BRAGG GRATING INSCRIPTIONS WITHIN STRAINED MONOMODE HIGH NA GERMANIA-DOPED FIBERS .1. EXPERIMENTATION

Bragg grating inscriptions have been performed within strained, high n umerical aperture (NA), germania-doped, monomode fibres. It is shown t hat the complex dynamics of Bragg grating spectrum formation recorded in these fibres depend strongly on the strain applied to the fibre at the time of photoimprinting. Thermal stability studies of gratings wri tten in strained fibres have been carried out through 30 min isochrona l bleaching experiments. It is shown that the stretching of the fibre during the grating fabrication is an important parameter governing the decay of the grating. The implications of these observations are disc ussed from a practical point of view.