A filled-enhanced high-sensitivity optical fiber temperature sensor

In this paper, a temperature sensing structure comprising single-mode fiber (SMF) and dual-core single-side hole fiber (DCSHF) is introduced and demonstrated to enhance temperature sensing performance based on modal interference. The biased air hole of DCSHF minimizes temperature-induced variations in the effective refractive index of the core mode, resulting in high sensitivity of temperature sensing. For further enhancement, alcohol with a high thermo-optical coefficient is introduced into the air hole, while barium titanate microsphere is innovatively inserted as coupling factor to enhance mode coupling efficiency. The experimental results prove that the maximum sensitivity of this sensor can reach up to −5.57 nm/°C. The sensor offers advantages such as simple preparation, high sensitivity, excellent repeatability, rapid response, and remarkable stability, suggesting wide-ranging potential applications in temperature sensing.