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High Performance Efficiency of Distributed Optical FiberRaman Amplifiers for Different Pumping Configurations inDifferent Fiber Cable Scheme Schemes

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High Performance Efficiency of Distributed Optical FiberRaman Amplifiers for Different Pumping Configurations inDifferent Fiber Cable Scheme Schemes Powered By Docstoc
					                           International Journal of Computer Science and Network (IJCSN)
                   Volume 1, Issue 1, February 2012 www.ijcsn.org ISSN 2277-5420



      High Performance Efficiency of Distributed Optical Fiber
     Raman Amplifiers for Different Pumping Configurations in
                                        Schemes
                  Different Fiber Cable Schemes
                    1
                        Abd El–Naser A. Mohamed, 2Ahmed Nabih Zaki Rashed, 3Mahmoud M. A. Eid
                               1,2,3
                                  Electronics and Electrical Communication Engineering Department
                           Faculty of Electronic Engineering, Menouf 32951, Menoufia University, EGYPT



Abstract                                                           for the much slower electrical processing to occur had to
Fiber Raman amplifiers (FRAs) are attractive for ultra wide        be built into the system. In order to overcome the
dense wavelength division multiplexing (UW-DWDM)                   limitations imposed by electrical regeneration, a means of
transmission systems due to their advantages of broad              optical amplification was sought. Two competing
amplification bandwidth and flexible central wavelength. With
                                                                   technologies emerged: the first was erbium-doped fiber
recent developments of optical pump sources with high power
near 1.4 µm wavelength and highly nonlinear fiber having a
                                                                   amplifiers (EDFA) [2, 3] and the second Raman
peak effective Raman gain coefficient more than ten times that     amplification [4]. In the first deployed systems EDFA
of conventional single mode fiber, distributed FRAs (DFRAs)        emerged as the preferred approach. One reason was that
are emerging as a practical optical amplifier technology,          the optical pump powers required for Raman
especially for opening new wavelength windows such as the          amplification were significantly higher than that for
short and ultra long wavelength bands. Optical pump powers         EDFA, and the pump laser technology could not reliably
required for Raman amplification were significantly higher than    deliver the required powers. However, with the
that for Erbium doped fiber amplifier (EDFA), and the pump         improvement of pump laser technology Raman
laser technology could not reliably deliver the required powers.
                                                                   amplification is now an important means of expanding
However, with the improvement of pump laser technology
Raman amplification is now an important means of expanding
                                                                   span transmission reach and capacity [5].
span transmission reach and capacity. In the present paper, we           In a multiple wavelength telecom system it is
have deeply investigated the proposed model for optical            important that all signal wavelengths have similar optical
distributed fiber Raman amplifiers in the transmission signal      powers. The variation in the gain provided to different
power and pump power within Raman amplification technique          wavelengths after passing through an amplifier is referred
in co-pumped, counter-pumped, and bi-directional pumping           to as the gain flatness. If the signal at one wavelength is
direction configurations through different types of fiber cable    disproportionately amplified, as it passes through several
media. The validity of this model was confirmed by using           amplifiers, it will grow super linearly relative to the other
experimental data and numerical simulations.                       channels reducing the gain to other channels [6]. The
Keywords: Distributed fiber Raman amplifier, Signal power,         system, however, will still be limited by the channel with
Pumping power, Forward pumping, Different fiber media,             the lowest gain. As a result, after each amplifier the gain
Backward pumping, and Bidirectional pumping configuration.         spectrum generally is flattened. One approach is to insert
                                                                   wavelength-dependent lossy elements, within the
1. Introduction                                                    amplifier, with the appropriate spectral profile. Raman
      The first fiber optical telecommunication systems            amplification offers the ability to achieve this without
emerged with the engineering of low loss optical fiber [1].        lossy elements. In Raman amplification a flat spectral
Even though the complexity of the system has increased,            profile can be obtained by using multiple pump
the basic elements remain the same. They consist of an             wavelengths [7, 8]. For a given fiber the location of the
optical source, a means of modulating the source, the              Raman gain is only dependent on the wavelength of the
transmission medium (i.e., the optical fiber), and a               pump, the magnitude of the gain is proportional to the
detector at the output end of the fiber. Fiber loss is one         pump power, and the shape of the gain curve is
limitation to the transmission distance of this system. In         independent of the pump wavelength. Therefore, if
the early days of fiber-optic communications the loss of           multiple pumps are used a flat spectral gain profile can be
the fiber was compensated for in long spans by using               obtained [9]. The required pump wavelengths and the gain
electrical regenerators. As their name implies, these              required at each wavelength can be predicted by summing
devices detected the signal, converted it to an electrical         the logarithmic gain profiles at the individual pump
signal, and using a new laser transmitted a new version of         wavelengths [10].
the signal. Electrical regenerators were expensive and also              In the present study, we have deeply analyzed the
limited the rate at which data could be transmitted as time        signal power, pumping power, rate of change of signal,
                            International Journal of Computer Science and Network (IJCSN)
                    Volume 1, Issue 1, February 2012 www.ijcsn.org ISSN 2277-5420

pumping powers with respect to transmission distance           both of the pump can be equal or different in the used
under the variations of signal, pump powers and signal         wavelength or the used amount of power, therefore in this
and pump wavelengths for different fiber link media in         case the following equation can be used to calculate the
different pumping direction configurations (forward,           pump power at point z [14]:
backward, and bi-directional) over wide range of the
operating parameters.
                                                                      PFB                         (       )
                                                                     P (z) = (rf)PpoFexp−αLp z +(1−rf ) PpoBexp−αLp(L− z)     [    ]
                                                                                                             (8)
                                                               Where rf is the percentage of pump power launched in the
2. Modeling Analysis
                                                               forward direction. If the values of PP are substituted in
     Signals fad with distance when they traveling through
                                                               differential Eq. (2), and is integrated from z=0 to z=L for
any type of media. As the optical signal moves along a
                                                               the signal power in the forward and the backward
SMF, it gets attenuated along the fiber. The signal power
when it travels through the distance z without any             pumping the result mathematical equation can be written
amplification, PsWNA can be expressed as following:            as mentioned in [13]:
      PsWNA (z ) = Pso exp (−α Ls z )        (1)                                        g                      
                                                                     PS (z ) = Pso exp  R            P L − α z  (9)
                                                                                        Aeff         po eff Ls
    Systems avoid this problem by amplifying signals                                                           
                                                                                                                  
along the way. So there is a need for using optical fiber      where Pso and Ppo denotes to the input signal and pump
amplifiers. The evolution of the input signal power (Ps)       power respectively. This means that Ppo = PpoF in case of
and the input pump power (Pp) propagating along the            forward pump and Ppo=PpoB in case of backward pump,
single mode optical fiber in watt; can be quantitatively       and Leff, is the effective length in km, over which the
described by different equations called propagation            nonlinearities still holds or SRS occurs in the fiber and is
equations. The rate of change of signal and pump power         defined as [15]:
with the distance z, can be expressed as mentioned in
                                                                     Leff =
                                                                                         (
                                                                               1 − exp − α Lp z   )                       (10)
[11]:
                                                                                     α Lp
      dPp                  λ
         = −α Lp Pp ( z ) − s g Re ff Ps ( z ) Pp ( z ) (2)    Recently, there have been many efforts to utilize fiber
      dz                   λp
                                                               Raman amplifier (FRA) in long-distance, high capacity
      dPs                   λ                                  WDM systems. This is mainly because FRA can improve
          = −α Ls Ps ( z ) + s g Re ff Ps ( z ) Pp ( z ) (3)
       dz                   λp                                 the optical signal to noise ratio (OSNR) and reduce the
Where λs and λp are the signal and pump wavelengths in         impacts of fiber nonlinearities [16].
µm respectively, z is the distance in km from z=0 to z=L,
αLs and αLp are the linear attenuation coefficient of the      3. Simulation Results and Analysis
signal and pump power in the optical fiber in km-1                   In the present study, the optical distributed Raman
respectively, The linear attenuation, αL can be expressed      amplifiers have been modeled and have been
as:                                                            parametrically investigated, based on the coupled
       α L = α /4.343                       (4)                differential equations of first order, and also based on the
Where α is the attenuation coefficient in dB/km. gReff is      set of the assumed of affecting operating parameters on
the Raman gain efficiency in W-1km-1 of the fiber cable        the system model. In fact, the employed software
length, L in km, which is a critical design issue and is       computed the variables under the following operating
given by the following equation:                               parameters as shown in Table 1.
                        gR                                     Table1. Vvalues of operating parameters in proposed model.
       g Reff =                             (5)
                  A eff × 10 − 18                               Operating
                                                                                 Symbol                           Value
Where gR is the maximum Raman gain in km W-1, Aeff the          parameter
effective area of the fiber cable used in the amplification    Operating
in µm2. Equation (1) can be solved when both sides of the      signal               λs                     1.45 ≤ λs, µm ≤ 1.65
equation are integrated. When using forward pumping, the       wavelength
pump power can be expressed as the following expression        Operating
[12]:                                                          pump                 λp                     1.40 ≤ λp, µm ≤ 1.44
       PPF (z ) = P poF exp (− α Lp z )       (6)              wavelength

Where PPoF , is the input pump power in the forward            Input signal
                                                                                    Pso                   0.002 ≤ Pso, W ≤ 0.02
direction in watt at z=0.                                      power
In the backward pumping the pump power is given by             Input pump
[13]:                                                          power
                                                                                   Ppo                    0.165 ≤ Ppo, W ≤ 0.365
       PPB (z ) = PpoB exp [− α Lp (L − z )]  (7)
                                                               Percentage of
Where PPoB , is the input pump power in the backward                                rf                             0.5
                                                               power
direction in watt at z=L. In the case of bi-directional pump
                             International Journal of Computer Science and Network (IJCSN)
                     Volume 1, Issue 1, February 2012 www.ijcsn.org ISSN 2277-5420

launched in                                                    parameters as displayed in Figs. (5-11), these figures
forward                                                        clarify the following results:
direction                                                          a- Without any amplification: with increasing
Attenuation                                                            distance, z, the output signal power decreases
of the signal                                                          exponentially.
power       in     αS                 0.25 dB/km
                                                                   b- In case of forward direction:
silica-doped
                                                                     1) For certain value of initial pumping power:
fiber
                                                                         i. Initial pumping power = 0.165 mW, for
Attenuation
of the pump
                                                                              distance z ≤ 2 km, the output signal power
power       in     αP                 0.3 dB/km                               increases exponentially, and for z ≥ 2 km, the
silica-doped                                                                  output signal power decreases exponentially.
fiber                                                                    ii. Initial pumping power = 0.265 mW, for
  Types of fiber cable    Truewave   LEAF                                     distance z ≤ 8 km, the output signal power
                                            SMF-28    Unit
        media
                            reach    (NZ-
                                            (NDSF)                            increases exponentially, and for z ≥ 8 km, the
                            fiber    DSF)                                     output signal power decreases exponentially.
Effective
                  Aeff       55       72     84.95   (µm) 2
                                                                        iii. Initial pumping power = 0.365 mW, for
Area                                                                          distance z ≤ 13 km, the output signal power
Raman Gain                                           (W.km)-
                                                                              increases exponentially, and for z ≥ 13 km,
                  gReff     0.6      0.45     0.38      1                     the output signal          power     decreases
Efficiency
                                                                              exponentially.
The following points of discussion will cover all operating          2) For certain value of distance z:
design parameters of multiplexing/demultiplexing based                   i. With increasing the initial pumping power,
optical distributed Raman amplifier device, such as, input                    the output signal power also will increase.
signal power, input pumping power, operating signal                      ii. With increasing the initial signal power, the
wavelength, operating pump wavelength, and different                          output signal power also will increase.
fiber link media. Then based on the basic model analysis             3) After using different media of optical fiber cable,
and the set of the series of the following figures are shown              it is indicated that the true wave reach fiber
below, the following facts can be obtained:                               presented the best results.
                                                                   c- In case of backward direction:
3. 1. Variations of the output pumping power, Pp                          The results are the same as in case of forward
      Variation of the output pumping power, Pp is                        direction.
investigated against variations of the controlling set of          d- In case of bi-directional:
parameters as displayed in Figs. (1-4), these figures               1) For certain value of initial pumping power:
clarify the following results:                                           i. Initial pumping power = 0.165 W, for
    a- In case of forward direction:                                          distance z ≤ 1 km, the output signal power
            i. As distance z increases, the output                            increases exponentially, for 1 ≤ z, km ≤50 the
                 pumping power decreases exponentially.                       output signal power decreases exponentially,
           ii. For certain value of distance z, with                          and for z ≥ 50 km, the output signal power
                 increasing the initial pumping power, the                    increases exponentially again.
                 output pumping power also will increase.                ii. Initial pumping power = 0.265 W, for
    b- In case of backward direction:                                         distance z ≤ 8 km, the output signal power
            i. As distance z increases, the output                            increases exponentially, for 8 ≤ z, km ≤49 the
                 pumping power increases exponentially.                       output signal power decreases exponentially,
           ii. For certain value of distance z, with                          and for z ≥ 49 km, the output signal power
                 increasing the initial pumping power, the                    increases exponentially again.
                 output pumping power also will increase.               iii. Initial pumping power = 0.365 W, for
    c- In case of bi-directional:                                             distance z ≤ 13 km, the output signal power
           i.    For z ≤ 50 km, the output pumping power                      increases exponentially, for 13 ≤ z, km ≤ 48
                 decreases exponentially, and for z ≥ 50                      the output signal          power     decreases
                 km, PpFB increases exponentially.                            exponentially, and for z ≥ 48 km, the output
          ii.    For certain value of distance z, with                        signal power increases exponentially again.
                 increasing the initial pumping power, the          2)        For certain value of distance z:
                 output pumping power also will increase.                i. With increasing the initial signal power, the
3. 2. Variations of the output signal power, Ps                               output signal power also will increase.
     Variation of the output signal power, Ps is                         ii. With increasing the initial pumping power,
investigated against variations of the controlling set of                     the output signal power also will increase.
                         International Journal of Computer Science and Network (IJCSN)
                 Volume 1, Issue 1, February 2012 www.ijcsn.org ISSN 2277-5420

    3) After using different media of optical fiber cable,
       it is indicated that the true wave reach fiber
       presented the best results.




Fig. 1. Variations of pump power in different configurations against variations of distance at the assumed set of the
         operating parameters.




Fig. 2. Variations of pump power in forward direction against variations of distance z at the assumed set of the operating
          parameters.
                         International Journal of Computer Science and Network (IJCSN)
                 Volume 1, Issue 1, February 2012 www.ijcsn.org ISSN 2277-5420




Fig. 3. Variations of pump power in backward direction against variations of distance z at the assumed set of the operating
           parameters.




Fig. 4. Variations of pump power in bi-directional case against variations of distance z at the assumed set of the operating
          parameters.
                         International Journal of Computer Science and Network (IJCSN)
                 Volume 1, Issue 1, February 2012 www.ijcsn.org ISSN 2277-5420




Fig. 5. Variations of signal power in different configurations against variations of distance z at the assumed set of the
          operating parameters.




.
Fig. 6. Variations of signal power in forward direction against variations of distance z at the assumed set of the operating
          parameters.
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                 Volume 1, Issue 1, February 2012 www.ijcsn.org ISSN 2277-5420




Fig. 7. Variations of signal power in forward direction against variations of distance z at the assumed set of the operating
          parameters.




Fig. 8. Variations of signal power in forward direction against variations of distance z at the assumed set of the operating
          parameters.
                          International Journal of Computer Science and Network (IJCSN)
                  Volume 1, Issue 1, February 2012 www.ijcsn.org ISSN 2277-5420




Fig. 9. Variations of signal power in bi-directional case against variations of distance z at the assumed set of the operating
           parameters.




Fig. 10. Variations of signal power in case of bi-directional case against variations of distance z at the assumed set of the
          operating parameters.
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                 Volume 1, Issue 1, February 2012 www.ijcsn.org ISSN 2277-5420




Fig. 11. Variations of signal power in bi-directional case against variations of distance z at the assumed set of the
          operating parameters.




Fig. 12. Variations of rate of change of pump power in different configurations against variations of distance z at the
          assumed set of the operating parameters.
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                 Volume 1, Issue 1, February 2012 www.ijcsn.org ISSN 2277-5420




Fig. 13. Variations of rate of change of pump power in forward direction against variations of distance z at the assumed
          set of the operating parameters.




Fig. 14. Variations of rate of change of pump power in forward direction against variations of distance z at the assumed
          set of the operating parameters.
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                 Volume 1, Issue 1, February 2012 www.ijcsn.org ISSN 2277-5420




Fig. 15. Variations of rate of change of pump power in backward direction against variations of distance z at the assumed
          set of the operating parameters.




Fig. 16. Variations of rate of change of pump power in bi-directional case against variations of distance z at the assumed
          set of the operating parameters.
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                 Volume 1, Issue 1, February 2012 www.ijcsn.org ISSN 2277-5420




Fig. 17. Variations of rate of change of pump power in bi-directional pumping case against variations of distance z at the
          assumed set of the operating parameters.




Fig. 18. Variations of rate of change of signal power in different configurations against variations of distance z at the
          assumed set of the operating parameters.
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                 Volume 1, Issue 1, February 2012 www.ijcsn.org ISSN 2277-5420




Fig. 19. Variations of rate of change of signal power in forward direction against variations of distance z at the assumed
          set of the operating parameters.




Fig. 20. Variations of rate of change of signal power in forward direction against variations of distance z at the assumed
          set of the operating parameters.
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                 Volume 1, Issue 1, February 2012 www.ijcsn.org ISSN 2277-5420




Fig. 21. Variations of rate of change of signal power in forward direction against variations of distance z at the assumed
          set of the operating parameters.




Fig. 22. Variations of rate of change of signal power in forward direction against variations of distance z at the assumed
          set of the operating parameters.
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                 Volume 1, Issue 1, February 2012 www.ijcsn.org ISSN 2277-5420




Fig. 23. Variations of rate of change of signal power in forward direction against variations of distance z at the assumed
          set of the operating parameters.




Fig. 24. Variations of rate of change of signal power in backward direction against variations of distance z at the assumed
          set of the operating parameters.
                           International Journal of Computer Science and Network (IJCSN)
                   Volume 1, Issue 1, February 2012 www.ijcsn.org ISSN 2277-5420




Fig. 25. Variations of rate of change of signal power in backward direction against variations of distance z at the assumed
          set of the operating parameters.




Fig. 26. Variations of rate of change of signal power in backward direction against variations of distance z at the assumed set of the
           operating parameters.
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                 Volume 1, Issue 1, February 2012 www.ijcsn.org ISSN 2277-5420




Fig. 27. Variations of rate of change of signal power in bi-directional case against variations of distance z at the assumed
          set of the operating parameters.




Fig. 28. Variations of rate of change of signal power in bi-directional pumping case against variations of distance z at the
          assumed set of the operating parameters.
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                 Volume 1, Issue 1, February 2012 www.ijcsn.org ISSN 2277-5420




Fig. 29. Variations of rate of change of signal power in bi-directional pumping case against variations of distance z at the
          assumed set of the operating parameters.




Fig. 30. Variations of rate of change of signal power in bi-directional pumping case against variations of distance z at the
          assumed set of the operating parameters.
                          International Journal of Computer Science and Network (IJCSN)
                  Volume 1, Issue 1, February 2012 www.ijcsn.org ISSN 2277-5420




Fig. 31. Variations of rate of change of signal power in bi-directional pumping case against variations of distance z at the
          assumed set of the operating parameters.

3. 3. Variations of rate of change of pump power,                     Variation of the rate of change of signal power in
dPp/dz                                                           different configurations; dPs/dz is investigated against
      Variation of the rate of change of pump power in           variations of the controlling set of parameters as displayed
different configurations; dPp/dz is investigated against         in Figs. (18-31), these figures clarify the following results:
variations of the controlling set of parameters as displayed          a- In case of forward direction:
in Figs. (12-17). these figures clarify the following results:        1) For certain value of initial pumping power:
    a- In case of forward direction:                                      i. Initial pumping power = 0.165 W, for 0 ≤ z,
             i. As distance z increases, dPpF/dz decreases                     km ≤ 3, dPsF/dz decreases linearly, for 3 ≤ z,
                 exponentially.                                                km ≤ 18, dPsF/dz increases exponentially, and
            ii. For certain value of distance z, with                          for z ≥ 18 km, dPsF/dz decreases
                 increasing the initial pumping power,                         exponentially.
                 dPpF/dz also will increase.                              ii. Initial pumping power = 0.265 W, for 0 ≤ z,
           iii. For certain value of distance z, with                          km ≤ 10, dPsF/dz decreases linearly, for 10 ≤
                 increasing the initial signal power, dPpF/dz                  z, km ≤ 24, dPsF/dz increases exponentially,
                 also will increase                                            for z ≥ 24 km, dPsF/dz decreases
    b- In case of backward direction:                                          exponentially.
             i. As distance z increases, dPpB/dz increases                iii. Initial pumping power = 0.365 W, for 0 ≤ z,
                 exponentially.                                                km ≤ 14, dPsF/dz decreases linearly, for 14 ≤
            ii. For certain value of distance z, with                          z, km ≤ 29, dPsF/dz increases exponentially,
                 increasing the initial pumping power,                         for z ≥ 29 km, dPsF/dz decreases
                 dPpB/dz also will increase.                                   exponentially.
    c- In case of bi-directional:                                     2) For any value of initial signal power: for 0 ≤ z,
            i.   For z ≤ 50 km, dPpFB/dz decreases                          km ≤ 3, dPsF/dz decreases linearly, for 3 ≤ z, km
                 exponentially, and for z ≥ 50km, dPpFB/dz                  ≤ 18, dPsF/dz increases exponentially, and for z ≥
                 increases exponentially.                                   18 km, dPsF/dz decreases exponentially.
           ii.   For certain value of distance z, with                3) For certain value of distance, z:
                 increasing the initial pumping power,                    i. With increasing the initial signal power,
                 dPpFB/dz also will increase.                                  dPpF/dz also will increase.
          iii.   For certain value of distance z, with                    ii. With increasing the initial pumping power,
                 increasing the initial signal power,                          dPpF/dz also will increase.
                 dPpFB/dz also will increase.                         4) For certain value operating signal wavelength, λs:
3. 4. Variations of rate of change of signal power,                       i. λs = 1.45 µm, for 0 ≤ z, km ≤ 2, dPsF/dz
dPs/dz                                                                         decreases linearly, for 2 ≤ z, km ≤ 17,
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         dPsF/dz increases exponentially, and for z ≥                    and for z ≥ 11 km, dPsFB/dz decreases
         17 km, dPsF/dz decreases exponentially.                         exponentially.
   ii. λs = 1.55 µm, for 0 ≤ z, km ≤ 3, dPsF/dz                    ii. Initial pumping power = 0.265 W, for 0 ≤ z,
         decreases linearly, for 3 ≤ z, km ≤ 18,                         km ≤ 10, dPsFB/dz decreases linearly, for 10 ≤
         dPsF/dz increases exponentially, and for z ≥                    z, km ≤ 18, dPsFB/dz increases exponentially,
         18 km, dPsF/dz decreases exponentially.                         for z ≥ 18 km, dPsFB/dz decreases
   iii. λs = 1.65 µm for 0 ≤ z, km ≤ 4, dPsF/dz                          exponentially.
         decreases linearly, for 4 ≤ z, km ≤ 19,                   iii. Initial pumping power = 0.365 W, for 0 ≤ z,
         dPsF/dz increases exponentially, and for z ≥                    km ≤ 14, dPsFB/dz decreases linearly, for 14 ≤
         19 km, dPsF/dz decreases exponentially.                         z, km ≤ 22, dPsFB/dz increases exponentially,
5) At the beginning with increasing the operating                        for z ≥ 22 km, dPsFB/dz decreases
     signal wavelength, λs dPsF/dz also will increase,                   exponentially.
     after that dPsF/dz decreases with increasing the         2)    For any value of initial signal power: for 0 ≤ z,
     operating signal wavelength, λs.                                km ≤ 3, dPsFB/dz decreases linearly, for 3 ≤ z, km
6) For certain value operating pump wavelength, λp:                  ≤ 11, dPsFB/dz increases exponentially, and for z
   i. λp = 1.40 µm, for 0 ≤ z, km ≤ 3, dPsF/dz                       ≥ 11 km, dPsFB/dz decreases exponentially.
         decreases linearly, for 3 ≤ z, km ≤ 18,              3)    For certain value of distance, z:
         dPsF/dz increases exponentially, and for z ≥              i. With increasing the initial signal power,
         18 km, dPsF/dz decreases exponentially.                         dPsFB/dz also will increase.
   ii. λp = 1.42 µm, for 0 ≤ z, km ≤ 2, dPsF/dz                    ii. With increasing the initial pumping power,
         decreases linearly, for 2 ≤ z, km ≤ 17,                         dPsFB/dz also will increase.
         dPsF/dz increases exponentially, and for z ≥         4)    For certain value operating signal wavelength, λs:
         17 km, dPsF/dz decreases exponentially.                   i. λs = 1.45 µm, for 0 ≤ z, km ≤ 2, dPsFB/dz
   iii. λp = 1.44 µm for 0 ≤ z, km ≤ 1, dPsF/dz                          decreases linearly, for 2 ≤ z, km ≤ 10,
         decreases linearly, for 1 ≤ z, km ≤ 16,                         dPsFB/dz increases exponentially, and for z ≥
         dPsF/dz increases exponentially, and for z ≥                    10 km, dPsFB/dz decreases exponentially.
         16 km, dPsF/dz decreases exponentially.                   ii. λs = 1.55 µm, for 0 ≤ z, km ≤ 3, dPsFB/dz
7) After using different media of optical fiber cable,                   decreases linearly, for 3 ≤ z, km ≤ 11,
     it is indicated that the true wave reach fiber                      dPsFB/dz increases exponentially, and for z ≥
     presented the best results.                                         11 km, dPsFB/dz decreases exponentially.
b- In case of backward direction:                                  iii. λs = 1.65 µm for 0 ≤ z, km ≤ 4, dPsFB/dz
 1) For certain value of initial pumping power:                          decreases linearly, for 4 ≤ z, km ≤ 12,
     i. Initial pumping power = 0.165 mW, for                            dPsFB/dz increases exponentially, and for z ≥
         distance z ≤ 2 km, dPsB/dz increases                            12 km, dPsFB/dz decreases exponentially.
         exponentially, and for z ≥ 2 km, dPsB/dz             5)    At the beginning with increasing the operating
         decreases exponentially.                                    signal wavelength, λs dPsFB/dz also will increase,
    ii. Initial pumping power = 0.265 mW, for                        after that dPsFB/dz decreases with increasing the
         distance z ≤ 8 km, dPsB/dz increases                        operating signal wavelength, λs.
         exponentially, and for z ≥ 8 km, dPsB/dz             6)    For certain value operating pump wavelength, λp:
         decreases exponentially.                                  i. λp = 1.40 µm, for 0 ≤ z, km ≤ 3, dPsFB/dz
   iii. Initial pumping power = 0.365 mW, for                            decreases linearly, for 3 ≤ z, km ≤ 11,
         distance z ≤ 13 km, dPsB/dz increases                           dPsFB/dz increases exponentially, and for z ≥
         exponentially, and for z ≥ 13 km, dPsB/dz                       11 km, dPsFB/dz decreases exponentially.
         decreases exponentially.                                  ii. λp = 1.42 µm, for 0 ≤ z, km ≤ 2, dPsFB/dz
 2) For certain value of distance z:                                     decreases linearly, for 2 ≤ z, km ≤ 11,
    iii. With increasing the initial pumping power,                      dPsFB/dz increases exponentially, and for z ≥
         dPsB/dz also will increase.                                     11 km, dPsFB/dz decreases exponentially.
    iv. With increasing the initial signal power,                  iii. λp = 1.44 µm for 0 ≤ z, km ≤ 1, dPsFB/dz
         dPsB/dz also will increase.                                     decreases linearly, for 1 ≤ z, km ≤ 11,
 3) After using different media of optical fiber cable,                  dPsFB/dz increases exponentially, and for z ≥
     it is indicated that the true wave reach fiber                      11 km, dPsFB/dz decreases exponentially.
     presented the best results.                                         After using different media of optical fiber
c- In case of bi-directional:                                            cable, it is indicated that the true wave reach
1) For certain value of initial pumping power:                           fiber presented the best results.
   i. Initial pumping power = 0.165 W, for 0 ≤ z,
         km ≤ 3, dPsFB/dz decreases linearly, for 3 ≤ z,   4. Conclusions
         km ≤ 11, dPsFB/dz increases exponentially,
                           International Journal of Computer Science and Network (IJCSN)
                   Volume 1, Issue 1, February 2012 www.ijcsn.org ISSN 2277-5420

      In a summary, The points of discussion indicated all          [8] S. Shahi, S. W. Harun, K. Dimyati, and H. Ahmad,
the        operating      design        parameters         of         "Brillouin Fiber Laser With Significantly Reduced Gain
multiplexing/demultiplexing based distributed optical                 Medium Length Operating in L Band Region," Progress In
fiber Raman amplifier device, such as input signal power,             Electromagnetics Research Letters, Vol. 8, No. 3, pp. 143-
                                                                      149, 2009.
input pumping power, operating signal wavelength,                   [9] A. Banerjee, "New Approach to Design Digitally Tunable
operating pump wavelength, and different fiber link                   Optical Fiber System for Wavelength Selective Switching
media. Therefore we have deeply investigated                          Based Optical Networks," Progress In Electromagnetics
multiplexing/demultiplexing based distributed optical                 Research Letters, Vol. 9, No. 2, pp. 93-100, 2009.
fiber Raman amplifier over wide range of the affecting              [10] Abd El-Naser A. Mohammed and Ahmed Nabih Zaki
parameters. As well as we have taken into account signal              Rashed, “Ultra Wide Band (UWB) of Optical Fiber Raman
power, pumping power, and the rate of change of both                  Amplifiers in Advanced Optical Communication Networks,”
signal power and pumping power along the transmission                 Journal of Media and Communication Studies (IJMCS), Vol.
distance within the variety of operating signal wavelength,           1, No. 4, pp. 56-78, 2009.
                                                                    [11] S. Makoui, M. Savadi-Oskouei, A. Rostami, and Z. D.
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pumping power, different fiber link media, and finally                Large Bandwidth and High Speed Optical Communications
Raman gain efficiency for all pumping direction                       Using Optimization Technique," Progress In Electromagnetics
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directional pumping. The effects of the verity of these             [12] M. El Mashade, M. B. and M. N. Abdel Aleem, "Analysis
parameters are mentioned in details in the previous                   of Ultra Short Pulse Propagation in Nonlinear Optical Fiber,"
section of the results and performance analysis. After                Progress In Electromagnetics Research B, Vol. 12, No. 3, pp.
using different media of optical fiber cable, it is indicated         219-241, 2009.
                                                                    [13] Abd El Naser A. Mohammed, Mohamed Metawe'e, Ahmed
that the true wave reach fiber presented the best candidate
                                                                      Nabih Zaki Rashed, and Mahmoud M. A. Eid, “Distributed
media for the highest signal transmission performance                 Optical Raman Amplifiers in Ultra High Speed Long Haul
efficiency.                                                           Transmission Optical Fiber Telecommunication Networks,”
                                                                      International Journal of Computer and Network Security
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DOCUMENT INFO
Description: Fiber Raman amplifiers (FRAs) are attractive for ultra wide dense wavelength division multiplexing (UW-DWDM) transmission systems due to their advantages of broad amplification bandwidth and flexible central wavelength. With recent developments of optical pump sources with high power near 1.4 µm wavelength and highly nonlinear fiber having a peak effective Raman gain coefficient more than ten times that of conventional single mode fiber, distributed FRAs (DFRAs) are emerging as a practical optical amplifier technology, especially for opening new wavelength windows such as the short and ultra long wavelength bands. Optical pump powers required for Raman amplification were significantly higher than that for Erbium doped fiber amplifier (EDFA), and the pump laser technology could not reliably deliver the required powers. However, with the improvement of pump laser technology Raman amplification is now an important means of expanding span transmission reach and capacity. In the present paper, we have deeply investigated the proposed model for optical distributed fiber Raman amplifiers in the transmission signal power and pump power within Raman amplification technique in co-pumped, counter-pumped, and bi-directional pumping direction configurations through different types of fiber cable media. The validity of this model was confirmed by using experimental data and numerical simulations.