High sensitivity sensor based on mode interference of fiber arc-shaped misaligned welding structure for strain and torsion sensing

We propose a compact and ultrasensitive all-fiber Mach–Zehnder interferometer sensor based on an arc-shaped misaligned structure that can measure strain and torsion sensing. The structure utilizes a single-mode fiber and was fabricated in an optical fiber fusion splicer through simple discharge and fusion splicing steps. The experimental and theoretical investigations of its response revealed an optimal strain sensitivity of up to ~267.17 pm /με¯. In addition, the maximum torsion sensitivities in the clockwise and counterclockwise rotation directions of the fiber cross section were ~ − 1.528 dB/(rad/cm) and ~1.2191 dB/(rad/cm), respectively. Further, the proposed device exhibited low temperature cross sensitivity. Therefore, this single-mode-fiber based core-cladding modal interferometer has great potential in the field of photoelectric sensing due to multiple advantages such as compact size, easy fabrication process, low cost, etc.