Optical fibre coupling devices

Kerr, Yann Henry Bernard (1981) Optical fibre coupling devices. MSc(R) thesis, University of Glasgow.

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Abstract

This thesis deals with optical coupling systems and is divided in two parts. The first one is concerned with directional coupling between two graded index fibres made by a diffusion process. The theory and physics of ion exchange is studied, providing a theoretical description of the refractive index change. A mathematical method of solving the concentration dependent diffusion equation is given. Theoretical index distributions are thus obtained for circular waveguides. To compare theory with experiment, a device directly measuring the index profile of a circular fibre is described. The theory of propagation in round graded index fibres, is reviewed and a simplified coupling coefficient derived in order to determine the coupling efficiency. The coupling arrangement is described and the results discussed. It is shown that efficient tapping of power can be done with the high order modes, and eventually, at a much lower efficiency with the low order ones. The second part describes a theoretical study of optical contradirectional coupling between a single mode sandwich ribbon fibre and a thin film planar waveguide, longitudinal phase matching being achieved by means of a periodic corrugation, which is typically a grating etched into the film. Film-fibre couplers were tested and achieved an estimated efficiency of only due to the poor quality of the gratings. With several improvements in the set-up and specimens, an efficiency of over 60 is quite feasible. The application of the method for linking integrated optical devices is considered as well as a possible demultiplexer. The study presented provides the ground work for future development of integrated optical devices links and an active device.

Item Type: Thesis (MSc(R))
Qualification Level: Masters
Additional Information: Adviser: P JR Laybourn
Keywords: Optics
Date of Award: 1981
Depositing User: Enlighten Team
Unique ID: glathesis:1981-73212
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 14 Jun 2019 08:56
Last Modified: 14 Jun 2019 08:56
URI: http://theses.gla.ac.uk/id/eprint/73212

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