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Optics Express

Optics Express

  • Editor: C. Martijn de Sterke
  • Vol. 18, Iss. 24 — Nov. 22, 2010
  • pp: 25415–25421
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Automatic dispersion compensation for 1.28Tb/s OTDM signal transmission using photonic-chip-based dispersion monitoring

Jürgen Van Erps, Jochen Schröder, Trung D. Vo, Mark D. Pelusi, Steve Madden, Duk-Yong Choi, Douglas A. Bulla, Barry Luther-Davies, and Benjamin J. Eggleton  »View Author Affiliations


Optics Express, Vol. 18, Issue 24, pp. 25415-25421 (2010)
http://dx.doi.org/10.1364/OE.18.025415


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Abstract

We present automatic dispersion control of 1.28Tb/s optical time domain multiplexed signals. The dispersion is monitored by measuring the power of the 1.28THz tone of the RF spectrum using a photonic-chip-based radio-frequency spectrum analyzer (PC-RFSA) and the dispersion compensation is realized by means of a spectral pulse shaper, via computer-controlled feedback from the PC-RFSA.

© 2010 Optical Society of America

1. Introduction

Fig. 1 Schematic principle of automatic dispersion compensation by monitoring the signal’s RF spectrum and computer-controlled feedback to a tunable dispersion compensator.

2. Generation and optimization of the 1.28Tb/s OTDM signal

The 1.28Tb/s signal is generated by using OTDM, as shown in Fig. 2. We use an active mode-locked fiber laser (MLFL) emitting ∼1.4-ps pulses at a 40-GHz repetition rate and centered at 1550nm. The pulses are subsequently compressed to 275fs using highly nonlinear fiber (HNLF) [17

17. T. Inoue and S. Namiki, “Pulse compression techniques using highly nonlinear fiber,” Laser Photon. Rev. 2, 83 (2008). [CrossRef]

] after two stages. The signal power is controlled using variable optical attenuators (VOAs). An external electro-optic Mach-Zehnder modulator (MZM) is used to encode data on the pulses at 40Gb/s with a 231 – 1 pseudo-random bit sequence (PRBS). After amplification in a low-noise erbium-doped fiber amplifier (EDFA), a five-stage fiber interferometer circuit of 27 – 1 bit delay-length optically multiplexes (MUX) the pulses up to 1.28Tb/s (return-to-zero on-off keying with ∼35% duty cyle).

Fig. 2 Experimental setup for the generation of the 1.28Tb/s OTDM signal.

To optimize the equalization and synchronization of the MUX stages, we make use of our PC-RFSA as shown in the experimental setup in Fig. 3. When the signal under test is co-propagated with a continuous wave (CW) probe, new frequencies (i.e. the RF spectrum of the signal) will be generated around the CW probe due to cross-phase modulation [9

9. G. P. Agrawal, Nonlinear Fiber Optics - 3rd ed., New York: Academic Press (2001).

] in a 7cm-long dispersion-engineered highly nonlinear chalcogenide (As2S3) planar waveguide [18

18. M. R. E. Lamont, C. M. de Sterke, and B. J. Eggleton, “Dispersion engineering of highly nonlinear As2S3 waveguides for parametric gain and wavelength conversion,” Opt. Express 15, 9458 (2007). [CrossRef] [PubMed]

]. The fabrication of the device is described in [19

19. D.-Y. Choi, S. Madden, D. A. Bulla, R. Wang, A. Rode, and B. Luther-Davies, “Sub-micrometer thick, low-loss As2S3 planar waveguides for nonlinear optical devices,” IEEE Photon. Technol. Lett. 22, 495 (2010). [CrossRef]

] and the 2μm-wide waveguide has a mode area Aeff = 1.23μm2, corresponding to a nonlinear coefficient γ = 104/W/km and an anomalous dispersion of about +29-ps/nm/km for the TM mode at 1550-nm. The polarization of the signal and the CW probe is aligned to the TM-mode of the waveguide by means of a polarization controller (PC), and the output of the waveguide is connected to an OSA. The signal and CW probe are combined by means of a wavelength division multiplexing (WDM) fiber coupler, and coupled into the waveguide using lensed fibers. The total (fiber-to-fiber) insertion loss of the waveguide is 12.7dB and the average power launched into the chip is 21dBm and 18dBm for signal and CW probe respectively.

Fig. 3 Experimental setup for photonic-chip-based RF spectrum monitoring for signal optimization and dispersion monitoring.

Figure 4 (top left graph) shows the optical spectrum of the optimized 1.28Tb/s OTDM signal, together with the CW probe at 1585nm and the XPM frequencies generated around this probe. The bottom graphs show the RF spectrum of the signal before (left) and after (right) optimization, the latter clearly showing that the MUX stages were very well aligned and that dispersion was optimized since the resulting RF spectrum is very clean with only one peak visible, i.e. the 1.28THz tone. The autocorrelation traces of the optimized 1.28Tb/s signal and of the 275fs compressed pulse are shown in the top right graph of Fig. 4.

Fig. 4 Opical spectrum (top left), autocorrelation trace (top right) and RF spectrum before (bottom left) and after (bottom right) optimization of the 1.28Tb/s signal.

3. Automatic dispersion compensation

Fig. 5 Plot of the power in the 1.28THz tone versus dispersion and selected RF spectra.
Fig. 6 Flow diagram of the automatic dispersion compensation strategy.

The automatic dispersion compensating action versus time is shown in Fig. 7. This graph shows that every time we apply a dispersion change at the transmitter side, the system successfully recovers by applying the appropriate opposite dispersion at the receiver side. We applied discrete steps in the dispersion to be able to determine the response time of the system, whereas in practice the dispersion will change in a much smoother fashion since it will be induced by temperature fluctuations. The largest step in dispersion (ΔD = 0.09ps/nm) we applied corresponds to 0.8×LD in terms of dispersion length. In principle, the response time of the system is primarily determined by the reconfiguration time of the SPS and the time needed to make a power measurement, i.e. in the order of a few 100ms. In the current stage, however, the required spectral phase modulation image to be applied to the LCoS is generated at each new step and therefore requires a few seconds. This could be improved by fetching the spectral phase image from a pre-defined library stored locally. The necessary control electronics could also be integrated in the tunable dispersion compensator, eliminating the need for a separate computer.

Fig. 7 Automatic dispersion compensation result. Applied dispersion (dashed line) and measured power in the 1.28THz tone (solid line) versus time.

4. Conclusion

In conclusion, we have successfully demonstrated a flexible scheme for automatic compensation of residual dispersion in a 1.28Tb/s transmission link. Automatic GVD compensation can be achieved by monitoring the power of the 1.28THz tone of the signal’s RF spectrum using a highly nonlinear planar As2S3 waveguide, a BPF and a simple PD. This scheme also works with phase-encoded signals [20

20. T. D. Vo, J. Schröder, M. D. Pelusi, S. J. Madden, D.-Y. Choi, D. A. Bulla, B. Luther-Davies, and B. J. Eggleton, “Photonic chip based simultaneous multi-impairment monitoring for phase-modulated optical signals,” J. Light-wave Technol. 28, 3176 (2010).

]. When using an OSA at the receiver side, other impairments such as higher-order dispersion could be monitored and compensated using an SPS, at the expense of a slower system response time. This will be the subject of further research.

Acknowledgments

This work was supported by an Australian Research Council (ARC) under the ARC Centres of Excellences Program and by a Linkage grant with Finisar Australia. The work of J. Van Erps was supported by the Fund for Scientific Research (FWO Vlaanderen) under a post-doctoral research fellowship, and additionally supported by Belspo-IAP, IWT-SBO, GOA, and the OZR of the Vrije Universiteit Brussel.

References and links

1.

H. Hansen Mulvad, L. K. Oxenløwe, M. Galili, A. T. Clausen, L. Grüner-Nielsen, and P. Jeppesen, “1.28 Tbit/s single-polarisation serial OOK optical data generation and demultiplexing,” Electron. Lett. 45, 280 (2009). [CrossRef]

2.

T. D. Vo, H. Hu, M. Galili, E. Palushani, J. Xu, L. K. Oxenlwe, S. J. Madden, D.-Y. Choi, D. A. Bulla, M. D. Pelusi, J. Schröder, B. Luther-Davies, and B. J. Eggleton, “Photonic chip based transmitter optimization and receiver demultiplexing of a 1.28 Tbit/s signal,” Opt. Express 18, 17252 (2010). [CrossRef] [PubMed]

3.

J. P. Curtis and J. E. Carroll, “Autocorrelation systems for the measurement of picosecond pulses from injection lasers,” Int. J. Electron. 60, 87 (1986). [CrossRef]

4.

J. Van Erps, F. Luan, M. D. Pelusi, T. Iredale, S. Madden, D.-Y. Choi, D. A. Bulla, B. Luther-Davies, and B. J. Eggleton, “High-resolution optical sampling of 640-Gb/s data using four-wave mixing in dispersion-engineered highly nonlinear As2S3 planar waveguides,” J. Lightwave Technol. 28, 209 (2010). [CrossRef]

5.

F. Luan, J. Van Erps, M. D. Pelusi, E. Mägi, T. Iredale, H. Thienpont, and B. J. Eggleton, “High-resolution optical sampling of 640 Gbit/s data using dispersion-engineered chalcogenide photonic wire,” Electron. Lett. 46, 223 (2010). [CrossRef]

6.

C. Dorrer and D. N. Maywar, “RF Spectrum analysis of optical signals using nonlinear optics,” J. Lightwave Technol. 22, 266 (2004). [CrossRef]

7.

M. Pelusi, F. Luan, T. D. Vo, M. Lamont, S. J. Madden, D. A. Bulla, D.-Y. Choi, B. Luther-Davies, and B. J. Eggleton, “Photonic-chip-based radio-frequency spectrum analyzer with terahertz bandwidth,” Nat. Photonics 3, 139 (2009). [CrossRef]

8.

T. D. Vo, M. D. Pelusi, J. Schröder, F. Luan, S. J. Madden, D.-Y. Choi, D. A. Bulla, B. Luther-Davies, and B. J. Eggleton, “Simultaneous multi-impairment monitoring of 640 Gb/s signals using photonic chip based RF spectrum analyzer,” Opt. Express 18, 3938 (2010). [CrossRef] [PubMed]

9.

G. P. Agrawal, Nonlinear Fiber Optics - 3rd ed., New York: Academic Press (2001).

10.

M. J. Hamp, J. Wright, M. Hubbard, and B. Brimacombe, “Investigation into the temperature dependence of chromatic dispersion in optical fiber,” IEEE Photon. Technol. Lett. 14, 1524 (2002). [CrossRef]

11.

D. Neilson, “MEMS-based dispersion compensator with flat passbands,” J. Lightwave Technol. 22, 101 (2004). [CrossRef]

12.

G.-H. Lee, S. Xiao, and A. M. Weiner, “Optical dispersion compensator with 4000-ps/nm tuning range using a virtually imaged phased array (VIPA) and spatial light modulator,” IEEE Photon. Technol. Lett. 18, 1819 (2007).

13.

P. S. Westbrook, B. J. Eggleton, G. Raybon, S. Hunsche, and T. Her, “Measurement of residual chromatic dispersion of a 40-Gb/s RZ signal via spectral broadening,” IEEE Photon. Technol. Lett. 14, 346–348 (2002). [CrossRef]

14.

P. S. Westbrook, T. H. Her, B. J. Eggleton, S. Hunsche, and G. Raybon, “Measurement of pulse degradation using all-optical 2R regenerator,” Elec. Lett. 38, 1193 (2002). [CrossRef]

15.

S. Wielandy, P. S. Westbrook, M. Fishteyn, P. Reyes, W. Schairer, H. Rohde, and G. Lehmann, “Demonstration of automatic dispersion control for 160 Gbit/s transmission over 275km deployed fibre,” Electron. Lett. 40, 690 (2004). [CrossRef]

16.

M. Roelens, S. Frisken, J. A. Bolger, D. Abakoumov, G. Baxter, S. Poole, and B. J. Eggleton, “Dispersion trimming in a reconfigurable wavelength selective switch,” J. Lightwave Technol. 26, 73 (2008). [CrossRef]

17.

T. Inoue and S. Namiki, “Pulse compression techniques using highly nonlinear fiber,” Laser Photon. Rev. 2, 83 (2008). [CrossRef]

18.

M. R. E. Lamont, C. M. de Sterke, and B. J. Eggleton, “Dispersion engineering of highly nonlinear As2S3 waveguides for parametric gain and wavelength conversion,” Opt. Express 15, 9458 (2007). [CrossRef] [PubMed]

19.

D.-Y. Choi, S. Madden, D. A. Bulla, R. Wang, A. Rode, and B. Luther-Davies, “Sub-micrometer thick, low-loss As2S3 planar waveguides for nonlinear optical devices,” IEEE Photon. Technol. Lett. 22, 495 (2010). [CrossRef]

20.

T. D. Vo, J. Schröder, M. D. Pelusi, S. J. Madden, D.-Y. Choi, D. A. Bulla, B. Luther-Davies, and B. J. Eggleton, “Photonic chip based simultaneous multi-impairment monitoring for phase-modulated optical signals,” J. Light-wave Technol. 28, 3176 (2010).

OCIS Codes
(190.4390) Nonlinear optics : Nonlinear optics, integrated optics
(130.2035) Integrated optics : Dispersion compensation devices

ToC Category:
Integrated Optics

History
Original Manuscript: October 13, 2010
Revised Manuscript: November 10, 2010
Manuscript Accepted: November 13, 2010
Published: November 19, 2010

Citation
Jürgen Van Erps, Jochen Schröder, Trung D. Vo, Mark D. Pelusi, Steve Madden, Duk-Yong Choi, Douglas A. Bulla, Barry Luther-Davies, and Benjamin J. Eggleton, "Automatic dispersion compensation for 1.28Tb/s OTDM signal transmission using photonic-chip-based dispersion monitoring," Opt. Express 18, 25415-25421 (2010)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-18-24-25415


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References

  1. H. Hansen Mulvad, L. K. Oxenløwe, M. Galili, A. T. Clausen, L. Grüner-Nielsen, and P. Jeppesen, "1.28 Tbit/s single-polarisation serial OOK optical data generation and demultiplexing," Electron. Lett. 45, 280 (2009). [CrossRef]
  2. T. D. Vo, H. Hu, M. Galili, E. Palushani, J. Xu, L. K. Oxenlwe, S. J. Madden, D.-Y. Choi, D. A. Bulla, M. D. Pelusi, J. Schröder, B. Luther-Davies, and B. J. Eggleton, "Photonic chip based transmitter optimization and receiver demultiplexing of a 1.28 Tbit/s signal," Opt. Express 18, 17252 (2010). [CrossRef] [PubMed]
  3. J. P. Curtis, and J. E. Carroll, "Autocorrelation systems for the measurement of picosecond pulses from injection lasers," Int. J. Electron. 60, 87 (1986). [CrossRef]
  4. J. Van Erps, F. Luan, M. D. Pelusi, T. Iredale, S. Madden, D.-Y. Choi, D. A. Bulla, B. Luther-Davies, and B. J. Eggleton, "High-resolution optical sampling of 640-Gb/s data using four-wave mixing in dispersion-engineered highly nonlinear As2S3 planar waveguides," J. Lightwave Technol. 28, 209 (2010). [CrossRef]
  5. F. Luan, J. Van Erps, M. D. Pelusi, E. Mägi, T. Iredale, H. Thienpont, and B. J. Eggleton, "High-resolution optical sampling of 640 Gbit/s data using dispersion-engineered chalcogenide photonic wire," Electron. Lett. 46, 223 (2010). [CrossRef]
  6. C. Dorrer, and D. N. Maywar, "RF Spectrum analysis of optical signals using nonlinear optics," J. Lightwave Technol. 22, 266 (2004). [CrossRef]
  7. M. Pelusi, F. Luan, T. D. Vo, M. Lamont, S. J. Madden, D. A. Bulla, D.-Y. Choi, B. Luther-Davies, and B. J. Eggleton, "Photonic-chip-based radio-frequency spectrum analyzer with terahertz bandwidth," Nat. Photonics 3, 139 (2009). [CrossRef]
  8. T. D. Vo, M. D. Pelusi, J. Schröder, F. Luan, S. J. Madden, D.-Y. Choi, D. A. Bulla, B. Luther-Davies, and B. J. Eggleton, "Simultaneous multi-impairment monitoring of 640 Gb/s signals using photonic chip based RF spectrum analyzer," Opt. Express 18, 3938 (2010). [CrossRef] [PubMed]
  9. G. P. Agrawal, Nonlinear Fiber Optics - 3rd ed., New York: Academic Press (2001).
  10. M. J. Hamp, J. Wright, M. Hubbard, and B. Brimacombe, "Investigation into the temperature dependence of chromatic dispersion in optical fiber," IEEE Photon. Technol. Lett. 14, 1524 (2002). [CrossRef]
  11. D. Neilson, "MEMS-based dispersion compensator with flat passbands," J. Lightwave Technol. 22, 101 (2004). [CrossRef]
  12. G.-H. Lee, S. Xiao, and A. M. Weiner, "Optical dispersion compensator with 4000-ps/nm tuning range using a virtually imaged phased array (VIPA) and spatial light modulator," IEEE Photon. Technol. Lett. 18, 1819 (2007).
  13. P. S. Westbrook, B. J. Eggleton, G. Raybon, S. Hunsche, and T. Her, "Measurement of residual chromatic dispersion of a 40-Gb/s RZ signal via spectral broadening," IEEE Photon. Technol. Lett. 14, 346-348 (2002). [CrossRef]
  14. P. S. Westbrook, T. H. Her, B. J. Eggleton, S. Hunsche, and G. Raybon, "Measurement of pulse degradation using all-optical 2R regenerator," Electron. Lett. 38, 1193 (2002). [CrossRef]
  15. S. Wielandy, P. S. Westbrook, M. Fishteyn, P. Reyes, W. Schairer, H. Rohde, and G. Lehmann, "Demonstration of automatic dispersion control for 160 Gbit/s transmission over 275km deployed fibre," Electron. Lett. 40, 690 (2004). [CrossRef]
  16. M. Roelens, S. Frisken, J. A. Bolger, D. Abakoumov, G. Baxter, S. Poole, and B. J. Eggleton, "Dispersion trimming in a reconfigurable wavelength selective switch," J. Lightwave Technol. 26, 73 (2008). [CrossRef]
  17. T. Inoue, and S. Namiki, "Pulse compression techniques using highly nonlinear fiber," Laser Photon. Rev. 2, 83 (2008). [CrossRef]
  18. M. R. E. Lamont, C. M. de Sterke, and B. J. Eggleton, "Dispersion engineering of highly nonlinear As2S3 waveguides for parametric gain and wavelength conversion," Opt. Express 15, 9458 (2007). [CrossRef] [PubMed]
  19. D.-Y. Choi, S. Madden, D. A. Bulla, R. Wang, A. Rode, and B. Luther-Davies, "Sub-micrometer thick, low-loss As2S3 planar waveguides for nonlinear optical devices," IEEE Photon. Technol. Lett. 22, 495 (2010). [CrossRef]
  20. T. D. Vo, J. Schröder, M. D. Pelusi, S. J. Madden, D.-Y. Choi, D. A. Bulla, B. Luther-Davies, and B. J. Eggleton, "Photonic chip based simultaneous multi-impairment monitoring for phase-modulated optical signals," J. Lightwave Technol. 28, 3176 (2010).

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