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XPM-induced crosstalk with variety of fiber in SCM–WDM optical transmission link
Optik 124 (2013) 2125–2127
Contents lists available at SciVerse ScienceDirect
Optik journal homepage: www.elsevier.de/ijleo
XPM-induced crosstalk with variety of fiber in SCM–WDM optical transmission link Naresh Kumar a,∗ , Ajay K. Sharma b , Vinod Kapoor a a b
National Institute of Technology, Hamirpur, H.P, India National Institute of Technology, Jalandhar, Punjab, India
a r t i c l e
i n f o
Article history: Received 1 February 2012 Accepted 19 June 2012
Keywords: Cross Phase Modulation Crosstalk Sub-Carrier Multiplexing Third order dispersion Wavelength Division Multiplexing
a b s t r a c t In this paper, XPM-induced crosstalk has been evaluated in a SCM–WDM communication link at different modulation frequencies, transmission lengths and optical powers for variety of fiber. Results show that XPM-induced crosstalk dominates at high frequency. As the dispersion and effective area of fiber (Aeff ) decrease, crosstalk increases with increase in modulation frequencies, transmission lengths and optical powers. The present work shows that out of five different types of fiber, Standard Single Mode Fiber (SMF) has minimum crosstalk (−78 to −38) dB, (−55 to −33) dB and (−46 to −34) dB at modulation frequencies, transmission lengths and optical powers. Dispersion compensation fiber (DCF) has maximum crosstalk (−60 to −12) dB, (−37 to −12) dB and (−27 to −12) dB at modulation frequencies, transmission lengths and optical powers. © 2012 Elsevier GmbH. All rights reserved.
1. Introduction Due to the explosive growth of wireless communication in recent years, network operators are having tremendous difficulty accommodating the increasing traffic. As demand on multimedia services including voice, data and video continue to grow, it is necessary to achieve a mature service with a high percentage of consumer use, lower and constant access charge, full time connectivity to service providers and higher bandwidth. In order to cope up with the various demands, future wireless communication systems require a large capacity. The converging requirements for subscriber mobility and high bandwidths have led to the proposal of micro cellular systems in which system capacity can be increased by augmenting the reuse efficiency of limited radio resources [1]. The micro cellular system poses problems, since installation of new radio base stations require time and a large investment. The combination of SCM and WDM is seen as a viable solution to the problems posed by a micro cellular system as it provides the so-called radio over fiber link using microwave photonics techniques. SCM–WDM systems however, suffer from nonlinear effects in fiber. When multiple wavelengths carrying SCM signals propagates in a single mode fiber, fiber nonlinearities can lead to crosstalk between subcarriers on different wavelengths. In a dispersive fiber, the dominant fiber nonlinearity that causes crosstalk is cross-phase modulation (XPM). Fiber nonlinearities such as Cross Phase Modulation (XPM) may
∗ Corresponding author. E-mail address: [email protected] (N. Kumar). 0030-4026/$ – see front matter © 2012 Elsevier GmbH. All rights reserved. http://dx.doi.org/10.1016/j.ijleo.2012.06.078
generate significant amounts of nonlinear crosstalk between adjacent SCM channels because they are very closely spaced [2–6]. In paper [7] investigated the SRS induced crosstalk for different types of fiber. This paper focuses on the analysis of nonlinear crosstalk caused by XPM on third order dispersion. With the advancement of communication systems, there is a trend of using higher modulation frequencies. So it is necessary to investigate the performance of SCM–WDM communication link at higher-order dispersion coefficients like third order dispersion with variety of fiber. The paper is organized as follows: Section 2 contains the theoretical analysis and the analysis of nonlinear crosstalk caused by XPM system. Section 3 discusses the parameter of different type fibers. Section 4 discusses the results of XPM for different types of fiber. Finally, Section 5 summarizes and concludes this paper. 2. Theoretical analysis The theoretical analysis begins with the nonlinear wave propagation equation [8]. Consider probe and pump optical signals, Aj (t, z) and Ak (t, z) co propagating in the same optical fiber: ∂Aj (t, z) ∂z
+
˛ iˇ3 ∂3 Aj (t, z) 1 ∂Aj (t, z) A (t, z) + − 2 j Vj 6 ∂t ∂t 3 = i[2Pk (t − djk z, z)]Aj (t, z)
(1)
where ˛ is the attenuation coefficient of the fiber, = ((2n2 )/(2 Aeff )) is the nonlinear coupling coefficient, n2 is the nonlinear refractive index, j and k are the probe and the pump signal wavelengths, Aeff is the fiber effective core area, Pk = |Ak |2
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N. Kumar et al. / Optik 124 (2013) 2125–2127
and Pj = |Aj |2 are optical powers of the pump and the probe signals, djk = V1 − V1 is the relative walk off between the two signals with j
k
Vjk , the group velocities of the two channels. Through linear approximation, the walk off can be expressed as djk = S0 ( − 0 )jk , where 0 and S0 are fiber zero-dispersion wavelength and dispersion slope and jk is the wavelength spacing between the probe and the pump signals. Hence ∂Aj (t, z) ∂z
iˇ3 ∂3 Aj (t, z) ˛ 1 ∂Aj (t, z) + Aj (t, z) − 2 Vj 6 ∂t ∂t 3
=−
+ i[2Pk (t − djk z, z)]Aj (t, z)
(2)
In order to simplify the analysis and to be able to focus our attention on the effect of interchannel crosstalk. Translating this propagation equation into the frequency domain using Fourier transformation, we have ∂Aj (ω, z) ∂z
=−
˛ 1 + 2 Vj
−
×
(−˛+iωdjk )z
dz
(4)
Now, look at the third term on the RHS of (3). This is the term responsible for the phase noise to intensity noise conversion in the probe signal. Phase noise generated at z = z is converted into intensity noise at the end of the fiber z = L due to chromatic dispersion. As discussed in [10], the in-phase component of this conversion is proportional to sin[(ω3 ˇ3 (L − z))/6]. Integrating all XPM contributions along the fiber, adding fiber loss and linear phase delay, we can obtain the total intensity noise at the end of the fiber z = L.
L
Aj (ω, L) = −2Pj (0)e(−˛−(iω/Vj )z ×
− sin
2j Pk (ω, 0)e(−˛−iωdjk )z 0
ω3 ˇ3 (L
− z)
6
dz
(5)
Now P j (L) = Pj (0)e−˛L Aj (ω, L) = Pj (L)e(iω/Vj )L 2j Pk (ω, 0)
× −
e−((iω ˇ3 L)/6) − e−(˛+iωdjk )L i[(˛ − iωdjk ) − ((iω3 ˇ3 )/6)] 3
e((iω ˇ3 L)/6) − e−(˛+iωdjk )L i[(˛ − iωdjk ) + ((iω3 ˇ3 )/6)] 3
−
(6)
where Pj (L) is the probe signal average optical power at the end of the fiber z = L. Under the assumptions that exp(−˛L) 1 and the modulation bandwidth is much smaller than the channel spacing, iω3 ˇ
i.e., djk 6 3 , we can find a simple form to describe the relative amplitude fluctuation induced by XPM as
Aj (ω, L) 2 Pj (L)
Pj (ω, L) =
−
e((iω ˇ3 L)/6) − e−(˛+iωdjk )L e−((iω ˇ3 L)/6) − e−(˛+iωdjk )L − i[(˛ − iωdjk ) − ((iω3 ˇ3 )/6)] i[(˛ − iωdjk ) + ((iω3 ˇ3 )/6)] 3
3
2 (7)
(3)
where Aj (ω, z) is the Fourier transformation of Aj (t, z) and Pk (ω, 0) is the power spectrum of the pump signal at the system input. On the RHS of (3), the first term accounts for attenuation and linear phase delay. The second term is responsible for phase modulation in the probe signal (j) induced by the pump signal (k). This phase modulation is proportional to the optical power in the pump signal and the fiber nonlinearity. In a short fiber section ∂z, the crosstalk phase modulation in the probe signal, induced by the pump signal, can be linearized under the small signal approximation [9]
Pj (ω, L) = 2j Pk (ω, 0)
iω3 ˇ3 6
+ ij [2Pk (ω, 0)eiωzdjk e−˛z ]Aj (ω, z)
djk (ω, z) = 2j Pk (ω, 0)e
Fig. 1. Variation of XPM induced crosstalk with modulation frequency with variety of fiber.
We define here the following dispersion parameters [11] ˇ2 =
2 D 2c
(8)
is the second-order dispersion parameter. ˇ3 =
2 (2c)2
[2 D1 + 2D]
(9)
is the third-order dispersion parameter. 3. Table Five different types fiber used in the simulations. They are Standard Single Mode Fiber (SMF), dispersion compensation fiber (DCF) for Standard Single Mode Fiber, True Wave fiber (TW), True WaveReduced Slope fiber (TW-RS) and Large Effective Area Fiber (LEAF) see [12] in Table 1. 4. Results and discussion Here, the results have been mentioned for XPM crosstalk at various modulation frequencies, transmission lengths and optical powers in the presence of third order dispersion by taking values of the various parameters like: phase matching factor (m) = 0.4, fiber loss ˛ = 0.25 dB/km, 1 = 1550 nm, 2 = 1552 nm, frequency spacing = 4 nm, transmission length = 50 km. Fig. 1 indicates the XPM-induced crosstalk versus modulation frequencies with variety of fiber and shows that the XPM-induced crosstalk at SSMF varies from (−78 to −38) dB. Further at TWRS it varies from (−74 to −30) dB, at LEAF it varies from (−78 to −36) dB, at TW it varies from (−72 to −28) dB, at dispersion compensation fiber (DCF) it varies from (−60 to −12) dB for SCM–WDM communication systems. Further Fig. 2 illustrates the exponential growth in the XPMinduced crosstalk versus transmission lengths with variety of fiber and shows that the XPM-induced crosstalk at SSMF varies from (−55 to −33) dB. Further at TWRS it varies from (−49 to −30) dB, at LEAF it varies from (−53 to −32) dB, at TW it varies from (−48 to −27) dB, at dispersion compensation fiber (DCF) it varies from (−37 to −12) dB for SCM–WDM communication systems. Similar results have been reported for XPM-induced crosstalk versus optical power with variety of fiber in Fig. 3 and shows that the XPM–induced crosstalk at SSMF varies from (−46 to −34) dB. Further at TWRS it varies from (−42 to −28) dB, at LEAF it varies
N. Kumar et al. / Optik 124 (2013) 2125–2127
2127
Table 1 Parameter of different fibers. Fiber SSMF DCF for SSMF TW TW-RS LEAF
D (ps/nm/km) 17 −90 3.5 4.4 3.77
D1 (ps/nm2 /km)
n2 (10−20 m2 /W)
Aeff (m2 )
A (dB/km)
0.058 0.058 × −90/17 0.08 0.045 0.11
2.8 4.3 3.45 3.2 3.0
80 14.3 45 55 72
0.25 0 0.25 0.25 0.25
Fig. 2. Variation of XPM induced crosstalk with transmission length with variety of fiber.
decrease, crosstalk increases with increase in modulation frequencies, transmission lengths and optical powers. In out of five different types of fiber, Standard Single Mode Fiber (SMF) has minimum crosstalk and Dispersion compensation fiber (DCF) has maximum crosstalk observed. At modulation frequency of 2 GHz, XPM-induced crosstalk for SSMF is −44 dB, for LEAF is −42 dB, for TWRS is −38 dB, for TW it is −35 dB and −26 dB for DCF. At transmission length of 40 km, XPM-induced crosstalk for SSMF is −34 dB, for LEAF is −33 dB, for TWRS is −31 dB, for TW it is −27 dB and −17 dB for DCF. At optical power of 40 mW, XPM-induced crosstalk for SSMF is −34 dB, for LEAF is −33 dB, for TWRS is −30 dB, for TW it is −27 dB and −15 dB for DCF for SCM–WDM communication systems. It is therefore concluded that XPM-induced crosstalk dominates at high frequency and shows that as the dispersion and effective area of fiber (Aeff ) decrease, crosstalk increases with increase in modulation frequencies, transmission lengths and optical powers. References
Fig. 3. Variation of XPM induced crosstalk with optical power with variety of fiber.
from (−44 to −32) dB, at TW it varies from (−38 to −28) dB, at dispersion compensation fiber (DCF) it varies from (−27 to −12) dB for SCM–WDM communication systems. 5. Conclusion Five different types of fiber are used in the simulations. They are Standard Single Mode Fiber (SMF), dispersion compensation fiber (DCF) for Standard Single Mode Fiber, True Wave fiber (TW), True Wave-Reduced Slope fiber (TW-RS) and Large Effective Area Fiber (LEAF). Our result shows that in Cross Phase Modulation (XPM) as the dispersion and effective area of fiber (Aeff )
[1] S. Subramanian, F.M. Abbou, H.T. Chuah, K.D. Dambul, Performance evaluation of SCM–WDM microcellular communication systems in the presence of XPM, IEICE Electron. Express 2 (6) (2005) 192–197. [2] R. Hui, B. Zhu, R. Huang, C. Allen, K. Demarest, D. Roberts, 10 Gb/s SCM systems using optical single side band modulation, Paper MM4, OFC’2001, Anaheim, CA, March 2001. [3] R. Hui, K. Demarest, C. Allen, Cross phase modulation in multi-span WDM optical fiber systems, IEEE J. Light Wave Technol. 17 (7) (1999) 1018. [4] M. Eiselt, limits on WDM systems due to four-wave mixing: a statistical approach, IEEE J. Light Wave Technol. 17 (11) (1999) 2261. [5] K.P. Ho, J.M. Kahn, Method for cross talk measurement and reduction in Dense WDM systems, J. Light Wave Technol. 14 (1996) 1127–1135. [6] S.K. Arya, A.K. Sharma, R.A. Agrawala, Impact of 2OD and 3OD on SRS- and XPMinduced crosstalk in SCM–WDM optical transmission link, Optik 120 (2009) 773–781. [7] N. Kumar, A.K. Sharma, V. Kapoor, Performance evaluation of SCM–WDM communication in the presence of SRS induced crosstalk for different types of fiber, Optik 122 (2011) 1862–1864. [8] G.P. Agrawal, Nonlinear Fiber Optics, Academic Press, San Diego, CA, 1989. [9] T.-K. chiang, N.M. Kagi, E. Marhic, L. Kazovky, Cross-phase modulation in fiber links with multiple optical amplifier and dispersion compensators, J. Light Wave Technol. 14 (1996) 249–260. [10] J. wang, K. Petermann, Small signal analysis for dispersion optical fiber communication systems, J. Light Wave Technol. 10 (1992) 96–100. [11] A. Singh, A.K. Sharma, T.S. Kamal, Four-wave mixing analysis in WDM optical communication systems with higher-order dispersion, Optik 119 (2008) 788–792. [12] ITU-T, Rec. G. 653, Characteristic of dispersion shifted single mode optical fiber cable, 1992, p. 6.
Contents lists available at SciVerse ScienceDirect
Optik journal homepage: www.elsevier.de/ijleo
XPM-induced crosstalk with variety of fiber in SCM–WDM optical transmission link Naresh Kumar a,∗ , Ajay K. Sharma b , Vinod Kapoor a a b
National Institute of Technology, Hamirpur, H.P, India National Institute of Technology, Jalandhar, Punjab, India
a r t i c l e
i n f o
Article history: Received 1 February 2012 Accepted 19 June 2012
Keywords: Cross Phase Modulation Crosstalk Sub-Carrier Multiplexing Third order dispersion Wavelength Division Multiplexing
a b s t r a c t In this paper, XPM-induced crosstalk has been evaluated in a SCM–WDM communication link at different modulation frequencies, transmission lengths and optical powers for variety of fiber. Results show that XPM-induced crosstalk dominates at high frequency. As the dispersion and effective area of fiber (Aeff ) decrease, crosstalk increases with increase in modulation frequencies, transmission lengths and optical powers. The present work shows that out of five different types of fiber, Standard Single Mode Fiber (SMF) has minimum crosstalk (−78 to −38) dB, (−55 to −33) dB and (−46 to −34) dB at modulation frequencies, transmission lengths and optical powers. Dispersion compensation fiber (DCF) has maximum crosstalk (−60 to −12) dB, (−37 to −12) dB and (−27 to −12) dB at modulation frequencies, transmission lengths and optical powers. © 2012 Elsevier GmbH. All rights reserved.
1. Introduction Due to the explosive growth of wireless communication in recent years, network operators are having tremendous difficulty accommodating the increasing traffic. As demand on multimedia services including voice, data and video continue to grow, it is necessary to achieve a mature service with a high percentage of consumer use, lower and constant access charge, full time connectivity to service providers and higher bandwidth. In order to cope up with the various demands, future wireless communication systems require a large capacity. The converging requirements for subscriber mobility and high bandwidths have led to the proposal of micro cellular systems in which system capacity can be increased by augmenting the reuse efficiency of limited radio resources [1]. The micro cellular system poses problems, since installation of new radio base stations require time and a large investment. The combination of SCM and WDM is seen as a viable solution to the problems posed by a micro cellular system as it provides the so-called radio over fiber link using microwave photonics techniques. SCM–WDM systems however, suffer from nonlinear effects in fiber. When multiple wavelengths carrying SCM signals propagates in a single mode fiber, fiber nonlinearities can lead to crosstalk between subcarriers on different wavelengths. In a dispersive fiber, the dominant fiber nonlinearity that causes crosstalk is cross-phase modulation (XPM). Fiber nonlinearities such as Cross Phase Modulation (XPM) may
∗ Corresponding author. E-mail address: [email protected] (N. Kumar). 0030-4026/$ – see front matter © 2012 Elsevier GmbH. All rights reserved. http://dx.doi.org/10.1016/j.ijleo.2012.06.078
generate significant amounts of nonlinear crosstalk between adjacent SCM channels because they are very closely spaced [2–6]. In paper [7] investigated the SRS induced crosstalk for different types of fiber. This paper focuses on the analysis of nonlinear crosstalk caused by XPM on third order dispersion. With the advancement of communication systems, there is a trend of using higher modulation frequencies. So it is necessary to investigate the performance of SCM–WDM communication link at higher-order dispersion coefficients like third order dispersion with variety of fiber. The paper is organized as follows: Section 2 contains the theoretical analysis and the analysis of nonlinear crosstalk caused by XPM system. Section 3 discusses the parameter of different type fibers. Section 4 discusses the results of XPM for different types of fiber. Finally, Section 5 summarizes and concludes this paper. 2. Theoretical analysis The theoretical analysis begins with the nonlinear wave propagation equation [8]. Consider probe and pump optical signals, Aj (t, z) and Ak (t, z) co propagating in the same optical fiber: ∂Aj (t, z) ∂z
+
˛ iˇ3 ∂3 Aj (t, z) 1 ∂Aj (t, z) A (t, z) + − 2 j Vj 6 ∂t ∂t 3 = i[2Pk (t − djk z, z)]Aj (t, z)
(1)
where ˛ is the attenuation coefficient of the fiber, = ((2n2 )/(2 Aeff )) is the nonlinear coupling coefficient, n2 is the nonlinear refractive index, j and k are the probe and the pump signal wavelengths, Aeff is the fiber effective core area, Pk = |Ak |2
2126
N. Kumar et al. / Optik 124 (2013) 2125–2127
and Pj = |Aj |2 are optical powers of the pump and the probe signals, djk = V1 − V1 is the relative walk off between the two signals with j
k
Vjk , the group velocities of the two channels. Through linear approximation, the walk off can be expressed as djk = S0 ( − 0 )jk , where 0 and S0 are fiber zero-dispersion wavelength and dispersion slope and jk is the wavelength spacing between the probe and the pump signals. Hence ∂Aj (t, z) ∂z
iˇ3 ∂3 Aj (t, z) ˛ 1 ∂Aj (t, z) + Aj (t, z) − 2 Vj 6 ∂t ∂t 3
=−
+ i[2Pk (t − djk z, z)]Aj (t, z)
(2)
In order to simplify the analysis and to be able to focus our attention on the effect of interchannel crosstalk. Translating this propagation equation into the frequency domain using Fourier transformation, we have ∂Aj (ω, z) ∂z
=−
˛ 1 + 2 Vj
−
×
(−˛+iωdjk )z
dz
(4)
Now, look at the third term on the RHS of (3). This is the term responsible for the phase noise to intensity noise conversion in the probe signal. Phase noise generated at z = z is converted into intensity noise at the end of the fiber z = L due to chromatic dispersion. As discussed in [10], the in-phase component of this conversion is proportional to sin[(ω3 ˇ3 (L − z))/6]. Integrating all XPM contributions along the fiber, adding fiber loss and linear phase delay, we can obtain the total intensity noise at the end of the fiber z = L.
L
Aj (ω, L) = −2Pj (0)e(−˛−(iω/Vj )z ×
− sin
2j Pk (ω, 0)e(−˛−iωdjk )z 0
ω3 ˇ3 (L
− z)
6
dz
(5)
Now P j (L) = Pj (0)e−˛L Aj (ω, L) = Pj (L)e(iω/Vj )L 2j Pk (ω, 0)
× −
e−((iω ˇ3 L)/6) − e−(˛+iωdjk )L i[(˛ − iωdjk ) − ((iω3 ˇ3 )/6)] 3
e((iω ˇ3 L)/6) − e−(˛+iωdjk )L i[(˛ − iωdjk ) + ((iω3 ˇ3 )/6)] 3
−
(6)
where Pj (L) is the probe signal average optical power at the end of the fiber z = L. Under the assumptions that exp(−˛L) 1 and the modulation bandwidth is much smaller than the channel spacing, iω3 ˇ
i.e., djk 6 3 , we can find a simple form to describe the relative amplitude fluctuation induced by XPM as
Aj (ω, L) 2 Pj (L)
Pj (ω, L) =
−
e((iω ˇ3 L)/6) − e−(˛+iωdjk )L e−((iω ˇ3 L)/6) − e−(˛+iωdjk )L − i[(˛ − iωdjk ) − ((iω3 ˇ3 )/6)] i[(˛ − iωdjk ) + ((iω3 ˇ3 )/6)] 3
3
2 (7)
(3)
where Aj (ω, z) is the Fourier transformation of Aj (t, z) and Pk (ω, 0) is the power spectrum of the pump signal at the system input. On the RHS of (3), the first term accounts for attenuation and linear phase delay. The second term is responsible for phase modulation in the probe signal (j) induced by the pump signal (k). This phase modulation is proportional to the optical power in the pump signal and the fiber nonlinearity. In a short fiber section ∂z, the crosstalk phase modulation in the probe signal, induced by the pump signal, can be linearized under the small signal approximation [9]
Pj (ω, L) = 2j Pk (ω, 0)
iω3 ˇ3 6
+ ij [2Pk (ω, 0)eiωzdjk e−˛z ]Aj (ω, z)
djk (ω, z) = 2j Pk (ω, 0)e
Fig. 1. Variation of XPM induced crosstalk with modulation frequency with variety of fiber.
We define here the following dispersion parameters [11] ˇ2 =
2 D 2c
(8)
is the second-order dispersion parameter. ˇ3 =
2 (2c)2
[2 D1 + 2D]
(9)
is the third-order dispersion parameter. 3. Table Five different types fiber used in the simulations. They are Standard Single Mode Fiber (SMF), dispersion compensation fiber (DCF) for Standard Single Mode Fiber, True Wave fiber (TW), True WaveReduced Slope fiber (TW-RS) and Large Effective Area Fiber (LEAF) see [12] in Table 1. 4. Results and discussion Here, the results have been mentioned for XPM crosstalk at various modulation frequencies, transmission lengths and optical powers in the presence of third order dispersion by taking values of the various parameters like: phase matching factor (m) = 0.4, fiber loss ˛ = 0.25 dB/km, 1 = 1550 nm, 2 = 1552 nm, frequency spacing = 4 nm, transmission length = 50 km. Fig. 1 indicates the XPM-induced crosstalk versus modulation frequencies with variety of fiber and shows that the XPM-induced crosstalk at SSMF varies from (−78 to −38) dB. Further at TWRS it varies from (−74 to −30) dB, at LEAF it varies from (−78 to −36) dB, at TW it varies from (−72 to −28) dB, at dispersion compensation fiber (DCF) it varies from (−60 to −12) dB for SCM–WDM communication systems. Further Fig. 2 illustrates the exponential growth in the XPMinduced crosstalk versus transmission lengths with variety of fiber and shows that the XPM-induced crosstalk at SSMF varies from (−55 to −33) dB. Further at TWRS it varies from (−49 to −30) dB, at LEAF it varies from (−53 to −32) dB, at TW it varies from (−48 to −27) dB, at dispersion compensation fiber (DCF) it varies from (−37 to −12) dB for SCM–WDM communication systems. Similar results have been reported for XPM-induced crosstalk versus optical power with variety of fiber in Fig. 3 and shows that the XPM–induced crosstalk at SSMF varies from (−46 to −34) dB. Further at TWRS it varies from (−42 to −28) dB, at LEAF it varies
N. Kumar et al. / Optik 124 (2013) 2125–2127
2127
Table 1 Parameter of different fibers. Fiber SSMF DCF for SSMF TW TW-RS LEAF
D (ps/nm/km) 17 −90 3.5 4.4 3.77
D1 (ps/nm2 /km)
n2 (10−20 m2 /W)
Aeff (m2 )
A (dB/km)
0.058 0.058 × −90/17 0.08 0.045 0.11
2.8 4.3 3.45 3.2 3.0
80 14.3 45 55 72
0.25 0 0.25 0.25 0.25
Fig. 2. Variation of XPM induced crosstalk with transmission length with variety of fiber.
decrease, crosstalk increases with increase in modulation frequencies, transmission lengths and optical powers. In out of five different types of fiber, Standard Single Mode Fiber (SMF) has minimum crosstalk and Dispersion compensation fiber (DCF) has maximum crosstalk observed. At modulation frequency of 2 GHz, XPM-induced crosstalk for SSMF is −44 dB, for LEAF is −42 dB, for TWRS is −38 dB, for TW it is −35 dB and −26 dB for DCF. At transmission length of 40 km, XPM-induced crosstalk for SSMF is −34 dB, for LEAF is −33 dB, for TWRS is −31 dB, for TW it is −27 dB and −17 dB for DCF. At optical power of 40 mW, XPM-induced crosstalk for SSMF is −34 dB, for LEAF is −33 dB, for TWRS is −30 dB, for TW it is −27 dB and −15 dB for DCF for SCM–WDM communication systems. It is therefore concluded that XPM-induced crosstalk dominates at high frequency and shows that as the dispersion and effective area of fiber (Aeff ) decrease, crosstalk increases with increase in modulation frequencies, transmission lengths and optical powers. References
Fig. 3. Variation of XPM induced crosstalk with optical power with variety of fiber.
from (−44 to −32) dB, at TW it varies from (−38 to −28) dB, at dispersion compensation fiber (DCF) it varies from (−27 to −12) dB for SCM–WDM communication systems. 5. Conclusion Five different types of fiber are used in the simulations. They are Standard Single Mode Fiber (SMF), dispersion compensation fiber (DCF) for Standard Single Mode Fiber, True Wave fiber (TW), True Wave-Reduced Slope fiber (TW-RS) and Large Effective Area Fiber (LEAF). Our result shows that in Cross Phase Modulation (XPM) as the dispersion and effective area of fiber (Aeff )
[1] S. Subramanian, F.M. Abbou, H.T. Chuah, K.D. Dambul, Performance evaluation of SCM–WDM microcellular communication systems in the presence of XPM, IEICE Electron. Express 2 (6) (2005) 192–197. [2] R. Hui, B. Zhu, R. Huang, C. Allen, K. Demarest, D. Roberts, 10 Gb/s SCM systems using optical single side band modulation, Paper MM4, OFC’2001, Anaheim, CA, March 2001. [3] R. Hui, K. Demarest, C. Allen, Cross phase modulation in multi-span WDM optical fiber systems, IEEE J. Light Wave Technol. 17 (7) (1999) 1018. [4] M. Eiselt, limits on WDM systems due to four-wave mixing: a statistical approach, IEEE J. Light Wave Technol. 17 (11) (1999) 2261. [5] K.P. Ho, J.M. Kahn, Method for cross talk measurement and reduction in Dense WDM systems, J. Light Wave Technol. 14 (1996) 1127–1135. [6] S.K. Arya, A.K. Sharma, R.A. Agrawala, Impact of 2OD and 3OD on SRS- and XPMinduced crosstalk in SCM–WDM optical transmission link, Optik 120 (2009) 773–781. [7] N. Kumar, A.K. Sharma, V. Kapoor, Performance evaluation of SCM–WDM communication in the presence of SRS induced crosstalk for different types of fiber, Optik 122 (2011) 1862–1864. [8] G.P. Agrawal, Nonlinear Fiber Optics, Academic Press, San Diego, CA, 1989. [9] T.-K. chiang, N.M. Kagi, E. Marhic, L. Kazovky, Cross-phase modulation in fiber links with multiple optical amplifier and dispersion compensators, J. Light Wave Technol. 14 (1996) 249–260. [10] J. wang, K. Petermann, Small signal analysis for dispersion optical fiber communication systems, J. Light Wave Technol. 10 (1992) 96–100. [11] A. Singh, A.K. Sharma, T.S. Kamal, Four-wave mixing analysis in WDM optical communication systems with higher-order dispersion, Optik 119 (2008) 788–792. [12] ITU-T, Rec. G. 653, Characteristic of dispersion shifted single mode optical fiber cable, 1992, p. 6.