EFFECTS OF THERMAL ANNEALING ON BRAGG FIBER GRATINGS IN BORON GERMANIA CO-DOPED FIBER/

This paper shows that two annealing processes must be considered when predicting the effect of temperature on fibre Bragg gratings that have been written by UV radiation in boron/germania co-doped fibres. Both the thermal decay of the grating-related refractive index and the anne aling of the boron-induced refractive index contribute to the waveleng th shift observed. We have combined the theory of these two effects to match data taken experimentally (accuracy +/-0.3 nm) and successfully explained a selection of observed wavelength shifts ranging from -2.8 3 to +0.75 nm.