Encapsulated Sapphire Fiber Bragg Grating Sensor with Improved High-Temperature Performance

Single-crystal sapphire fiber sensors typically have a significant performance deterioration at high temperatures due to the corrosion of pollutants in the external environment. Thus, we propose and demonstrate a novel packaging method to protect them. Such an inert gas packaging method could effectively suppress the formation of microstructural features, such as loss spots, on the surface of sapphire fiber at high temperatures. Therefore, the high-temperature stability of sapphire fiber Bragg grating (SFBG) sensors is greatly enhanced, and they can work stably at 1600 °C for up to 20 hours. In addition, the high-temperature response of these inert-gas-packaged SFBG sensors was tested, and the experimental results showed that they are available for temperature sensing up to 1800 °C with a sensitivity of 49.6 pm/°C, Such inert-gas-packaged SFBG sensors are ideal candidates for high-temperature sensing in many areas such as the aerospace field and the petrochemical industry.