Predicting thermal stability of fibre Bragg gratings - isothermal annealing within isochronal annealing

Comparison is made of the results of isothermal annealing (ITA) and isochronal annealing (ICA) on Bragg gratings written in unloaded germanosilicate fibres with the aim of accurately predicting the reliability of such gratings. A novel aspect of the reported work is the gathering of ITA data within the ICA routine. This procedure has a distinct advantage in that it provides a cross-referencing methodology leading to self-validation of the results, thereby improving the confidence levels in the accelerated aging measurements.