Influence of wafer materials on the response speed of extrinsic optical fiber Fabry-Perot high temperature sensors

Silicon and sapphire crystal materials have excellent thermal stability and heat transfer characteristics, making them widely used in the field of high temperature sensing. Based on the optical properties of silicon and sapphire crystals, we have fabricated two different kinds of extrinsic optical fiber Fabry-Perot high temperature sensors and matching signal transmission waveguides to investigate the effects of different temperature-sensitive materials on the response speed of the high temperature sensors. The first kind of sensor uses a C-plane double-sided polished sapphire wafer as the temperature sensing element. Heterogeneous fiber splicing between sapphire fiber and multimode silica fiber is realized for long-distance transmission of interference signals. The second kind of sensor uses a single-crystal silicon wafer as the temperature sensing element. Single-mode optical fiber of silicon dioxide is used as transmission waveguide. A series of high temperature assault experiments for heating and cooling processes from room temperature to 800°C, were performed on the two kinds of sensors to investigate their difference on the temperature response speed. In the experiment, the response time of the sapphire fiber high temperature sensor in the heating section is 38s, and the response time in the cooling section is 31.6s. The response time of the silicon-based fiber high temperature sensor in the heating section is 35.8s, and the response time in the cooling section is 28.2s. Due to the higher thermal conductivity of silicon, the silicon-based fiber sensor responded 5.78% faster than the sapphire fiber sensor in the temperature rise experiment and 10.85% faster than the sapphire fiber sensor in the temperature drop experiment