Ultra-Long-Haul WDM Transmission with High Spectral Efficiency

Yi CAI  Jin-Xing CAI  Carl R. DAVIDSON  Dmitri G. FOURSA  Alan J. LUCERO  Oleg V. SINKIN  Yu SUN  Alexei N. PILIPETSKII  Georg MOHS  Neal S. BERGANO  

IEICE TRANSACTIONS on Communications   Vol.E94-B   No.2   pp.392-399
Publication Date: 2011/02/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E94.B.392
Print ISSN: 0916-8516
Type of Manuscript: INVITED PAPER (Special Section on Extremely Advanced Optical Transmission Technologies and Transmission Optical Fiber Technologies towards Exabit Era)
optical fiber communication,  spectral efficiency,  coherent detection,  pre-filtering,  MAP detection,  

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We review our recent work on ultra-long-haul wavelength division multiplexed (WDM) transmission with high spectral efficiency (SE) employing tight pre-filtering and multi-symbol detection. We start the discussion with a theoretical evaluation of the SE limit of pre-filtered modulation in optical fiber communication systems. We show that pre-filtering induced symbol correlation generates a modulation with memory and thus, a higher SE limit than that of the original memory-less modulation. We also investigate the merits of utilizing the pre-filtering induced symbol correlation with multi-symbol detection to achieve high SE transmission. We demonstrate transoceanic WDM transmission of a pre-filtered polarization division multiplexed return-to-zero quaternary phased shift keying (PDM-RZ-QPSK) modulation format with multi-symbol detection, achieving 419% SE which is higher than the SE limit of the original memory-less PDM-RZ-QPSK format.