Optical fiber-based sensor system having dual optical fibers providing measurements of a first and a second phase difference

An optical fiber-based sensor system, comprising:

• a first optical fiber having:
• a first fiber grating at a first location in the first optical fiber, reflecting light of a first wavelength;
• and
• a second fiber grating at a second location in the first optical fiber, reflecting light of a second wavelength;
• a second optical fiber;
• and
• an optical read-out arrangement adapted to generate the light of the first wavelength and the light of the second wavelength, to inject the light of the first wavelength and the light of the second wavelength in the first optical fiber and in the second optical fiber, to measure a first phase difference between the light of the first wavelength emanating from the first optical fiber and the light of the first wavelength emanating from the second optical fiber, to measure a second phase difference between the light of the second wavelength emanating from the first optical fiber and the light of the second wavelength emanating from the second optical fiber, and to provide a measurement result based on a difference between the first phase difference and the second phase.