Fiber-optic, extrinsic Fabry-Perot interferometric dual-cavity sensor interrogated by a dual-segment, low-coherence Fizeau interferometer for simultaneous measurements of pressure and temperature.

A fiber-optic, extrinsic Fabry-Perot interferometric (EFPI), dual-cavity sensor made of sapphire was fabricated and interrogated by a dual-segment, low-coherence Fizeau interferometer to achieve simultaneous pressure and temperature measurements. The fiber-optic EFPI, dual-cavity sensor had an initial basal cavity length of 680 µm and an vacuum cavity length of 80 µm and was experimentally tested based on temperature and pressure measurements. It was demonstrated that simultaneous pressure and temperature measurement could be achieved in the respective pressure and temperature ranges of 0.1-3 MPa and 20-350 °C.