An Anti-Jamming High-Temperature Sensor Based on Optical Fiber In-Line Mach–Zehnder Interferometer Structure

In this paper, an anti-jamming high temperature sensor up to 1000 °C based on optical fiber in-line Mach-Zehnder interferometer (MZI) structure fabricated by cutting and splicing single-mode fiber (SMF), multimode fiber (MMF), and suspended core fiber (SCF) consisting of pure silica material to a sandwich-like compact structure under optimized discharge parameters is proposed. The MMFs function as a light coupler and the silica core modes and the air cladding modes are excited to interference. A temperature response of 45.75 pm/°C is achieved, thanks to the significant thermo-optic coefficient exhibited by these two modes, while maintaining a high linearity of 0.99867. In addition, an investigation reveals a maximum temperature fluctuation of 2.56 °C at 1000 °C and a maximum hysteresis error within 0.225 nm. Furthermore, the proposed structure demonstrates exceptional resistance to interference from bending, strain, fluctuations in external refractive index (RI), and vibration. This proposed sensor showcases outstanding anti-jamming capabilities, along with high repeatability and stability, positioning it as an excellent alternative for measuring high temperatures in harsh environments.