Discriminative strain and temperature sensing using a ring-hyperbolic tangent fiber sensor

Abstract

Brillouin fiber sensors have demonstrated strong capability in discriminative and high-sensitivity multiparameter measurements. In this study, we proposed and numerically investigated novel ring core fiber–based stimulated Brillouin scattering for the simultaneous measurement of temperature and strain. The novel fiber, referred to as ring hyperbolic tangent (R-HTAN) fiber, is characterized by a shape parameter (α) that controls the optical refractive index and longitudinal acoustic velocity profiles. Numerical modal simulations indicated that the Brillouin gain spectrum contained multiple widely spaced and high-gain peaks, which were attributed to the strong interaction between the optical linearly polarized mode (i.e., LP0,1 as a pump wave) and multiple high-order longitudinal acoustic modes. The designed R-HTAN fiber enabled the discriminative sensing of temperature and strain with levels that clearly surpassed values recently reported in the literature. In case of straight R-HTAN fiber (α = 0), the maximum C ( α = 0 ) T and C ( α = 0 ) ε are 1.928 MHz/ ∘ C and 0.087 MHz, respectively. In case of graded R-HTAN fiber (α = 1), the maximum C ( α = 1 ) T and C ( α = 1 ) ε are 1.872 MHz/ ∘ C and 0.0842 MHz/μɛ, respectively. The errors associated with temperature measurements (maximum δT(α=0) = 0.0846 ∘ C and maximum δT(α=1) = 7.4184 ∘ C) and strain measurements (maximum δɛ(α=0) = 0.7250 μɛ and maximum δɛ(α=1) = 7.4184 μɛ) demonstrated that the proposed fiber could be a promising candidate for next-generation Brillouin sensing systems for enabling temperature and strain discrimination.