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(IJCSIS) International Journal of Computer Science and Information Security,
Vol. 8, No. 4, July 2010
Improvement of the Performance of Advanced Local Area
Optical Communication Networks by Reduction the Effects
of the Propagation Problems
*
Mahmoud I. Abd-Alla Fatma M. Aref M. Houssien
Electronics & Communication Department, Faculty of Engineering, Zagazig University, EGYPT
Email: mabdalla@gmail.com, *E-mail: fatma_shahin2010@yahoo.com
Abstract
In the present paper, the improvement of transmission distance when the light traveling down a fiber optic cable
and bit rates of Advanced Local Area Optical Communication “spreads out,” becomes longer in wavelength and
Networks (ALAOCN) are investigated by reducing the effects eventually dissipates. Attenuation, a reduction in the
of propagation problems over wide range of the affecting
transmitted power, has long been a problem for the fiber
parameters. Dispersion characteristics in high-speed optical
transmission systems are deeply analyzed over a span of
optics community. However, researchers have
optical wavelengths from 1.2 μm up to 1.65 μm. Two different established three main sources of this loss: absorption,
fiber structures for dispersion management are investigated. scattering, and dispersion [2, 3]. Fiber to the Home
Two types of fabrication material link of single mode fiber (FTTH) technology is one of the main research
made of Germania doped Silica and plastic fibers are objectives of the lasts years in optical fiber
suggested. Two successive segments of single mode fiber communication. The increasing development of data
made of Germania doped Silica are suggested to be employed communications and the emerging of applications
periodically in the long-haul systems. The two successive demand a redesign of the access networks in order to
segments are: i) of different chemical structures (x), or ii) of accomplish new bandwidth and latency requirements.
different relative refractive index differences (Δn). As well as Wireless communications are a good alternative for
the total spectral losses of both fabrication materials and total
insertion losses of connectors and splices of these fabrication
quick deployments and low cost implementations but
materials are presented under the thermal effect of to be this technology cannot compete against optical
processed to handle both transmission lengths and bit rates per communications in terms of available bandwidth,
channel for cables of multi links over wide range of the latency and robustness. Since 1980, several techniques
affecting parameters. Within soliton and maximum time have been proposed and applied to reduce such
division multiplexing (MTDM) transmission techniques, both phenomenon which severely reduces the transmitted bit-
the transmission bit rate and capacity-distance product per rate [4, 5]. The rapid increase of transmission capacity
channels for both of silica doped and plastic fabrication need is requiring higher speed optical communication
materials are estimated. The bit rates are studied within system. However, the upgrade of most installed system
thermal sensitivity effects, loss and dispersion sensitivity
effects of the refractive index of the fabrication core materials
at third window to multi-Giga-bit rate is limited by the
are taken into account to present the effects on the high linear chromatic dispersion of the optical standard
performance of optical fiber cable links. Dispersion fiber deployed worldwide [6, 7]. To upgrade existing
characteristics and dispersion management are deeply studied networks based on standard single-mode 1310 nm
where two types of optical fiber cable core materials are used. optimized optical fibers, several all-optical dispersion
A chromatic dispersion management technique in optical compensation techniques have been proposed [6].Recent
single mode fiber is introduced which is suitable for progress in optical fiber amplifier technology makes
(ALAOCN) to facilitate the design of the highest and the best fiber dispersion the ultimate limiting factor for high-
transmission performance of bit rates in optical networks. speed long-distance optical fiber transmission. Low-
Keywords: Propagation problems, Single mode fiber (SMF), chirp, high-speed optical sources are indispensable for
Fiber losses, Dispersion types, Dispersion management, long-haul multi Giga bit-per-second optical
Soliton Bit rate thermal sensitivity, optical link design, communication systems [7].Traffic demand has been
Thermal effects, Advanced-optical networks. increasing steadily in the last few years. In order to
support this increasing traffic demand the optical links
1. Introduction between the main cities, which are typically terrestrial
links with hundreds of kilometers operating at 10
Fiber optic transmission and communication
Gbit/sec per channel, have to be upgraded. A solution
are technologies that are constantly growing and
for the upgrading of these links is to increase the bit rate
becoming more modernized and increasingly being used
per channel to 40, 80 or even to 160 Gbit/s. Access
in the modern day industries [1]. Dispersion occurs
optical networks are capable of solving those
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(IJCSIS) International Journal of Computer Science and Information Security,
Vol. 8, No. 4, July 2010
requirements for present and future applications. The α S ≡ Rayleigh scattering
⎛ 0 . 75 + 66 Δ n ⎞ ⎛ T
=⎜ ⎟ ⎜
⎞
⎟ dB/km (3)
⎜ ⎟ ⎜T ⎟
recent explosive growth of the internet has triggered the ⎝ λ4 ⎠ ⎝ 0 ⎠
introduction of broadband access network based on Where we have assumed that the scattering loss is
FTTH. To deal with various demands [6], access and linearity is related to the ambient temperature (Τ) and
metro networks require scalability in terms of capacity (T0) is a reference temperature (300 °K), (Δn) and (λ)
and accommodation and flexibility with regard to are the relative refractive index difference and optical
physical topology [7]. Therefore, new specific signal wavelength respectively. The absorption losses (α
components are required. The advanced high speed UV: Ultra-violet losses) and (α IR: Infra-red losses) are
technology of core networks is expected to provide cost given as in reference [14]:
effective migration of the component solutions towards αUV = 1.1×10−4 ω ge 0 0 e 4.9λ dB/km (4)
access applications; however, improvements in terms of 2
⎛ − 24 ⎞
the integration of functions and low cost packaging have α IR = ⎜ 7 × 10−5 e λ⎟ dB/km (5)
⎜ ⎟
⎝ ⎠
to be made. Dense wavelength division multiplexing
(DWDM) is widely becoming accepted as a technology Where (ωge %) is the weight percentage of Germania,
for meeting growing bandwidth, and WDM systems GeO2 added to optical silica fibers to improve its optical
beginning to be deployed in undersea transmission characteristics.
telecommunications links [8, 9]. 2.1.2. Plastic fibers attenuation model
As complexity of optical dense wavelength Plastics PMMA Polymethyl Methacrylate, as all
division multiplexing (DWDM) networks increases due any organic materials, absorb light in the ultraviolet
to the large number of channels involved, managing the spectrum region. The mechanism for the absorption
large spectral variations in the dispersion and gain depends on the electronic transitions between energy
becomes more difficult as the desired spectral bandwidth levels in molecular bonds of the material. Generally the
increases. Dispersion managed soliton, now being electronic transition absorption peaks appear at
developed by a number of different groups, can resolve wavelengths in the ultraviolet region, and their
the technical problems that in the past have prevented absorption tails have an influence on the plastic optical
the use of the soliton transmission format in optical fiber fiber (POF) transmission loss [15]. According to
communication systems [10-12]. Optical solitons are urbach’s rule, the attenuation coefficient αe due to
stable nonlinear pulses formed in optical fibers when the electronic transitions in POF is given by the following
nonlinearity induced by the optical intensity is sufficient expression [15]:
α e (PMMA) = 1.10 × 10 − 5 exp⎜ ⎟ dB/km (6)
⎛8⎞
to balance the dispersion of the fiber. In an ideal lossless ⎜ ⎟
⎝λ⎠
fiber, solitons would not distort in either the time or
Where: (λ) is the optical signal wavelength of light in
frequency domains, regardless of the distance over
(μm). In addition, there is another type of intrinsic loss,
which they propagated. A dispersion managed fiber is
caused by fluctuations in the density, and composition
made by alternating sections of positive and negative
of the material, which is known as Rayleigh scattering.
dispersion fiber to create a transmission line with high
This phenomenon gives the rise to scattering coefficient
local dispersion and low total dispersion [13].
(αR) that is inversely proportional to the fourth power of
2. Modeling Basics and Analysis the wavelength, i.e., the shorter is (λ) the higher the
Special emphasis is given to the propagation losses are. For POF, it is shown that (αR) is [16]:
problems in silica-doped and plastic fibers as promise ⎛ 0.633 ⎞
α R (PMMA) = 13 ⎜ ⎟
4
dB/km (7)
⎝ λ ⎠
links in long and short–distance advanced optical Then the total losses of plastic optical fibers are given:
communication networks. Silica-doped and plastic fibers 4
⎛8⎞ ⎛ 0 .633 ⎞
characteristics (spectral loss and chromatic dispersion) α total (PMMA ) = 1 .10 × 10 − 5 exp ⎜ ⎟ + 13 ⎜ ⎟ dB/km
are thermal dependent, thus, these two variables must be ⎝ λ⎠ ⎝ λ ⎠
taken into account when studying the transmission (8)
capacity of the fibers. The processed propagation
2.1.3. Connector and splice attenuation model
problems in this study will deeply defined, analyzed,
There are many types of connectors developed for
investigated parametrically and treated over wide range
fiber cable. A connector is used to join a fiber cable to a
of the affecting parameters.
transmitter or receiver, or is used to join together strands
2.1. Simplified attenuation model of fiber. A connector for fiber is similar in concept to a
2.1.1. Silica-doped fibers attenuation model traditional electrical connector, but the fiber connector is
Based on the models are given in reference [14], the actually more delicate, as it must precisely align the
spectral losses of silica-doped fibers are cast as: internal fibers to insure a proper flow of data through the
α = α I + α S + α UV + α IR dB/km (1) cables. Before connecting one fiber with the other fiber
Where α I ≡ the intrinsic loss ≅ 0.003 dB/km, and (2) in the fiber optic communication link, one must decide
whether the joint should be permanent or demountable.
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Based on this, two types of joints are presented. A pulse spreading) arises from the use of sources with a
permanent joint is done by splice and a demountable finite spectral spread, since signals impressed on a fiber
joint is done by connector. The insertion loss of any at different wavelengths will have different group
connector can be expressed as given by [17]: velocities. The transit time τ(λ) of a mode at a
⎛ P ⎞ dB/km (9) wavelength (λ) may be related to that at the mean source
IL( Insertion Loss) = 10 log ⎜ i ⎟
⎜P ⎟
⎝ t⎠
wavelength (λo) by expanding as a Taylor series about
Where (Pi) is the incident power in (mWatt) and (Pt) is (λo) as given in [19-21]:
the transmitted power in (mwatt). For single mode fibers
(SMF), the Fresnel reflection loss caused by the dτ 1 d 2τ
τ (λ ) = τ (λo ) + (λ − λo ) + (λ − λo ) 2
differences between the refractive indices of the silica- dλ λ 2 dλ2 λ
o o
doped, (n=n1) and plastic fibers, (n=n2) and the material
separation are given as the following [18]: 1 d 3τ
+ (λ − λo )3 (23)
⎛ 4n n ⎞ 6 dλ3 λo
Loss = 20 log ⎜ 1 clad ⎟ dB/km (10)
⎝ 1 clad ) ⎠
⎜ (n + n 2⎟
dτ 1 d 2τ 1 d 3τ
⎛ 4n n ⎞ Δτ = Δλ + (Δλ ) 2 + (Δλ )3 (24)
Loss = 20 log ⎜ 2 clad ⎟ dB/km (11) dλ λ 2 dλ2 6 dλ3
⎜ (n + n )2 ⎟ o λo λo
⎝ 2 clad ⎠
Lm
Where (n1) is the refractive-index of silica-doped core Noting that: τ = (25)
C
material, and (n2) is the refractive-index of plastic core
material. The cladding refractive-index can be expressed Where (L), (C), and (m) are the fiber length, the velocity
as a function of both silica-doped and plastic core of light in vacuum, and the group index for the mode
refractive-indices and relative refractive-index respectively, (m) is given by assuming good
dn1
difference as the following: confinement in [20]: m = n1 − λ (26)
dλ
nclad = (1 − Δn ) n1 (12)
We can deduce that
nclad = (1 − Δn ) n2 (13)
L ⎡ dn1 ⎤
Then by substituting with equations (12, 13) into τ= ⎢n1 − λ dλ ⎥ (27)
C ⎣ ⎦
equations (10, 11), we can obtain: The use of Eq. (27) into Eq. (24) yields per unit length:
⎛ 4 (1 − Δn ) n 2 ⎞
Loss (silica − doped ) = 20 log ⎜ 1 ⎟ dB/km (14) ⎡ d 3n ⎤
⎜ (2 n − Δn ⋅ n )2 ⎟ Δλ d 2 n1 (Δλ ) 2 ⎢λ
2
1 + d n1 ⎥
⎝ 1 1 ⎠ Δτ = .λ −
⎛ 4 (1 − Δn ) n 2 ⎞
C dλ2 2C ⎢ dλ3
⎣ dλ2 ⎥
⎦ λo
dB/km (15) λo
Loss ( plastic ) = 20 log ⎜ 2 ⎟
⎜ (2 n − Δn ⋅ n )2 ⎟
⎝ 2 2 ⎠
2.2. Simplified dispersion model analysis (Δλ )3 ⎡ d 4 n1
⎢λ d 3n1 ⎤
⎥ (28)
− +2
2.2.1. Silica-doped fiber dispersion model 6C ⎢ dλ 4
dλ3 ⎥
⎣ ⎦ λo
We have employed Germania-doped Silica fiber as
a communication channel, where (x) is the mole fraction Where higher-order dispersion modes are considered,
of Germania added to silica material. The refractive following the same spirit of Refs. [20, 21], in separating
index of silica-doped material may be evaluated the various contributions to the total chromatic
following the three terms Sellmeier equation [19]: dispersion in single mode fibers of radius (a), we have:
2 3 Ai λ2 (Δτch/Δλ.L) = Dt = total chromatic dispersion
n1 = 1 + ∑ (16)
2
i =1 λ − λi 2 coefficient= (Mmd + Mwd + Mpd), (29)
Where: Mmd = material dispersion coefficient
Where (n1), (λ), (Ai), and (λi) are the core refractive
⎡ ⎤
index, the oscillator strength and the oscillator wave λ d 2 n1 Δλ ⎢ d 3n1 d 2 n1 ⎥
= + λ +
length respectively. For GeO2-SiO2 fibers of x % GeO2 C dλ2 2C ⎢ dλ3 dλ2 λ ⎥
⎥
λo ⎢
⎣ o⎦
(mole), the two sets (Ai) and (λi) are given [19]:
A1 = (0.6961663 + 0.11070010 x) fT 1 , (17) ⎡ ⎤
(Δλ ) 2 ⎢ d 4 n1 d 3n1 ⎥
A2 = (0.4079426 + 0.31021588 x) f T 1 , (18) − λ +2 (30)
6C ⎢ dλ4 dλ3
⎥
⎢
⎣ λo ⎥
⎦
A3 = (0.8974794 − 0.04331091x) f T 1 , (19)
Mwd = waveguide dispersion coefficient
λ1 = (0.0684043 + 0.00568306 x) f T 2 , (20) 2
λ 2 = (0.1162414 + 0.03772465x) f T 2 , (21) n Δn ⎛ m ⎞
= 1. ⎜ ⎟ M (V ) (31)
C λ ⎜ n1 ⎟
⎝ ⎠
And λ3 = (9.896161 + 1.94577 x) f T 2 . (22)
Where fT1=0.93721+2.0857x10-4T, fT2=T0/T, (T0) is a Mpd = profile dispersion coefficient
reference temperature and T is the medium (fiber n Δn \ ⎛ λ Δn \ m ⎞
= 1 ⎜ − ⎟ M (V ) (32)
temperature) [19-21]. Chromatic dispersion (a cause of C ⎜ 4 Δn n1 ⎟
⎝ ⎠
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(n1 − nclad ) 1
Δn = (33) ⎛ ⎛ N Δn ⎞2 ⎛ α − 2 − ε ⎞ 2 2α ⎞
2
n1 P = ⎜⎜ 1 ⎟ ⎜ ⎟ × ⎟ (46)
⎜ ⎝ cλ ⎠ ⎝ α + 2 ⎠ 3α + 2 ⎟
\dΔn ⎝ ⎠
Δn = (34)
dλ Where the group index for the mode is given by:
dn2
V = 2π 2
a n12 − nclad / λ , and (35) N1 = n2 − λ (47)
dλ
2 Where: (Δτ) is the total pulse spreading due to chromatic
M (V ) = 0.08 + 0.549(2.834 − V ) (36)
dispersion in nsec, (Wmd) is the material dispersion
Equation (30), in our suggested basic model, accounts coefficient in nsec/nm.km, (P) is the profile dispersion
for the material dispersion (the first, the second, and the coefficient in nsec/nm.km, and (Δn) is the relative
third -order dispersion effects simultaneously). Then the refractive index difference defined as:
use of Eq. (16) yields:
n2 − ncladding
2 2
(48)
2
3 − Ai λi λ Δn =
n1n1\ = ∑ (37) 2
2 n2
(
i =1 λ2 − λ2 2
i ) Where (n2) is the cable core refractive index, (ncladding) is
3 A λ2 (3λ3 + λi )
2 the core cladding refractive index, and (C1) is a constant
n1n1\ \ + n1\ 2 = ∑ i i , and (38)
i =1 (
λ2 − λi2 3
) and is given by the following expression:
α − 2−ε
C1 = (49)
2 2
3 − 12 Ai λi λ (λ2 + λi )
n1n1\ \ \ + 3n1\ n1\ \ = ∑ (39) α +2
i =1 (
λ2 − λi2 4
) Where (α) is the index exponent, (ε) is the profile
2 2 2 2
3 12 AiT λiT (5λ4 + 10λiT λ2 + λiT )
dispersion parameter, and is given by the following:
n1n1\ \ \ \ + 4n1\ n1\ \ \ + 3n1\ \ = ∑ 2 n λ dΔn
i =1 λ2 − λiT
2
(
5
) ε =− 2
N1 Δn dλ
(50)
(40)
2.2.2. Plastic fiber dispersion model 3. Transmission Techniques for Reducing
The plastic cable core material which the Propagation Problems
investigation of the spectral variations of the refractive- The need of communication is an all time need
index (n2) requires Sellemeier equation given in [22]: of human beings. For communication some channel is
needed. Fiber is one channel among many other
2 3 Bi λ2
n2 = 1 + ∑ (41) channels for communication. The dispersion
2
i =1 λ − λi 2
phenomenon is a problem for high bit rate and long haul
For the plastic fiber material, the coefficients of the optical communication systems. An easy solution of this
Sellmeier equation and refractive-index variation with problem is optical solitons pulses that preserve their
ambient temperature are [22]: B1= 0.4963, λ1= 0.6965 shape over long distances. Soliton based optical
(T/T0), B2= 0.3223, λ2= 0.718 (T/T0), B3= 0.1174, and communication systems can be used over distances of
λ3= 9.237. Then the first and second differentiation of several thousands of kilometers with huge information
Eq. (41) with respect to (λ) yields: carrying capacity by using optical amplifiers. Soliton
2 communication systems are a leading candidate for
3 − Bi λi λ
n2 n2 \ = ∑ (42) long-haul light wave transmission links because they
i =1 (λ2 − λi2 )2 offer the possibility of dynamic balance between group
3 Bi λi (3λ3 + λi )
2 2 velocity dispersion (GVD) and self-phase modulation
n2 n2 \ \ + n2 \ 2 = ∑ (43)
i =1 (λ2 − λi23
) (SPM), the two effects that severely limit the
performance of non soliton systems. Most system
The total chromatic dispersion ( Dt ) of the output pulse experiments employ the technique of lumped
width in single mode fibers of (POF) is given by [22]: amplification and place fiber amplifiers periodically
Δτ along the transmission line for compensating the fiber
Dt = = ( W md + P ) nsec/nm.km (44) loss. However, lumped amplification introduces large
Δλ ⋅ L
peak-power variations, which limit the amplifier spacing
The output pulse width from single mode plastic optical to a fraction of the dispersion length. Soliton
fiber (POF) was taken into account both material and propagation is employed where the controlling
profile dispersions, and thus modal dispersion is equal to parameters lead to a balance between the pulse
zero for single mode fibers [23]: spreading due to dispersion and the pulse shrinking due
1
⎛ λ3 dn 2λ ⎛ d 2 n2 ⎞ ⎞ 2 to nonlinearity. The balance between the non-linearity
Wmd = ⎜ − 2 ⎜ ⎟ (N Δn ) × C ⎛ 2α ⎞ ⎟
⎜ c dλ − c ⎜
⎜ 2 ⎟ 1 1⎜ ⎟⎟
⎝ α + 2 ⎠⎟
effects from one side and the dispersion effects from the
⎝ ⎝ dλ ⎠ ⎠ other side creates a solitary wave [24]. The dispersion of
(45) a medium (in the absence of non-linearity) makes the
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various frequency components propagate at different Where: (nnl) is the nonlinear Kerr coefficient in m2/watt,
velocities; while the non-linearity (in the absence of (Aeff) is the effective area in µm2/Watt,
dispersion) causes the pulse energy to be continually (Pso) is the optical signal power in Watt,
injected, via harmonic generation, into higher frequency (λs) is the optical signal wavelength in µm,
modes. That is to say, the dispersion effect results in and (Dt) is the total chromatic dispersion coefficient in
broadening the pulse while the non-linearity tends to nsec/nm.km. Ref. [27] derived the condition for MTDM
sharpen it. Analysis given in references [25, 26], the where the bit rate Brm is given by:
soliton bit rate per channel (Brs) is given by: 0.25
Brm = Gbit / sec (52)
− − λ Aeff 3.2 x10 −20 τ min
Brs2 = 59.7 Pso1( s )( )( ) Dt x106 (51)
1.54 20 nnl
Where: (τmin) is the minimum pulse broadening in nsec. B
S Drm =
D dBrm
. . = .
2
(
2 2 3 4 3 3 2
D 14.7 λs Aeff B1 A1 λs + T B2 A1 λs )2
The spectral and thermal sensitivities are the guide of Brm dD Brm
(
nnl Pso T B1 A2 λs − A2 B1 λ4
2 3 2 2 4
)3
the measurement the relative variations of the outputs
s
and the relative variations of the inputs. The soliton and (58)
MTDM bit rate within thermal, loss, dispersion Using the series of the set of equations analysis
sensitivity coefficients, and parameters as ( ST ), Brs
from Eq. (1) to Eq. (59), the transmission bit rates per
( Sα ), ( S D ), ( ST ), ( Sα ), and ( S D ) are taken
Brs Brs Brm Brm Brm channel for both silica-doped and plastic materials are
investigated under wide optical ranges which give the
into account as criteria of a complete comparison
minimum values of both total losses and total
between silica doped and plastic materials and are given:
dispersion. The calculations are based on the values:
T dBrs T A1 B1 3λ3 B1 + Dt λ1
2 2
( 2
) (53)
Central optical signal wavelength (λ0) is selected to be
( )
B
ST rs = . = .
Brs dT Brs λ3 − A2 B 2 + Dt2λ2 A2 B 3
(1.2 μm ≤ λ0 ≤ 1.65μm), relative refractive index
1 2 2
B
Sα rs =
α
.
dBrs
=
α 0.633 B1 α t 2λs A1B3 T + λs A2 B1 T
.
2 2
(
2 2 4 3 4 3
)
2
(54) difference for silica-doped material (Δn) is chosen to be
Brs dα Brs 2
( 3 3 2 33
A1 λs T + α t B2 λs ) ( 0.006 ≤ Δn ≤ 0.008 ), source spectral line width (Δλ) is
selected to be (0.1 nm ≤ Δλ ≤ 0.5 nm), GeO2 mole
B
S Drs =
D dBrs
. = .
2 2 2 3 3
(3 3 2
D 14.7 λs Aeff A1 B1 T λs + A2 B1 λs )
3
(55) fraction (x) is chosen to be ( 0.0 ≤ x ≤ 0.2 ), relative
Brs dD Brs 3 2
(2 2 4 42
nnl Pso A1B2 λs − T B2 A1 λs ) refractive index difference for plastic material (Δn) is
determined where ( 0.05 ≤ Δn ≤ 0.07 ), and fiber
B
ST rm =
T dBrm
. =
2 2 3 2 3 3
T B1 A2 4 λ A1 + Dt λ1 A2 B2
.
( ) (56) temperature (T) is chosen to be (290°K ≤ T ≤ 330°K).
Brm dT Brm 2 2 2
(3 2 4 2
λ + B2 A3 − Dt λB2 A2 )
B
Sα rm =
α
.
dBrm
=
α
2
s (
0.633 A1 α t 2λ2 B1 A3 T 5 + λ4 B2 A1
2
s
3 4 )2
dα .
Brm Brm
(2 2 3
B1 λs α t5 + T 2 A2 λ3
s )
(57)
4. Results and Discussions
We have analyzed the propagation problems of ambient temperature (T0 ), and relative refractive-index
these materials in the interval of 1.2 µm to 1.65 µm difference (Δn)}, both the effective performance of
under the set of affecting parameters at temperature plastic, and Germania-doped silica fibers are processed
range varies from 290 °K to 330 °K. The following based on the transmission bit rate or capacity-distance
numerical sets of data are used to obtain transmission bit product per channel: Transmitted bit-rate x transmission
rate and capacity-distance product per channel as distance (L) is given by:
follows: (1.2 μm ≤ λ0 ≤ 1.65 μm); (λ0): central optical Pr = B r × L , Gbit.km/sec (59)
signal wavelength, (0.1 nm ≤ Δλ ≤ 0.5 nm); (Δλ): The transmitted bit-rate per optical channel is also a
spectral line width of the optical source, effective area; special criterion for comparison for different fiber cable
Aefff= 85 µm2, (2 Km ≤ L ≤ 10 Km); (L): transmission materials of plastic and silica-doped fibers. Based on the
distance, (0.0 ≤ x ≤ 0.2); (x): percentage of Germania clarified variations in figures (1- 20), the facts are
doped in silica fibers, (0.05 ≤ ΔnPMMA ≤ 0.07); assured:
(ΔnPMMA): relative refractive-index difference, (0.006 ≤
Δnsilica-doped ≤ 0.008), (Δnsilica-doped): relative refractive-
index difference for silica-doped, (4 mwatt ≤ Ps ≤ 30
mwatt); (Ps): optical signal power. At the set of
affecting parameters {optical signal wavelength ( λs),
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i- Figs. (1, 2) prove that as λ0 increases, the total spectral T increases, total dispersion coefficient also increases
losses decrease at constant both T, and Δn for silica- at constant λ0.
doped fibers. But as Δn, and T increase, the total vi- Figs. (11, 12) indicate that as the Pt increases, the
spectral losses also increase at constant λ0. total insertion loss decreases for both silica-doped and
ii- Figs. (3-4) indicate that as L increases, the plastic fibers at constant Δn. As well as Δn increases,
transmission bit rate per channel decreases for both the total insertion loss also increases at constant Pt.
silica-doped and plastic fibers at constant T. As well vii- Figs. (13, 14) demonstrate that as L increases, the
as T increases, the transmission bit rate per channel transmission bit rate per channel decreases for both
decreases at the constant L. silica-doped and plastic fibers at constant Δn. But
iii- Figs. (5-6) assure that as T increases, the capacity- as Δn increases, the transmission bit rate per
distance product per channel decreases for both channel decreases at constant L.
silica-doped and plastic fibers at constant L. viii- Figs. (15, 16) assure that as Dt increases, the soliton
Moreover as L increases, the capacity-distance and MTDM bit rates decrease for both silica-doped
product per channel also increases at constant both and plastic materials, but with silica-doped presents
T. higher bit rates than plastic materials at minimum
iv- Figs. (7, 8) demonstrate that as λ0 increases, total losses.
dispersion coefficient also increases for both silica- x- Figs. (17, 18) indicate that as T increases, Soliton
doped and plastic fibers at the constant Δn. As well as bit rate thermal sensitivity also increases at constant
Δn increases, total dispersion coefficient also Dt, but with increasing Dt, we have observed that
increases at constant λ0. soliton bit rate thermal sensitivity deceases at
v- Figs. (9, 10) prove that as λ0 increases, total constant T for both silica-doped and plastic
dispersion coefficient also increases for both silica- materials.
doped and plastic fibers at the constant T. As well as
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(IJCSIS) International Journal of Computer Science and Information Security,
Vol. 8, No. 4, July 2010
xi- Figs. (19, 20) prove that as T increases, MTDM bit technique and offers the best conditions for the
rate thermal sensitivity also increases at constant Dt, performance of transmission bit rates and capacity-
but with increasing Dt, we have observed that distance products of silica-doped and plastic materials
MTDM bit rate thermal sensitivity increases at for different transmission distances in advanced local
constant T for both silica-doped and plastic area optical communication networks for suitable
materials. operating conditions as shown in Table 1.
Therefore we can summarize reduction of the
propagation problems within soliton transmission
Table 1: Transmission bit rates and capacity-distance product for both silica-doped and plastic core materials.
Fiber cable core materials
Silica-doped material Plastic material
Best conditions of operation Best conditions of operation
Transmission at Δn = 0.006 and T = 290 ºK at Δn = 0.05 and T = 290 ºK
Distance Capacity-distance Capacity-distance
Transmission bit product/channel Transmission bit product/channel
rate/channel (Gbit/sec) (Gbit.km/sec) rate/channel (Gbit/sec) (Gbit.km/sec)
L = 2 Km 8 Gbit/sec 30 Gbit.km/sec 0.5 Gbit/sec 1.5 Gbit.km/sec
L = 5 Km 5 Gbit/sec 45 Gbit.km/sec 0.3 Gbit/sec 2 Gbit.km/sec
L = 8 Km 2 Gbit/sec 60 Gbit.km/sec 0.1 Gbit/sec 2.5 Gbit.km/sec
5. Conclusions fibers will be increased. Therefore we can say that the
The characteristics of both of silica doped and lowest total dispersion and total losses of silica-doped
plastic fibers are investigated under the different fibers make these fibers as the best candidate media for
affecting parameters. soliton and MTDM high long haul optical transmission in advanced optical
transmission techniques are employed for reducing the communication networks.
propagation problems as limiting factors such as total
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