Strain sensitivity comparison in multi- and single-mode fibers for distributed sensors based on Rayleigh scattering

This work presents a comparison between multi- and single-mode fibers concerning the strain sensitivity based on the Rayleigh backscattering for distributed sensing applications. The experimental setup is composed of two 120 cm optical fibers (one MMF and one SMF). These fibers are attached to linear translation stages where the strain transmitted to the optical fiber is controlled by the stage displacement. The optical fibers are divided into three sections: Section 1 is placed between 90 and 120 cm, Section 2 is located between 50 and 80 cm, and Section 3 is situated between 10 and 40 cm. In each section, the stage displacement has varied from 10 mu m to 50 mu m in steps of 10 mu m. For the SMF, the obtained strain sensitivity was 14.94 GHz/mu epsilon, 14.62 GHz/mu epsilon, and 14.49 GHz/mu epsilon, for sections 1, 2, and 3, respectively. For the MMF, the obtained strain sensitivity was 14.65 GHz/mu epsilon, 15.51 GHz/mu epsilon, and 19.76 GHz/mu epsilon, for sections 1, 2, and 3, respectively. Despite the intrinsic difference in the Rayleigh backscattering phenomenon in MMF and SMF, for the analyzed length range the strain sensitivity for both fiber types was in the same order. Finally, both MMF and SMF could be used as a strain distributed sensor.