## Building up low-complexity spectrally-efficient Terabit superchannels by receiver-side duobinary shaping |

Optics Express, Vol. 20, Issue 9, pp. 10271-10282 (2012)

http://dx.doi.org/10.1364/OE.20.010271

Acrobat PDF (1340 KB)

### Abstract

Recently, an increasing interest has been put on spectrally-efficient multi-carrier superchannels for beyond 100G. Apart from orthogonal frequency-division multiplexing (OFDM) and Nyquist wavelength-division multiplexing (WDM), another low-complexity WDM approach based on transmitter-side pre-filtering and receiver-side duobinary shaping is proposed to build up multi-carrier superchannels. This approach is referred to as receiver-side duobinary-shaped WDM (RS-DBS-WDM). Generation and transmission of a 1.232-Tbit/s 11-carrier superchannel is experimentally demonstrated. The superchannel signal can be well fit inside the passband of multiple 300-GHz reconfigurable optical add and drop multiplexers (ROADMs). In the superchannel scenario, the proposed RS-DBS-WDM is qualitatively compared with OFDM and Nyquist-WDM in terms of implementation complexity. In sum, the proposed RS-DBS-WDM approach features high transceiver analog-bandwidth efficiency, high spectral-efficiency, the absence of specific spectral manipulation, compatibility with conventional WDM technologies and coherent detection algorithms, and comparable implementation penalty.

© 2012 OSA

## 1. Introduction

1. 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]

6. J. Yu, Z. Dong, J. Zhang, X. Xiao, H.-C. Chien, and N. Chi, “Generation of coherent and frequency-locked multi-carriers using cascaded phase modulators for 10Tb/s optical transmission,” J. Lightwave Technol. **30**(4), 458–465 (2012). [CrossRef]

1. 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]

2. 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]

3. A. Sano, E. Yamada, H. Masuda, E. Yamazaki, T. Kobayashi, E. Yoshida, Y. Miyamoto, R. Kudo, K. Ishihara, and Y. Takatori, “No-guard-interval coherent optical OFDM for 100-Gb/s long-haul WDM transmission,” J. Lightwave Technol. **27**(16), 3705–3713 (2009). [CrossRef]

6. J. Yu, Z. Dong, J. Zhang, X. Xiao, H.-C. Chien, and N. Chi, “Generation of coherent and frequency-locked multi-carriers using cascaded phase modulators for 10Tb/s optical transmission,” J. Lightwave Technol. **30**(4), 458–465 (2012). [CrossRef]

7. 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]

10. R. Cigliutti, E. Torrengo, G. Bosco, N. P. Caponio, A. Carena, V. Curri, P. Poggiolini, Y. Yamamoto, T. Sasaki, and F. Forghieri, “Transmission of 9×138Gb/s prefiltered PM-8QAM signals over 4000 km of pure silica-core fiber,” J. Lightwave Technol. **29**(15), 2310–2318 (2011). [CrossRef]

7. 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]

8. 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]

9. 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]

10. R. Cigliutti, E. Torrengo, G. Bosco, N. P. Caponio, A. Carena, V. Curri, P. Poggiolini, Y. Yamamoto, T. Sasaki, and F. Forghieri, “Transmission of 9×138Gb/s prefiltered PM-8QAM signals over 4000 km of pure silica-core fiber,” J. Lightwave Technol. **29**(15), 2310–2318 (2011). [CrossRef]

11. G. Gavioli, E. Torrengo, G. Bosco, A. Carena, V. Curri, V. Miot, P. Poggiolini, M. Belmonte, F. Forghieri, C. Muzio, S. Piciaccia, A. Brinciotti, A. L. Porta, C. Lezzi, S. Savory, and S. Abrate, “Investigation of the impact of ultra-narrow carrier spacing on the transmission of a 10-carrier 1Tb/s superchannel,” in Proc. OFC 2010, San Diego, CA, March 2010, Paper OThD3.

17. N. Alic, M. Karlsson, M. Skold, O. Milenkovic, P. A. Andrekson, and S. Radic, “Joint statistics and MLSD in filtered incoherent high-speed fiber-optic communications,” J. Lightwave Technol. **28**(10), 1564–1572 (2010). [CrossRef]

21. J. Li, Z. Tao, H. Zhang, W. Yan, T. Hoshida, and J. C. Rasmussen, “Spectrally efficient quadrature duobinary coherent systems with symbol-rate digital signal processing,” J. Lightwave Technol. **29**(8), 1098–1104 (2011). [CrossRef]

## 2. Building up RS-DBS-WDM superchannels

22. R. Nagarajan, D. Lambert, M. Kato, V. Lal, G. Goldfarb, J. Rahn, M. Kuntz, J. Pleumeekers, A. Dentai, H. -S. Tsai, R. Malendevich, M. Missey, K. -T. Wu, H. Sun, J. McNicol, J. Tang, J. Zhang, T. Butrie, A. Nilsson, M. Reffle, F. Kish, and D. Welch, “10 channel, 100Gbit/s per channel, dual polarization, coherent QPSK, monolithic InP receiver photonic integrated circuit,” in Proc. OFC2011, Mar. 2011, Paper OML7.

## 3. Experiments

### 3.1 Experimental setup and DSP algorithms

21. J. Li, Z. Tao, H. Zhang, W. Yan, T. Hoshida, and J. C. Rasmussen, “Spectrally efficient quadrature duobinary coherent systems with symbol-rate digital signal processing,” J. Lightwave Technol. **29**(8), 1098–1104 (2011). [CrossRef]

24. 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]

*T*/2-spaced finite impulse-response (FIR) filters adapted by the classic constant-modulus algorithm (CMA). It has been demonstrated in [12] that CMA works well even in the presence of more aggressive pre-filtering. Carrier recovery was done including the frequency offset estimation based on the fast Fourier transform (FFT) method [26] and carrier phase estimation based on 4th-power Viterbi-Viterbi algorithm [27

27. S. J. Savory, “Digital coherent optical receivers: algorithms and subsystems,” IEEE J. Sel. Top. Quantum Electron. **16**(5), 1164–1179 (2010). [CrossRef]

### 3.2 B2B performance

^{−3}. Secondly, aggressive optical filtering was applied on the single-carrier 112 Gbit/s PM-QPSK signal by inserting the 25/50GHz interleaver after the QPSK modulation. In this case, the post-filter and MLSD were activated to replace the hard decision. The single-carrier 28 Gbaud PM-QPSK signal passing the 25/50GHz interleaver only suffers from ~0.7 dB OSNR penalty (empty squares). In contrast, the OSNR penalty increases to ~1.5 dB if the hard decision is applied (filled squares). Thirdly, since the linear crosstalk only originates from its most adjacent carriers in practical systems, we turned on the two most adjacent carriers by configuring WSS1 in order to investigate the impact of the inter-carrier linear crosstalk. Another 1.1 dB OSNR penalty appears (empty triangles). In total, there is about 1.8 dB OSNR penalty for BER = 10

^{−3}in the presence of both aggressive filtering and linear crosstalk. In the 11-carrier case, there is an extra OSNR penalty of ~0.8 dB. This is because the optical QPSK signal in even or odd carriers were generated using a single I/Q modulator, thereby suffering from an additional amount of linear crosstalk. However, this will not happen in practical systems. In contrast, the BER is unable to reach 10

^{−3}if we used direct hard decision (filled triangles). Referring to the four curves with triangles and squares, one can conclude that a larger performance improvement is obtained by the post-filter and MLSD in the presence of linear crosstalk (i.e. 3-carrier case) as compared to the 1-carrier case. Note that these results are consistent with those in [12,18] where the WaveShapers programmed with super Gaussian profile were used to perform the aggressive pre-filtering, indicating the feasibility of using commercial WDM components.

### 3.3 Fiber transmission performance

### 3.4 Tolerance to concatenated WSSs

## 4. Complexity comparison of different solutions to building up superchannels

23. S. Chandrasekhar and X. Liu, “Experimental investigation on the performance of closely spaced multi-carrier PDM-QPSK with digital coherent detection,” Opt. Express **17**(24), 21350–21361 (2009). [CrossRef] [PubMed]

*N*:1 optical couplers.

8. 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]

9. 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]

10. R. Cigliutti, E. Torrengo, G. Bosco, N. P. Caponio, A. Carena, V. Curri, P. Poggiolini, Y. Yamamoto, T. Sasaki, and F. Forghieri, “Transmission of 9×138Gb/s prefiltered PM-8QAM signals over 4000 km of pure silica-core fiber,” J. Lightwave Technol. **29**(15), 2310–2318 (2011). [CrossRef]

11. G. Gavioli, E. Torrengo, G. Bosco, A. Carena, V. Curri, V. Miot, P. Poggiolini, M. Belmonte, F. Forghieri, C. Muzio, S. Piciaccia, A. Brinciotti, A. L. Porta, C. Lezzi, S. Savory, and S. Abrate, “Investigation of the impact of ultra-narrow carrier spacing on the transmission of a 10-carrier 1Tb/s superchannel,” in Proc. OFC 2010, San Diego, CA, March 2010, Paper OThD3.

*N*:1 optical couplers are preferred to AWGs when combining the carriers together in order to keep the rectangular spectral shape. Thus, the resultant high insertion loss and low delivered OSNR would be problems.

28. V. M. Eyuboglu and S. U. Qureshi, “Reduced-state sequence estimation for coded modulation on intersymbol interference channels,” IEEE J. Sel. Areas Comm. **7**(6), 989–995 (1989). [CrossRef]

29. S. Olcer, “Reduced-state sequence detection of multilevel partial-response signals,” IEEE Trans. Commun. **40**(1), 3–6 (1992). [CrossRef]

## 5. Conclusion

## Appendix

- •
*x*: the input 2PAM symbol in the_{k}*k*^{th}trellis stage or the*k*^{th}time slot.*x*takes two possible levels, i.e._{k}*x*∈ {1, −1}._{k} - •
*s*: the state in the_{k}*k*^{th}trellis stage. Since the memory length is one symbol for duobinary-shaped signal,*s*is directly given by_{k}*x*._{k} - •
*y*: the duobinary-shaped noiseless 2PAM symbol in the_{k}*k*^{th}trellis stage.*y*takes three possible levels, i.e._{k}*y*∈ {2, 0, −2}, since_{k}*y*=_{k}*x*+_{k}*x*_{k}_{-1}. - •
*n*: the AWGN sample in the_{k}*k*^{th}trellis stage. - •
*z*: the received noisy signal in the_{k}*k*^{th}trellis stage. We have*z*=_{k}*y*+_{k}*n*._{k}

*k*

^{th}stage or time slot, the Viterbi algorithm computes several distance metrics for each state in a recursive way. The distance metrics for each state is given by [12]

*DM*(

*x*) denotes the distance metric assigned to state

_{k}*x*in the

_{k}*k*

^{th}stage; ∆

*DM*(

*x*

_{k}_{-1},

*x*) denotes the distance metric increment corresponding to the trellis branch from

_{k}*x*

_{k}_{-1}to

*x*in the

_{k}*k*

^{th}stage. Since the entire distance metrics are all made up of the accumulated metric increments, we can only focus on the ∆

*DM*(

*x*

_{k}_{-1},

*x*) for notation convenience.

_{k}*z*

_{k}^{2}in the

*k*

^{th}stage. Thus, we can subtract

*z*

_{k}^{2}from all the distance metric increments in each stage.

*y*takes three possible levels, i.e.

_{k}*y*∈ {2, 0, −2},

_{k}*y*/ 2 ∈ {1, 0, −1}. Then, we can represent the distance metric increment in the

_{k}*k*

^{th}stage as

## References and links

1. | 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. |

2. | 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 |

3. | A. Sano, E. Yamada, H. Masuda, E. Yamazaki, T. Kobayashi, E. Yoshida, Y. Miyamoto, R. Kudo, K. Ishihara, and Y. Takatori, “No-guard-interval coherent optical OFDM for 100-Gb/s long-haul WDM transmission,” J. Lightwave Technol. |

4. | S. Chandrasekhar, X. Liu, B. Zhu, and D. W. Peckham, “Transmission of a 1.2 Tb/s 24-carrier no-guard-interval coherent OFDM superchannel over 7200-km of ultra-large-area fiber,” presented at the ECOC 2009, Vienna, Austria, Sep. 20–24, 2009, Paper PD2.6. |

5. | 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. |

6. | J. Yu, Z. Dong, J. Zhang, X. Xiao, H.-C. Chien, and N. Chi, “Generation of coherent and frequency-locked multi-carriers using cascaded phase modulators for 10Tb/s optical transmission,” J. Lightwave Technol. |

7. | 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. |

8. | 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 |

9. | 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. |

10. | R. Cigliutti, E. Torrengo, G. Bosco, N. P. Caponio, A. Carena, V. Curri, P. Poggiolini, Y. Yamamoto, T. Sasaki, and F. Forghieri, “Transmission of 9×138Gb/s prefiltered PM-8QAM signals over 4000 km of pure silica-core fiber,” J. Lightwave Technol. |

11. | G. Gavioli, E. Torrengo, G. Bosco, A. Carena, V. Curri, V. Miot, P. Poggiolini, M. Belmonte, F. Forghieri, C. Muzio, S. Piciaccia, A. Brinciotti, A. L. Porta, C. Lezzi, S. Savory, and S. Abrate, “Investigation of the impact of ultra-narrow carrier spacing on the transmission of a 10-carrier 1Tb/s superchannel,” in Proc. OFC 2010, San Diego, CA, March 2010, Paper OThD3. |

12. | 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,” to be published in J. Lightwave Technol. |

13. | J. G. Proakis, |

14. | G. D. Forney Jr., “Maximum likelihood sequence estimation of digital sequences in the presence of intersymbol interference,” IEEE Trans. Inf. Theory |

15. | H. Kobayashi, “Correlative level coding and maximum likelihood decoding,” IEEE Trans. Inf. Theory |

16. | N. Alic, G. C. Papen, R. E. Saperstein, R. Jiang, C. Marki, Y. Fainman, S. Radic, and P. A. Andrekson, “Experimental demonstration of 10 Gb/s NRZ extended dispersion-limited reach over 600km-SMF link without optical dispersion compensation,” presented in OFC 2006, Anaheim, CA, March 2006, paper OWB7. |

17. | N. Alic, M. Karlsson, M. Skold, O. Milenkovic, P. A. Andrekson, and S. Radic, “Joint statistics and MLSD in filtered incoherent high-speed fiber-optic communications,” J. Lightwave Technol. |

18. | 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 OFC 2012, Los Angeles, CA, March 2012, Paper OM3H.2. |

19. | I. Lyubomirsky, “Quadrature duobinary modulation for 100G transmission beyond the Nyquist limit,” in Proc. OFC 2010, San Diego, CA, March 2010, Paper OThM4. |

20. | I. Lyubomirsky, “Quadrature duobinary for high-spectral efficiency 100G transmission,” J. Lightwave Technol. |

21. | J. Li, Z. Tao, H. Zhang, W. Yan, T. Hoshida, and J. C. Rasmussen, “Spectrally efficient quadrature duobinary coherent systems with symbol-rate digital signal processing,” J. Lightwave Technol. |

22. | R. Nagarajan, D. Lambert, M. Kato, V. Lal, G. Goldfarb, J. Rahn, M. Kuntz, J. Pleumeekers, A. Dentai, H. -S. Tsai, R. Malendevich, M. Missey, K. -T. Wu, H. Sun, J. McNicol, J. Tang, J. Zhang, T. Butrie, A. Nilsson, M. Reffle, F. Kish, and D. Welch, “10 channel, 100Gbit/s per channel, dual polarization, coherent QPSK, monolithic InP receiver photonic integrated circuit,” in Proc. OFC2011, Mar. 2011, Paper OML7. |

23. | S. Chandrasekhar and X. Liu, “Experimental investigation on the performance of closely spaced multi-carrier PDM-QPSK with digital coherent detection,” Opt. Express |

24. | 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. |

25. | K. Horikoshi, T. Kobayashi, S. Yamanaka, E. Yamazaki, A. Sano, E. Yoshida, and Y. Miyamoto, “Spectrum-narrowing tolerant 171-Gbit/s PDM-16QAM transmission over 1,200 km using maximum likelihood sequence estimation,” in Proc. ECOC 2011, Paper We.10.P1.73. |

26. | 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. |

27. | S. J. Savory, “Digital coherent optical receivers: algorithms and subsystems,” IEEE J. Sel. Top. Quantum Electron. |

28. | V. M. Eyuboglu and S. U. Qureshi, “Reduced-state sequence estimation for coded modulation on intersymbol interference channels,” IEEE J. Sel. Areas Comm. |

29. | S. Olcer, “Reduced-state sequence detection of multilevel partial-response signals,” IEEE Trans. Commun. |

**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:**

Fiber Optics and Optical Communications

**History**

Original Manuscript: January 11, 2012

Revised Manuscript: February 23, 2012

Manuscript Accepted: March 19, 2012

Published: April 19, 2012

**Citation**

Jianqiang Li, Martin Sjödin, Magnus Karlsson, and Peter A. Andrekson, "Building up low-complexity spectrally-efficient Terabit superchannels by receiver-side duobinary shaping," Opt. Express **20**, 10271-10282 (2012)

http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-20-9-10271

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### References

- 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]
- 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]
- A. Sano, E. Yamada, H. Masuda, E. Yamazaki, T. Kobayashi, E. Yoshida, Y. Miyamoto, R. Kudo, K. Ishihara, and Y. Takatori, “No-guard-interval coherent optical OFDM for 100-Gb/s long-haul WDM transmission,” J. Lightwave Technol.27(16), 3705–3713 (2009). [CrossRef]
- S. Chandrasekhar, X. Liu, B. Zhu, and D. W. Peckham, “Transmission of a 1.2 Tb/s 24-carrier no-guard-interval coherent OFDM superchannel over 7200-km of ultra-large-area fiber,” presented at the ECOC 2009, Vienna, Austria, Sep. 20–24, 2009, Paper PD2.6.
- 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.
- J. Yu, Z. Dong, J. Zhang, X. Xiao, H.-C. Chien, and N. Chi, “Generation of coherent and frequency-locked multi-carriers using cascaded phase modulators for 10Tb/s optical transmission,” J. Lightwave Technol.30(4), 458–465 (2012). [CrossRef]
- 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]
- 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]
- 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]
- R. Cigliutti, E. Torrengo, G. Bosco, N. P. Caponio, A. Carena, V. Curri, P. Poggiolini, Y. Yamamoto, T. Sasaki, and F. Forghieri, “Transmission of 9×138Gb/s prefiltered PM-8QAM signals over 4000 km of pure silica-core fiber,” J. Lightwave Technol.29(15), 2310–2318 (2011). [CrossRef]
- G. Gavioli, E. Torrengo, G. Bosco, A. Carena, V. Curri, V. Miot, P. Poggiolini, M. Belmonte, F. Forghieri, C. Muzio, S. Piciaccia, A. Brinciotti, A. L. Porta, C. Lezzi, S. Savory, and S. Abrate, “Investigation of the impact of ultra-narrow carrier spacing on the transmission of a 10-carrier 1Tb/s superchannel,” in Proc. OFC 2010, San Diego, CA, March 2010, Paper OThD3.
- 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,” to be published in J. Lightwave Technol.
- J. G. Proakis, Digital Communications, 4th ed. (New York McGraw-Hill, 2001).
- G. D. Forney., “Maximum likelihood sequence estimation of digital sequences in the presence of intersymbol interference,” IEEE Trans. Inf. Theory18(3), 363–378 (1972). [CrossRef]
- H. Kobayashi, “Correlative level coding and maximum likelihood decoding,” IEEE Trans. Inf. Theory17(5), 586–594 (1971). [CrossRef]
- N. Alic, G. C. Papen, R. E. Saperstein, R. Jiang, C. Marki, Y. Fainman, S. Radic, and P. A. Andrekson, “Experimental demonstration of 10 Gb/s NRZ extended dispersion-limited reach over 600km-SMF link without optical dispersion compensation,” presented in OFC 2006, Anaheim, CA, March 2006, paper OWB7.
- N. Alic, M. Karlsson, M. Skold, O. Milenkovic, P. A. Andrekson, and S. Radic, “Joint statistics and MLSD in filtered incoherent high-speed fiber-optic communications,” J. Lightwave Technol.28(10), 1564–1572 (2010). [CrossRef]
- 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 OFC 2012, Los Angeles, CA, March 2012, Paper OM3H.2.
- I. Lyubomirsky, “Quadrature duobinary modulation for 100G transmission beyond the Nyquist limit,” in Proc. OFC 2010, San Diego, CA, March 2010, Paper OThM4.
- I. Lyubomirsky, “Quadrature duobinary for high-spectral efficiency 100G transmission,” J. Lightwave Technol.28(1), 91–96 (2010). [CrossRef]
- J. Li, Z. Tao, H. Zhang, W. Yan, T. Hoshida, and J. C. Rasmussen, “Spectrally efficient quadrature duobinary coherent systems with symbol-rate digital signal processing,” J. Lightwave Technol.29(8), 1098–1104 (2011). [CrossRef]
- R. Nagarajan, D. Lambert, M. Kato, V. Lal, G. Goldfarb, J. Rahn, M. Kuntz, J. Pleumeekers, A. Dentai, H. -S. Tsai, R. Malendevich, M. Missey, K. -T. Wu, H. Sun, J. McNicol, J. Tang, J. Zhang, T. Butrie, A. Nilsson, M. Reffle, F. Kish, and D. Welch, “10 channel, 100Gbit/s per channel, dual polarization, coherent QPSK, monolithic InP receiver photonic integrated circuit,” in Proc. OFC2011, Mar. 2011, Paper OML7.
- S. Chandrasekhar and X. Liu, “Experimental investigation on the performance of closely spaced multi-carrier PDM-QPSK with digital coherent detection,” Opt. Express17(24), 21350–21361 (2009). [CrossRef] [PubMed]
- 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]
- K. Horikoshi, T. Kobayashi, S. Yamanaka, E. Yamazaki, A. Sano, E. Yoshida, and Y. Miyamoto, “Spectrum-narrowing tolerant 171-Gbit/s PDM-16QAM transmission over 1,200 km using maximum likelihood sequence estimation,” in Proc. ECOC 2011, Paper We.10.P1.73.
- 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.
- S. J. Savory, “Digital coherent optical receivers: algorithms and subsystems,” IEEE J. Sel. Top. Quantum Electron.16(5), 1164–1179 (2010). [CrossRef]
- V. M. Eyuboglu and S. U. Qureshi, “Reduced-state sequence estimation for coded modulation on intersymbol interference channels,” IEEE J. Sel. Areas Comm.7(6), 989–995 (1989). [CrossRef]
- S. Olcer, “Reduced-state sequence detection of multilevel partial-response signals,” IEEE Trans. Commun.40(1), 3–6 (1992). [CrossRef]

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