MZ Fiber Optic Temperature Sensor Based on Staggered Fusion Double Cone Type

In this paper, we propose a MZ interferometric fiber temperature sensor based on staggered fusion splice and double cone, in which the required single-mode fiber-multimode fiber-seven-core fiber-single-mode fiber (S-M-TTSc-S) sensing unit structure is fabricated by discharge dissolution splice method and hydroxide flame fusion pulling cone method, and the higher-order mode is excited by the staggered fusion splice, and then the strong swift field characteristics of the cone region are used to fully interact with the external environment to perform temperature sensing. The experimental results show that the temperature response characteristics of the designed single-mode fiber-multimode fiber-seven-core fiber-single-mode fiber sensing unit are investigated in the temperature range of 26~36°C, and the effect of different girdle diameters on the temperature sensitivity is explored, resulting in the highest wavelength sensitivity of about 287.06 pm/°C with $\mathrm{R}^{2}=$0.99208. The sensor has the advantages of high sensitivity, fabrication simple, low cost and other advantages, which has potential applications in temperature detection.