Introduction to the optical communications by simulating an optical high debit transmission chain using optisystem with comparison of optical windows

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Introduction to the optical communications by simulating an optical high debit transmission chain using optisystem with comparison of optical windows. This article proposes a global study of an optical high debit chain presenting a complete simulation by comparing between the tree optical windows of telecommunications, led as an experience for teaching optical communications which are currently characterized by a grand demand for their exceptional transmission quality offering high debit, long distance of propagation and strong immunity against noise.
International Journal of Computer Networks and Communications Security
VOL. 3, NO. 2, FEBRUARY 2015, 53–62
Available online at: www.ijcncs.org
E-ISSN 2308-9830 (Online) / ISSN 2410-0595 (Print)
Introduction to the Optical Communications by Simulating an
Optical High Debit Transmission Chain Using OptiSystem with
Comparison of Optical Windows
ABDELHAKIM BOUDKHIL1, ASMAA OUZZANI2 and BELABBES SOUDINI3
1, 3 Dept. of Electronics, Faculty of Technology, University of Sidi Bel abbes, Sidi Bel Abbes, ALGERIA
2 Dept. of Electronics, Faculty of Technology, University of Saida, Saida, ALGERIA
E-mail: 1wboudkhil.abdelhakim@yahoo.fr, 2asma.ouzzani@yahoo.fr, 3sba_soudini@yahoo.fr
ABSTRACT
This article proposes a global study of an optical high debit chain presenting a complete simulation by
comparing between the tree optical windows of telecommunications, led as an experience for teaching
optical communications which are currently characterized by a grand demand for their exceptional
transmission quality offering high debit, long distance of propagation and strong immunity against noise.
The aim of this work extends to introduce the concepts and advantages provided by optical transmission
systems using optical fiber, to observe and analyze the various limitations introduced in such systems and
also to justify the choice of the optical window according to the use.
Keywords: Optical Communication, Laser Diode, Optical Fiber, PIN Photodiode, Optical Windows.
1
INTRODUCTION
Today, we can’t speak about telecommunications
systems
without
mention
the
optical
Since the history of telecommunications knew its
communication systems. Citing that the capacities
birth, the aim of researchers was always to optimize
of
current
optical
transmissions
will
be
more
a system which provides more reliable transmission
adequate the next few years, reaching a debit of the
of information, and offers a very high capacity of
scale of Tbit/s characterizing by a growth rate of
transport for very long distances with all protection
transmission flow estimated by 25% per year [2],
of transmitted information against all disturbances
this has motivated us to study a model of an optical
and noise which make the received signal different
high debit communication chain using OptiSystem
from that emitted. In this purpose, the crucial key to
software by describing its structure and exposing
increase
these
performances
has
integrated
each block as well its main role in the constitution
optoelectronic
components
into
telecommunica-
of the transmission chain in order to understand all
tions systems. Then, a new era was appeared with
principles
employed
in
such
kind
of
optical
the revelation of optical communication systems
transmission.
where the interaction between electronic and optical
In this context, E. Cassan [3]
studied several
technologies made concretized the hybrid spatiality:
simple
and
multiplexed
optical
links
using
Optoelectronics-Telecommunications,
allying
the
COMSIS
software,
focusing
on
the
major
intrinsic
qualities
of
optics
into
transmission
limitations
introduced
by
the
various
optical
systems having enormously progressed [1]. Since
components (laser source, optical amplifier, optical
that
time,
the
development
of
communication
fiber...).
systems all-optics would be prodigious face the
Equally,
D.
Bensoussan
[4]
treated
several
emergence
of
new
telecommunications
means
principles that underlie the various technologies of
(internet,
telephony,
imagery...)
which
can
be
optical communications in order to understand and
measured
today
by
the
number
of
networks
conceive
practically
these
optical
links
with
deployed across continents and oceans.
different orders (long range links, short range links,
local networks, high speed networks...).
54
A. Boudkhil et. al / International Journal of Computer Networks and Communications Security, 3 (2), February 2015
In view of this importance, we are interested on
available before the invention of the laser in
the simulation of an optical high debit transmission
chain using OptiSystem where we propose to
exploit and compare between the three optical
windows used as spectral regions in optical
1960 [5]. This substance offered the
opportunity of sending a luminous signal
with enough power over a long distance.
telecommunications field according to the optical
fiber used. Indeed, this work mainly presents:
Later, in his “Standard Telecommunications
Laboratories” publication of 1964, Charles
First, a history of optical communication by
Kao
described
an
optical
communication
illustrating
its
chronological
development
system for a long distance taking advantage
and the improvements that it bring into the
on the joint use of laser and optical fiber.
world of telecommunications.
Shortly
afterwards,
in
1966,
he
had
Second, an approach about light and its
properties in order to describe the luminous
wave approved as support in such systems to
understand the principle used for
propagation in the optical fiber.
experimentally demonstrated in
collaboration with Georges Hockman, that it
is possible to convey information in form of
light over a long distance thanks to optical
fiber. This experience was often considered
as the first data transmission via optical
Third, a description of the optical communi-
fiber.
cation system studied by exposing its three
main blocks: optical emitter, optical channel
and optical receiver.
Gradually, optical communication systems
began to plot their development passing
through several generations (4 generations).
Fourth, a complete simulation of an optical
high debit transmission chain using Opti-
System where we represent the shape of the
transmitted signal at each block, from
Today, a fifth generation is taking shape by
using new techniques such as transmission
with soliton, increasing of wavelength
numbers, use of fiber based on photonic
crystals (μ-structured)… Once these
emission to reception.
techniques will be mastered, the debit will
pass to the Tbit/s. In fact, a debit of 160
2
HISTORY OF OPTICAL
COMMUNICATIONS
Gbit/s to 10 Tbit/s was tested by Alcatel-
Lucent researchers who had successfully
conveyed a cumulative flow rate of 25.6
One of the most important problematic that
always consists a subject for research is how to
transmit signals by using light? This question is not
new because lots of optical signals were found able
to transmit certain information from very early eras:
For example, at the middle age, smoke
Tbit/s over a single fiber that sets a new
record in the field of optical transmissions.
Now, certain “pseudo-dreamers” are already
talking about a debit of Pbit/s that suggests
an enormous potential of optical
communications in the future [6].
signals used by Indians in North America
3
LIGHT IN OPTICAL FIBER
were the first old
communications.
example
of
optical
In order to eventually imagine and conceive the
optoelectronic components using for telecomm-
Also, along the Rhine Rhone's axe, warning
signals were transmitted over dozens of
kilometers from castle to castle when
detecting danger by using mirrors to reflect
sun rays. This simple system had inspired the
first modern test of optical communications.
unications, it is very interesting to know what is
light as well as its properties, this allows approving
the optical communications.
The light is a form of energy such as electricity. It
is composed of minuscule particles called
“photons” that move under wave forms (Figure 1).
It is generated by the vibration of electrons in atoms
In fact, optical communications were not
[7].
55
A. Boudkhil et. al / International Journal of Computer Networks and Communications Security, 3 (2), February 2015
Superior orbit
Electron
Electromagnetic
wave
Magnetic field
Normal orbit
Nucleus
Luminous wave
« photon »
Electric field
Fig. 1. Generation Of Luminous Waves “Photons”.
Fig. 2. Nature Of Electromagnetic Luminous Wave.
It is a mixture of electric and magnetic waves
producing
an
electromagnetic
wave
(Figure
2)
whose
optic
physical
properties
are
based
on
Maxwell's equations reacting on all phenomena of
luminous ray propagation [8].
Total reflection
Glass cladding
Optical
fiber
Incident
ray
n1
Fiber
core
n2
Reflected
ray
Total reflection
n1: Refraction Index Of The Fiber Core.
n2: Refraction Index Of The Fiber Glass Cladding.
Fig. 3. Principle Of Luminous Reflection In Optical Fiber.
Emission
Information
« data »
Coding
module
Modulator
Power
« current »
Optical source
« laser diode »
Luminous signal
Optical
fiber
Optical
fiber
Information
Photodetector
Electrical
amplifier
Filter
Decoding
« retrieved
data »
Clock
Synchronization
Reception
module
Fig. 4. Schematic Diagram Of The Optical High Debit Communication System Proposed For Study.
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Introduction to the optical communications by simulating an optical high debit transmission chain using optisystem with comparison of optical windows. This article proposes a global study of an optical high debit chain presenting a complete simulation by comparing between the tree optical windows of telecommunications, led as an experience for teaching optical communications which are currently characterized by a grand demand for their exceptional transmission quality offering high debit, long distance of propagation and strong immunity against noise..

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International Journal of Computer Networks and Communications Security VOL. 3, NO. 2, FEBRUARY 2015, 53–62 Available online at: www.ijcncs.org E-ISSN 2308-9830 (Online) / ISSN 2410-0595 (Print) Introduction to the Optical Communications by Simulating an Optical High Debit Transmission Chain Using OptiSystem with Comparison of Optical Windows ABDELHAKIM BOUDKHIL1, ASMAA OUZZANI2 and BELABBES SOUDINI3 1, 3 Dept. of Electronics, Faculty of Technology, University of Sidi Bel abbes, Sidi Bel Abbes, ALGERIA 2 Dept. of Electronics, Faculty of Technology, University of Saida, Saida, ALGERIA E-mail: 1wboudkhil.abdelhakim@yahoo.fr, 2asma.ouzzani@yahoo.fr, 3sba_soudini@yahoo.fr ABSTRACT This article proposes a global study of an optical high debit chain presenting a complete simulation by comparing between the tree optical windows of telecommunications, led as an experience for teaching optical communications which are currently characterized by a grand demand for their exceptional transmission quality offering high debit, long distance of propagation and strong immunity against noise. The aim of this work extends to introduce the concepts and advantages provided by optical transmission systems using optical fiber, to observe and analyze the various limitations introduced in such systems and also to justify the choice of the optical window according to the use. Keywords: Optical Communication, Laser Diode, Optical Fiber, PIN Photodiode, Optical Windows. 1 INTRODUCTION Since the history of telecommunications knew its birth, the aim of researchers was always to optimize a system which provides more reliable transmission of information, and offers a very high capacity of transport for very long distances with all protection of transmitted information against all disturbances and noise which make the received signal different from that emitted. In this purpose, the crucial key to increase these performances has integrated optoelectronic components into telecommunica-tions systems. Then, a new era was appeared with the revelation of optical communication systems where the interaction between electronic and optical technologies made concretized the hybrid spatiality: Optoelectronics-Telecommunications, allying the intrinsic qualities of optics into transmission systems having enormously progressed [1]. Since that time, the development of communication systems all-optics would be prodigious face the emergence of new telecommunications means (internet, telephony, imagery...) which can be measured today by the number of networks deployed across continents and oceans. Today, we can’t speak about telecommunications systems without mention the optical communication systems. Citing that the capacities of current optical transmissions will be more adequate the next few years, reaching a debit of the scale of Tbit/s characterizing by a growth rate of transmission flow estimated by 25% per year [2], this has motivated us to study a model of an optical high debit communication chain using OptiSystem software by describing its structure and exposing each block as well its main role in the constitution of the transmission chain in order to understand all principles employed in such kind of optical transmission. In this context, E. Cassan [3] studied several simple and multiplexed optical links using COMSIS software, focusing on the major limitations introduced by the various optical components (laser source, optical amplifier, optical fiber...). Equally, D. Bensoussan [4] treated several principles that underlie the various technologies of optical communications in order to understand and conceive practically these optical links with different orders (long range links, short range links, local networks, high speed networks...). 54 A. Boudkhil et. al / International Journal of Computer Networks and Communications Security, 3 (2), February 2015 In view of this importance, we are interested on the simulation of an optical high debit transmission chain using OptiSystem where we propose to exploit and compare between the three optical windows used as spectral regions in optical telecommunications field according to the optical fiber used. Indeed, this work mainly presents: available before the invention of the laser in 1960 [5]. This substance offered the opportunity of sending a luminous signal with enough power over a long distance.  Later, in his “Standard Telecommunications Laboratories” publication of 1964, Charles • First, a history of optical communication by Kao described an optical communication illustrating its chronological development system for a long distance taking advantage and the improvements that it bring into the on the joint use of laser and optical fiber. world of telecommunications. Shortly afterwards, in 1966, he had • Second, an approach about light and its properties in order to describe the luminous wave approved as support in such systems to understand the principle used for propagation in the optical fiber. • Third, a description of the optical communi- experimentally demonstrated in collaboration with Georges Hockman, that it is possible to convey information in form of light over a long distance thanks to optical fiber. This experience was often considered as the first data transmission via optical fiber. cation system studied by exposing its three main blocks: optical emitter, optical channel and optical receiver. • Fourth, a complete simulation of an optical high debit transmission chain using Opti-System where we represent the shape of the transmitted signal at each block, from emission to reception. 2 HISTORY OF OPTICAL COMMUNICATIONS One of the most important problematic that always consists a subject for research is how to transmit signals by using light? This question is not new because lots of optical signals were found able to transmit certain information from very early eras:  For example, at the middle age, smoke signals used by Indians in North America  Gradually, optical communication systems began to plot their development passing through several generations (4 generations). Today, a fifth generation is taking shape by using new techniques such as transmission with soliton, increasing of wavelength numbers, use of fiber based on photonic crystals (μ-structured)… Once these techniques will be mastered, the debit will pass to the Tbit/s. In fact, a debit of 160 Gbit/s to 10 Tbit/s was tested by Alcatel-Lucent researchers who had successfully conveyed a cumulative flow rate of 25.6 Tbit/s over a single fiber that sets a new record in the field of optical transmissions. Now, certain “pseudo-dreamers” are already talking about a debit of Pbit/s that suggests an enormous potential of optical communications in the future [6]. 3 LIGHT IN OPTICAL FIBER were the first old example of optical communications.  Also, along the Rhine Rhone's axe, warning signals were transmitted over dozens of kilometers from castle to castle when detecting danger by using mirrors to reflect sun rays. This simple system had inspired the first modern test of optical communications.  In fact, optical communications were not In order to eventually imagine and conceive the optoelectronic components using for telecomm-unications, it is very interesting to know what is light as well as its properties, this allows approving the optical communications. The light is a form of energy such as electricity. It is composed of minuscule particles called “photons” that move under wave forms (Figure 1). It is generated by the vibration of electrons in atoms [7]. 55 A. Boudkhil et. al / International Journal of Computer Networks and Communications Security, 3 (2), February 2015 Superior orbit Electron Normal orbit Electromagnetic wave Magnetic field Nucleus Luminous wave « photon » Fig. 1. Generation Of Luminous Waves “Photons”. It is a mixture of electric and magnetic waves producing an electromagnetic wave (Figure 2) whose optic physical properties are based on Maxwell's equations reacting on all phenomena of luminous ray propagation [8]. Electric field Fig. 2. Nature Of Electromagnetic Luminous Wave. Total reflection Glass cladding Optical fiber Incident ray n1 Fiber core n2 Reflected ray Total reflection n1: Refraction Index Of The Fiber Core. n2: Refraction Index Of The Fiber Glass Cladding. Fig. 3. Principle Of Luminous Reflection In Optical Fiber. Information « data » Emission module Coding Modulator Power « current » Optical source Luminous signal « laser diode » Optical fiber Optical fiber Photodetector Electrical amplifier Decoding Filter Information « retrieved data » Clock Synchronization Reception module Fig. 4. Schematic Diagram Of The Optical High Debit Communication System Proposed For Study. 56 A. Boudkhil et. al / International Journal of Computer Networks and Communications Security, 3 (2), February 2015 Light is an electromagnetic wave which propagates at a speed depending on the transmission environment, it suggests the principles of geometrical optics: refraction and reflection of which the principle of total reflection (null refraction) is applied to realize elements which guide light, for this, we simply place a material of n1 index between two materials of n2 index in a way where n2 is less than n1 (n2 < n1); this is exactly the principle of optical fiber where the two interfaces forming the glass cladding act as mirrors one facing the other on which luminous ray propagate along the core achieving a total reflection in a waveguide as illustrates the figure 3 [9, 10]. In fact, light is only a vibration created by the circulation of a current on a physical support which is the optical fiber that provides a guided transmission of luminous rays emitted from the optical source “diode” to the optical detector “photodiode”. humidity for example), andminimal attenu-ation. The idea of this optical transmission is still based on the baseband transmission principles (Figure 4) [13, 14]: • First, information is coded in order to increase the transmission gain, converted into a luminous signal and modulated with a coherent monochromatic optical source which is “laser diode”. • After, the optical signal will propagate over a long distance (thousands of miles) through an optical support which is "the optical fiber", this recent innovation which has quickly taken a major role in the world of telecommunications for its capacity to convey a large amount of information over a long distance. As objective, the optical fiber 4 OPTICAL TRANSMISSION SYSTEM presents a waveguide that imprisons luminous rays on the core for propagating In 1948, the American mathematician Claude Shannon was the first one who formulated a theory of information applied to the general model of any system of communication from guided or unguided type, such as radio, wired or optical system where both source and detector constitute two separated entities connected by a channel which presents the support of transmission [11, 12]. In fact, every communication is summarized in three main modules that constitute the transmission chain: without loss by borrowing a zigzag path (Figure 3). In reality, the power luminous wave will be attenuated during its propagation in fiber where losses are due to the fluctuations related at the channel density in a scale lower than the considered wavelength; this phenomenon is known by Rayleigh diffusion. In this case, three wavelength windows (Figure 5) can be used with conventional fibers where the minimum • Emission module that adapts the generated message from the source to the channel. • Channel of communication that presents the physical medium on which the message propagates until the receiver. • Reception module that must reconstruct the emitted massage depending on the received message. attenuation of 0.22 dB/Km is not far from the theoretical minimum of the silica; the difference is explained by the act of the non-usage of the pure silica. It is obligatory to dope either fiber core or glass cladding; this increases the fluctuations of composition and therefore diffusion losses [15, 16]. • Finally, the information can be recuperated at the reception through an optoelectronic • In this purpose, transmit information in conversion ensured by “the photodiode”; the optical manner demands the use of optical fiber as a useful transmission medium to obtain a very important debit for long distance by ensuring enormous electromag- netic immunity (against temperature and information is shaped, demodulated, decoded and corrected, it is finally transmitted. The schematic diagram displayed in figure 4 [14] represents the example of the optical high debit transmission system chosen for simulation. 57 A. Boudkhil et. al / International Journal of Computer Networks and Communications Security, 3 (2), February 2015 Attenuation 5 SIMULATION AND RESULTS (dB/Km) 1.2 0.4 0.2 λ (nm) 850 nm 1300 nm 1550 nm Window 1 Window 2 Window 3 Fig. 5. Spectral Attenuation For Standard Optical Fiber According To The Optical Windows. We have chosen for simulation, the OptiSystem software which permitted to analyze and conceive all optical system modules in form of schematic blocks. We have simulated an optical high debit transmission chain presented in figure 4, in fact, the model of simulation is illustrated in the figure 6 where we have attributed to this chain the following parameters: emitted power Pe = 50 mW, transmission debit D = 10 Gbit/s, laser diode wavelength λ = 1552.52 nm, mono-mode fiber length LFib = 50 Km, PIN photodiode sensitivity S = 0.8 A/W. Fig. 6. Model of Simulation: Optical High Debit Transmission Chain « Pe = 50 mW, D = 10 Gbit/s, λ = 1552.52 nm, LFib = 50 Km, S = 0.8 A/W ». The aim is to study the transmission processes produced in such chain by examining the luminous transmitted signal in every block using a temporal visualization (in terms of time using an optical time domain visualizer) or a spectral visualization(in terms of frequency using an optical spectrum analyzer). The results are respectively represented as following: 5.1 Bit sequence generator It is a binary source which delivers a pseudo-random sequence that represents the emitted information, in other terms, it modules binary symbols (0 or 1) using a function that generates symbols in a random manner, so, this source plays the role of transmitted digital data. We have chosen to use for this simulation a data size of 10 Gbit/s. 5.2 RZ pulse generator This modulator driver modifies high and low pulses of the generated binary sequence (transmitted information) to be modulated. A large number of studies has already compared between RZ and NRZ formats used for modulation : for transmissions which use a unique channel (non-multiplexed transmission), several experiences were demonstrated that performances are better for the RZ format than the NRZ format especially in terms of resistance against non-linear effects, however, for multiplexed transmissions using WDM “Wavelength Division Multiplexing” technique for example, the NRZ format supports 58 A. Boudkhil et. al / International Journal of Computer Networks and Communications Security, 3 (2), February 2015 some penalties in term of transmission contrary to the RZ format; this is due to the greater spectral extension of multiplexed channel comparing with unique channel [17]. For this, we consider the RZ modulation format since we haven't used a multiplexing technique (Figure 7). 5.3 Bias generator It constitutes an electrical source that generates current on the laser input, it used an amplitude of 0.23 equivalent to a power of 50 mW. This value can be varied according to the choice or the necessity. 5.4 Laser diode Due to its advantages offered for high speed optical communications, we have chosen the laser diode as an optical source for the considered chain. This diode is described by its internal physical parameters (wavelength, power, coefficient of differential gain, photon life-time...). At first, we have attributed to the laser a wavelength of 1552 nm which corresponds to the third optical window, after we have respectively used a length of 1300 nm and 850 according to the second and the first optical window in order to compare between these optical windows used in telecommunications as previously presented in the section 4. It is important to mention that the laser output depends on the injected current whose the power is continuous. The emitted laser spectrum is composed of several rays centred on the principal laser length 1552 nm (depending on the optical window), it is characterized by a narrow wavelength providing a small emitted zone to be compatible with the dimensions of the fiber core (Figure 8, a, b). Fig. 7. Emitted Data - RZ Pulse Generator Output. (a) Spectral Visualization Of Laser, λ = 1552 nm.

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