Induction of the refractive index change in B-doped optical fibers through relaxation of the mechanical stress

The structural model for the residual stress has often been used to account for the photosensitivity in Ge-doped optical fibers, and we used this approach in this paper to analyze the effect of the mechanical stress on the refractive index change in B-doped optical fibers. In particular, we will discuss the mechanism of refractive index modulation in long period fiber gratings induced by CO2 laser irradiation using B-doped depressed clad and matched clad fibers for the first time as far as the authors are aware. The analysis presented in this work will strengthen the structural model for description of the fiber grating formation. (C) 2000 Published by Elsevier Science B.V.