Abstract

We present an optical multipath error correction technique for differentially encoded modulation formats such as differential-phase-shift-keying (DPSK) and differential polarization shift keying (DPolSK) for fiber-based and free-space communication. This multipath error correction method combines optical and electronic logic gates. The scheme can easily be implemented using commercially available interferometers and high speed logic gates and does not require any data overhead therefore does not affect the effective bandwidth of the transmitted data. It is not merely compatible but also complementary to error correction codes commonly used in optical transmission systems such as forward-error-correction (FEC). The technique consists of separating the demodulation at the receiver in multiple paths. Each path consists of a Mach-Zehnder interferometer with a different integer bit delay used in each path. Some basic logic operations follow and the three paths are compared using a simple majority vote algorithm. Experimental results show that the scheme improves receiver sensitivity by 1.5 dB at BER of 10-3,in back-to-back configuration. Numerical results indicate a 1.6 dB improvement in the presence of Chromatic Dispersion for a 25% increase in tolerance for a 3dB penalty from ±1220 ps/nm to ±1520 ps/nm. and a 0.35 dB improvement for back-to-back operation.

© 2007 Optical Society of America

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  1. A. H. Gnauck and P. J. Winzer, "Optical phase-shift-keyed transmission," J. Lightwave Technol. 23, 115-130. (2005).
    [CrossRef]
  2. P. J. Winzer and R. -J. Essiambre, "Advanced modulation formats for high-capacity optical transport networks," J. Lightwave Technol. 24, 4711-4728 (2006).
    [CrossRef]
  3. A. H. Gnauck, "40-Gb/s RZ-differential phase shift keyed transmission," in Proc. OFC2003, paper ThE1, (2003).
  4. X. Liu, "Nonlinear effects in phase shift keyed transmission," in Proc. OFC2004, paper ThM4 (2004).
  5. X. Liu, Y.-H. Kao, M. Movassaghi, and R. C. Giles, "Tolerance to in-band coherent crosstalk of differential phase-shift-keyed signal with balanced detection and FEC," IEEE Photon. Technol. Lett. 16, 1209-1911 (2004).
    [CrossRef]
  6. F. Seguin and F. Gonthier, "Tuneable all-fiber, delay-line interferometer for DPSK demodulation," in Proc. OFC2005, paper OFL5, (2005).
  7. M. Nazarathy and E. Simony, "Multi-Chip Differential Phase Encoded Optical Transmission," IEEE Photon. Technol. Lett. 17, 1133-1135 (2005).
    [CrossRef]
  8. Y. Yadin, A. Bilenca, and M. Nazarathy, "Soft detection of multichip DPSK over the nonlinear fiber-optic channel," IEEE Photon. Technol. Lett. 17, 2001-2003 (2005).
    [CrossRef]
  9. X. Liu, "Digital implementation of soft detection for 3-chip-DBPSK with improved receiver sensitivity and dispersion tolerance," in Proc. OFC 2006, paper OTuI2, (2006).
  10. M. Nazarathy, X. Liu, Y. Yadin, and M. Orenstein, "Multi-chip detection of optical differential phase-shift keying and complexity reduction by interferometric decision feedback," in Proc. ECOC 2006, We3.P.79, (2006).
  11. M. Nazarathy and Y. Yadin, "Simplified decision feedback-aided multi-chip binary DPSK receivers," IEEE Photon. Technol. Lett. 18, 1771 - 1773 (2006).
    [CrossRef]
  12. X. Liu, "Receiver sensitivity improvement in optical DQPSK and DQPSK/ASK through data-aided multi-symbol phase estimation," in Proc. ECOC 2006, We2.5.6 (2006).
  13. X. Liu, X. Liu, S. Chandrasekhar, A. H. Gnauck, C. R. Doerr, I. Kang, D. Kilper, L. L. Buhl, and J. Centanni, "DSP-enabled compensation of demodulator phase error and sensitivity improvement in direct-detection 40-Gb/s DQPSK, postdeadline paper Th4.4.5 in ECOC'06 Cannes, France, 2006.
  14. M. Nazarathy, Y. Yadin, M. Orenstein, Y. K. Lize, L. Christen, and Alan Willner, "Enhanced self-coherent optical decision-feedback-aided detection of multi-symbol M-DPSK/PolSK in particular 8-DPSK/BPolSK at 40 Gbps," Optical Fiber Conference, paper JWA43, Anaheim, CA (2007).
  15. L. Christen, Y. K. Lize, S. R. Nuccio, X. Liu, M. Nazarathy, and A. E. Willner, "DPSK error correction using multi-bit detection for enhanced sensitivity and compensation of impairments," in Proc. OFC2007, paper JThA50, Anaheim, CA (2007).
  16. T. Mizuochi, K. Kubo, H. Yoshida, H. Fujita, H. Tagami, M. Akita, and K. Motoshima, "Next generation FEC for optical transmission systems," in Proc OFC 2003, paper ThN1, Atlanta, GA, (2003).
  17. D. Lombard and J. C. Imbeaux, "Multidifferential PSK-demodulation for TDMA transmission," in Proc. International Conference on Satellite Communication Systems Technology, (1975), pp. 207-213.
  18. F. Buchali, G. Thielecke, and H. Bulow, "Viterbi equalizer for mitigation of distortions from chromatic dispersion and PMD at 10 Gb/s," in Proc. OFC 2004, paper MF85, (2004).
  19. H. Haunstein, R. Schlenk, K. Sticbt, A. Dittrich, W. Sauer-Greff, and R. Urbansky, "Optimized filtering for electronic equalizers in the presence of chromatic dispersion and PMD," in Proc. OFC 2004, paper MF6, (2004).
  20. H. Haunstein, R. Schlenk, K. Sticbt, A. Dittrich, W. Sauer-Greff, and R. Urbansky, "Control of combined electrical feed-forward and decision feedback equalization by conditional error counts from FEC in the presence of PMD," in Proc.OFC 2003,  2, pp. 474-476.
  21. R. Urbansky, A. Dittrich, W. Sauer-Greff, and H. Haunstein, "Electrical equalization and error correction coding for optical channels," Holey Fibers and Photonic Crystals/Polarization Mode Dispersion/Photonics Time/Frequency Measurement and Control, 2003 Digest of the LEOS Summer Topical Meetings, (2003), pp. WB1.1/59-WB1.1/60.
  22. Y. K. Lize, L. Christen, S. Nuccio, P. Saghari, R. Gomma, J.-Y. Yang, A. E. Willner, and R. Kashyap, "Power penalty in multibit differential phase shift keying demodulation," in Proc. ECOC2006, paper Tu3.2.3, Cannes, France (2006).

2006 (2)

P. J. Winzer and R. -J. Essiambre, "Advanced modulation formats for high-capacity optical transport networks," J. Lightwave Technol. 24, 4711-4728 (2006).
[CrossRef]

M. Nazarathy and Y. Yadin, "Simplified decision feedback-aided multi-chip binary DPSK receivers," IEEE Photon. Technol. Lett. 18, 1771 - 1773 (2006).
[CrossRef]

2005 (3)

A. H. Gnauck and P. J. Winzer, "Optical phase-shift-keyed transmission," J. Lightwave Technol. 23, 115-130. (2005).
[CrossRef]

M. Nazarathy and E. Simony, "Multi-Chip Differential Phase Encoded Optical Transmission," IEEE Photon. Technol. Lett. 17, 1133-1135 (2005).
[CrossRef]

Y. Yadin, A. Bilenca, and M. Nazarathy, "Soft detection of multichip DPSK over the nonlinear fiber-optic channel," IEEE Photon. Technol. Lett. 17, 2001-2003 (2005).
[CrossRef]

2004 (1)

X. Liu, Y.-H. Kao, M. Movassaghi, and R. C. Giles, "Tolerance to in-band coherent crosstalk of differential phase-shift-keyed signal with balanced detection and FEC," IEEE Photon. Technol. Lett. 16, 1209-1911 (2004).
[CrossRef]

2003 (1)

H. Haunstein, R. Schlenk, K. Sticbt, A. Dittrich, W. Sauer-Greff, and R. Urbansky, "Control of combined electrical feed-forward and decision feedback equalization by conditional error counts from FEC in the presence of PMD," in Proc.OFC 2003,  2, pp. 474-476.

Bilenca, A.

Y. Yadin, A. Bilenca, and M. Nazarathy, "Soft detection of multichip DPSK over the nonlinear fiber-optic channel," IEEE Photon. Technol. Lett. 17, 2001-2003 (2005).
[CrossRef]

Dittrich, A.

H. Haunstein, R. Schlenk, K. Sticbt, A. Dittrich, W. Sauer-Greff, and R. Urbansky, "Control of combined electrical feed-forward and decision feedback equalization by conditional error counts from FEC in the presence of PMD," in Proc.OFC 2003,  2, pp. 474-476.

Essiambre, R. -J.

Giles, R. C.

X. Liu, Y.-H. Kao, M. Movassaghi, and R. C. Giles, "Tolerance to in-band coherent crosstalk of differential phase-shift-keyed signal with balanced detection and FEC," IEEE Photon. Technol. Lett. 16, 1209-1911 (2004).
[CrossRef]

Gnauck, A. H.

Haunstein, H.

H. Haunstein, R. Schlenk, K. Sticbt, A. Dittrich, W. Sauer-Greff, and R. Urbansky, "Control of combined electrical feed-forward and decision feedback equalization by conditional error counts from FEC in the presence of PMD," in Proc.OFC 2003,  2, pp. 474-476.

Kao, Y.-H.

X. Liu, Y.-H. Kao, M. Movassaghi, and R. C. Giles, "Tolerance to in-band coherent crosstalk of differential phase-shift-keyed signal with balanced detection and FEC," IEEE Photon. Technol. Lett. 16, 1209-1911 (2004).
[CrossRef]

Liu, X.

X. Liu, Y.-H. Kao, M. Movassaghi, and R. C. Giles, "Tolerance to in-band coherent crosstalk of differential phase-shift-keyed signal with balanced detection and FEC," IEEE Photon. Technol. Lett. 16, 1209-1911 (2004).
[CrossRef]

Movassaghi, M.

X. Liu, Y.-H. Kao, M. Movassaghi, and R. C. Giles, "Tolerance to in-band coherent crosstalk of differential phase-shift-keyed signal with balanced detection and FEC," IEEE Photon. Technol. Lett. 16, 1209-1911 (2004).
[CrossRef]

Nazarathy, M.

M. Nazarathy and Y. Yadin, "Simplified decision feedback-aided multi-chip binary DPSK receivers," IEEE Photon. Technol. Lett. 18, 1771 - 1773 (2006).
[CrossRef]

Y. Yadin, A. Bilenca, and M. Nazarathy, "Soft detection of multichip DPSK over the nonlinear fiber-optic channel," IEEE Photon. Technol. Lett. 17, 2001-2003 (2005).
[CrossRef]

M. Nazarathy and E. Simony, "Multi-Chip Differential Phase Encoded Optical Transmission," IEEE Photon. Technol. Lett. 17, 1133-1135 (2005).
[CrossRef]

Sauer-Greff, W.

H. Haunstein, R. Schlenk, K. Sticbt, A. Dittrich, W. Sauer-Greff, and R. Urbansky, "Control of combined electrical feed-forward and decision feedback equalization by conditional error counts from FEC in the presence of PMD," in Proc.OFC 2003,  2, pp. 474-476.

Schlenk, R.

H. Haunstein, R. Schlenk, K. Sticbt, A. Dittrich, W. Sauer-Greff, and R. Urbansky, "Control of combined electrical feed-forward and decision feedback equalization by conditional error counts from FEC in the presence of PMD," in Proc.OFC 2003,  2, pp. 474-476.

Simony, E.

M. Nazarathy and E. Simony, "Multi-Chip Differential Phase Encoded Optical Transmission," IEEE Photon. Technol. Lett. 17, 1133-1135 (2005).
[CrossRef]

Sticbt, K.

H. Haunstein, R. Schlenk, K. Sticbt, A. Dittrich, W. Sauer-Greff, and R. Urbansky, "Control of combined electrical feed-forward and decision feedback equalization by conditional error counts from FEC in the presence of PMD," in Proc.OFC 2003,  2, pp. 474-476.

Urbansky, R.

H. Haunstein, R. Schlenk, K. Sticbt, A. Dittrich, W. Sauer-Greff, and R. Urbansky, "Control of combined electrical feed-forward and decision feedback equalization by conditional error counts from FEC in the presence of PMD," in Proc.OFC 2003,  2, pp. 474-476.

Winzer, P. J.

Yadin, Y.

M. Nazarathy and Y. Yadin, "Simplified decision feedback-aided multi-chip binary DPSK receivers," IEEE Photon. Technol. Lett. 18, 1771 - 1773 (2006).
[CrossRef]

Y. Yadin, A. Bilenca, and M. Nazarathy, "Soft detection of multichip DPSK over the nonlinear fiber-optic channel," IEEE Photon. Technol. Lett. 17, 2001-2003 (2005).
[CrossRef]

IEEE Photon. Technol. Lett. (4)

M. Nazarathy and E. Simony, "Multi-Chip Differential Phase Encoded Optical Transmission," IEEE Photon. Technol. Lett. 17, 1133-1135 (2005).
[CrossRef]

Y. Yadin, A. Bilenca, and M. Nazarathy, "Soft detection of multichip DPSK over the nonlinear fiber-optic channel," IEEE Photon. Technol. Lett. 17, 2001-2003 (2005).
[CrossRef]

M. Nazarathy and Y. Yadin, "Simplified decision feedback-aided multi-chip binary DPSK receivers," IEEE Photon. Technol. Lett. 18, 1771 - 1773 (2006).
[CrossRef]

X. Liu, Y.-H. Kao, M. Movassaghi, and R. C. Giles, "Tolerance to in-band coherent crosstalk of differential phase-shift-keyed signal with balanced detection and FEC," IEEE Photon. Technol. Lett. 16, 1209-1911 (2004).
[CrossRef]

J. Lightwave Technol. (2)

OFC (1)

H. Haunstein, R. Schlenk, K. Sticbt, A. Dittrich, W. Sauer-Greff, and R. Urbansky, "Control of combined electrical feed-forward and decision feedback equalization by conditional error counts from FEC in the presence of PMD," in Proc.OFC 2003,  2, pp. 474-476.

Other (15)

R. Urbansky, A. Dittrich, W. Sauer-Greff, and H. Haunstein, "Electrical equalization and error correction coding for optical channels," Holey Fibers and Photonic Crystals/Polarization Mode Dispersion/Photonics Time/Frequency Measurement and Control, 2003 Digest of the LEOS Summer Topical Meetings, (2003), pp. WB1.1/59-WB1.1/60.

Y. K. Lize, L. Christen, S. Nuccio, P. Saghari, R. Gomma, J.-Y. Yang, A. E. Willner, and R. Kashyap, "Power penalty in multibit differential phase shift keying demodulation," in Proc. ECOC2006, paper Tu3.2.3, Cannes, France (2006).

F. Seguin and F. Gonthier, "Tuneable all-fiber, delay-line interferometer for DPSK demodulation," in Proc. OFC2005, paper OFL5, (2005).

A. H. Gnauck, "40-Gb/s RZ-differential phase shift keyed transmission," in Proc. OFC2003, paper ThE1, (2003).

X. Liu, "Nonlinear effects in phase shift keyed transmission," in Proc. OFC2004, paper ThM4 (2004).

X. Liu, "Digital implementation of soft detection for 3-chip-DBPSK with improved receiver sensitivity and dispersion tolerance," in Proc. OFC 2006, paper OTuI2, (2006).

M. Nazarathy, X. Liu, Y. Yadin, and M. Orenstein, "Multi-chip detection of optical differential phase-shift keying and complexity reduction by interferometric decision feedback," in Proc. ECOC 2006, We3.P.79, (2006).

X. Liu, "Receiver sensitivity improvement in optical DQPSK and DQPSK/ASK through data-aided multi-symbol phase estimation," in Proc. ECOC 2006, We2.5.6 (2006).

X. Liu, X. Liu, S. Chandrasekhar, A. H. Gnauck, C. R. Doerr, I. Kang, D. Kilper, L. L. Buhl, and J. Centanni, "DSP-enabled compensation of demodulator phase error and sensitivity improvement in direct-detection 40-Gb/s DQPSK, postdeadline paper Th4.4.5 in ECOC'06 Cannes, France, 2006.

M. Nazarathy, Y. Yadin, M. Orenstein, Y. K. Lize, L. Christen, and Alan Willner, "Enhanced self-coherent optical decision-feedback-aided detection of multi-symbol M-DPSK/PolSK in particular 8-DPSK/BPolSK at 40 Gbps," Optical Fiber Conference, paper JWA43, Anaheim, CA (2007).

L. Christen, Y. K. Lize, S. R. Nuccio, X. Liu, M. Nazarathy, and A. E. Willner, "DPSK error correction using multi-bit detection for enhanced sensitivity and compensation of impairments," in Proc. OFC2007, paper JThA50, Anaheim, CA (2007).

T. Mizuochi, K. Kubo, H. Yoshida, H. Fujita, H. Tagami, M. Akita, and K. Motoshima, "Next generation FEC for optical transmission systems," in Proc OFC 2003, paper ThN1, Atlanta, GA, (2003).

D. Lombard and J. C. Imbeaux, "Multidifferential PSK-demodulation for TDMA transmission," in Proc. International Conference on Satellite Communication Systems Technology, (1975), pp. 207-213.

F. Buchali, G. Thielecke, and H. Bulow, "Viterbi equalizer for mitigation of distortions from chromatic dispersion and PMD at 10 Gb/s," in Proc. OFC 2004, paper MF85, (2004).

H. Haunstein, R. Schlenk, K. Sticbt, A. Dittrich, W. Sauer-Greff, and R. Urbansky, "Optimized filtering for electronic equalizers in the presence of chromatic dispersion and PMD," in Proc. OFC 2004, paper MF6, (2004).

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Figures (9)

Fig. 1.
Fig. 1.

Conceptual diagram of multipath demodulation with majority vote error correction. The DPSK precoder uses a 4-bit delay. The optical logic is performed by the passive DLI DPSK demodulator. The electronic logic recovers the original signal before majority vote is applied.

Fig. 2.
Fig. 2.

Experimental setup for the demonstration of multipath DPSK demodulation majority vote error correction. Using 3 commercial DLIs, three 10Gbps bit error rate tester and a 20Gs/s real time scope. Logic operations were processed offline.

Fig. 3.
Fig. 3.

Numerical results for the 1 bit-delay, the 2 bit delay and 4-bit delay paths and majority vote. Ideal majority vote performance if errors were uncorrelated is shown.

Fig. 4.
Fig. 4.

Optical spectra for the destructive arm of the 4 bit delay (2.5 GHz) , 2bit delay (5 GHz) and 1 bit delay (10 GHz) demodulators on an optical spectrum analyzer (OSA). The longer delays were passive devices resulting in asymmetric spectra.

Fig. 5.
Fig. 5.

Eye diagrams of the destructive port for 4 bit delay, 2bit delay and 1 bit delay demodulator. The longer delays demodulator were passive devices in our experiment making them more difficult to align the frequency of the laser to the transmission frequency of the DLI which resulted in a penalty.

Fig. 6.
Fig. 6.

Experimental results for the 3 paths and the majority vote combined output. A 1.5dB is observed at BER 10-3 in back-to-back configuration. The better experimental results are a results of errors being decorrelated between path due to non-optimal optical and electrical filtering and modulator driving voltage slightly less than 2Vπ.

Fig. 7.
Fig. 7.

DPSK contour plot of required OSNR at BER 10–3 for electrical and optical filter bandwidth combination.

Fig. 8.
Fig. 8.

Majority vote multipath demodulation contour plot showing very good tolerance to optical filtering.

Fig. 9.
Fig. 9.

OSNR penalty versus CD for DPSK and majority vote demodulation. A 25% increase in CD tolerance is found for a 1.6dB improvement at BER=10-3.

Equations (16)

Equations on this page are rendered with MathJax. Learn more.

c k = b k c k 4
d k ( 1 ) = c k c k 1 ε k ( 1 )
d k ( 2 ) = c k c k 2 ε k ( 2 )
d k ( 4 ) = c k c k 4 ε k ( 4 )
b ̂ k ( 1 ) = d k ( 1 ) d k 1 ( 1 ) d k 2 ( 1 ) d k 3 ( 1 )
b ̂ k ( 2 ) = d k ( 2 ) d k 2 ( 2 )
b ̂ k ( 4 ) = d k ( 4 )
b ̂ k = b ̂ k ( 1 ) & b ̂ k ( 2 ) b ̂ k ( 1 ) & b ̂ k ( 3 ) b ̂ k ( 2 ) & b ̂ k ( 3 )
b ̂ k ( 4 ) = d k ( 4 ) = c k c k 4 = b k c k 4 c k 4 = b k
b ̂ k ( 2 ) = d k ( 2 ) d k 2 ( 2 ) = ( c k c k 2 ) ( c k 2 c k 4 )
= c k c k 2 c k 2 c k 4 = c k c k 4 = d k ( 4 ) = b k
b ̂ k ( 1 ) = d k ( 1 ) d k 1 ( 1 ) d k 2 ( 1 ) d k 3 ( 1 )
= c k c k 1 c k 1 c k 2 c k 2 c k 3 c k 3 c k 4 = c k c k 4 = b k
b ̂ k ( Δ ) = b k η k ( i ) , i { 1,2,4 }
η k ( 1 ) ε k ( 1 ) ε k 1 ( 1 ) ε k 2 ( 1 ) ε k 3 ( 1 ) , η k ( 2 ) ε k ( 2 ) ε k 2 ( 2 ) , η k ( 4 ) ε k ( 4 )
[ E R ( 1 ) E R ( 2 ) ( 1 E R ( 4 ) ) ] + [ E R ( 1 ) ( 1 E R ( 2 ) ) E R ( 4 ) ] + [ ( 1 E R ( 1 ) ) E R ( 2 ) E R ( 4 ) ]

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