Towards a practical implementation of coherent WDM: analytical, numerical, and experimental studies

Selwan K. Ibrahim, Jian A. Zhao, Fatima C. Garcia Gunning, Paola Frascella, F.H. Peters, Andrew D. Ellis

    Research output: Contribution to journalArticlepeer-review


    Future optical networks will require the implementation of very high capacity (and therefore spectral efficient) technologies. Multi-carrier systems, such as Orthogonal Frequency Division Multiplexing (OFDM) and Coherent WDM (CoWDM), are promising candidates. In this paper, we present analytical, numerical, and experimental investigations of the impact of the relative phases between optical subcarriers of CoWDM systems, as well as the effect that the number of independently modulated subcarriers can have on the performance. We numerically demonstrate a five-subcarrier and three-subcarrier 10-GBd CoWDM system with direct detected amplitude shift keying (ASK) and differentially/coherently detected (D) phase shift keying (PSK). The simulation results are compared with experimental measurements of a 32-Gbit/s DPSK CoWDM system in two configurations. The first configuration was a practical 3-modulator array where all three subcarriers were independently modulated, the second configuration being a traditional 2-modulator odd/even configuration, where only odd and even subcarriers were independently modulated. Simulation and experimental results both indicate that the independent modulation implementation has a greater dependency on the relative phases between subcarriers, with a stronger penalty for the center subcarrier than the odd/even modulation scheme.
    Original languageEnglish
    Article number5560707
    Pages (from-to)833-847
    Number of pages15
    JournalIEEE Photonics Journal
    Issue number5
    Publication statusPublished - Oct 2010

    Bibliographical note

    © 2010 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.


    • optical fiber communication
    • optical modulation
    • phase modulation


    Dive into the research topics of 'Towards a practical implementation of coherent WDM: analytical, numerical, and experimental studies'. Together they form a unique fingerprint.

    Cite this