Optical fiber sensor system

An optical fiber sensor system comprising:

• a light source unit including a light source and a polarization controller, the light source unit being configured to output measured light;
• a modulation unit including a loop-shaped optical path and a coil around which the optical path is wound, the modulation unit being configured to modulate light passing through the optical path according to stress applied to the coil;
• an optical coupler optically coupled to the light source unit and both ends of the optical path and configured to input the measured light, branch the measured light into first light and second light having polarization states different from a polarization state of the measured light, output the first light from one end of the optical path to the other end, output the second light from the other end of the optical path to the one end, and couple the first light input to the other end and the second light input to the one end to output interference light;
• a polarization separator optically coupled to the optical coupler and configured to input the interference light output from the optical coupler and separate the interference light into a first component and a second component having polarization states orthogonal to each other to output the first and second components;
• and
• a detection unit optically coupled to the polarization separator, including a first light detector to which the first component output from the polarization separator is input, and configured to detect stress by converting the first component input to the first light detector into a first electrical signal,
• wherein the polarization controller controls the polarization state of light output from the light source so that the first electrical signal is proportional to the stress.