Disordered mullite grains in a sapphire-derived fiber for high-temperature sensing

In this study, a sapphire-derived fiber (SDF)-based Fabry-Perot interferometer (FPI) is proposed and experimentally demonstrated as a high-temperature sensor using the arc discharge crystallization process, forming a region with disordered mullite grains. This shows that the disordered mullite grains are related to the gradual temperature distribution during the arc discharge process, which results in a larger refractive index (RI) modulation of the SDF near the fusing area, forming a reflection mirror. An FPI was obtained by combining the optical fiber end facet. Considering the high-temperature resistance of the fiber, the fabricated FPI was used for high-temperature sensing. This shows that the device can operate at temperatures of up to 1200 degrees C with a sensitivity of 15.47 pm/degrees C, demonstrating that the proposed devices have potential applications in high-temperature environments. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement