OSA's Digital Library

Optics Express

Optics Express

  • Editor: Michael Duncan
  • Vol. 13, Iss. 7 — Apr. 4, 2005
  • pp: 2251–2255
« Show journal navigation

Suppression of ghost pulses in 40Gbps optical transmission systems with fixed-pattern phase modulation

Mingyuan Zou, Minghua Chen, and Shizhong Xie  »View Author Affiliations


Optics Express, Vol. 13, Issue 7, pp. 2251-2255 (2005)
http://dx.doi.org/10.1364/OPEX.13.002251


View Full Text Article

Acrobat PDF (154 KB)





Browse Journals / Lookup Meetings

Browse by Journal and Year


   


Lookup Conference Papers

Close Browse Journals / Lookup Meetings

Article Tools

Share
Citations

Abstract

Novel fixed-pattern phase modulation scheme is proposed to suppress the IFWM-induced ghost pulses in 40Gbps RZ optical transmission systems through destructing the interference of the IFWM components in symmetric patterns. More than 3dBm launch power margin is achieved. It is a cost-effective method to improve the performance of 40Gbps RZ systems due to greater nonlinearity tolerance.

© 2005 Optical Society of America

1. Introduction

In high bit-rate return-to-zero (RZ) systems beyond 40 Gbps, the ghost pulse induced by intrachannel nonlinear interactions has attracted much attention because it is known as one of the dominant limiting factors affecting the performance of transmission systems [1

1. S. Kumar,et al, “Intrachannel nonlinear penalties in dispersion-managed transmission systems” IEEE J. Sel. Top. Quantum Electron. 8, 626–631, (2002) [CrossRef]

3

3. M. J. Ablowitz and T. Hirooka, “Resonant nonlinear intrachannel interactions in strongly dispersion-managed transmission systems,” Opt. Lett. 25, 1750–1752, (2000) [CrossRef]

]. As discussed in many papers, the worst pattern in 40 Gbps RZ transmission systems is the one “0” bit around with several “1” bits, and the symmetric pattern of 1110111 is generally mentioned [4

4. Nikola Alic and Yeshaiahu Fainman, “Data-Dependent Phase Coding for Suppression of Ghost Pulses in Optical Fibers” IEEE Photon. Technol. Lett. 16, 1212–1214, (2004) [CrossRef]

6

6. P. J. Winzer, A. H. Gnauck, G. Raybon, S. Chandrasekhar, Y. Su, and J. Leuthold, “40-Gb/s return-to-zero alternate-mark-inversion (RZ-AMI) transmission over 2000 km,” IEEE J. Sel. Top. Quantum Electron. 15, 766–768, (2003)

]. With the phase sensitivity of intra-channel four-wave-mixing (IFWM) interaction, data-dependent phase-encoding schemes [4

4. Nikola Alic and Yeshaiahu Fainman, “Data-Dependent Phase Coding for Suppression of Ghost Pulses in Optical Fibers” IEEE Photon. Technol. Lett. 16, 1212–1214, (2004) [CrossRef]

], such as AMI [5

5. X. Liu, X. Wei, A. H. Gnauck, C. Xu, and L. K. Wickham, “Suppression of intrachannel four-wave-mixing-induced ghost pulses in high-speed transmissions by phase inversion between adjacent marker blocks,” Opt. Lett. 27, 1177–1179, (2002) [CrossRef]

6

6. P. J. Winzer, A. H. Gnauck, G. Raybon, S. Chandrasekhar, Y. Su, and J. Leuthold, “40-Gb/s return-to-zero alternate-mark-inversion (RZ-AMI) transmission over 2000 km,” IEEE J. Sel. Top. Quantum Electron. 15, 766–768, (2003)

], have been proposed to suppress the IFWM induced ghost pulses in symmetric patterns. However, the realization of phase encoding needs a data-dependent electrical encoder, which is always complex and much expensive when the bit rate is up to 40Gbps. In this paper, a novel scheme, using the phase modulation with the fixed 8-bit patterns of ππ0π00π0 or ππππ0000, is proposed to suppress the ghost pulses. Meanwhile, because the pattern of the phase modulation is independent of the input data stream, the phase encoder is not necessary and the two kinds of patterns can be realized simply by commercial 40Gbps electrical multiplexers.

2. Principle and modeling

To destruct the interference of the IFWM components in symmetric patterns, Wei X. et al indicated that the two symmetric IFWM components in the mth time slot counteracted each other with the phase-match condition of [4

4. Nikola Alic and Yeshaiahu Fainman, “Data-Dependent Phase Coding for Suppression of Ghost Pulses in Optical Fibers” IEEE Photon. Technol. Lett. 16, 1212–1214, (2004) [CrossRef]

]

φm+n+φm+qφm+q=π+φmn+φmqφmk
(1)

where φm+n is the initial phase of the pulse in time slot (m+n), n, q, k (n, q≠0) is the arbitrary slot numbers away from the slot m with the slot-match condition of n+q=k [1

1. S. Kumar,et al, “Intrachannel nonlinear penalties in dispersion-managed transmission systems” IEEE J. Sel. Top. Quantum Electron. 8, 626–631, (2002) [CrossRef]

]. According Ablowitz and Hirooka’s paper [3

3. M. J. Ablowitz and T. Hirooka, “Resonant nonlinear intrachannel interactions in strongly dispersion-managed transmission systems,” Opt. Lett. 25, 1750–1752, (2000) [CrossRef]

], IFWM components induced between adjacent pulses are greatly larger than those between distant pulses. Consequently the effects of the IFWM components induced between distant pulses can be neglected and only the effects between the adjacent pulses should be considered. In our scheme the IFWM interactions between 7 adjacent bits of pattern 1110111 are considered, where the bit slot occupied by the “zero” is defined as the mth slot. With the slot-matching condition of IFWM, there are 13 items of the IFWM components contributing to the ghost pulse in the mth slot, in which three items with “zero” bits in the IFWM components can be neglected because of their trivial effects. The other ten symmetric IFWM components are significant and need to be mitigated with the phase-match condition. According Eq. (1), there are

φm+1+φm+1φm+2=π+φm1+φm1φm2
(2.1)
φm+2+φm1φm+1=π+φm2+φm+1φm1
(2.2)
φm+2+φm+1φm+3=π+φm2+φm1φm3
(2.3)
φm+3+φm1φm2=π+φm3+φm+1φm+2
(2.4)
φm+3+φm2φm+1=π+φm3+φm+2φm1
(2.5)

In our phase modulation scheme the modulated phase of every pulse is a two-value variable, 0 or π. The items of 2φm+1 and 2φm-1 can be neglected in the Eqs. (2.1) and (2.2) for their value will be 0 or 2π. Thus from Eqs. (2), we get

φm2=π+φm+2
(3.1)
φm+3+φm1=φm3+φm+1
(3.2)

It means that in the symmetric pattern, the effects of IFWM components are counteracted on condition that the phase of the (m+2)th slot pulse is inverse of that of the (m-2)th slot pulse as well as the sum of the phases of the pulses in the (m+3)th and the (m-1)th slots is identical with that of the pulses in the (m-3)th and the (m+1)th slots. Actually, these phase-match conditions are also satisfied in those phase constructed schemes [4

4. Nikola Alic and Yeshaiahu Fainman, “Data-Dependent Phase Coding for Suppression of Ghost Pulses in Optical Fibers” IEEE Photon. Technol. Lett. 16, 1212–1214, (2004) [CrossRef]

, 5

5. X. Liu, X. Wei, A. H. Gnauck, C. Xu, and L. K. Wickham, “Suppression of intrachannel four-wave-mixing-induced ghost pulses in high-speed transmissions by phase inversion between adjacent marker blocks,” Opt. Lett. 27, 1177–1179, (2002) [CrossRef]

], but all of them are data-dependent and need data encoding. Indeed, the simplest scheme should be data-independent, which means that the phase-match condition of Eqs. (3) should be satisfied for the pulse in the arbitrary slot in the data stream. With this additional obligated condition, the phase-match condition to suppress the IFWM induced ghost pulses in symmetric patterns can be rewritten as

φi=π+φi+4
(4)

Fig. 1. Scheme of the proposed fixed-pattern phase modulation transmitter

3. Results and discussion

Fig.2 . cheme of the proposed fixed phase pattern modulation

Fig. 3. Calculated growth of ghost pulses as the average power in “zero” bit-slots against transmission distance

Figure 3 illustrates the average energy in “zeros” versus transmission length with a launch power of 3dBm. It is shown that the average energy in “zeros” accumulated with the distance expanding and almost linearly increased after 600km transmission distance. With the fixed-pattern phase modulation scheme adopted, the average energy in “zeros” was greatly decreased to one third of that in normal RZ systems. In fiber systems the energies in “zeros” generally come from several unrelated sources, such as the energies due to IFWM components, tails from the adjacent “ones” and pulse broadening, etc. Since the fixed-pattern phase modulations of ππ0π00π0 and ππππ0000 mainly suppress the symmetric IFWM-induced components, it can be discovered that the symmetric IFWM-induced components contributes to the energy in “zeros” dominantly, about 70%. Meanwhile, the average energies in “zeros” are slightly different in the two fixed-pattern phase modulation systems with fix patterns of ππ0π00π0 and ππππ0000. This phenomenon can be understood through two reasons. First, the performances of mitigation of symmetric IFWM components are identical with the two types of fixed patterns of ππ0π00π0 and ππππ0000; second, the pattern of ππ0π00π0 will destruct more interference of tails from the adjacent “ones” and pulse broadening than that of ππππ0000 while the fixed pattern of ππ0π00π0 has more phase alteration in adjacent pulses (This kind of destruct effect was carefully discussed in [7

7. Shamil Appathurai, Vitaly Mikhailov, Robert I. Killey, and Polina Bayvel, “Investigation of the Optimum Alternate-Phase RZ Modulation Format and Its Effectiveness in the Suppression of Intra-channel Nonlinear Distortion in 40-Gbit/s Transmission Over Standard Single-Mode Fiber” IEEE J. Sel. Top. Quantum Electron. 10, 239–249, (2004) [CrossRef]

] when referring to alternate-phase RZ format).

Fig. 4. Q value against transmission distance with 3dBm of launch power (a) and the Q value against launch power after 800 km transmission (b)

Figure 4(a) shows the Q factor versus transmission distance with a launch power of 3dBm. It illustrates that the RZ formats with the fixed-pattern phase modulation can expand the transmission length from 1000km to 1600km contrasting with the normal RZ format, when the system performance requests Q factor above 12dB, corresponding to BER=10-9. The fixed-pattern phase modulation scheme does not only expand the transmission distance, but also improves the system performance. Figure 4(b) shows the Q factor versus the launch power after 800 km transmission. The optimal input power of RZ format with the fixed-pattern phase of ππ0π00π0 has extended about 3dBm than the normal RZ format and the optimal Q factor of RZ format with the fixed-pattern phase of ππ0π00π0 has improved about 4 dB after 800km SMF transmission in Fig. 4(b). With the reason mentioned earlier, the Q-factor of the system with the fixed-pattern phase of ππ0π00π0 is slightly higher than that of the system with the fixed-pattern phase of ππππ0000.

4. Conclusions

Phase modulation schemes with data-independent fixed-pattern ππ0π00π0 and ππππ0000 are proposed to suppress the IFWM-induced ghost pulses through destructing the interference of the IFWM components in symmetric patterns in 40Gbps RZ systems over the standard single-mode fiber. It is a cost-effective method to extend the nonlinearity tolerance of 40Gbps RZ systems and improve system performance.

Acknowledgments

This work was supported by National Natural Science Foundation China under Grant 90104003.

References and links

1.

S. Kumar,et al, “Intrachannel nonlinear penalties in dispersion-managed transmission systems” IEEE J. Sel. Top. Quantum Electron. 8, 626–631, (2002) [CrossRef]

2.

P. V. Mamyshev and N. A. Mamysheva, “Pulse-overlapped dispersionmanaged data transmission and intrachannel four-wave mixing,” Opt. Lett. 24, 1454–1456, (1999) [CrossRef]

3.

M. J. Ablowitz and T. Hirooka, “Resonant nonlinear intrachannel interactions in strongly dispersion-managed transmission systems,” Opt. Lett. 25, 1750–1752, (2000) [CrossRef]

4.

Nikola Alic and Yeshaiahu Fainman, “Data-Dependent Phase Coding for Suppression of Ghost Pulses in Optical Fibers” IEEE Photon. Technol. Lett. 16, 1212–1214, (2004) [CrossRef]

5.

X. Liu, X. Wei, A. H. Gnauck, C. Xu, and L. K. Wickham, “Suppression of intrachannel four-wave-mixing-induced ghost pulses in high-speed transmissions by phase inversion between adjacent marker blocks,” Opt. Lett. 27, 1177–1179, (2002) [CrossRef]

6.

P. J. Winzer, A. H. Gnauck, G. Raybon, S. Chandrasekhar, Y. Su, and J. Leuthold, “40-Gb/s return-to-zero alternate-mark-inversion (RZ-AMI) transmission over 2000 km,” IEEE J. Sel. Top. Quantum Electron. 15, 766–768, (2003)

7.

Shamil Appathurai, Vitaly Mikhailov, Robert I. Killey, and Polina Bayvel, “Investigation of the Optimum Alternate-Phase RZ Modulation Format and Its Effectiveness in the Suppression of Intra-channel Nonlinear Distortion in 40-Gbit/s Transmission Over Standard Single-Mode Fiber” IEEE J. Sel. Top. Quantum Electron. 10, 239–249, (2004) [CrossRef]

8.

G.P. Agrawal, Nonlinear Fiber Optics (Academic, San Diego, 2001)

OCIS Codes
(060.2330) Fiber optics and optical communications : Fiber optics communications
(060.4080) Fiber optics and optical communications : Modulation

ToC Category:
Research Papers

History
Original Manuscript: January 19, 2005
Revised Manuscript: February 22, 2005
Published: April 4, 2005

Citation
Mingyuan Zou, Minghua Chen, and Shizhong Xie, "Suppression of ghost pulses in 40Gbps optical transmission systems with fixed-pattern phase modulation," Opt. Express 13, 2251-2255 (2005)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-13-7-2251


Sort:  Journal  |  Reset  

References

  1. S. Kumar,et al, �??Intrachannel nonlinear penalties in dispersion-managed transmission systems�?? IEEE J. Sel. Top. Quantum Electron. 8, 626-631, (2002) [CrossRef]
  2. P. V. Mamyshev and N. A. Mamysheva, �??Pulse-overlapped dispersion-managed data transmission and intrachannel four-wave mixing,�?? Opt. Lett. 24, 1454�??1456, (1999) [CrossRef]
  3. M. J. Ablowitz and T. Hirooka, �??Resonant nonlinear intrachannel interactions in strongly dispersion-managed transmission systems,�?? Opt. Lett. 25, 1750�??1752, (2000) [CrossRef]
  4. Nikola Alic, Yeshaiahu Fainman, "Data-Dependent Phase Coding for Suppression of Ghost Pulses in Optical Fibers" IEEE Photon. Technol. Lett. 16, 1212�??1214, (2004) [CrossRef]
  5. X. Liu, X.Wei, A. H. Gnauck, C. Xu, and L. K.Wickham, �??Suppression of intrachannel four-wave-mixing-induced ghost pulses in high-speed transmissions by phase inversion between adjacent marker blocks,�?? Opt. Lett. 27, 1177�??1179, (2002) [CrossRef]
  6. P. J. Winzer, A. H. Gnauck, G. Raybon, S. Chandrasekhar, Y. Su, and J. Leuthold, �??40-Gb/s return-to-zero alternate-mark-inversion (RZ-AMI) transmission over 2000 km,�?? IEEE J. Sel. Top. Quantum Electron. 15, 766�??768, (2003)
  7. Shamil Appathurai, Vitaly Mikhailov, Robert I. Killey and Polina Bayvel, "Investigation of the Optimum Alternate-Phase RZ Modulation Format and Its Effectiveness in the Suppression of Intrachannel Nonlinear Distortion in 40-Gbit/s Transmission Over Standard Single-Mode Fiber" IEEE J. Sel. Top. Quantum Electron. 10, 239-249, (2004) [CrossRef]
  8. G.P. Agrawal, Nonlinear Fiber Optics (Academic, San Diego, 2001)

Cited By

Alert me when this paper is cited

OSA is able to provide readers links to articles that cite this paper by participating in CrossRef's Cited-By Linking service. CrossRef includes content from more than 3000 publishers and societies. In addition to listing OSA journal articles that cite this paper, citing articles from other participating publishers will also be listed.

Figures

Fig. 1. Fig.2 . Fig. 3.
 
Fig. 4.
 

Next Article »

OSA is a member of CrossRef.

CrossCheck Deposited