Electric-arc-induced gratings in non-hydrogenated fibres: fabrication and high-temperature characterizations

Long-period fibre gratings are written in non-hydrogenated standard single-mode fibres, using electric discharge. We have obtained a transmitted spectrum with low insertion loss (<0.2 dB) and resonance peak isolation of -24 dB at 1545 nm. The model, based on coupled mode theory, predicts reasonably well the peak positions and isolations. We have performed very high temperature characterizations of the realized gratings, in the range 30-1200 °C. We have shown a specific spectral shift of the resonance peaks with temperature. We report a modal dependence of wavelength shift with temperature. Temperature annealing of the gratings, at 200, 400 and 600 °C show high thermal stability compared with CO 2 and UV-induced ones, but annealing at 800 and 900 °C exhibit an irreversible spectral shift. The temperature sensitivity values are in good agreement with recently published works. These characterizations will help us to understand the writing mechanism of the grating by an electric discharge in standard single-mode fibres.