Induction of the refractive index change in B-doped optical fibers throughrelaxation 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 appr oach in this paper to analyze the effect of the mechanical stress on the re fractive index change in B-doped optical fibers. In particular, we will dis cuss the mechanism of refractive index modulation in long period fiber grat ings induced by CO2 laser irradiation using B-doped depressed clad and matc hed clad fibers for the first time as far as the authors are aware. The ana lysis presented in this work will strengthen the structural model for descr iption of the fiber grating formation. (C) 2000 Published by Elsevier Scien ce B.V.