A complex grating decay process is observed at elevated temperatures as predicted by a recently proposed three-energy-level model. We have also measured thermal stability of fiber gratings of both positive and negative index changes in a boron-codoped germanosilicate fiber in order to characterize the energy levels of the system and to predict grating lifetimes. The negative index gratings are found to be able to operate at 300 °C for more than 25 years without significant degradation.
© 1997 Optical Society of America
Original Manuscript: February 12, 1997
Revised Manuscript: June 18, 1997
Published: November 1, 1997
L. Dong and W. F. Liu, "Thermal decay of fiber Bragg gratings of positive and negative index changes formed at 193 nm in a boron-codoped germanosilicate fiber," Appl. Opt. 36, 8222-8226 (1997)