High capacity optical fibre transmission systems
In this thesis a number of system design options are studied for the generation and processing of ultra—high speed optical data, based on the technique of Optical Time Division Multiplexing. The limits are investigated with regard to maximum unregenerated transmission distances for linear propagation over single mode fibre with large chromatic dispersion. Overall, the aim is to minimise the bandwidth requirements of electronic and opto—electronic system components for a given optical line capacity whilst at the same time maximising the chromatic dispersion limited propagation distances, thus exploring the potential for future system and network operating speeds of several tens of Gbit/s. A summary of standard system designs and their performance in terms of maximum system speed and dispersive fibre propagation provides an introduction into the field of high performance fibre optic data communication systems. Particular examples are used to introduce the device models subsequently employed in the analysis of new system configurations. This includes a description of the system performance measurements which are the basis for the performance analyses of the proposed ultra—high speed systems. In the field of fibre transmission research a variety of electrical interface and optical line signal formats are being investigated, each being appropriate for particular application areas and offering varying compromises between performance, complexity and user friendliness. In the context of this thesis the investigations are limited to high capacity time division multiplexed configurations, which represent a medium to longer term alternative as well as a complementary approach to the currently widely pursued system capacity upgrades by means of optical wavelength or frequency division multiplexing. Moreover, ultra—high speed time division multiplexed transmission is fundamentally compatible with WDM system operation, providing a future upgrade path for multi—wavelength systems being developed at the present time. The vehicle for these investigations is a set of computer models. Optical signal generation, pulse propagation in single—mode fibre, optical time domain processing, amplification and optical receiver detection are all included in the models to allow end—to—end system performance studies. Experimental results are presented at various stages to validate the models employed.