Comparison of isochronal and isothermal decays of bragg gratings written through continuous-wave exposure of an unloaded germanosilicate fiber.

We compare the results of thermally induced isochronal and isothermal decays of fiber Bragg gratings written through cw exposure of an unloaded germanosilicate fiber. We show that isochronal step decays can be used to predict isothermal decays, provided that some corrections are carried out to take into account a reversible change in grating reflectivity induced by the increase of the fiber temperature. The isochronal accelerated-aging method enables one to sample most of the initial distribution of trapped site energies in a fairly short time.