Abstract: An optical fiber-based sensor system includes a sensing optical fiber having fiber gratings that reflect light at respective wavelengths. A first fiber grating reflects light at a first wavelength. A second fiber grating reflects light at a second wavelength. The system also has a reference optical fiber. An optical read-out arrangement generates light at the first and second wavelengths. The light is injected in the sensing optical fiber and in the reference optical fiber. A first phase difference is measured between light at the first wavelength emanating from the sensing optical fiber and the reference optical fiber. In addition, a second phase difference is measured between light at the second wavelength emanating from the sensing optical fiber the reference optical fiber. A measurement result is based on a difference between the first phase difference and the second phase difference.

Abstract: An optical sensor system includes an optical sensor arrangement that includes a Fabry-Perot structure having two reflective surfaces spaced apart at a distance from each other. A spectral acquisition arrangement acquires successive spectral responses from the optical sensor arrangement during successive time intervals. A spectral analysis arrangement detects a periodicity in at least one of the successive spectral responses that have been acquired. The spectral analysis arrangement further detects a phase evolution of the periodicity throughout the successive spectral responses. The phase evolution of the periodicity provides a relatively precise measurement of a variation in an optical path length between the two reflective surfaces of the Fabry-Perot structure. A variation in a physical quantity can cause the variation in the optical path length. Accordingly, a relatively precise measurement of the physical quantity can be achieved.