Balloon-like angle and micro-displacement sensor based on bent single-mode fiber

• A simple balloon-like fiber sensing system for angle and micro-displacement is proposed. • A new way for angle and micro-displacement measurement. • The proposed fiber sensing system has the advantages of low manufacturing cost, easy manufacture. In this paper, a simple balloon-like fiber sensing system based on a Mach-Zehnder modal interferometer by bending single-mode fiber (SMF) into a balloon-like structure is proposed, and the experiment proves that the system can be used for angle and micro-displacement measurement. The sensor system is only composed of SMF. Firstly, the transmission spectrum curves under different sensitive lengths and bending diameters are analyzed. It is found that the maximum extinction ratio of 24 dB can be achieved when the bending diameter of SMF is 8 mm. Then, by comparing the angle and micro-displacement sensitivity under different sensitivity lengths, it is found that the angle and micro-displacement sensitivity of balloon-like structures increase with the increase of sensitivity lengths. The angle measurement sensitivity is 253.1 pm/°, the detection range is −90° ∼ 90°, and the micro-displacement measurement sensitivity is 327.4 pm/μm. This sensor system has a great potential in the field of angle and micro-displacement measurement, and provides a new idea for angle and micro-displacement measurement.