High Sensitivity Temperature and Curvature Sensor Based on Mach-Zehnder Interferometer With Tapered Two Peanut-Shaped Structures

A high-sensitivity temperature and curvature microfiber Mach-Zehnder interferometer (MMZI) with two peanut-shaped structures is proposed and demonstrated for the first time. The interferometer consists of a section of microfiber and two peanut-shaped structures. The microfiber can be easily affected by the external environment due to its strong evanescent field on the surface and the peanut-shaped structure is conducive to excite fundamental mode to high-order mode, which is beneficial to realize high-sensitivity sensing detection. The experimental results show that the maximum temperature sensitivity of −678.67 pm $/$ °C is obtained in the range of 30 °C to 42 °C, which is the highest temperature sensitivity we have known in the peanut-shaped structure sensor. Furthermore, the sensor is also used for curvature measurements. The curvature sensitivity can be up to −79.09 nm $/\text{m}$ ⁻¹ from 0.10188 m⁻¹ to 0.20374 m⁻¹. Therefore, the proposed sensor will have good application prospects in the field of biological detection and environment monitoring due to the advantage of high temperature sensitivity.