High temperature fiber sensor based on spherical-shape structures with high sensitivity

An optical fiber high temperature sensor is proposed and fabricated by cascading two spherical-shape structures, which are built by a section of single mode fiber (SMF). The spherical-shape structures can realize the coupling and recoupling between the core mode and the cladding modes. Experimental results show that the sensor is capable of monitoring temperature change from 25 °C to 735 °C with sensitivity of 0.1193 nm/°C and the sensitivity of microstrain is −0.0012 nm/με which is beneficial for encapsulation. The characteristics of the proposed sensor indicate compact, high sensitive and inexpensive properties, which can be widely applied in many fields.