Optical fiber strain sensor with double S-tapers

An optical fiber Mach–Zehnder interferometer based on double S-tapers is proposed for strain sensing. The double S-taper strain sensor is formed by two steps. The fiber is pulled during arc discharging, and a second arc discharge is performed while the fixtures are misaligned to form a S-taper. The transmission spectra were collected with different structural parameters, including the axial offset, taper region diameter, and transition region length. The transmission spectra of each group of parameters are compared and analyzed. This work is meaningful for further research on double S-taper strain sensors. When the axial offset is 60 μm, the S2-taper region diameter is 54 μm, the transition region length is 0.7 cm, the strain experiment is tested from 0 με to 800 με, and the strain sensitivity is 6.63 pm/με. In addition, the stability, reversibility, and temperature sensitivity were experimentally characterized.