The presence of Tb3+ is found to sensitize greatly phosphosilicate and germanosilicate optical fibers to photodarkening when they are exposed to 488-nm light. The darkening is a three-photon process and may involve the photoionization of Tb3+ to Tb4+. This sensitivity raises the possibility of side writing refractive-index gratings into silica-based optical fibers with 488-nm light.
© 1994 Optical Society of America
Original Manuscript: October 4, 1993
Published: June 15, 1994
G. R. Atkins and A. L. G. Carter, "Photodarkening in Tb3+-doped phosphosilicate and germanosilicate optical fibers," Opt. Lett. 19, 874-876 (1994)