Saad Akram, Cho Yonghyun, Ahmed Farid, Jun Martin Byung-Guk
Department of Mechanical Engineering, University of Victoria, Victoria, BC V8W 2Y2, Canada.
School of Mechanical Engineering, Purdue University, West Lafayette, IN 47906, USA.
Materials (Basel). 2016 Nov 21;9(11):941. doi: 10.3390/ma9110941.
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.
本文提出了一个三维有限元模型，用于预测飞秒激光辐射引起的强度依赖型折射率分布。使用COMSOL5.2多物理场商业软件包，将脉冲激光照射的光纤纤芯建模为一个受预定义边界条件约束的圆柱体。利用数值获得的折射率变化，在相同激光条件下，对纯石英纤芯单模光纤中的长周期光纤光栅（LPFG）进行数值设计和实验制作。为了降低高计算需求，在上述数值模型中采用了光束包络法。对本工作中考虑的周期数、光栅长度和光栅周期进行了数值量化。数值获得的建模LPFG的光谱增长似乎与实验制作的LPFG单模光纤的传输一致。通过改变周围介质的折射率来测试建模LPFG的传感能力。与变化折射率对应的数值获得的光谱与实验结果显示出良好的一致性。
