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Optics Express

Optics Express

  • Editor: C. Martijn de Sterke
  • Vol. 15, Iss. 1 — Jan. 8, 2007
  • pp: 24–32
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An experimental demonstration of a soft-failure approach to PMD mitigation in an installed optical link

Anthony S. Lenihan, William A. Babson, Hua Jiao, Jerry Sobieski, and Gary M. Carter  »View Author Affiliations


Optics Express, Vol. 15, Issue 1, pp. 24-32 (2007)
http://dx.doi.org/10.1364/OE.15.000024


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Abstract

We present a field-trial implementation of the soft-failure approach to polarization-mode dispersion (PMD) impairment mitigation, in which information about the PMD of the installed link is utilized by our modified control plane software to make decisions on data routing over available links. This allows us to maintain loss-free end-to-end data service, even at high PMD levels.

© 2007 Optical Society of America

1. Introduction

2. Network testbed

We performed our demonstration of the integration of a PMD sensor with network control software on an installed fiber network connecting College Park, MD and Baltimore, MD. Our implementation uses standard Generalized Multiprotocol Label Switching (GMPLS) open shortest path first traffic engineering(OSPF-TE) mechanisms [13

13. A. Farrel and I. Bryskin, GMPLS: Architecture and Applications, The Morgan Kaufmann Series in Networking (Elsevier Inc., San Francisco, CA, 2006).

], through a modified version of the DRAGON (Dynamic Resource Allocation via GMPLS Optical Networks) control plane software [14

14. Information on the DRAGON project is available at http://dragon.maxgigapop.net.

]. As a result, only those network nodes which have sensors installed would need to have the software extended in order for the entire existing network to be able to use the sensor information.

A simplified schematic of our experimental testbed is shown in Fig. 1. The VSLR switching nodes were located at our laboratories in College Park, MD and in Baltimore, MD. In our experiment, a VLSR was composed of a computer, a Raptor ER-1010 ethernet switch, and a Movaz RayExpress optical add-drop multiplexer (OADM), each handling its respective network layer. The OADMs included the optical transponders (XPDR), the requisite MUX/DEMUX filters, and an erbium-doped fiber amplifier (EDFA) on the receiver side to compensate for the fiber loss. Two ITU 100 GHz grid compatible [15

15. International Telecommunication Union, Telecommunication Standardization Sector of ITU, ITU-T Standard G.694.1, Spectral grids for WDM applications: DWDM frequency grid (2002).

] optical channels were utilized for our tests: Ch. 31 (1552.52 nm) which operated at 10 Gb/s, and Ch. 35 (1549.32 nm) which operated at 1 Gb/s. Both channels utilized the non-return-to-zero (NRZ), on-off keyed (OOK) format.

The two nodes were connected by an installed 52 km single-mode fiber pair. We performed our measurements on the southbound (from Baltimore to College Park) fiber path, which had a total loss of approximately 20 dB, and total accumulated dispersion of ~875 ps/nm near 1550 nm. Because the accumulated dispersion was well within the limits of the transponders, no dispersion compensation was used. In order to have more control over the level of system impairment due to PMD, we placed a commercial DGD emulator (General Photonics DynaDelay 90) in the southbound fiber path at the output of the Baltimore node OADM, as indicated in Fig. 1. A programmable polarization controller was also inserted before the emulator, in order to vary the signal state of polarization (SOP) at the emulator input. We note that both the 1 Gb/s and 10 Gb/s signal channels pass through the emulator setup, so that both experience a similar physical fiber link. To compensate for the loss of these components, we added an additional EDFA at the emulator output.

Fig. 1. Schematic of the experimental network testbed, consisting of an installed fiber link between Baltimore and College Park, Maryland. Signal routing was controlled using the DRAGON User Interface (UI), while end-to-end packet loss was measured using the NUTTCP test program. ES: End Station; VLSR: Virtual Link State Router; SNMP: Simple Network Management Protocol; OADM: Optical Add-Drop Multiplexer; XPDR: Optical Transponder; EDFA: Erbium doped fiber amplifier; SMF: single mode fiber
Fig. 2. (a) Schematic of the PMD sensor, based on detection of the half-bit-rate RF tone. PD: Photodiode; MPD: Microwave power detector. (b) The measured back-to-back sensor response as a function of the DGD emulator setting. For each setting, 100 random input SOPs were used; the worst case output is highlighted as the blue dots.

For the PMD monitor, we utilized a simple scheme based on the detection of the half-bit rate (~5 GHz) RF tone from the signal spectrum [16

16. G. Ishikawa and H. Ooi, “Polarization-mode dispersion sensitivity and monitoring in 40-Gbit/s OTDM and l0-Gbit/s NRZ transmission experiments,” In Proc. Opt. Fiber Commun. Conf. (OFC1998), San Jose, CA, Paper WC5.

]. The PMD is kept low enough that it does not impair the 1 Gb/s link, so for this proof-of-principle experiment we only monitored the 10 Gb/s link. A schematic of our sensor is shown in Fig. 2(a). The 10 Gb/s optical signal was detected using a standard photodetector (Agilent 83440C), and then amplified using a wide-bandwidth (2–18 GHz) electrical amplifier, which was followed by a 250 MHz bandpass filter (BPF) centered near 5 GHz to isolate the desired RF tone from the signal spectrum. In order to ensure that no other spectral regions contributed to the sensor output, the BPF had a stopband that extended past 20 GHz. An additional narrow-bandwidth electrical amplifier (4–8 GHz) was used to boost the RF tone at the input to the microwave power detector (Narda 4503A-03). In Fig. 2(b) we show the relation between the sensor output voltage and the DGD level. For this result, we utilized a back-to-back geometry, with the sensor located immediately after the DGD emulator. In this way, we could avoid any effects resulting from signal transmission over the fiber link. For each DGD setting, the sensor output was recorded for 100 random settings of the polarization controller. The worst case SOP results are indicated by the connected blue points. As expected for the 5 GHz tone, these decrease towards zero output as the DGD increases towards the bit slot time of 100 ps [16

16. G. Ishikawa and H. Ooi, “Polarization-mode dispersion sensitivity and monitoring in 40-Gbit/s OTDM and l0-Gbit/s NRZ transmission experiments,” In Proc. Opt. Fiber Commun. Conf. (OFC1998), San Jose, CA, Paper WC5.

].

3. Results and discussion

Fig. 3. Measured packet loss for the 10 Gb/s path as a function of the PMD sensor voltage. A packet loss of 100% indicates that connectivity between end stations could not be established, as determined by an ICMP echo request test. The dashed vertical lines indicate the upper and lower threshold voltage settings of 242 mV and 198 mV, used in subsequent measurements.

As the DGD increases and the sensor output voltage decreases below 200 mV, the system performance begins to deteriorate, with an increasing rate of packet loss. Sensor output voltages below ~100 mV correspond to DGD emulator settings above 75 ps combined the worst case input SOPs to the emulator. In these cases, we cannot establish connectivity between the end stations (as determined by the ICMP echo test described in Section 2) and therefore record 100% packet loss. We note that the received power at the College Park OADM EDFA input fluctuated at most 0.7 dB over the entire data set, so that signal power fluctuations do not account for the observed variation in sensor values and system performance.

Fig. 4. Sensor voltages (upper trace), packet losses (center trace), and unreserved bandwidth (BW) for each channel (lower trace), recorded while the polarization controller settings were varied over time. For all measurements, the sensor’s ability to modify the link metrics was disabled. The emulator DGD settings were (a) 0 ps and (b) 80 ps. The polarization controller was adjusted through the same series of points for both cases.

Fig. 5. Sensor voltages (upper trace), packet losses (center trace), and unreserved bandwidth (BW) for each channel (lower trace), recorded while the polarization controller settings were varied over time. For all measurements, the sensor’s ability to modify the link metrics was enabled. The emulator DGD settings were (a) 0 ps and (b) 80 ps. The polarization controller was adjusted through the same series of points for both cases.

4. Conclusion

Acknowledgments

The authors would to thank the following people for their assistance and encouragement: C. Tracy and D. Magorian of Mid-Atlantic Crossroads; J. Zweck, J.Wen, and C. Menyuk of the University of Maryland Baltimore County; X. Yang of the USC Information Sciences Institute; W. Chimiak of the Laboratory for Telecommunication Sciences; and P. Lang and B. Fink of the NASA Goddard Space Flight Center. This work was financially supported by the Laboratory for Telecommunication Sciences, and by the National Science Foundation under grant numbers 0400535 and 0335266.

References and links

1.

M. Yagi, S. Tanaka, S. Satomi, S. Ryu, K. Okamura, M. Aoyagi, and S. Asano, “Field Trial of GMPLS triple plane integration for 40 Gbit/s dynamically reconfigurable wavelength path network,” Electron. Lett. 41,492–494 (2005). [CrossRef]

2.

A. S. Lenihan, O. V. Sinkin, B. S. Marks, G. E. Tudury, R. J. Runser, A. Goldman, C. R. Menyuk, and G. M. Carter, “Nonlinear Timing Jitter in an Installed Fiber Network With Balanced Dispersion Compensation,” IEEE Photon. Technol. Lett. 17,1558–1560 (2005). [CrossRef]

3.

M. Karlsson, J. Brentel, and P. A. Andrekson, “Long-Term Measurement of PMD and Polarization Drift in Installed Fibers,” J. Lightwave Technol. 18,941–951 (2000). [CrossRef]

4.

H. Kogelnik, R. M. Jopsen, and L. E. Nelson, “Polarization-Mode Dispersion,” in Optical Fiber Communications, vol. IVb, I. Kaminow and T. Li, Ed., pp.725–861 (Academic Press, San Diego, CA, 2002).

5.

M. Akbulut, A. M. Weiner, and P. J. Miller, “Broadband All-Order Polarization Mode Dispersion Compensation Using Liquid-Crystal Modulator Arrays,” J. Lightwave Technol. 24,251–261 (2006). [CrossRef]

6.

H. Miao and C. Yang, “Feed-Forward Polarization-Mode Dispersion Compensation With Four Fixed Differential Group Delay Elements,” IEEE Photon. Technol. Lett. 16,1056–1058 (2004). [CrossRef]

7.

P. Oswald, C. K. Madsen, and R. L. Konsbruck, “Analysis of Scalable PMD Compensators Using FIR Filters and Wavelength-Dependent Optical Power Measurements,” J. Lightwave Technol. 22,647–657 (2004). [CrossRef]

8.

P. B. Phua, H. A. Haus, and E. P. Ippen, “All-Frequency PMD Compensator in Feedforward Scheme,” J. Lightwave Technol. 22,1280–1289 (2004). [CrossRef]

9.

D. Peterson, B. Ward, K. Rochford, P. Leo, and G. Simer, “Polarization mode dispersion compensator field trial and field fiber characterization,” Opt. Express 10,614–621 (2002). [PubMed]

10.

H. Sunnerud, C. Xie, M. Karlsson, R. Samuelsson, and P. J. Andrekson, “A Comparison Between Different PMD Compensation Techniques,” J. Lightwave Technol. 20,368–378 (2002). [CrossRef]

11.

J. Zweck and C. R. Menyuk, “Detection and Mitigation of Soft Failure due to Polarization-Mode Dispersion in Optical Networks,” In Proc. Opt. Fiber Commun. Conf. (OFC2006), Anaheim, CA, Paper OFG5.

12.

H. Kogelnik, P.J. Winzer, L. E. Nelson, R. M. Jopsen, M. Boroditsky, and M. Brodsky, “First-Order PMD Outage for the Hinge Model,” IEEE Photon. Technol. Lett. 17,1208–1210 (2005). [CrossRef]

13.

A. Farrel and I. Bryskin, GMPLS: Architecture and Applications, The Morgan Kaufmann Series in Networking (Elsevier Inc., San Francisco, CA, 2006).

14.

Information on the DRAGON project is available at http://dragon.maxgigapop.net.

15.

International Telecommunication Union, Telecommunication Standardization Sector of ITU, ITU-T Standard G.694.1, Spectral grids for WDM applications: DWDM frequency grid (2002).

16.

G. Ishikawa and H. Ooi, “Polarization-mode dispersion sensitivity and monitoring in 40-Gbit/s OTDM and l0-Gbit/s NRZ transmission experiments,” In Proc. Opt. Fiber Commun. Conf. (OFC1998), San Jose, CA, Paper WC5.

17.

The NUTTCP software is the product of B. Fink and is available at ftp://ftp.lcp.nrl.navy.mil/pub/nuttcp/latest/nuttcp.html.

18.

H. van Helvoort, Next Generation SONET: Evolution or Revolution (John Wiley and Sons, Ltd., 2005). [CrossRef]

19.

X. Yang and B. Ramamurthy, “Dynamic Routing in Translucent WDM Optical Networks: The Intradomain Case,” J. Lightwave Technol. 23,955–971 (2005). [CrossRef]

OCIS Codes
(060.0060) Fiber optics and optical communications : Fiber optics and optical communications
(060.4250) Fiber optics and optical communications : Networks

ToC Category:
Fiber Optics and Optical Communications

History
Original Manuscript: October 24, 2006
Revised Manuscript: December 18, 2006
Manuscript Accepted: December 19, 2006
Published: January 8, 2007

Citation
Anthony S. Lenihan, William A. Babson, Hua Jiao, Jerry Sobieski, and Gary M. Carter, "An experimental demonstration of a soft-failure approach to PMD mitigation in an installed optical link," Opt. Express 15, 24-32 (2007)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-15-1-24


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References

  1. M. Yagi, S. Tanaka, S. Satomi, S. Ryu, K. Okamura, M. Aoyagi, and S. Asano, "Field Trial of GMPLS triple plane integration for 40 Gbit/s dynamically reconfigurable wavelength path network," Electron. Lett. 41, 492-494 (2005). [CrossRef]
  2. A. S. Lenihan, O. V. Sinkin, B. S. Marks, G. E. Tudury, R. J. Runser, A. Goldman, C. R. Menyuk, and G. M. Carter, "Nonlinear Timing Jitter in an Installed Fiber Network With Balanced Dispersion Compensation," IEEE Photon. Technol. Lett. 17, 1558-1560 (2005). [CrossRef]
  3. M. Karlsson, J. Brentel, and P. A. Andrekson, "Long-Term Measurement of PMD and Polarization Drift in Installed Fibers," J. Lightwave Technol. 18, 941-951 (2000). [CrossRef]
  4. H. Kogelnik, R. M. Jopsen, and L. E. Nelson, "Polarization-Mode Dispersion," in Optical Fiber Communications, vol. IVb, I. Kaminow and T. Li, Ed., pp. 725-861 (Academic Press, San Diego, CA, 2002).
  5. M. Akbulut, A. M. Weiner, and P. J. Miller, "Broadband All-Order Polarization Mode Dispersion Compensation Using Liquid-Crystal Modulator Arrays," J. Lightwave Technol. 24, 251-261 (2006). [CrossRef]
  6. H. Miao and C. Yang, "Feed-Forward Polarization-Mode Dispersion Compensation With Four Fixed Differential Group Delay Elements," IEEE Photon. Technol. Lett. 16, 1056-1058 (2004). [CrossRef]
  7. P. Oswald, C. K. Madsen, and R. L. Konsbruck, "Analysis of Scalable PMD Compensators Using FIR Filters and Wavelength-Dependent Optical Power Measurements," J. Lightwave Technol. 22, 647-657 (2004). [CrossRef]
  8. P. B. Phua, H. A. Haus, and E. P. Ippen, "All-Frequency PMD Compensator in Feedforward Scheme," J. Lightwave Technol. 22, 1280-1289 (2004). [CrossRef]
  9. D. Peterson, B. Ward, K. Rochford, P. Leo, and G. Simer, "Polarization mode dispersion compensator field trial and field fiber characterization," Opt. Express 10, 614-621 (2002). [PubMed]
  10. H. Sunnerud, C. Xie, M. Karlsson, R. Samuelsson, and P. J. Andrekson, "A Comparison Between Different PMD Compensation Techniques," J. Lightwave Technol. 20, 368-378 (2002). [CrossRef]
  11. J. Zweck and C. R. Menyuk, "Detection and Mitigation of Soft Failure due to Polarization-Mode Dispersion in Optical Networks," In Proc. Opt. Fiber Commun. Conf. (OFC2006), Anaheim, CA, Paper OFG5.
  12. H. Kogelnik, P. J. Winzer, L. E. Nelson, R. M. Jopsen, M. Boroditsky, and M. Brodsky, "First-Order PMD Outage for the Hinge Model," IEEE Photon. Technol. Lett. 17, 1208-1210 (2005). [CrossRef]
  13. A. Farrel and I. Bryskin, GMPLS: Architecture and Applications, The Morgan Kaufmann Series in Networking (Elsevier Inc., San Francisco, CA, 2006).
  14. Information on the DRAGON project is available at http://dragon.maxgigapop.net.
  15. International Telecommunication Union, Telecommunication Standardization Sector of ITU, ITU-T Standard G.694.1, Spectral grids for WDM applications: DWDM frequency grid (2002).
  16. G. Ishikawa and H. Ooi, "Polarization-mode dispersion sensitivity and monitoring in 40-Gbit/s OTDM and l0-Gbit/s NRZ transmission experiments," In Proc. Opt. Fiber Commun. Conf. (OFC1998), San Jose, CA, Paper WC5.
  17. The NUTTCP software is the product of B. Fink and is available at ftp://ftp.lcp.nrl.navy.mil/pub/nuttcp/latest/nuttcp.html.
  18. H. van Helvoort, Next Generation SONET: Evolution or Revolution (John Wiley and Sons, Ltd., 2005). [CrossRef]
  19. X. Yang and B. Ramamurthy, "Dynamic Routing in Translucent WDM Optical Networks: The Intradomain Case," J. Lightwave Technol. 23, 955-971 (2005). [CrossRef]

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