Highly Spectrally Efficient DWDM Transmission at 7.0 b/s/Hz Using 8 × 65.1-Gb/s Coherent PDM-OFDM

Hidenori Takahashi, Abdullah Al Amin, Itsuro Morita, Hideaki Tanaka, Sander L. Jansen

Research output: Contribution to journalArticlepeer-review

56 Citations (Scopus)


In this paper, we discuss the realization of wave-length-division multiplexing (WDM) transmission at high spectral efficiency. For this experiment, coherent polarization-division multiplexing—orthogonal frequency-division multiplexing (PDM-OFDM) is used as a modulation format. PDM-OFDM uses training symbols for channel estimation. This makes OFDM easily scalable to higher level modulation formats as channel estimation is realized with training symbols that are independent of the constellation size. Furthermore, because of its well-defined spectrum OFDM requires only a small guard band between WDM channels. The dependence of the number of OFDM subcarriers is investigated with respect to the interchannel linear crosstalk. At a constant data rate the number of OFDM subcarriers is estimated to achieve lower linear crosstalk in order to achieve higher spectral efficiency. We then experimentally demonstrate dense WDM (DWDM) transmission with 7.0-b/s/Hz net spectral efficiency using 8 x 65.1-Gb/s coherent PDM-OFDM signals with 8-GHz WDM channel spacing utilizing 32-quadrature-amplitude-modulation subcarrier modulation. Successful transmission is achieved over 240 km standard single-mode fiber (SSMF) spans with hybrid erbium-doped fiber amplifiers/Raman amplification.

Original languageEnglish
Article number5256210
Pages (from-to)406-414
Number of pages9
JournalJournal of Lightwave Technology
Issue number4
Publication statusPublished - 2010 Feb 15
Externally publishedYes


  • Fiber-optic transmission systems
  • long-haul transmission
  • orthogonal frequency-division multiplexing (OFDM)

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics


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