Optical fiber sensor system

An optical fiber sensor system, comprising:

• a light source that outputs measurement light;
• a modulation unit that includes a looped optical path and a coil around which the optical path is wound, and modulates light passing through the optical path using stress applied to the coil;
• an optical coupler that is optically coupled to the light source and both ends of the optical path, receives the measurement light, causes the measurement light to branch into first light and second light of which polarization states are different from that of the measurement light, outputs the first light from the one end of the optical path to the other end, outputs the second light from the other end of the optical path to the one end, combines the first light input to the other end with the second light input to one end, and outputs interference light;
• a polarization separator that separates the interference light into a first component and a second component of which polarization states are orthogonal to each other and outputs the first component and the second component;
• a first polarization controller optically coupled to the polarization separator;
• and
• a first detection unit that includes a first optical detector that is optically coupled to the polarization separator and receives the first component output from the polarization separator, and converts the first component input to the first optical detector into a first electrical signal,
• wherein the first polarization controller controls a polarization state of light input to the polarization separator so that the first electrical signal exhibits a first-order response to the stress.