A Novel Optical Fiber Sensor Based on Microfiber Mach-Zehnder Interferometer With Two Spindle-Shaped Structures

A microfiber Mach-Zehnder interferometer (MMZI) with two spindle-shaped structures was reported for measuring temperature and curvature. Due to the core-separated structure, the MMZI could excite more high-order modes, which improves the sensitivity more efficiently. When the central waist region is 4 μm, the sensitivities for temperature and curvature were 1290.4pm /°C and 56.1947 nm/m-1, respectively. Furthermore, the sensitivity could be improved effectively by increasing the length of the central waist region. Increasing the length of central waist region to 6 μm, the temperature sensitivity of the sensor could up to 1756.3 pm/°C, which was the highest temperature sensitivity we have known in MMZI.