Direct-Bonding Sapphire Fiber Microcavity Sensor for Ultra-High-Temperature Measurement

Sapphire fiber microcavity sensors have attracted much attention in high-temperature measurements under harsh environments. We propose a direct-bonding ultra-high-temperature sensor based on the sapphire fiber Fabry-Perot interferometer. The wafer cavity is directly exposed to the measurement environment, and the transmission sapphire fiber is protected with Argon gas sealing. The temperature response of the sensor is characterized experimentally. The sensor achieved temperature measurement from 25 °C to 1800 °C with a mean resolution of 0.3 °C and a 4.48 nm/°C at 1800 °C. The sensor demonstrated a stable sensing performance at 1600 °C for up to 24 hours. The sensor's response time is 0.31s. The spectral fringe visibility is good at 1800°C, implying it has the potential to work with higher temperatures, and thus the proposed sensor provides an excellent candidate for high-temperature monitoring in harsh environments.