Intensity-Modulated Strain Sensor Based on Fiber In-Line Mach–Zehnder Interferometer

We demonstrated a novel intensity-modulated strain sensor based on a fiber in-line Mach-Zehnder interferometer with a large fringe visibility of up to 17 dB, which was fabricated by splicing a section of thin core fiber between two sections of single mode fibers with one misalignment-spliced joint. Such a strain sensor exhibited an ultrahigh sensitivity of -0.023 dBm/με within a measurement range of 500 με, which is about one order of magnitude higher than that reported in references. Displacement and stress distributions at the misalignment spliced joint were simulated by use of finite element method. In addition, the proposed strain sensor has an advantage of compact size of ~10 mm.