Experimental and theoretical investigation of systems with potential for terabit capacity

Research output: Book/ReportPh.D. thesis

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Internet traffic has been growing with tremendous speed in the last decade and analysis indicate that the growth will continue in the future. The apparent unlimited capacity will within a few years be utilised completely, thus preventing the expected boom in new broadband demanding services. New techniques for utilising the existing Internet infrastructure more efficiently, either by replacing or complementing existing techniques, are therefore indispensable.

Optical Time Division Multiplexing (OTDM) is one option out of a number of schemes, which offer more efficient utilisation of the bandwidth either alone or in conjunction with e.g. Wavelength Division Multiplexing (WDM) or with advanced modulation formats.

The objective of this thesis is to extract and provide design parameters allowing an optimised performance of an OTDM system. A basic point-to-point bit interleaved OTDM system can be divided into a few sub-systems and each chapter in the thesis is dedicated to a specific part. The first sub-system attended is the pulse source, where the temporal Full Width Half Maximum (FWHM) width and the Pulse Tail Extinction Ratio (PTER) are examined. Subsequently, Clock Recovery is covered, by deriving a modified Phase Locked Loop theory, which is useful when extracting a base rate clock from an aggregated high-speed OTDM signal. Stability of the modified Clock Recovery sub-systems is analysed using Bode plots with special emphasise on impact of the often-substantial optical time delays within the loop. Extraction of the tributary channels using switches for demultiplexing is presented, and design parameters in terms of temporal FWHM width, Extinction Ratio and timing jitter are provided. Error-free experimental demultiplexing of 320 to 10 Gbit/s using a Non-linear Optical Loop Mirror (NOLM) is shown. Finally, some of the additional required functionalities when expanding from OTDM point-topoint systems to networks are discussed, with special focus on channel identification schemes.
Original languageEnglish
PublisherTechnical University of Denmark
Number of pages269
Publication statusPublished - 2006

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