Torsion Sensor Based on In-line Mach-Zehnder Interferometer via Femtosecond Laser Inscription

In this paper, we propose an in-line Mach-Zehnder interferometer (MZI) based on an S-shaped waveguide inscribed by femtosecond(fs) laser beside the core of a single- mode fiber. This device shows an interesting sinusoidal response to external torsion with the torsion rate range from 0 to 62.8 rad/m. By segmentally fitting, the highest torsion sensitivity is about 0.93 mm/(rad/m). . Meanwhile, it is almost insensitive to ambient temperature and axial strain. Therefore, the proposed device is very promising in the application of high - performance torsion sensing.