Fiber Optic Temperature Sensor System Using Air-Filled Fabry-Pérot Cavity with Variable Pressure

• Published in: Sensors (Basel, Switzerland) Vol. 23; no. 6; p. 3302
• Main Authors: Chowdhury, Hasanur R, Han, Ming
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 21-03-2023; MDPI
• Subjects: Accuracy; Chemistry; Control equipment; Engineering; Equipment and supplies; Fabry-Perot interferometers; Fabry–Pérot interferometer; fiber optic sensor; Fiber optics; Fused silica; Graphene; High resolution; High temperature; Instruments & Instrumentation; Interferometry; Interrogation; OTHER INSTRUMENTATION; Polyvinyl alcohol; resolution; Sensors; Temperature; Temperature measurement; Temperature measurements; Temperature sensors; Wavelet transforms; fiber optic sensor; temperature measurement; resolution; Fabry–Pérot interferometer
• ISSN: 1424-8220; 1424-8220
• DOI: 10.3390/s23063302

We report a high-resolution fiber optic temperature sensor system based on an air-filled Fabry-Pérot (FP) cavity, whose spectral fringes shift due to a precise pressure variation in the cavity. The absolute temperature can be deduced from the spectral shift and the pressure variation. For fabrication, a fused-silica tube is spliced with a single-mode fiber at one end and a side-hole fiber at the other to form the FP cavity. The pressure in the cavity can be changed by passing air through the side-hole fiber, causing the spectral shift. We analyzed the effect of sensor wavelength resolution and pressure fluctuation on the temperature measurement resolution. A computer-controlled pressure system and sensor interrogation system were developed with miniaturized instruments for the system operation. Experimental results show that the sensor had a high wavelength resolution (<0.2 pm) with minimal pressure fluctuation (~0.015 kPa), resulting in high-resolution (±0.32 ℃) temperature measurement. It shows good stability from the thermal cycle testing with the maximum testing temperature reaching 800 ℃.