Abstract
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 language | English (US) |
|---|---|
| Article number | 5233794 |
| Pages (from-to) | 1773-1775 |
| Number of pages | 3 |
| Journal | IEEE Photonics Technology Letters |
| Volume | 21 |
| Issue number | 23 |
| DOIs | |
| State | Published - Dec 1 2009 |
| Externally published | Yes |
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics
- Electrical and Electronic Engineering
Keywords
- High-speed optical transmission
- Multilevel modulation
- Polarization-mode dispersion (PMD)
- Turbo equalization