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Optics Express

Optics Express

  • Editor: C. Martijn de Sterke
  • Vol. 20, Iss. 26 — Dec. 10, 2012
  • pp: B223–B231
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Transmission of 1.936 Tb/s (11 × 176 Gb/s) DP-16QAM superchannel signals over 640 km SSMF with EDFA only and 300 GHz WSS channel

Jianqiang Li, Magnus Karlsson, Peter A. Andrekson, and Kun Xu  »View Author Affiliations


Optics Express, Vol. 20, Issue 26, pp. B223-B231 (2012)
http://dx.doi.org/10.1364/OE.20.00B223


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Abstract

With an improved receiver-side spectral shaping technique by introducing and optimizing one tap coefficient in the intermediate response, we successfully transmitted 1.936 Tb/s (11 × 176 Gb/s) DP-16QAM superchannel signal over 8 × 80 km SSMF with EDFA-only and two 280 GHz wavelength selective switches (WSSs) in support of future 1.6 Tb/s Ethernet with up to 20% forward error correction overhead. The 280 GHz 3-dB bandwidth of the WSS passband permits a sufficient guardband if the 1.936 Tb/s superchannel signals are placed in a 300 GHz WSS channel.

© 2012 OSA

1. Introduction

2. Optimization of the intermediate response for DP-16QAM

3. Experimental setup and DSP algorithms

4. Experimental results

The B2B results are shown in Fig. 5
Fig. 5 BER performance at B2B.
. Firstly, the performance of single-carrier 22 Gbaud DP-16QAM without interleaver was measured. Since there is no pre-filtering, the post-filter and MLSD were replaced by the conventional hard decision. As compared to the theory, there is <3 dB implementation penalty at BER = 10−3. Secondly, the 25/50 GHz interleaver was inserted. In this case, the post-filter and MLSD were activated. The tap coefficient α was optimized to minimize the BER. It can be seen that the insertion of the 25/50 GHz interleaver brought <1dB optical signal-to-noise ratio (OSNR) penalty at BER = 10−3.Thirdly, we turned on the two adjacent carriers around the carrier under study. In this case, the optimal α is 0.4, as shown in Fig. 2(b). With the optimal α, there is ~3.7 dB OSNR penalty at BER = 10−3 in the presence of both the pre-filtering and linear crosstalk. For the entire 11-carrier superchannel (stars in Fig. 5), the required OSNR at BER = 10−3 is 10.6 dB higher than that of the single-carrier with two neighbors ON (triangles in Fig. 5), showing negligible excess penalty during the formation of the superchannel. The performance at B2B for three typical α is shown in Fig. 6
Fig. 6 B2B performance for different α.
. Note that the case with α = 0 is equivalent to the hard decision since no spectral shaping was done and the MLSD didn’t have any memory to use. It can be seen that the optimization of α brought dramatic performance improvement. This is because the filtering profile of the commercial 25/50 GHz interleaver is broad w.r.t. the 22 Gbaud 16QAM signal, and the duobinary is no more suitable as the target of the receiver-side spectral-shaping. For both cases with the duobinary shaping and the hard decision, the BER is unable to reach 10−3.

Figure 7
Fig. 7 Performance after fiber transmission.
shows the average BER of entire 11-carrier superchannel after 640 km transmission with two WSSs and the corresponding received OSNR as a function of the launched optical power to the fiber. At optimal launched power, there is a large margin as compared to the FEC threshold with 20% overhead, and the BER is even below the hard-decision FEC (HD-FEC) threshold with 7% overhead [23

23. M. Scholten, T. Coe, and J. Dillard, “Continuously-interleaved BCH (CI-BCH) FEC delivers best in class NECG for 40G and 100G metro applications,” presented at OFC2010, San Diego, CA, Mar. 2010, paper NTuB3.

]. Figure 7 also shows the recovered constellation of the central carrier before the spectral-shaping post-filter. In Fig. 8
Fig. 8 Optical spectra and BERs for 11 carriers after transmission.
, we show the optical spectra of the superchannel before and after transmission and BERs of all 11 carriers, as well as the measured passband of the two cascaded 280 GHz WSSs. Note that the two outer carriers subject to one-sided linear crosstalk have lower BERs. It was found that there was no performance loss for the two outer carriers after passing through 2 concatenated 280 GHz WSSs. The Q-penalties of 1st and 11th carriers as a function of the 3-dB bandwidth of WSSs are plotted in Fig. 9
Fig. 9 Optical spectra and BERs for 11 carriers after transmission.
. Note that the narrowband filtering effect induced by the concatenation of multiple WSSs mainly influence the most outer two carriers (i.e. 1st and 11th carriers). Given a Q-penalty within 1 dB, the two carriers can tolerant a 3-dB WSS bandwidth of as low as 270 GHz. This means the 1.934 Tb/s superchannel signal can be well fit into a 300GHz WSS channel with sufficient guardband.

5. Conclusion

DP-16QAM is less tolerant to the noise and linear crosstalk as compared to DP-QPSK. Consequently, the symbol rate has to be reduced below the carrier spacing for DP-16QAM to avoid significant narrowband filtering and linear crosstalk. If we continue to apply the proposed receiver-side spectral shaping technique in DP-16QAM superchannel systems, the intermediate response needs to be optimized. By introducing one tap coefficient α, we can have one degree of freedom to optimize the intermediate response while maintaining the same one-symbol memory and the state count of MLSD. With the improved receiver-side spectral shaping technique, we have experimentally demonstrated 1.936 Tb/s DP-16QAM superchannel transmissions over 640 km SSMF with EDFA-only and 300 GHz WSS channel with sufficient guardband. The transmission reach can be further increased by employing advanced FEC with ~20% overhead.

Acknowledgment

This work was supported in part by 863 Program in China (2011AA010306, 2011AA010305), the Swedish Foundation for Strategic Research (SSF), and Beijing Excellent Doctoral Thesis Project under Grant YB20101001301.

References and links

1.

P. J. Winzer, “Beyond 100G Ethernet,” IEEE Commun. Mag. 48(7), 26–30 (2010). [CrossRef]

2.

X. Liu, S. Chandrasekhar, B. Zhu, P. J. Winzer, A. H. Gnauck, and D. W. Peckham, “448-Gb/s reduced-guard-interval CO-OFDM transmission over 2000 km of ultra-large-area fiber and five 80-GHz-grid ROADMs,” J. Lightwave Technol. 29(4), 483–490 (2011). [CrossRef]

3.

Y. Ma, Q. Yang, Y. Tang, S. Chen, and W. Shieh, “1-Tb/s single-channel coherent optical OFDM transmission over 600-km SSMF fiber with subwavelength bandwidth access,” Opt. Express 17(11), 9421–9427 (2009). [CrossRef] [PubMed]

4.

J. Yu, Z. Dong, X. Xiao, Y. Xia, S. Shi, C. Ge, W. Zhou, N. Chi, and Y. Shao, “Generation of 112 coherent multi-carriers and transmission of 10 Tb/s (112x100Gb/s) single optical OFDM superchannel over 640 km SMF,” in Proc. OFC2011, Mar. 2011, Paper PDPA6.

5.

G. Bosco, A. Carena, V. Curri, P. Poggiolini, and F. Forghieri, “Performance limits of Nyquist-WDM and CO-OFDM in high-speed PM-QPSK systems,” IEEE Photon. Technol. Lett. 22(15), 1129–1131 (2010). [CrossRef]

6.

R. Schmogrow, M. Winter, M. Meyer, D. Hillerkuss, S. Wolf, B. Baeuerle, A. Ludwig, B. Nebendahl, S. Ben-Ezra, J. Meyer, M. Dreschmann, M. Huebner, J. Becker, C. Koos, W. Freude, and J. Leuthold, “Real-time Nyquist pulse generation beyond 100 Gbit/s and its relation to OFDM,” Opt. Express 20(1), 317–337 (2012). [CrossRef] [PubMed]

7.

X. Zhou, L. E. Nelson, P. Magill, R. Isaac, B. Zhu, D. W. Peckham, P. I. Borel, and K. Carlson, “PDM-Nyquist-32QAM for 450-Gb/s per-channel WDM transmission on the 50 GHz ITU-T grid,” J. Lightwave Technol. 30(4), 553–559 (2012). [CrossRef]

8.

J.-X. Cai, C. R. Davidson, A. Lucero, H. Zhang, D. G. Foursa, O. V. Sinkin, W. W. Patterson, A. N. Pilipetskii, G. Mohs, and N. S. Bergano, “20 Tbit/s transmission over 6860 km with sub-Nyquist channel spacing,” J. Lightwave Technol. 30(4), 651–657 (2012). [CrossRef]

9.

C. Cole, “Beyond 100G client optics,” IEEE Commun. Mag. 20(2), S58–S66 (2012). [CrossRef]

10.

J. Li, E. Tipsuwannakul, M. Karlsson, and P. A. Andrekson, “Low-complexity duobinary signaling and detection for sensitivity improvement in Nyquist-WDM coherent system,” presented in OFC2012, LA, CA, Mar. 2012, Paper OM3H.2.

11.

J. Li, E. Tipsuwannakul, T. Eriksson, M. Karlsson, and P. A. Andrekson, “Approaching Nyquist limit in WDM systems by low-complexity receiver-side duobinary shaping,” J. Lightwave Technol. 30(11), 1664–1676 (2012). [CrossRef]

12.

J. Yu, Z. Dong, H. -C. Chien, Z. Jia, D. Huo, H. Yi, M. Li, Z. Ren, N. Lu, L. Xie, K. Liu, X. Zhang, Y. Xia, Y. Cai, M. Gunkel, P. Wagner, H. Mayer, and A. Schippel, “Field trial Nyquist-WDM transmission of 8×216.4Gb/s PDM-CSRZ-QPSK exceeding 4b/s/Hz spectral efficiency,” in Proc. OFC2012, Los Angeles, CA, Mar. 2012, post-deadline paper PDP5D.3.

13.

H.-C. Chien, J. Yu, Z. Jia, Z. Dong, and X. Xiao, “Performance assessment of noise-suppressed Nyquist-WDM for terabit superchannel transmission,” to be published in J. Lightwave Technol.

14.

J. Yu, Z. Dong, H.-C. Chien, Z. Jia, X. Li, and N. Chi, “WDM transmission of 108.4-Gbaud PDM-QPSK signals (40×433.6-Gb/s) over 2800-km SMF-28 with EDFA only,” presented at the ECOC 2012, Amsterdam, Netherland, Sep. 15–20, 2012, paper Mo.2.C.2.

15.

J. Li, M. Sjödin, M. Karlsson, and P. A. Andrekson, “Building up low-complexity spectrally-efficient Terabit superchannels by receiver-side duobinary shaping,” Opt. Express 20(9), 10271–10282 (2012). [CrossRef] [PubMed]

16.

H. Wang, J. Li, D. Kong, Y. Li, W. Li, J. Wu, K. Xu, and J. Lin, “Multi-carrier group detection in receiver-side duobinary-shaped WDM superchannel systems,” IEEE Photon. Technol. Lett. 24(14), 1206–1208 (2012). [CrossRef]

17.

J. Li, M. Karlsson, and P. A. Andrekson, “1.94Tb/s (11×176Gb/s) DP-16QAM superchannel transmission over 640 km EDFA-only SSMF and two 280GHz WSSs,” presented at ECOC2012, Amsterdam, Netherland, Sep. 2012, paper Th.2.C.1.

18.

P. J. Winzer, and A. H. Gnauck, “112-Gb/s polarization-multiplexed 16-QAM on a 25-GHz WDM grid,” presented at ECOC2008, Brussels, Belgium, Sep. 2008, paper Th.3.E.5.

19.

A. H. Gnauck, P. J. Winzer, C. R. Doerr, and L. L. Bu, “10x112-Gb/s PDM 16-QAM transmission over 630km of fiber with 6.2-b/s/Hz spectral efficiency,” presented at OFC2009, San Diego, CA, Mar. 2009, paper PDPB8.

20.

M. S. Alfiad, M. Kuschnerov, S. L. Jansen, T. Wuth, D. van den Borne, and H. de Waardt, “11×224-Gb/s POLMUX-RZ-16QAM transmission over 670 km of SSMF with 50-GHz channel spacing,” IEEE Photon. Technol. Lett. 22(15), 1150–1152 (2010). [CrossRef]

21.

M. Selmi, Y. Jaouën, and P. Ciblat, “Accurate digital frequency offset estimator for coherent PolMux QAM transmission systems,” in Proc. ECOC 2009, Sep. 2009, Paper P3.08.

22.

J. Li, L. Li, Z. Tao, T. Hoshida, and J. C. Rasmussen, “Laser-linewidth- tolerant feed-forward carrier phase estimator with reduced complexity for QAM,” J. Lightwave Technol. 29(16), 2358–2364 (2011). [CrossRef]

23.

M. Scholten, T. Coe, and J. Dillard, “Continuously-interleaved BCH (CI-BCH) FEC delivers best in class NECG for 40G and 100G metro applications,” presented at OFC2010, San Diego, CA, Mar. 2010, paper NTuB3.

OCIS Codes
(060.1660) Fiber optics and optical communications : Coherent communications
(060.2330) Fiber optics and optical communications : Fiber optics communications
(060.4230) Fiber optics and optical communications : Multiplexing

ToC Category:
Transmission Systems and Network Elements

History
Original Manuscript: October 1, 2012
Revised Manuscript: November 11, 2012
Manuscript Accepted: November 11, 2012
Published: November 29, 2012

Virtual Issues
European Conference on Optical Communication 2012 (2012) Optics Express

Citation
Jianqiang Li, Magnus Karlsson, Peter A. Andrekson, and Kun Xu, "Transmission of 1.936 Tb/s (11 × 176 Gb/s) DP-16QAM superchannel signals over 640 km SSMF with EDFA only and 300 GHz WSS channel," Opt. Express 20, B223-B231 (2012)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-20-26-B223


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References

  1. P. J. Winzer, “Beyond 100G Ethernet,” IEEE Commun. Mag.48(7), 26–30 (2010). [CrossRef]
  2. X. Liu, S. Chandrasekhar, B. Zhu, P. J. Winzer, A. H. Gnauck, and D. W. Peckham, “448-Gb/s reduced-guard-interval CO-OFDM transmission over 2000 km of ultra-large-area fiber and five 80-GHz-grid ROADMs,” J. Lightwave Technol.29(4), 483–490 (2011). [CrossRef]
  3. Y. Ma, Q. Yang, Y. Tang, S. Chen, and W. Shieh, “1-Tb/s single-channel coherent optical OFDM transmission over 600-km SSMF fiber with subwavelength bandwidth access,” Opt. Express17(11), 9421–9427 (2009). [CrossRef] [PubMed]
  4. J. Yu, Z. Dong, X. Xiao, Y. Xia, S. Shi, C. Ge, W. Zhou, N. Chi, and Y. Shao, “Generation of 112 coherent multi-carriers and transmission of 10 Tb/s (112x100Gb/s) single optical OFDM superchannel over 640 km SMF,” in Proc. OFC2011, Mar. 2011, Paper PDPA6.
  5. G. Bosco, A. Carena, V. Curri, P. Poggiolini, and F. Forghieri, “Performance limits of Nyquist-WDM and CO-OFDM in high-speed PM-QPSK systems,” IEEE Photon. Technol. Lett.22(15), 1129–1131 (2010). [CrossRef]
  6. R. Schmogrow, M. Winter, M. Meyer, D. Hillerkuss, S. Wolf, B. Baeuerle, A. Ludwig, B. Nebendahl, S. Ben-Ezra, J. Meyer, M. Dreschmann, M. Huebner, J. Becker, C. Koos, W. Freude, and J. Leuthold, “Real-time Nyquist pulse generation beyond 100 Gbit/s and its relation to OFDM,” Opt. Express20(1), 317–337 (2012). [CrossRef] [PubMed]
  7. X. Zhou, L. E. Nelson, P. Magill, R. Isaac, B. Zhu, D. W. Peckham, P. I. Borel, and K. Carlson, “PDM-Nyquist-32QAM for 450-Gb/s per-channel WDM transmission on the 50 GHz ITU-T grid,” J. Lightwave Technol.30(4), 553–559 (2012). [CrossRef]
  8. J.-X. Cai, C. R. Davidson, A. Lucero, H. Zhang, D. G. Foursa, O. V. Sinkin, W. W. Patterson, A. N. Pilipetskii, G. Mohs, and N. S. Bergano, “20 Tbit/s transmission over 6860 km with sub-Nyquist channel spacing,” J. Lightwave Technol.30(4), 651–657 (2012). [CrossRef]
  9. C. Cole, “Beyond 100G client optics,” IEEE Commun. Mag.20(2), S58–S66 (2012). [CrossRef]
  10. J. Li, E. Tipsuwannakul, M. Karlsson, and P. A. Andrekson, “Low-complexity duobinary signaling and detection for sensitivity improvement in Nyquist-WDM coherent system,” presented in OFC2012, LA, CA, Mar. 2012, Paper OM3H.2.
  11. J. Li, E. Tipsuwannakul, T. Eriksson, M. Karlsson, and P. A. Andrekson, “Approaching Nyquist limit in WDM systems by low-complexity receiver-side duobinary shaping,” J. Lightwave Technol.30(11), 1664–1676 (2012). [CrossRef]
  12. J. Yu, Z. Dong, H. -C. Chien, Z. Jia, D. Huo, H. Yi, M. Li, Z. Ren, N. Lu, L. Xie, K. Liu, X. Zhang, Y. Xia, Y. Cai, M. Gunkel, P. Wagner, H. Mayer, and A. Schippel, “Field trial Nyquist-WDM transmission of 8×216.4Gb/s PDM-CSRZ-QPSK exceeding 4b/s/Hz spectral efficiency,” in Proc. OFC2012, Los Angeles, CA, Mar. 2012, post-deadline paper PDP5D.3.
  13. H.-C. Chien, J. Yu, Z. Jia, Z. Dong, and X. Xiao, “Performance assessment of noise-suppressed Nyquist-WDM for terabit superchannel transmission,” to be published in J. Lightwave Technol.
  14. J. Yu, Z. Dong, H.-C. Chien, Z. Jia, X. Li, and N. Chi, “WDM transmission of 108.4-Gbaud PDM-QPSK signals (40×433.6-Gb/s) over 2800-km SMF-28 with EDFA only,” presented at the ECOC 2012, Amsterdam, Netherland, Sep. 15–20, 2012, paper Mo.2.C.2.
  15. J. Li, M. Sjödin, M. Karlsson, and P. A. Andrekson, “Building up low-complexity spectrally-efficient Terabit superchannels by receiver-side duobinary shaping,” Opt. Express20(9), 10271–10282 (2012). [CrossRef] [PubMed]
  16. H. Wang, J. Li, D. Kong, Y. Li, W. Li, J. Wu, K. Xu, and J. Lin, “Multi-carrier group detection in receiver-side duobinary-shaped WDM superchannel systems,” IEEE Photon. Technol. Lett.24(14), 1206–1208 (2012). [CrossRef]
  17. J. Li, M. Karlsson, and P. A. Andrekson, “1.94Tb/s (11×176Gb/s) DP-16QAM superchannel transmission over 640 km EDFA-only SSMF and two 280GHz WSSs,” presented at ECOC2012, Amsterdam, Netherland, Sep. 2012, paper Th.2.C.1.
  18. P. J. Winzer, and A. H. Gnauck, “112-Gb/s polarization-multiplexed 16-QAM on a 25-GHz WDM grid,” presented at ECOC2008, Brussels, Belgium, Sep. 2008, paper Th.3.E.5.
  19. A. H. Gnauck, P. J. Winzer, C. R. Doerr, and L. L. Bu, “10x112-Gb/s PDM 16-QAM transmission over 630km of fiber with 6.2-b/s/Hz spectral efficiency,” presented at OFC2009, San Diego, CA, Mar. 2009, paper PDPB8.
  20. M. S. Alfiad, M. Kuschnerov, S. L. Jansen, T. Wuth, D. van den Borne, and H. de Waardt, “11×224-Gb/s POLMUX-RZ-16QAM transmission over 670 km of SSMF with 50-GHz channel spacing,” IEEE Photon. Technol. Lett.22(15), 1150–1152 (2010). [CrossRef]
  21. M. Selmi, Y. Jaouën, and P. Ciblat, “Accurate digital frequency offset estimator for coherent PolMux QAM transmission systems,” in Proc. ECOC 2009, Sep. 2009, Paper P3.08.
  22. J. Li, L. Li, Z. Tao, T. Hoshida, and J. C. Rasmussen, “Laser-linewidth- tolerant feed-forward carrier phase estimator with reduced complexity for QAM,” J. Lightwave Technol.29(16), 2358–2364 (2011). [CrossRef]
  23. M. Scholten, T. Coe, and J. Dillard, “Continuously-interleaved BCH (CI-BCH) FEC delivers best in class NECG for 40G and 100G metro applications,” presented at OFC2010, San Diego, CA, Mar. 2010, paper NTuB3.

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