An all-sapphire fiber temperature sensor for high-temperature measurement

Abstract

An all-sapphire high-temperature optical fiber sensor with an extrinsic Fabry-Perot interferometer (EFPI) structure is proposed and experimentally demonstrated. The EFPI structure of the sensor is composed of a sapphire ferrule with a sapphire fiber and a polished solid sapphire crystal rod. The first reflection occurs on the left end of the sapphire ferrule, and the second reflection occurs on the right end of the sapphire rod, forming double-beam interference. The interference signal is picked up by the sapphire fiber and transmitted to the white light interferometric demodulator by the multimode fiber. The picked-up signal is demodulated by the Fourier transform and interference algorithms. Experimental results show that the temperature response of the sensor is quadratic, and the sensitivity changes linearly with the temperature range from room temperature to 1500 ℃. The first-order thermal expansion coefficient and the second-order thermal expansion coefficient are 5.4575ⅹ10-6 and 7.3755ⅹ10-9, respectively. The thermal expansion coefficient is linearly related to temperature. Due to all sapphire structure, this sensor solves the problem of thermal expansion coefficient mismatch, which was observed in a previous sensor made of sapphire and ceramic materials. In addition, it improves the high-temperature resistance, so it can be fully qualified for long-term high-temperature measurements above 1000-1500 ℃.

Current Status and State-of-Art Developments in Temperature Sensor Technology

“…Jiang's group [11] conducted a series of studies on sapphire fiber optic sensors, which resulted in the development of an all-sapphire fiber optic temperature sensor [12]. This sensor is packaged in an all-sapphire structure, as shown in Figure 9, which effectively eliminates the mismatch in the coefficient of thermal expansion of the material under high-temperature conditions.…”

“…The device operated for two years from 150°C to 500°C and exhibited no failures or significant wavelength drift. All-sapphire fiber optic temperature sensor [12].…”

The high-temperature gas soft measurement method based on the temperature attenuation patterns of flowing argon gas inside a cavity

“…The widely used K-type thermocouple has an upper limit of temperature measurement up to 1500 K, while specialized thermocouples can extend this upper limit to 3000 K. Another contact-based temperature measurement method suitable for high-temperature environments is the blackbody optical fiber temperature measurement. This approach involves embedding a blackbody into the area under measurement and utilizing optical fibers to capture the emitted radiation signal from the blackbody [15,16] proposed an allsapphire high-temperature optical fiber sensor, which can be fully qualified for long-term high-temperature measurements above 1000-1500 degrees. However, due to the melting point of optical fibers, the upper limit of temperature measurement for most studies using blackbody optical fiber thermometers is 2200 K.…”

Construction of a High-Temperature Sensor for Industry Based on Optical Fibers and Ruby Crystal

“…Furthermore, a vibration sensors can be also based on optical principles. Cui et al described an all-sapphire high-temperature optical fiber sensor [ 11 ]. Additionally, Cui et al reported on a sapphire fiber high-temperature vibration sensor capable of measuring temperatures up to 1500 °C [ 12 ].…”