Ultra-sensitive curvature sensor based on liquid crystal-infiltrated fiber interferometer

All-fiber curvature sensors based on a liquid crystal-filled fiber Mach–Zehnder interferometer (LCF-MZI) are proposed and experimentally demonstrated for high performance measurements of very small curvatures from 0 to 0.0667 m⁻¹, which is usually hard to be precisely monitored by well-known methods. Such a curvature sensor can be easily fabricated by splicing a section of an LC-filled hollow core fiber between two single mode fibers. Our experimental results show that the maximum curvature sensitivity of the proposed sensor is  −724.3 nm/m⁻¹ for a wavelength shift and 632 dB/m⁻¹ for peak intensity. These results are at least 10 times better than those of previously reported fiber interferometer sensors. (paper)