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Title: Active optical waveguide devices for telecommunications networks
Author: Evans, T.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2005
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Two active optical waveguide devices were investigated using a variety of theoretical techniques for their potential application to telecommunications networks. A reconfigurable transverse waveguide grating was numerically modelled and shown to offer switching up to 1x16 with high refractive index modulating materials or 1x4 with much faster, but lower refractive index modulating materials. Furthermore, a method was shown for combining the grating with a finer fixed grating to select a wavelength multiplexed signal. A previously devised dynamic gain flattening filter device was also numerically analysed to determine its general characteristics and the limitations of its configuration. Its effects on attenuation control and data signal distortion were analysed under a range of conditions and guidelines for keeping that distortion limited determined. A simplified model of the filter operation was used to form a control algorithm allowing immediate jumps in the attenuation levels to be accomodated. Finally, an experimental implementation of the filter with an arrayed waveguide grating and free space imaged liquid crystal phase modulating array was demonstrated. Unfortunately errors in the construction of this filter prevented typical attenuation profiles from being illustrated, but the resulting measurements were found consistent with the filter modelling. It was judged that the gain flattening filter could potentially be used for both generating a set of data modulated wavelength channels as a source and for correcting the relative levels of those channels after different transmission paths had modified them. Both of these features would be particularly desirable in an optically routed system. The wide switching capabilities of the transverse grating (1x16) could be useful for initial network configuration or recovery from link failure, but unfortunately it does not offer sufficient advantages over an array of simpler junctions to make its development clearly worthwhile. Electrically selecting a single wavelength channel from many using the fixed and reconfigurable grating combination would potentially be useful in an add/drop multiplexer component.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available