Al-doped optical fiber to enhance strain sensitivity of Brillouin based optical fiber sensors

摘要

In order to meet application requirements, dependence of the Brillouin frequency shift to strain should be enhanced. We evaluated the influence of several optical fiber dopants on Brillouin scattering strain sensitivity. Based on a FEM-2D modeling, we developed a model for Brillouin gain spectrum and its strain sensitivity. Geometrical profile, doping composition and drawing conditions are taken into account. We show alumina is a very interesting dopant to enhance strain sensitivity in optical fibers. This result is experimentally validated: up to 0.0639MHz/με is obtained with a 5.2mol% Al_2O_3 doped fiber. We expect to reach 0.1MHz/με with 25mol% doping level.