Numerical Approach to Modeling and Characterization of Refractive Index Changes for a Long-Period Fiber Grating Fabricated by Femtosecond Laser
Date
2016-11
Authors
Saad, Akram
Cho, Yonghyun
Ahmed, Farid
Guk-Byung, Martin
Journal Title
Journal ISSN
Volume Title
Publisher
Materials
Abstract
A 3D finite element model constructed to predict the intensity-dependent refractive index profile induced by femtosecond laser radiation is presented. A fiber core irradiated by a pulsed laser is modeled as a cylinder subject to predefined boundary conditions using COMSOL5.2 Multiphysics commercial package. The numerically obtained refractive index change is used to numerically design and experimentally fabricate long-period fiber grating (LPFG) in pure silica core single-mode fiber employing identical laser conditions. To reduce the high computational requirements, the beam envelope method approach is utilized in the aforementioned numerical models. The number of periods, grating length, and grating period considered in this work are numerically quantified. The numerically obtained spectral growth of the modeled LPFG seems to be consistent with the transmission of the experimentally fabricated LPFG single mode fiber. The sensing capabilities of the modeled LPFG are tested by varying the refractive index of the surrounding medium. The numerically obtained spectrum corresponding to the varied refractive index shows good agreement with the experimental findings.
Description
Keywords
refractive index, Gaussian beam, femtosecond laser, LPFG model, beam envelop, grating period, grating length, index sensor
Citation
Saad, A., Cho, Y., Ahmed, F. & Byung-Guk, M. (2016). Numerical Approach to Modeling and Characterization of Refractive Index Changes for a Long-Period Fiber Grating Fabricated by Femtosecond Laser. Materials, 9(11), 941. https://doi.org/10.3390/ma9110941