A High-Sensitivity Two-Loop Sensor for Measurements of Displacement and Refractive Index

We design a high-sensitivity optical-fiber sensor for measurements of displacement and refractive index based on dual-coating-stripped loop-shaped single-mode fibers. For this, we produced two unrelated interference dips as a consequence of different radii of two loop-shaped fibers. Since loop-shaped optical fibers are assigned different tasks at the same time, the two dips present their own characteristics; thus, the parameters of displacement and refractive index can be measured by these two loop-shaped fibers. In order to ensure the accuracy of experimental data, we carried experiments with increasing and decreasing displacement and refractive index. The experimental results show that the refractive index and displacement sensitivities of the sensor are 290.35 nm/RIU,† 321.35 nm/RIU, and – 554.40 pm/μm, respectively.