1 / 29

Cross-Polarization Modulation in Polarization-Multiplexed Systems

M. Winter, D. Kroushkov, and K. Petermann IEEE Summer Topicals July 2010. Cross-Polarization Modulation in Polarization-Multiplexed Systems. typical DWDM system with a nonlinearity probe. ► CW probe is unaffected by linear effects / SPM ► other channels are 10 Gbps OOK in 50 GHz grid.

mahina
Download Presentation

Cross-Polarization Modulation in Polarization-Multiplexed Systems

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. M. Winter, D. Kroushkov, and K. Petermann IEEE Summer Topicals July 2010 Cross-Polarization Modulation in Polarization-Multiplexed Systems

  2. typical DWDM system with a nonlinearity probe ► CW probe is unaffected by linear effects / SPM ► otherchannelsare 10 Gbps OOK in 50 GHz grid

  3. SOP evolutionTx output (fully polarized)

  4. significant nonlinear depolarizationrapid (symbol-to-symbol) fluctuations of the SOP what is going on and is this a problem? SOP evolution(without amplifier noise)

  5. ► basics cross-polarization modulation (XPolM) ► statistical models ► XPolM and polarization multiplex ► experiments

  6. XPolM basics

  7. XPolM is closely related to XPM

  8. nonlinear polarization effects known since at least 1969 ► e.g. Kerr shutter (Duguay and Hansen, APL, pp. 192+, 1969) XPolM first described in its „current version“ in 1995 ► Stokes space Manakov equation ► collision of two solitons ► Mollenauer et al., Optics Letters, pp. 2060+, 1995 many-channel formulation in 2006 ► Menyuk and Marks, JLT, pp. 2806+, 2006

  9. Poincaré sphere probe channel DWDM interferers Stokes vector sum nonlinear rotation

  10. statistical models

  11. ► length (intensity) varies due to walk-off►(interferer and probe group velocity differs) ► direction (SOP) varies due to PMD► (interferer and probe birefringence differs) ► both effects are random various models have been proposed to describe this behavior (interferer) Stokes vectors are not constant

  12. ► Karlsson‘s statistical model (JLT, pp. 4127+, 2006) ► influence on PMD compensation ► mostly two-channel system, no PMD dependence ► diffusion model (Winter et al., JLT, pp. 3739+, 2009) ► SOPs evolve as random walk ► ensemble mean values only ► carousel model (Bononi et al., JLT, pp. 1903+, 2003) ► pump and probe rotate when both carry a mark ► two-channel system, no PMD

  13. SOP distribution resembles diffusion

  14. DWDM power/channel threshold for mean probe DOP=0.97 ► resonant dispersion map, 10 × 10 Gbps OOK interferers► @ 50 GHz spacing

  15. depolarization of probe vs. number of 3 dBm interferers ► difficult to simulate, expensive to measure► saturates at about 20

  16. XPolM and polarization multiplex

  17. a typical PolDM system ► selective upgrade: 10G NRZ » 100G PolDM RZ-QPSK ► fits into 50 GHz grid

  18. detected field at y-Rx: ► otherwise crosstalk occurs from x to y and vice versa ► crosstalk increases with misalignment angle and with►length of field vector polarization DEMUX must be aligned to PolDM subchannels (visualization in Jones space)

  19. XPolM causes symbol-to-symbol fluctuations around mean SOP ► cannot be compensated (again like XPM) modern coherent receivers can handle subchannel SOP changes with PMD time constants ► DCF abuse with a screwdriver: 280 µrad/ns(Krummrich and Kotten, OFC 2004, FI3)

  20. field amplitude at y-Rx aligned subchannels interleaved subchannels time ► crosstalk is never zero because pulses at Rx are no longer RZ (accumulated GVD, PMD, noise) interleaving RZ-shaped symbols minimizes crosstalk generation

  21. 10 × 10G NRZ interferers w/ 100G PolDM-RZ-QPSK probe ► 256 ps/nm RDPS, 10 interferers, SSMF, no PMD ► power/channel threshold is reduced by up to 2 dB

  22. the statistical ensemble (mean DOP = 0.975) ► DOPs and ROSNRs spread over large range ► for DOPs < 0.98 (0.97), ROSNR penalties become significant

  23. Xie showed how PolDM interferers can cause negligible XPolM compared to single-polarization (PTL, pp. 274+, 2009) ► requires RZ pulse shape and subchannel interleaving ► neighboring half-symbol slots have orthogonal polarization states ► probe SOP oscillates but rotation does not accumulate

  24. experiments

  25. ► onset of nonlinear penalties at much lower powers ► (near) saturation of penalties for large channel spacing (van den Borne et al., ECOC, 2004, Mo 4.5.5)

  26. ► saturation of penalties for large number of interferers (Renaudier et al., PTL, pp. 1816+, 2009)

  27. ► benefit of PolDM vs. OOK interferers (Bertran-Pardo et al., OFC, 2008, OTuM5)

  28. summary

  29. ► XPolM in DWDM systems causes depolarization ► diffusion model correctly predicts simulated behavior ► depolarization creates detrimental PolDM crosstalk ► can be reduced by interleaving PolDM subchannels slides available at http://www.marcuswinter.de/publications/ST2010

More Related