Characterizations at very high temperature of electric arc-induced long-period fiber gratings

Electric arc-induced long-period fiber gratings, with low insertion loss (<0.2 dB) and high isolation peaks (-24 dB), have been fabricated in standard single-mode fiber (Corning SMF28). High temperature characterizations of the fabricated gratings in the range of 30 to 1200 degreesC have been performed. The sensitivity are in good agreement with recent published works. Specific spectral shift of the resonance peaks with temperature have been shown. Temperature annealing of the gratings, at 200, 400 and 600 degreesC show high thermal stability compared with UV-induced gratings. More particularly, modal dependence of the resonance shift and time dependence during annealing cycles, have been investigated at high temperature. The evolutions of the spectra have been related to the development of internal stresses in the fiber. These temperature characterizations help to explain the writing mechanism of these gratings. (C) 2002 Elsevier Science B.V. All rights reserved.