Abstract

Although in-fiber photoinduced structures are widely used in practical applications [1] the nature and the microscopic mechanisms of glass photosensitivity is still unclear. To explain the phenomena observed in fibers under UV-irradiation, several models have been suggested: color center transformation [2], initial stress relief [3], UV-induced glass densification [4]. However these models are not in complete agreement with the experiments. It is well known that germanium oxygen deficient centers (GODCs) play an important role, at least at the initial stage of photoinduced glass transformation. As a rule, the intense GODC absorption band centered at 242 nm is used to write refractive index gratings in germanosilicate fibers.

© 1997 Optical Society of America