INVESTIGATION OF PROPAGATION PROPERTIES INSIDE NANOPARTICLE DOPED FIBERS

Abstract

This thesis investigates the optical behavior of nanoparticles-doped fibers through numerical simulations using a Finite Element Method (FEM) based software. The primary aim is to analyze and comprehend the impact of nanoparticles on the propagation properties of the fiber. The fiber's cross-sectional structures were randomly generated using estimated data of refractive indices and nanoparticle distributions. The simulations were focused on analyzing the equivalent refractive index (neq) of the fiber. The results suggest that the presence of nanoparticles has a substantial impact on the fiber's propagation properties. Specifically, an inverse relationship was observed between the neq of the fiber and the concentration of nanoparticles. The reason for this phenomenon can be elucidated by the fact that the refractive indices of nanoparticles are lower than those of the host material. To determine the neq of the fiber, the simulations revealed that the size distribution of nanoparticles has a significant impact. Specifically, the neq of the fiber increased as the average nanoparticle size increased. This outcome can be attributed to the fact that larger nanoparticles scatter less light and, therefore, have a lower impact on the effective refractive index of the fiber. In addition to examining the neq, the simulations also explored other propagation properties of the fiber, such as the mode field distribution and the effective mode area. The results suggest that the presence of nanoparticles can also affect these properties. In summary, this study enhances our understanding of the effects of nanoparticles on the optical behavior of fibers, which could prove useful in optimizing fibers for various applications, including sensing, telecommunications, and laser amplification.