 = 63
Errors bit 2 = 50
Errors bit 3 = 46
Errors bit 4 = 47
BER bit 1 = 0.9613771E-03
BER bit 2 = 0.7629977E-03
BER bit 3 = 0.7019579E-03
BER bit 4 = 0.7172178E-03
Figure 8. BER for each carrier while setting the non-linearities.
Source: own elaboration.
4. CONCLUSIONS
This paper described the dual carrier PM-QPSK in coherent system. In single carrier PM-
QPSK, the local frequency is set as the transmitted carrier’s frequency. As a result, the real
and imaginary part of received electromagnetic eld tries to overlap, correspond to the
baseband signal. However in DC-PMQPSK, since the carriers are apart by half the symbol
rate, the eect of cross talk is minimized by varying the non-linearity of the optical bre.
The various settings for the local oscillator frequency exist in the literature and frequency
osets may appear in the detected signal. For this the two local oscillators – each tuned
to corresponding transmitted carrier are used and thus avoiding the frequency osets at
each detected output. In future this idea can also be extended for multichannel (WDM)
optical communication systems. Thus, optimizing the distance between two carriers cross
talk amount is reduced thus justifying the title.
240
https://doi.org/10.17993/3ctecno.2021.specialissue8.231-241
3C Tecnología. Glosas de innovación aplicadas a la pyme. ISSN: 2254 – 4143 Edición Especial Special Issue
Noviembre 2021
ACKNOWLEDGEMENT
The author thanks the Department of Electronics and Communication Engineering of
Kalasalingam University, (Kalasalingam Academy of Research and Education), Tamil
Nadu for permitting, to utilize the OptSim software available in the research lab.
REFERENCES
Akhtari, S., & Krummrich, P. M. (2013). Impact of mode beating eects in optical
multi-mode ampliers for space division multiplexing. IEEE Photonics Technology
Letters, 25(24), 2482–2485. https://ieeexplore.ieee.org/document/6651699
Askarov, D., & Kahn, J. M. (2012). Design of transmission bers and doped ber
ampliers for mode-division multiplexing. IEEE Photonics Technology Letters, 24(21),
1945–1948. https://ieeexplore.ieee.org/document/6316068
Bigot, L., Le Cocq, G., & Quiquempois, Y. (2015). Few-mode erbium-doped ber
ampliers: A review. Journal of Lightwave Technology, 33(3), 588–596. https://ieeexplore.
ieee.org/document/6983523
Chen, Y., Lobato, A., Jung, Y., Chen, H.,. Sleier, V., Kuschnerov, M., Fontaine,
N., Ryf, R., Richardson, D., Lankl, B., & Hanik, N. (2015). 41.6 Tbit/s C-Band
SDM OFDM transmission through 12 Spatial and polarization modes over 74.17
Km few mode ber. Journal of Lightwave Technology, 33(7), 1440–1444. https://www.
osapublishing.org/jlt/abstract.cfm?uri=jlt-33-7-1440
Essiambre, R.-J., Kramer, G., Winzer, P. J., Foschini, G. J., & Goebel, B. (2015).
Capacity limits of optical ber networks. Journal of Lightwave Technology, 28(4), 662–
701. https://ieeexplore.ieee.org/document/5420239
Essiambre, R.-J., Kramer, G., Winzer, P. J., Foschini, G. J., & Goebel, B. (2015).
Capacity limits of optical ber networks. Journal of Lightwave Technology, 28(4), 662–
701. https://ieeexplore.ieee.org/document/5420239
Genevaux, P., Simonneau, C., Le Cocq, G., Quiquempois, Y., Bigot, L., Boutin,
A., & Charlet, G. (2016). A Five Mode Erbium Doped Amplier For Mode Division
241
https://doi.org/10.17993/3ctecno.2021.specialissue8.231-241
3C Tecnología. Glosas de innovación aplicadas a la pyme. ISSN: 2254 – 4143 Edición Especial Special Issue
Noviembre 2021
Multiplexing Transmission. Journal of Lightwave Technology, 34(2), 456-462. https://
ieeexplore.ieee.org/document/7274319
Ip, E. (2012). Gain equalization for few-mode ber ampliers beyond two propagating
mode groups. IEEE Photonics Technology Letters, 24(21), 1933–1936. https://ieeexplore.
ieee.org/document/6316074
Ryf, R., Randel, S., Gnauck, A. H., Bolle, C., Sierra, A., Mumtaz, S., Esmaeelpour,
M., Burrows, E. C., Essiambre, E.-J., Winzer, P. J., Peckham, D. W.,
McCurdy, A. H., & Lingle, R. (2012). Mode-division multiplexing over 96 km of
fewmode ber using coherent 6 × 6 MIMO processing. Journal of Lightwave Technology,
30(4), 521–531. https://ieeexplore.ieee.org/document/6074912
Spellmeyer, N. W. (2000). Communications performance of a multimode EDFA.
IEEE Photonics Technology Letters, 12(10), 1337–1339. https://ieeexplore.ieee.org/
document/883822
Wada, M., Sakamoto, T., Mori, T., Yamamoto, T., Hanzawa, N., Yamamoto, N.,
& Yamamoto, F. (2014). Modal gain controllable 2-LP-mode ber amplier using
PLC type coupler and long-period grating. Journal of Lightwave Technology, 32(24),
4694–4700. https://ieeexplore.ieee.org/document/6924757
