Advanced fiber Bragg grating sensors for high temperature sensing

In this thesis, the regeneration of UV-inscribed gratings (FBGs and TFBGs) in standard and photosensitive optical fibers was experimentally studied. The so-called regenerated gratings can operature up to 1000°C. The improvement of regeneration efficiency was investigated by studying the effect of involved parameters in thermal regeneration. This thesis demonstrated that efficient regeneration depends on the thermal profile, heating rate, and target temperature, whereas the laser type and wavelength have no significant effect on the regeneration efficiency. The design of the experiment (DoE) approach was applied for FBG sensign and the regeneration process. The obtained interaction coefficients between the variables were used to calibrate the sensor. DoE of three factors in the regeneration process, including the heating rate, the grating length, and the number of UV pulses, showed that these parameters interact together in a non-linear way.