Dwdm Systems

A thesis submitted in fulfilment of the requirement for the degree of Doctor of Philosophy School of Electrical Engineering and Telecommunications The University of New South Wales November 2010 THE UNIVERSITY OF NEW SOUTH WALES Thesis/Dissertation Sheet Surname or Family name: JI First name: PHILIP Other name/s: NAN Abbreviation for degree as given in the University calendar: PhD School: ELECTRICAL ENGINEERING AND TELECOMMUNICATIONS Faculty: ENGINEERING Title: DEVELOPMENT OF NOVEL FIBRE OPTIC DEVICES AND SUBSYSTEMS FOR NEXT GENERATION DWDM SYSTEMS Abstract As the backbone for the global communication network, optical dense wavelength division multiplexed (DWDM) systems are facing challenges in capacity, flexibility, reliability and cost effectiveness. In my thesis research I developed five novel optical devices or subsystems to combat these technical challenges. Each of these devices/subsystems is described in an individual chapter including background survey, proposal of new features, theoretical analysis, hardware design, prototype fabrication and characterization, and experimental verification in DWDM systems. The first is a novel tunable asymmetric interleaver that allows the interleaving ratio to be adjusted dynamically. Two design methods were proposed and implemented. Spectral usage optimisation and overall system performance improvement in 10G/40G and 40G/100G systems were successfully demonstrated through simulations and experiments. The second is a colourless intra-channel optical equalizer. It is a passive periodic filter that restores the overall filter passband to a raised cosine profile to suppress the filter narrowing effect and mitigate the inter-symbol interference. 20% passband widening and 40% eye opening were experimentally achieved. The third is a flexible band tunable filter that allows simultaneous tuning of centre frequency and passband width. Based mainly on this filter, a low cost expendable reconfigurable optical add/drop multiplexer (ROADM) node was developed. Its flexible switching features were experimentally demonstrated in a two-ring four-node network testbed. The fourth is a transponder aggregator subsystem for colourless and directionless multi-degree ROADM node. Using the unique characteristics of the coherent receiver, this technology eliminates the requirement of wavelength selector, thus reduces power consumption, size and cost. I experimentally demonstrated that it can achieve < 0.5 dB penalty between receiving single channel and 96 channels. The last is a real-time feedforward all-order polarization mode dispersion (PMD) compensator. It first analyses spectral interference pattern to retrieve phase information and calculate PMD, then it uses a pulse shaper to restore the pulse shape and thus compensates the PMD. These functions were demonstrated through experiments and simulations. All of these novel devices and subsystems deliver new functional features and are suitable to be applied in the next generation DWDM systems to improve capacity, flexibility, and reliability and to reduce cost. Declaration relating to disposition of project thesis/dissertation I hereby grant to the University of New South Wales or its agents the right to archive and to make available my thesis or dissertation in whole or in part in the University libraries in all forms of media, now or here after known, subject to the provisions of the Copyright Act 1968. I retain all property rights, such as patent rights. I also retain the right to use in future works (such as articles or books) all or part of this thesis or dissertation. I also authorise University Microfilms to use the 350 word abstract of my thesis in Dissertation Abstracts International (this is applicable to doctoral theses only). …………………………………………………………… ……………………………………..……………… ……….……………………...…….… Signature Witness Date The University recognises that there may be exceptional circumstances requiring restrictions on copying or conditions on use. Requests for restriction for a period of up to 2 years must be made in writing. Requests for a longer period of restriction may be considered in exceptional circumstances and require the approval of the Dean of Graduate Research. FOR OFFICE USE ONLY Date of completion of requirements for Award: ORIGINALITY STATEMENT ‘I hereby declare that this submission is my own work and to the best of my knowledge it contains no materials previously published or written by another person, or substantial proportions of material which have been accepted for the award of any other degree or diploma at UNSW or any other educational institution, except where due acknowledgement is made in the thesis. Any contribution made to the research by others, with whom I have worked at UNSW or elsewhere, is explicitly acknowledged in the thesis. I also declare that the intellectual content of this thesis is the product of my own work, except to the extent that assistance from others in the project's design and conception or in style, presentation and linguistic expression is acknowledged.’ Signed …………………………………………….............. Date …………………………………………….............. This thesis would not have been possible without the guidance and the help of several individuals who in one way or another contributed and extended their valuable assistance in the preparation and completion of this study: First and foremost, the late Professor Pak-Lim Chu, for leading me into this wonderful world of fibre optics, and for being my mentor and being the godly role model that I always look up to. My supervisor, Professor Gang-Ding Peng, for all the precious guidance, advice and instruction throughout my entire post-graduate study. My co-supervisor, Dr. Ting Wang, for giving me the great opportunities to explore many new and exciting research fields, and for the invaluable guidance and support during my research. All my fellow students and staffs at the Photonics and Optical Communications Group, University of New South Wales, for the assistance and encouragement throughout my long PhD pursuit. All my colleagues at NEC Laboratories America, for the fruitful collaborations and all the important technical supports in this research. My late parents, for their constant prayers and encouragement, and for their life-long sacrifice. They have always been my source of motivation and strength in the pursuit of knowledge and truth. My dearest wife, Jennifer, for her constant love and support which accompanied and sustained me in this long and challenging journey. My two beautiful children, Jonathan and Zachary, for all the joy I received. iv !"#$%&'%(%) !"#$%&'%(%)!"#$%&'%(%) All my brothers and sisters in Christ from Overseas Christian Fellowship Australia, West Sydney Chinese Christian Church, and Princeton Christian Church, for their prayers, fellowship and encouragement that upheld me during my study. Most importantly, my Heavenly Father, my Lord and Saviour, the Wonderful Counsellor, the Creator of the heavens and the earth, and the Creator of the ultimate broadband communication network, for the blessings, grace, mercy, guidance, and provision, throughout this research and throughout my entire life. May all glory and honour be unto Him. The heavens declare the glory of God, and the sky above proclaims his handiwork. Day to day pours out speech, and night to night reveals knowledge. There is no speech, nor are there words, whose voice is not heard. Their voice goes out through all the earth, and their words to the end of the world. … Let the words of my mouth and the meditation of my heart be acceptable in your sight, O Lord, my rock and my redeemer. Psalm 19:1-4, 14 (ESV) v As the backbone for the global communication network, optical dense wavelength division multiplexed (DWDM) systems are facing challenges in capacity, flexibility, reliability and cost effectiveness. In my thesis research I developed five novel optical devices or subsystems to combat these technical challenges. Each of these devices/subsystems is described in an individual chapter including background survey, proposal of new features, theoretical analysis, hardware design, prototype fabrication and characterization, and experimental verification in DWDM systems. The first is a novel tunable asymmetric interleaver that allows the interleaving ratio to be adjusted dynamically. Two design methods were proposed and implemented. Spectral usage optimisation and overall system performance improvement in 10G/40G and 40G/100G systems were successfully demonstrated through simulations and experiments. The second is a colourless intra-channel optical equalizer. It is a passive periodic filter that restores the overall filter passband to a raised cosine profile to suppress the filter narrowing effect and mitigate the inter-symbol interference. 20% passband widening and 40% eye opening were experimentally achieved. The third is a flexible band tunable filter that allows simultaneous tuning of centre frequency and passband width. Based mainly on this filter, a low cost expendable reconfigurable optical add/drop multiplexer (ROADM) node was developed. Its flexible switching features were experimentally demonstrated in a two- ring four-node network testbed. The fourth is a transponder aggregator subsystem for colourless and directionless multi-degree ROADM node. Using the unique characteristics of the coherent receiver, this technology eliminates the requirement of wavelength selector, thus reduces power consumption, size and cost. I experimentally demonstrated that it can achieve <

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