Citation:
C. Y. Wei, C. C. Ye, S. W. James, R. P. Tatam and P. E. Irving, The influence of hydrogen loading and the fabrication process on the mechanical strength of optical fibre Bragg gratings, Optical Materials, Volume 20, Issue 4, November-December 2002, Pages 241-251.
Abstract:
This paper investigates the influence of hydrogen loading and other stages of
the fabrication process on the mechanical strength of fibre Bragg gratings.
Following UV irradiation, tensile tests were carried out on Ge–B codoped
photosensitive fibres with and without hydrogen loading. Fibre Bragg gratings
(FBGs) were written using a range of UV wavelengths, namely 246, 255 and 266 nm.
The tensile strength of the optical fibres was determined in their as-received
status and following the various stages of FBG fabrication. The mechanical
strength was assessed using Weibull statistics. The results indicate that the
strength of FBGs is influenced by the UV irradiation parameters and by the
hydrogen-loading process. FBGs fabricated using shorter UV wavelengths and low
pulse power intensity exhibit a high mechanical strength. The FBGs written in
hydrogen loaded fibres have less than 50% of the strength of FBGs that have not
been hydrogen loaded. Fibre fracture morphology observed by scanning electron
microscope reveals fracture mechanisms of FBGs, which are correlated with the
structural change of the silica fibres induced during the FBG inscription
process. Combined with surface information gathered by atomic force microscopy,
fracture mechanics is applied to understand the mechanisms of strength
degradation caused by the FBG inscription proces