Abstract

Ultra-high-speed optical communication systems which can support ≥ 1Tb/s per channel transmission will soon be required to meet the increasing capacity demand. However, 1Tb/s over a single carrier requires either or both a high-level modulation format (i.e. 1024QAM) and a high baud rate. Alternatively, grouping a number of tightly spaced “sub-carriers” to form a terabit superchannel increases channel capacity while minimizing the need for high-level modulation formats and high baud rate, which may allow existing formats, baud rate and components to be exploited. In ideal Nyquist-WDM superchannel systems, optical subcarriers with rectangular spectra are tightly packed at a channel spacing equal to the baud rate, thus achieving the Nyquist bandwidth limit. However, in practical Nyquist-WDM systems, precise electrical or optical control of channel spectra is required to avoid strong inter-channel interference (ICI). Here, we propose and demonstrate a new “super receiver” architecture for practical Nyquist-WDM systems, which jointly detects and demodulates multiple channels simultaneously and mitigates the penalties associated with the limitations of generating ideal Nyquist-WDM spectra. Our receiver-side solution relaxes the filter requirements imposed on the transmitter. Two joint DSP algorithms are developed for linear ICI cancellation and joint carrier-phase recovery. Improved system performance is observed with both experimental and simulation data. Performance analysis under different system configurations is conducted to demonstrate the feasibility and robustness of the proposed joint DSP algorithms.

© 2013 OSA

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  3. X. Liu, S. Chandrasekhar, B. Zhu, P. J. Winzer, A. H. Gnauck, and D. W. Peckham, “Transmission of a 448-Gb/s reduced-guard-interval CO-OFDM signal with a 60-GHz optical bandwidth over 2000 km of ULAF and five 80-GHz-grid ROADMs,” OFC 2010, PDPC2.
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    [CrossRef] [PubMed]
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    [CrossRef]
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  7. 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]
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    [CrossRef]
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  10. R. Dischler and F. Buchali, “Transmission of 1.2 Tb/s continuous waveband PDM-OFDM-FDM signal with spectral efficiency of 3.3 bit/s/Hz over 400 km of SSMF,” OFC 2009, Paper PDPC2.
  11. 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).
  12. S. Chandrasekhar and X. Liu, “Terabit superchannels for high spectral efficiency transmission,” ECOC 2010, Tu.3.C.5.
  13. D. Hillerkuss, M. Winter, M. Teschke, A. Marculescu, J. Li, G. Sigurdsson, K. Worms, W. Freude, and J. Leuthold, “Low-complexity optical FFT scheme enabling Tbit/s all-optical OFDM communication,” ITG Symposium on Photonic Networks, 2010.
  14. K. Takiguchi, M. Oguma, T. Shibata, and H. Takahashi, “Optical OFDM demultiplexer using silica PLC based optical FFT circuit,” OFC 2009, OWO3.
  15. 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. La 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,” OFC 2010, OThD3.
  16. A. J. Viterbi and A. M. Viterbi, “Nonlinear estimation of PSK-modulated carrier phase with application to burst digital transmission,” IEEE Trans. Inf. Theory29(4), 543–551 (1983).
    [CrossRef]
  17. Z. Dong, J. Yu, H.-C. Chien, N. Chi, L. Chen, and G.-K. Chang, “Ultra-dense WDM-PON delivering carrier-centralized Nyquist-WDM uplink with digital coherent detection,” Opt. Express19(12), 11100–11105 (2011).
    [CrossRef] [PubMed]
  18. H.-C. Chien, J. Yu, Z. Dong, Z. Jia, “Offset RZ pulse shape for 128 Gb/s PDM-QPSK subject to aggressive filtering,” OFC 2012, Paper OM3H.3.
  19. J. Pan, C. Liu, T. Detwiler, A. Stark, Y.-T. Hsueh, and S. E. Ralph, “Inter-channel crosstalk cancellation for Nyquist-WDM superchannel applications,” J. Lightwave Technol.30(24), 3993–3999 (2012).
    [CrossRef]
  20. C. Liu, J. Pan, T. Detwiler, A. Stark, Y.-T. Hsueh, G.-K. Chang, and S. E. Ralph, “Joint digital signal processing for superchannel coherent optical system: joint CD compensation for joint ICI cancellation,” ECOC 2012, Paper Th.1.A.4.

2012

2011

2010

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).

2009

1983

A. J. Viterbi and A. M. Viterbi, “Nonlinear estimation of PSK-modulated carrier phase with application to burst digital transmission,” IEEE Trans. Inf. Theory29(4), 543–551 (1983).
[CrossRef]

Baeuerle, B.

Becker, J.

Ben-Ezra, S.

Bolle, C.

Bosco, G.

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).

Burrows, E.

Carena, A.

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).

Chandrasekhar, S.

Chang, G.-K.

Chen, L.

Chi, N.

Chien, H.-C.

Curri, V.

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).

Detwiler, T.

Dong, Z.

Dreschmann, M.

Esmaeelpour, M.

Essiambre, R. J.

Forghieri, F.

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).

Freude, W.

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]

D. Hillerkuss, M. Winter, M. Teschke, A. Marculescu, J. Li, G. Sigurdsson, K. Worms, W. Freude, and J. Leuthold, “Low-complexity optical FFT scheme enabling Tbit/s all-optical OFDM communication,” ITG Symposium on Photonic Networks, 2010.

Gnauck, A.

Hillerkuss, D.

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]

D. Hillerkuss, M. Winter, M. Teschke, A. Marculescu, J. Li, G. Sigurdsson, K. Worms, W. Freude, and J. Leuthold, “Low-complexity optical FFT scheme enabling Tbit/s all-optical OFDM communication,” ITG Symposium on Photonic Networks, 2010.

Hsueh, Y.-T.

Huebner, M.

Ishihara, K.

Kobayashi, T.

Koos, C.

Kudo, R.

Leuthold, J.

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]

D. Hillerkuss, M. Winter, M. Teschke, A. Marculescu, J. Li, G. Sigurdsson, K. Worms, W. Freude, and J. Leuthold, “Low-complexity optical FFT scheme enabling Tbit/s all-optical OFDM communication,” ITG Symposium on Photonic Networks, 2010.

Li, J.

D. Hillerkuss, M. Winter, M. Teschke, A. Marculescu, J. Li, G. Sigurdsson, K. Worms, W. Freude, and J. Leuthold, “Low-complexity optical FFT scheme enabling Tbit/s all-optical OFDM communication,” ITG Symposium on Photonic Networks, 2010.

Lingle, R.

Liu, C.

Liu, X.

Ludwig, A.

Marculescu, A.

D. Hillerkuss, M. Winter, M. Teschke, A. Marculescu, J. Li, G. Sigurdsson, K. Worms, W. Freude, and J. Leuthold, “Low-complexity optical FFT scheme enabling Tbit/s all-optical OFDM communication,” ITG Symposium on Photonic Networks, 2010.

Masuda, H.

McCurdy, A.

Meyer, J.

Meyer, M.

Miyamoto, Y.

Mumtaz, S.

Nebendahl, B.

Pan, J.

Peckham, D.

Poggiolini, P.

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).

Ralph, S. E.

Randel, S.

Ryf, R.

Sano, A.

Schmogrow, R.

Sierra, A.

Sigurdsson, G.

D. Hillerkuss, M. Winter, M. Teschke, A. Marculescu, J. Li, G. Sigurdsson, K. Worms, W. Freude, and J. Leuthold, “Low-complexity optical FFT scheme enabling Tbit/s all-optical OFDM communication,” ITG Symposium on Photonic Networks, 2010.

Stark, A.

Takatori, Y.

Teschke, M.

D. Hillerkuss, M. Winter, M. Teschke, A. Marculescu, J. Li, G. Sigurdsson, K. Worms, W. Freude, and J. Leuthold, “Low-complexity optical FFT scheme enabling Tbit/s all-optical OFDM communication,” ITG Symposium on Photonic Networks, 2010.

Viterbi, A. J.

A. J. Viterbi and A. M. Viterbi, “Nonlinear estimation of PSK-modulated carrier phase with application to burst digital transmission,” IEEE Trans. Inf. Theory29(4), 543–551 (1983).
[CrossRef]

Viterbi, A. M.

A. J. Viterbi and A. M. Viterbi, “Nonlinear estimation of PSK-modulated carrier phase with application to burst digital transmission,” IEEE Trans. Inf. Theory29(4), 543–551 (1983).
[CrossRef]

Winter, M.

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]

D. Hillerkuss, M. Winter, M. Teschke, A. Marculescu, J. Li, G. Sigurdsson, K. Worms, W. Freude, and J. Leuthold, “Low-complexity optical FFT scheme enabling Tbit/s all-optical OFDM communication,” ITG Symposium on Photonic Networks, 2010.

Winzer, P. J.

Wolf, S.

Worms, K.

D. Hillerkuss, M. Winter, M. Teschke, A. Marculescu, J. Li, G. Sigurdsson, K. Worms, W. Freude, and J. Leuthold, “Low-complexity optical FFT scheme enabling Tbit/s all-optical OFDM communication,” ITG Symposium on Photonic Networks, 2010.

Yamada, E.

Yamazaki, E.

Yoshida, E.

Yu, J.

IEEE Photon. Technol. Lett.

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).

IEEE Trans. Inf. Theory

A. J. Viterbi and A. M. Viterbi, “Nonlinear estimation of PSK-modulated carrier phase with application to burst digital transmission,” IEEE Trans. Inf. Theory29(4), 543–551 (1983).
[CrossRef]

J. Lightwave Technol.

Opt. Express

Other

Y. Ma, Q. Yang, Y. Tang, S. Chen, and W. Shieh, “1-Tb/s per channel coherent optical OFDM transmission with subwavelength bandwidth access,” OFC 2009, Paper PDPC1.

R. Dischler and F. Buchali, “Transmission of 1.2 Tb/s continuous waveband PDM-OFDM-FDM signal with spectral efficiency of 3.3 bit/s/Hz over 400 km of SSMF,” OFC 2009, Paper PDPC2.

E. Torrengo, R. Cigliutti, G. Bosco, G. Gavioli, A. Alaimo, A. Carena, V. Curri, F. Forghieri, S. Piciaccia, M. Belmonte, A. Brinciotti, A. La Porta, S. Abrate, and P. Poggiolini, “Transoceanic PM-QPSK terabit superchannel transmission experiments at baud-rate subcarrier spacing,” ECOC 2010, We.7.C.2.

Y. Cai, J. X. Cai, C. R. Davidson, D. Foursa, A. Lucero, O. Sinkin, A. Pilipetskii, G. Mohs, and N. S. Bergano, “High spectral efficiency long-haul transmission with pre-filtering and maximum a posteriori probability detection,” ECOC 2010, We.7.C.4.

X. Liu, S. Chandrasekhar, B. Zhu, P. J. Winzer, A. H. Gnauck, and D. W. Peckham, “Transmission of a 448-Gb/s reduced-guard-interval CO-OFDM signal with a 60-GHz optical bandwidth over 2000 km of ULAF and five 80-GHz-grid ROADMs,” OFC 2010, PDPC2.

Y. Cai, J. X. Cai, C. R. Davidson, D. Foursa, A. Lucero, O. Sinkin, A. Pilipetskii, G. Mohs, and N. S. Bergano, “Achieving high spectral efficiency in long-haul transmission with pre-filtering and multi-symbol detection,” ACP 2010, page 349–350.

H.-C. Chien, J. Yu, Z. Dong, Z. Jia, “Offset RZ pulse shape for 128 Gb/s PDM-QPSK subject to aggressive filtering,” OFC 2012, Paper OM3H.3.

C. Liu, J. Pan, T. Detwiler, A. Stark, Y.-T. Hsueh, G.-K. Chang, and S. E. Ralph, “Joint digital signal processing for superchannel coherent optical system: joint CD compensation for joint ICI cancellation,” ECOC 2012, Paper Th.1.A.4.

S. Chandrasekhar and X. Liu, “Terabit superchannels for high spectral efficiency transmission,” ECOC 2010, Tu.3.C.5.

D. Hillerkuss, M. Winter, M. Teschke, A. Marculescu, J. Li, G. Sigurdsson, K. Worms, W. Freude, and J. Leuthold, “Low-complexity optical FFT scheme enabling Tbit/s all-optical OFDM communication,” ITG Symposium on Photonic Networks, 2010.

K. Takiguchi, M. Oguma, T. Shibata, and H. Takahashi, “Optical OFDM demultiplexer using silica PLC based optical FFT circuit,” OFC 2009, OWO3.

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. La 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,” OFC 2010, OThD3.

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Figures (12)

Fig. 1
Fig. 1

Spectra and pulse shapes for ideal (dash) and practical (solid) Nyquist-WDM superchannel systems.

Fig. 2
Fig. 2

“Super receiver” architecture for superchannel coherent systems. Optical filters depicted before multiplexer and after demultiplexer represent the net optical filtering of the Tx mux and Rx demux respectively.

Fig. 3
Fig. 3

Joint-DSP procedure for linear-ICI cancellation based on adaptive LMS algorithm. Processing is conventional until after timing and carrier-phase recovery.

Fig. 4
Fig. 4

Block diagram of 5-channel joint ICI cancellation with scalable computational complexity.

Fig. 5
Fig. 5

Joint-DSP procedure for joint carrier-phase recovery based on Viterbi-Viterbi algorithm. Processing is conventional until after timing recovery.

Fig. 6
Fig. 6

(a) Superchannel optical filter scenarios examined. Scenario 1 is the case where no optical filtering is used either at the Tx or Rx for each individual subchannel. Scenario 2 depicts a more typical case where each subchannel is optically pre-filtered at Tx. Subcarrier separation is done in the electrical domain at the receiver for both scenarios. (b) Examples of Tx optical spectral shapes of 32GBaud QPSK signal under different optical Tx filter bandwidths (ideal 32GBaud Nyquist spectrum, no Tx filter, 38GHz, and 30GHz filter cases).

Fig. 7
Fig. 7

Two-subchannel, DP-QPSK, proof-of-concept BTB experimental setup based on the “super receiver” architecture. Neither channel is optically filtered (scenario 1). Both channels use separate but synchronously sampled coherent receivers.

Fig. 8
Fig. 8

Comparison between the proposed joint LMS ICI equalizer and conventional independent channel methods for both experimental and simulation results of the two-subchannel 28GBaud system of Fig. 6. Joint ICI cancellation substantially mitigates ICI penalties for this scenario with no sub channel optical filtering and hence strong ICI at narrow channel spacing.

Fig. 9
Fig. 9

Required OSNR to obtain BER = 10−2 and 10−3 vs. channel spacing under different optical filter bandwidth configurations (three-subchannel 32GBaud BTB setup, scenario 2). The ICI cancellation methods are shown to systematically reduce OSNR penalties associated with narrow channel spacing for all filter bandwidths.

Fig. 10
Fig. 10

Required OSNR to obtain BER = 10−2 and 10−3 vs. channel spacing under different channel spacing conditions (three-subchannel 32GBaud BTB setup, scenario 2). ICI cancellation algorithm is shown to systematically reduce OSNR penalties associated with narrow channel spacing, and eliminate performance sensitivity to optical filter bandwidth.

Fig. 11
Fig. 11

(a) BER vs. OSNR of LMS ICI equalization and conventional methods for both BTB and through 12 spans (960km). Three 32GBaud subchannels at Nyquist channel spacing with 34GHz optical filters. Single channel performance is shown for reference; (b) OSNR gain at BER = 10−2 (dashed) and 10−3 (solid) vs. the number of time-domain offset symbols under different ICI-filter tap lengths.

Fig. 12
Fig. 12

(a) Joint carrier phase recovery performance for three-subchannel BTB configurations at different channel-spacings. Conventional Viterbi-Viterbi (V-V) methods shown as reference; (b) Five-subchannel case, 31.25GHz channel spacing, for joint V-V on all 5 channels and joint V-V only using outer channels.

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