Mechanical and optical characterisation of glass optical fibres for sensing applications

Abstract

The capacity of glass optical fibres to handle stress experienced in sensing application is critical in many areas including biomedical sensing. Accordingly, it is important to determine the tensile strength of optical fibre, providing better understanding of optical fibre strength and the behaviour of optical fibre under certain stresses. This thesis covers the mechanical and optical characterisation of a range of solid glass optical fibres, including solid fibres made of various glass materials, stored lead silicate solid fibre and microstructured optical fibre made of silica glass material. This thesis employs standard mechanical testing techniques such as tensile testing. Data collected from the tensile strength tests is used to understand the statistical behaviour of solid fibres and characterise them mechanically using the statistical Weibull distribution technique. In addition, the strength of numerous solid glass optical fibres made of different glass materials are compared. Firstly, data indicates that depending on the glass material, the strength of the fibre under tensile load varies from very high strength for standard telecommunication fibre, such as solid SMF28, to very low strength for ZBLAN fluoride glass fibres. Secondly, using the same statistical technique for data analysis, an investigation of the effect of aging (storage time) in F2 solid glass fibre was carried out. Results indicate that the aging effect does not have significant effect on the strength of solid F2 glass fibres. Additionally, an investigation was undertaken into the effect of capillary hole size (inflation ratio) and presence of multiple holes on the strength of microstructured glass optical fibres. Results indicate that the inflation ratio and presence of multiple holes in the fibre affects the strength of the fibre. This thesis presents an investigation of the optical characterisation of solid and hollow core optical fibres. Raman spectroscopy of the glass materials was also conducted to explore their potential application in biomedical sensing.