Dispersion analysis of photonic crystal fibers considering thermal and external stress effects

Abstract

Analysis of the effects of thermal and external stress on the properties of solid core Photonic Crystal Fiber (PCF) has been carried out in this research work, by using the fmite element method (FEM). The PCF is modeled here using the COMSOL Multiphysics software, where structural mechanics module and electromagnetic module have been employed for carrying out the stress analysis and optical analysis, respectively. The external stress acting on the holey fiber induces a specific stress distribution in the fiber's cross section. This stress distribution causes isotropic fiber material to become birefringent. In the PCF, due to the external stress, the refractive index of the material changes due to the photoelastic effect. So, stress analysis has been carried out first using plane strain approximation to find the new anisotropic index of the fiber material when there is stress-optic effect associated with the PCF. Here, a simultaneous linear system of equations resulting from plane-strain approximation has been solved for nodal displacements. Finally, with the new refractive index of the fiber material, optical analysis has been carried out to obtain effective refractive index. Finally, different propagation properties, like, group birefringence, beat length, effective mode area, modal confmement, polarization mode dispersion, group velocity dispersion, etc. are determined and the effects of thermal and external stress on all theses properties have been discussed. Also, wavelength dependence and structural dependence, of the propagation properties have been studied and presented in this work.