Towards athermal Brillouin strain sensing based on heavily germania-doped core optical fibers

Abstract

Owing to their interesting linear and nonlinear optical properties, germania-based core optical fibers are being widely used in a wide range of applications ranging from nonlinear optics to optical sensing. We here examine both the strain and temperature coefficients of stimulated Brillouin scattering in heavily doped core optical fibers with ultrahigh GeO 2 doping level up to 98-mol. %. Our results show that the temperature dependence of the Brillouin gain spectrum becomes almost negligible (C T = 0.07 MHz/ ° C) for high doping content, while its Brillouin strain coefficient remains significant (C ε = 21.4 kHz με −1 ) compared to that of standard single-mode optical fibers (C ε = 48.9 kHz με −1 ). It is further shown that the temperature coefficient tends to zero when removing the fiber coating, indicating that those athermal highly GeO 2 -doped-core optical fibers could advantageously be used for Brillouin fiber strain sensing.