“Visible range curvature fiber-optic sensor with low strain-temperature dependence”

This manuscript introduces and demonstrates a visible curvature fiber optic sensor using an all-fiber Mach-Zehnder interferometer. The all-fiber interferometer was constructed using an in-line optical fiber sandwich structure, utilizing fibers specifically designed for the visible range. We demonstrate the reproducibility of the curvature sensor fabricating several distinct interferometers. These devices were subjected to curvature testing, exhibiting suitable wavelength shifts and achieving a maximal sensitivity of -10.44 nm/m-1. The hysteresis analysis shows minimal path deviation, and the statistical ANOVA analysis reveals a consistent mean trend with a minimal Prob>F value of 9.30472×10-55. Consequently, the hysteresis analysis indicates that the error in the curvature direction has a minimal impact on the measurement, and the low Prob>F value ensures that the curvature measurements cannot overlap. Then, accurate and high reproducibility of the curvature measurements can be expected. The results validate that the optical fiber structure is among the limited approaches to phase modulation interference within the visible range, representing a competitive alternative for curvature measurement.