PMD compensation in polarization-multiplexed multilevel modulations by turbo equalization

Lyubomir L. Minkov, Ivan B. Djordjevic, Lei Xu, Ting Wang

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


We propose the multilevel maximum a posteriori probability (MAP) detector suitable for use in polarization-multiplexed optical communications using multilevel modulation and coherent detection. The proposed multilevel MAP detection scheme considers two symbols transmitted over two orthogonal polarization states as a two-component symbol. We demonstrate experimentally that the proposed MAP scheme is effective in eliminating the bit-error-ratio (BER) floor phenomenon introduced by the conventional MAP equalizer, which considers the symbols transmitted over both polarizations independently. To improve further tolerance to optical fiber polarization-mode dispersion, we iterate extrinsic soft information between the MAP detector and soft-iterative decoder, in a turbo equalization fashion. Penalty of less than 1.5 dB at 20 Gb/s (and BER of 10-6) for differential group delay of 100 ps is reported.

Original languageEnglish (US)
Article number5233794
Pages (from-to)1773-1775
Number of pages3
JournalIEEE Photonics Technology Letters
Issue number23
StatePublished - Dec 1 2009


  • High-speed optical transmission
  • Multilevel modulation
  • Polarization-mode dispersion (PMD)
  • Turbo equalization

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Electrical and Electronic Engineering


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