The work within this thesis investigates the characteristics and sensing
properties of novel near- and mid-infrared tellurite and germanate glass fibres and their
potential as sensing elements.
An asymmetric splicing method for fusion-splicing tellurite and germanate glass
fibres to standard silica fibre is demonstrated. The thermal and strain sensing properties
of these glass fibres have been studied by analysing the properties of optical fibre
Fabry-Perot cavities, which were formed when these high refractive index fibres were
spliced to silica fibre, and fibre Bragg gratings. Using fibre F-P interferometer, the
normalized thermal sensitivity of tellurite and germanate fibre was measured to be
10.76×10-6/°C and 15.56×10-6/°C respectively, and the normalized strain sensitivity of
tellurite and germanate fibre was also measured with values of 0.676×10-6 /με and
0.817×10-6 /με respectively. These results show good agreement with measurements
using fibre Bragg gratings in these fibres and are reasonably consistent with the values
predicted using available published data for glasses of similar compositions. Tellurite
and germanate glass fibres show potential as thermal sensing and load sensing elements
compared with silica fibre.
The design of an evanescent field gas sensor using tapered germanate fibre for
methane gas species detection was investigated and modelled. This model shows the
maximum gas cell length (sensing fibre length), detectable gas concentration range, and
required gas cell length range for the expected minimum detectable gas concentration of
a fibre evanescent field sensor, which gives guidance for the effective gas cell length
choosen according to different minimum detectable gas concentration requirement in
practise.
The investigation of tellurite and germanate glass fibre characteristics and
sensing properties offer guidance for their applications in sensing areas.Engineering and Physical Sciences Research Council (EPSRC
