24 August 2024 Simultaneous measurement of temperature and strain by cascaded fiber Bragg grating-silicon Fabry-Perot interferometer sensor
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Abstract

We report a fiber-optic sensor configuration with a cascaded fiber Bragg grating (FBG) and a silicon Fabry-Perot interferometer (FPI) for simultaneous measurement of temperature and strain. The sensor is composed of a 5 mm FBG on a single mode fiber and a 100 μm thick silicon FPI attached to the tip of the optical fiber. The FBG is surface mounted on the host structure, and the FPI tip is suspended. Due to the stress-free, cantilever configuration, the silicon FPI is insensitive to strain, but sensitive to temperature with a sensitivity much higher than the FBG due to the large thermo-optic coefficient of silicon. The sensor is tested from room temperature to 100°C with varying strain up to 150 με. The silicon FPI provides high temperature sensitivity of 89 pm/°C unaffected by strain. Since the FBG is attached to the host structure, it is affected by both thermal and mechanical strain; the sensitivity of these was experimentally obtained 32 pm/°C and 1.09 pm/με, respectively. Interrogated with a broadband light source and a high-speed spectrometer, the sensor shows temperature and strain resolutions of 1.9×103 °C and 0.042 με, respectively. Due to the small size, enhanced sensitivity, and high resolution, this cascaded FBG-FPI sensor can be used in applications where accurate measurement of temperature and strain is required.

© 2024 Society of Photo-Optical Instrumentation Engineers (SPIE)
Hasanur Rahman Chowdhury, Xiaoli Wang, and Ming Han "Simultaneous measurement of temperature and strain by cascaded fiber Bragg grating-silicon Fabry-Perot interferometer sensor," Optical Engineering 63(8), 086103 (24 August 2024). https://doi.org/10.1117/1.OE.63.8.086103
Received: 21 May 2024; Accepted: 2 August 2024; Published: 24 August 2024
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KEYWORDS
Fiber Bragg gratings

Temperature metrology

Sensors

Silicon

Bragg wavelengths

Silica

Optical engineering

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