Bend-resistant temperature sensor realized by optical fiber microsphere and photonic crystal fiber mode controller

In this paper, a fiber temperature sensor based on a Single mode fiber Microsphere-Photonic Crystal Fiber-Single mode fiber Microsphere (SM-PCF-SM) splicing structure was designed and prepared. This fiber structure can excite high-order modes and promote inter-mode interference, and the interference spectrum can be used for temperature sensing. The temperature sensing experiment shows that when the temperature rises from 30 °C to 405 °C, the interference spectrum produces a linear red shift of ~30.08 nm, and the sensitivity reaches ~80.21 pm/°C. In addition, after applying appropriate bending to the sensing structure, only the interference spectrum intensity changes, indicating that the sensor has good anti-bending performance. In summary, the sensor has significant advantages in sensitivity, stability and anti-interference ability, and can be widely used in temperature measurement fields such as industry, aerospace, etc.