A high sensitivity optical fiber strain sensor based on hollow core tapering

An optical fiber strain sensor based on a Mach-Zehnder interferometer (MZI) is demonstrated experimentally. The sensor is fabricated by fusion splicing a tapered hollow core fiber (THCF) with a 500 mu m taper region between two single mode fibers (SMFs). Tapering on the HCF increases the sensor's strain sensitivity to 2.7 pm/mu epsilon in a measurement range of 0 mu epsilon to 2100 mu epsilon, 1.5 times larger than that of all-fiber MZI strain sensors without tapered areas (approximately 1.8 pm/mu epsilon). The experimental results show that the sensor has good stability and repeatability. This sensor has high strain sensitivity and low temperature sensitivity and can be used in environments with little temperature fluctuation.