Single-mode tapered optical fiber for temperature sensor based on multimode interference

A temperature sensor using a single-mode tapered fiber coated by thermo-sensitive material is presented. It works on the multimode interference influenced by the small change of the ambient refractive index. To better understand the tapered optical fiber, simulations that change parameters such as the taper waist diameter and the ambient refractive index are performed using RSOFT BeamPROP. It is illustrated that optical losses vary with the ambient refractive index, and reduce diameter within a certain range can increase the sensitivity. In our experiment, with the high thermo-sensitive coefficient of material, a good temperature sensing result was achieved. The range of temperature measured is from ~20°C to 80°C. The results show that the temperature sensor has high temperature sensitivity and good repeatability.