Abstract

Recently, material science on Bragg gratings are well studied, yet, there is still much room for investigation. For example, whether the 5eV optical absorption band in Ge doped silica is essential for the photo-sensitivity or not is highly debatable point. One of the reasons why photo-sensitive phenomena are complicate is that different light sources and samples have been used in each reports. Even if laser power for excitation is very week, two-photon process might not be negligible. For instance, Ge electron center (GEC)¹ is induced in the Ge-doped silica with UV illumination at 5eV by KrF excimer laser, in contrast, it is not observed in the sample illuminated at 5eV using Xe/Hg discharged lamp.² In this article, relationship between intensity at 5eV and GEC was examined. Secondly, relation between GEC generation and excitation photon energy was also examined.

© 1997 Optical Society of America