Effects of Polymer Coatings on Temperature Sensitivity of Brillouin Frequency Shift Within Double-Coated Fibers

This paper demonstrates theoretically and experimentally the effects of polymer coatings on temperature sensitivity of Brillouin frequency shift (TSoBFS) within double-coated silica optical fibers. A theoretical analysis of TSoBFS has been made by considering geometrical, thermal, and mechanical properties of the outer polymer coating. It is shown that TSoBFS increases with Young´s modulus, thickness, and thermal expansion coefficient of the outer polymer coating; whereas TSoBFS has a negligible correlation with Poisson´s ratio of the polymer coating. Optical fibers with four different coatings are experimented via Brillouin optical time-domain analysis technique at temperature ranging from 10^°C to 80^°C. The experimental results confirm the enhanced TSoBFS as theoretical prediction. This numerical evaluation can aid in designing double-coated fibers for temperature sensors based on Brillouin scattering.