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.