Tapered hollow‐core fiber sensor for monitoring axial strain, magnetic field, and refractive index

Abstract

A high sensitivity sensor is proposed to measure axial strain, magnetic field, and refractive index. Hollow‐core fiber (HCF) and single mode fiber (SMF) are fused together to form the “SMF–HCF–SMF,” then tapering HCF, and finally forming a sensor. The light in the sensor structure forms an antiresonant reflection optical waveguide mechanism. The sensor has particularly thin waist circumference, therefore the surface evanescent field of the sensor is easily affected by environmental parameters, making it particularly sensitive to environmental parameters. The axial strain sensitivity obtained by the sensor is as high as −31.87 pm/µε. The magnetic field sensitivity obtained by combining the sensor with magnetostrictive material Terfenol‐D in the range of 10–40 mT is 123.9 pm/mT. The sensor measures the refractive index of NaCl solution with a sensitivity of up to 2109.308 nm/RIU (RIU: refractive index unit). Additionally, the sensor has good stability and repeatability when measuring three physical quantities. The sensor has a compact structure, stable performance, simple manufacturing, and can measure multiple parameters in biochemical engineering, industrial structural health detection, and marine resource detection.