Laser beam self-focusing in optical fiber controlled through FBG integration
Optical fibers are elements that are mainly used
as a means to transmit light. In this paper, a fiber optic
constituted by a core, a cladding and a Bragg grating in the core
center has been studied. A laser beam with a Gaussian shape is
let to propagate through the core of the fiber with an intensitydependent
refractive index. In the center of the fiber, the
refractive index will reach the highest value, focusing the beam.
This property of the Gaussian beam to a specific intensity
induces positive focusing is called self-focusing. A fiber Bragg
grating is integrated inside the core of the fiber in order to
control the self-focusing phenomenon. Five different materials
are used for the grating for this purpose. An important
relationship between the intensity of the beam inside the grating
and, thus, the self-focusing and the material used is shown. The
setup arrangement of the optical sensor is modeled through
Comsol Multiphysics (Wave Optics Module), based on the FEM
(Finite Element Method) solver.