Abstract
Differential group delay (DGD) generation by inducing birefringence in uniform fiber Bragg gratings (FBG) is studied. Applying a transverse load, a birefringence is induced on a uniform FBG creating a tunable differential group delay. A theoretical behavior of this phenomenon is presented being in good agreement with the experimental results obtained. A maximum experimental tunable DGD of similar to 60 ps was obtained with this induced birefringent process in the uniform FBG. (C) 2007 Wiley Periodicals. Inc.

Abstract
A linear tunable dispersion compensation device based on a chirped grating (CFBG) mounted on a stretching mechanical structure is described. The tunability is obtained changing the CFBG bandwidth without modification of the total length structure. (c) 2007 Wiley Periodicals, Inc.

Abstract
We demonstrate that under certain conditions it is possible to fabricate in a B/Ge co-doped fiber an arc-induced long-period grating whose spectrum contains a dual set of resonances. These two sets of resonances are formed by distinct mechanisms and are caused by coupling to cladding modes of different symmetries. They behave differently at high temperatures: the set produced by symmetric perturbation disappears during annealing at a temperature of 800 degrees C, while the other set produced by an antisymmetric mechanism can withstand temperatures above 1000 degrees C. (C) 2007 Optical Society of America

Abstract
We study the origin of antisymmetric perturbation of the fiber in arc-induced long-period gratings that couple the core mode into the antisymmetric cladding modes. We demonstrate that this perturbation is caused by the temperature gradient in the fiber, which is induced, in turn, by the temperature gradient in the arc discharge. The reproducibility of the process of the grating inscription is higher when the fiber is placed in a region with larger temperature gradient. (c) 2007 Optical Society of America.

Abstract

Abstract
A neodymium-doped glass waveguide laser based on a new structure employing two core layers is reported. This double-layer structure allows a photosensitive layer to be integrated with an efficient gain layer. Singlemode operation was obtained with a lasing threshold of 93 mW and an efficiency of 0.6%.